US20050182389A1 - Implantable medical device and patch system and method of use - Google Patents

Abstract

A system, method and apparatus relating to a therapeutic substance delivery patch for attachment to a patient such that the patch is in contact with the patient's skin, wherein the patch coordinates its delivery of the therapeutic substance to the patient based on information received relating to the operation of the implanted device. The information received by the patch may be received through telemetry from the implanted device, or alternatively from the patch sensing the action of the implanted device, or alternatively from the patch sensing the patient's physiologic reaction to the action taken by the implanted device.

Description

RELATED APPLICATIONS
• This application claims priority to provisional U.S. Application Ser. No. 60/287,521, filed Apr. 30, 2001, which is incorporated by reference herein.
CROSS REFERENCES
• This application is related to the following co-pending applications entitled “Permanent Magnet Solenoid Pump For An Implantable Therapeutic Substance Delivery Device” by Olsen (attorney docket no. P9740.00); “Low Profile Inlet Valve For A Piston Pump Therapeutic Substance Delivery Device” by Olsen (attorney docket no. P9746.00); “Implantable Therapeutic Substance Delivery Device Having A Piston Pump With An Anti-Cavitation Valve” by Olsen (attorney docket no. P9851.00); “Closed Loop Drug Delivery System And Remote Management Thereof” by Thompson (attorney docket no. P9622.00); and, “Transcutaneous Physiologic Monitoring System Utilizing Therapeutic Electrical Stimuli From An Implanted Device As A Signalling Mechanism” by Riff (attorney docket no. P10797.00 being filed on the same date as this application), which are not admitted as prior art with respect to this application by its mention in this cross reference section but which are incorporated by reference herein.
FIELD OF THE INVENTION
• The present invention generally relates to medical devices. Specifically, the invention relates to a system, method and apparatus relating to a therapeutic substance delivery patch for attachment to a patient such that the patch is in contact with the patient's skin, wherein the patch coordinates its delivery of the therapeutic substance to the patient based on information received relating to the operation of an implanted device in the patient. Such information may be received through telemetry from the implanted device, or alternatively from the patch sensing the action of the implanted device, or alternatively from the patch sensing the patient's physiologic reaction to the action taken by the implanted device.
BACKGROUND OF THE INVENTION
• Previously, a peripheral memory patch apparatus for attachment to a patient's skin has been disclosed. U.S. Pat. No. 6,200,265 to Walsh et al., which is incorporated by reference herein, discloses such a memory patch including a high capacity memory for storing physiologic data uplinked from an implantable medical device.
• Furthermore, earlier patents discuss various transdermal drug delivery devices. For example, U.S. Pat. No. 5,135,480 to Bannon et al discloses a transdermal drug delivery device. More specifically, the Bannon invention relates to a transdermal device having a detachably mounted electrode with a first surface adapted for contact with human skin and through which a drug substance contained in the electrode passes to the skin under the influence of an iontophoretic or electro-osmotic force and a second surface which is electrically conducting, the electrode has a surface area in contact with the skin, in use, in the range 0.1 to 30 square centimeters and a drug dissolved or dispersed in a hydrophilic medium at a concentration in the range 0.1 to 15% (w/v) based on the hydrophilic medium.
• Previous disclosures have also included the use of an implanted medical device as a network device including an ultimate result of delivering a drug to a patient. European Patent No. 1,022,035 to Arent discloses a network device that can be implanted in a subject. The device is configured to communicate over an internal wireless network or over an external computer network. In one embodiment, the device includes an internal interface in physiological communication with the subject. The internal interface is coupled with, and configured to send signals to a processor. The processor is configured to receive and process the signals, and is further configured to communicate over a computer network with another such device. Such devices can be used to monitor and communicate information regarding a host's physiological status, monitor and/or control natural and/or artificial organs, and prosthetic devices, and/or dispense medication. Drug delivery is accomplished through a separate drug reservoir and intravenous line or through another implanted device.
• As can be seen by the above prior art, therapeutic substance therapy in conjunction with the activities and information obtained by an implanted medical device is an important consideration in the overall treatment of a patient. However, there is a need for a system, apparatus and method wherein a device is affixed to the body in contact with the skin, wherein such device delivers a therapeutic substance to the patient while allowing the patient to remain mobile. While mobility might be achieved by a second implanted drug delivery device, it is desired to avoid the complications and invasiveness of a second implanted device for the storage and delivery of the therapeutic substance.
BRIEF SUMMARY OF THE INVENTION
• A system, method and apparatus relating to a therapeutic substance delivery patch for attachment to a patient such that the patch is in contact with the patient's skin, wherein the patch coordinates its delivery of the therapeutic substance to the patient based on information received relating to the operation of the implanted device. The information received by the patch may be received through telemetry from the implanted device, or alternatively from the patch sensing the action of the implanted device, or alternatively from the patch sensing the patient's physiologic reaction to the action taken by the implanted device.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a schematic of one embodiment of the system according to the principles of the invention;
• FIG. 2 is a schematic of one embodiment of a therapeutic substance delivery patch according to the principles of the invention;
• FIG. 3 is a schematic of one embodiment of the system according to the invention;
• FIG. 4 is a top perspective partial cutaway view of another embodiment patch according to the principles of the invention;
• FIG. 5 is a bottom perspective view of the embodiment patch ofFIG. 4;
• FIG. 6 is a top perspective view of the embodiment patch ofFIGS. 4 and 5;
• FIG. 7 shows a permanent magnet solenoid pump of the embodiment patch shown inFIG. 4;
• FIG. 8 shows an exploded view of the permanent magnet solenoid pump ofFIG. 7 embodiment;
• FIG. 9 shows an exploded view of a pump piston for a permanent magnet solenoid pump three-coil embodiment for the patch embodiment ofFIG. 4;
• FIG. 10 shows an isometric cross-section view of a pump piston for a permanent magnet solenoid pump three-coil embodiment for the patch embodiment ofFIG. 4;
• FIG. 11 shows a cross section view of a pump piston for a permanent magnet solenoid pump three-coil embodiment for the patch embodiment ofFIG. 4;
• FIG. 12 shows an isometric cross-section view of a permanent magnet solenoid pump two-coil embodiment for the patch embodiment ofFIG. 4;
• FIG. 13 shows a cross section view of a permanent magnet solenoid pump two-coil embodiment for the patch embodiment ofFIG. 4;
• FIGS. 14aand14bshow a pump piston with an alternative piston fluid path embodiments for the patch embodiment ofFIG. 4;
• FIG. 15 shows an outlet valve embodiment for the patch embodiment ofFIG. 4;
• FIG. 16 shows a schematic of a two-coil permanent magnet solenoid pump embodiment for the patch embodiment ofFIG. 4;
• FIG. 17 shows a schematic of a two-coil with permanent magnet pole pieces permanent magnet solenoid pump embodiment for the patch embodiment ofFIG. 4;
• FIG. 18 shows a schematic of a three-coil permanent magnet solenoid pump embodiment for the patch embodiment ofFIG. 4;
• FIG. 19 shows a schematic of a three-coil with permanent magnet pole pieces permanent magnet solenoid pump embodiment for the patch embodiment ofFIG. 4;
• FIG. 20 shows a flow diagram of a method for operating a permanent magnet solenoid therapeutic substance delivery device embodiment for the patch embodiment ofFIG. 4.
• FIG. 21 represents another embodiment patch in bi-directional communications with an implanted medical device;
• FIG. 22 shows an external programmer or a remote home device such as used to uplink and downlink data with both patch and the implanted medical device for the embodiment ofFIG. 21;
• FIG. 23 represents one aspect of the remote communication and monitoring system of theFIG. 21 embodiment;
• FIG. 24 is a schematic block diagram of an automatic atrial cardioverter and pain alleviating system of theFIG. 21 embodiment of the present invention employing the automatic delivery of pain alleviating drug therapy;
• FIG. 25 illustrates another representative therapeutic substance delivery patch;
• FIG. 26 is a schematic drug delivery system block diagram;
• FIG. 27 represents a high-level logic flow diagram of theFIG. 21 embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
• Preferred embodiments of this invention provide a method, apparatus or system in which a smart externalized infusion patch attached to the skin of a patient receives information from an implantable medical device and infuses a therapeutic substance based on the information.
• A patch is defined as a device configured to be external to the body, but also including the possibility of being partly internal to the body (for example a patch may include a needle that protrudes through the skin), wherein the device is configured to be in contact with the skin of the patient. For example, a patch may be adhered to the skin of the patient, it may be maintained in contact via a strap such as with a wristwatch, it may be a ring worn around a patient's finger, or it may be attached via a larger strap worn around a patient's torso or other body part.
• The patch may be attached to the skin of a patient at any location on the patient where the patch can receive the necessary information to make a determination to deliver a therapeutic substance to the patient and advantageously deliver the therapeutic substance. In a preferred embodiment the patch is near the location of the implanted device to maximize ability to best receive the information. However, any patch location is acceptable as long as the patch is capable of receiving the information.
• Via this remote interaction, the external patch is able to read cardiac, neurological or other physiological patient data that is accessed by the implanted medical device, and program the external patch for therapeutic substance delivery. Among events may be therapies that combine drug administration and electrical stimulation for pain, atrial fibrillation (AF), heart failure (HF), Parkinson disease, epilepsy, etc. by continually or periodically obtaining physiologic input from the implanted device and then subsequently controlling the delivery of solutions that have either narrow therapeutic indices, strict patient compliance requirements, or rapid delivery versus event detection requirements (e.g., ischemia).
• Various preferred embodiments of this system and method may be used for delivery of anti-arrhythmic drugs, diuretic drugs, vasodilators, muscle relaxants, pain drugs, anti-clotting drugs, blood thinners, anti-seizure drugs, naturitic peptides, insulin and any other therapeutic substance whose administration would be improved if the delivery could be optimally timed to the receipt of physiological information from an implantable medical device.
• FIG. 1 is a block diagram of a medical therapy system including an implantedmedical device30 and apatch32 for attachment to the skin of a patient. The implanted medical device (IMD)30 may be any implanted medical device for providing a therapy to a patient or for monitoring physiological information about a patient or for providing both therapy and monitoring functions. For example,IMD30 may be any of the following, but is not limited to a pacemaker, defibrillator, cardioverter, pacemaker/cardioverter/defibrillator (PCD), oxygen sensing device, nerve stimulator, brain stimulator, muscle stimulator, infusion pump, drug delivery device, monitoring device, left ventricular assist device or total artificial heart device.
• TheIMD30 may include communication capabilities for communicating with thepatch32. Such communication capabilities may include telemetry or any other medical device communication system.
• IMD30 may also include asensor31 for sensing a physiological condition of the patient. Thesensor31 may sense temperature; oxygen saturation; blood pressure; activity level, lung wetness, glucose level, impedence, EKG, heart rate, respiration rate, EMG, EEG, position of the patient and any host of other physiologic conditions that are relevant to the delivery of a therapeutic substance such as a drug. Many different types of sensors for sensing the above conditions are known in the art.
• Patch32 includes acommunication module34,control module36 and a delivery module38.Patch32 may optionally include asensor33 whereby thepatch32 may obtain information regarding the implanted device and/or physiologic condition by sensing as opposed to by telemetry, or in combination with telemetric information.Patch32 is configured for attachment to the patient's body such that the patch is in contact with the skin of the patient to provide for mobility. Attachment of thepatch32 to the skin of the patient may be through adhesives, straps, or any other means known.
• Communication module34 provides telemetry or other communication capabilities that allow thepatch32 to communicate with theIMD30.
• Control module36 functions to control the operation of thepatch32 including control of the therapeutic substance delivery functions.
• Delivery module38 includes a reservoir for holding the therapeutic substance and therapeutic substance delivery means for providing the therapeutic substance to the patient in an appropriate amount.
• Thepatch32 may optionally include the capability to communicate with systems outside the patient. For example, thepatch32 may communicate with a network that in turn communicates with the Internet. Physicians, patients and others may then access any information deemed useful. Furthermore, data may be downloaded for storage and review.
• Thepatch32 may optionally include the capability to provide an indication to the patient, doctor or others regarding the condition of the patient throughindicator40.Indicator40 may reside on thepatch32 or it may be located elsewhere and communicate with the patch through telemetry or any other medical device communication means.
• One embodiment of the invention resides in a therapy for administering a therapeutic substance to a patient having an implanted medical device. The method includes attaching apatch32 containing the therapeutic substance to the patient's body such that the patch is in contact with the skin of the patient. The method further includes generation of a signal from theIMD30. In response to the signal generated by the medical device, the patch then administers the therapeutic substance to the patient.
• Numerous, more specific, example therapies of the above embodiment of the invention are provided below. It is noted however, that the inclusion of these examples is not meant to be limiting to the scope of the present invention. The absence of any additional examples does not exclude such therapies from being covered by the claims appended hereto.
• For the disease state of hyper or hypotension the likely parameter sensed by the implanted medical device is blood pressure. Blood pressure may be monitored by the implanted Chronicle® hemodynamic monitor sold by Medtronic, Inc. Other blood pressure monitors may also be used.
• When high blood pressure is sensed by the implanted monitor or other device, such information is sent to the external patch device by telemetry or other wireless communication. The external patch device then determines whether to provide a therapeutic substance to the patient and how much therapeutic substance to provide.
• Some drugs that may be used to treat hyper or hypotension include diuretic drugs such as Furosemide and Bumentanide; beta blockers such as Propranolol and Metaprolol; and vasodilators such as Nitroglycerine and Isosorbide. However, the scope of this invention is not limited by the use of the drugs listed here. Certainly any drugs that have a therapeutic effect on hyper or hypotension, or that have an effect on any negative effects of the treatment by the implanted device, or that are developed in the future, are contemplated for use by this invention.
• For the disease state of epilepsy and the associated seizures, the likely parameter sensed by the implanted medical device is the electric potentials of the brain, which is oftentimes recorded in an electroencephalogram (EEG). Electric potential of the brain may be measured by electrodes attached to the scalp or in other locations near the brain. Electric potentials in the brain may also be measured by deep brain stimulation leads (DBS leads) or cortical surface electrodes. In this case the likely implanted medical device is a neurostimulator. However, other implanted devices that have the capability to sense electric potentials of the brain may be used.
• When seizure activity is anticipated, predicted or detected by the implanted medical device such information is sent to the external patch device by telemetry or other wireless communication. The external patch device then determines whether to provide a drug to the patient and how much drug to provide.
• Some drugs that may be used for epilepsy therapy include Phenytoin and Conantonkin-G. However, the scope of this invention is not limited by the use of the drugs listed here. Certainly any drugs that have a therapeutic effect on epileptic seizure activity, or that have an effect on any negative effects of the treatment by the implanted device, or that are developed in the future are contemplated for use by this invention.
• For the disease state of diabetes, including hyperglycemia and hypoglycemia, the likely parameter sensed is glucose level in the blood or tissue. Glucose level may be measured through many well known methods and devices including, for example, the use of an implanted glucose monitor.
• When the implanted glucose monitor senses hyperglycemia, the implanted glucose monitor sends such information to the external patch device by telemetry or other wireless communication. The external patch device then determines whether to provide insulin or glucagons to the patient. For the case of hyperglycemia the external patch device delivers insulin to the patient. For the case of hypoglycemia the external patch device delivers glucagons to the patient.
• For the disease state of ischemic heart disease, the likely parameter sensed is heart rate or arrythmias. Heart rate may be sensed, for example, by a pacemaker lead.
• When the implanted pacemaker senses a heart rate above a certain point, the pacemaker sends such information to the external patch by telemetry or other wireless communication. The external patch then determines whether to provide nitrates/BNP, biologics or peptides to the patient.
• For the disease state of myocardial infarction, the likely parameter sensed by the implanted medical device is abnormalities in the EKG. EKG may be sensed by many methods and devices known including, for example, an implanted pacemaker or sensor such as a Reveal™ implanted loop recorder.
• When the implanted pacemaker or monitor senses abnormalities in the EKG, the implanted device sends such information to the external patch by telemetry or other wireless communication. The external patch then determines whether to provide an anticoagulant such as heparin or Tissue Plasminogen Activator (TPA) or an anti-arrythmic drug to the patient.
• Another embodiment therapy of the invention, a method of administering a therapeutic substance to a patient in response to a sensed reading of the patient's physiologic reaction to an action taken by an implanted device is provided. The method includes attaching a patch containing the therapeutic substance to the patient such that the patch is in contact with the skin of the patient and a sensor for sensing a physiologic reaction to the action taken by the medical device. The method further includes sensing with the sensor the physiologic reaction to the action taken by the implanted medical device. The method also includes administering the therapeutic substance to the patient in response to the reaction sensed by the sensor.
• A more specific example of the above alternative embodiment therapy relates to respiratory depression in response to delivery of morphine. In this example, the implanted medical device is an implanted drug pump such as the Synchromed® implantable drug pump made by Medtronic, Inc. The implanted drug pump may be used to deliver an opioid, such as morphine, fentanyl, sufentanil, and hydromorphone, to the spinal cord. Patients taking morphine may experience respiratory depression as a side effect. Therefore, if the patch senses a respiration rate that is lower than normal, it may respond by delivering a narcotic antagonist to the patient. The narcotic antagonist counters the effects of the morphine or other opioid. An example narcotic antagonist is naloxone. Respiration depression may also be sensed by the patch by sensing parameters such as heart rate, temperature, activity, galvanic response, etc. Note alternatively that respiration rate could also be sensed directly by the IMD and communicated to the patch for a drug delivery response.
• Another example therapy in which the patch senses the physiologic reaction to the action taken by the IMD relates to bupivicaine drug delivery. In the example of bupivicaine drug delivery by an implanted drug pump, cardiotoxicity can occur resulting in a higher, then a very low heart rate. The patch could detect those higher and then lower heart rates and infuse a vasodilator such as epinephrine.
• Another embodiment of the invention resides in a therapy for administering a therapeutic substance to a patient having an implanted medical device. The method includes attaching apatch32 containing a therapeutic substance, the patch including asensor33, to the patient such that the patch is in contact with the skin of the patient. The method further includes sensing with the sensor the action taken by the implanted medical device and administering the therapeutic substance to the patient in response to the action sensed by the sensor.
• Another embodiment of the invention resides in a therapy for administering a therapeutic substance to a patient having an implanted medical device that is adapted to take an action on the patient. The method includes attaching a patch containing the therapeutic substance to the patient such that the patch is in contact with the skin of the patient. The patch includes a sensor for determining if the medical device has taken an action on the patient. The method further includes determining with the sensor whether the medical device has taken an action on the patient. The method further includes administering the therapeutic substance to the patient in response to the determination carried out in the determining step.
• One embodiment of therapeuticsubstance delivery patch32 ispatch45 shown inFIG. 2.Patch45 includes anantenna47 for telemetry applications, an integrated circuit49,battery51,valve53,drug reservoir55 and drug propulsion means57.
• One embodiment system includes patch59 and implanted medical device61. Implanted medical device61 includes a therapeutic block63 andcommunication block65. The therapeutic block63 is configured to provide some therapy to the patient's body. Patch59 includes acommunication block67 for communicating with the implanted medical device61, sensingblock69 including a sensor for the capability of sensing conditions in the body,therapy control block71,power management block73 for managing the power resources on board the patch,patient control block75, and overhead blocks77.
• Various means for delivering the therapeutic substance from the reservoir on the patch to the patient are considered for this invention including, but not limited to, hypodermic needle, implanted catheter access port and iontophoresis.
• It is also noted that the patch of the invention or a portion of the patch may be disposable. For example, the therapeutic substance reservoir could be disposable and replaced with a new reservoir module after the therapeutic substance is used.
Detailed Exemplary Embodiment Patch (Patch130)
• Another embodiment ofpatch32 of the present invention will now be described in conjunction withFIGS. 4-20.FIG. 4 shows a therapeuticsubstance delivery patch130.Patch130 includes ahousing141, therapeutic substance reservoir142, apower source144,electronics146, and a permanentmagnet solenoid pump148.
• The above components of the patch may be contained within a single housing member or may be provided in a two member housing such as shown inFIG. 4. In the embodiment ofFIG. 4,housing141 includes abase portion110 for positioning adjacent the skin of the patient (seeFIG. 5), as well as twoupper housing members112 and114.
• Base portion110 is designed to be positioned adjacent the exterior of the patient's skin surface.Base portion110 may be flat or it may be curved somewhat to fit along the curvatures of the patient's body at the point of application.
• In one embodiment,base portion110 includes an adhesive on the side adjacent the skin surface for attaching the patch to the patient's skin. Other means for attaching thepatch130 may be utilized such as a strap or belt.
• Theupper housing member112 forms the reservoir142 configured for containing atherapeutic substance136 and may use geometries such as metal bellows, polymeric bag, and the like. The therapeutic substance reservoir142 has areservoir outlet152 and can have a septum140 for refilling the reservoir142. Thepatch130 operates to infuse thetherapeutic substance136 at a programmed rate into a patient.
• Atherapeutic substance136 is a product or substance intended to have a therapeutic effect such as pharmaceutical compositions, genetic materials, biologics, and other substances. Pharmaceutical compositions are chemical formulations intended to have a therapeutic effect such as antispasmodics, analgesics, pain medications, chemotherapeutic agents, and the like. Genetic materials are substances intended to have a direct or indirect genetic therapeutic effect such as genetic vectors, genetic regulator elements, genetic structural elements, DNA, and the like. Biologics are substances that are living matter or derived from living matter intended to have a therapeutic effect such as stem cells, platelets, hormones, biologically produced chemicals, and the like. Other substances are substances intended to have a therapeutic effect yet are not easily classified such as saline solution, fluoroscopy agents, and the like.
• Thepower source144 is carried in thehousing member114 ofhousing141. Thepower source144 is selected to operate thesolenoid pump148 andelectronics146 such as a lithium ion (Li+) battery, capacitor, and the like. Theelectronics146 are coupled to thepower source144 and typically include memory and a controller. The controller can be an Application Specific Integrated Circuit (ASIC) state machine, a gate array, or may include a microprocessor. Theelectronics146 are configured to control thesolenoid pump148 infusion rate and can be configured to operate many other features such as patient alarms and the like. Theelectronics146 can also include telemetry circuitry configured to receive and send information when the therapeuticsubstance delivery device130 is implanted to allow programming of the infusion rate. In this embodiment, thetelemetry antenna116 is positioned on thebase portion110. Thesolenoid pump148 is coupled to theelectronics146 and coupled to the therapeuticsubstance reservoir outlet152 and configured for pumpingtherapeutic substance136 from the therapeutic substance reservoir142 through aninfusion needle154 at a programmed rate.
• Infusion needle154 is configured for insertion through a patient's skin for delivery of the therapeutic substance into the body. In one implementation of the therapy, thepatch130 may be attached to the patient's skin for about 4-8 days with the needle inserted through the skin. Various methods known in the art may be utilized to prevent infection with such a system.
• FIGS. 7-11 show a three coil embodiment of the solenoid pump. The permanentmagnet solenoid pump148 comprises apump cylinder156, apump piston158, a biasingelement160, aninlet valve162, anoutlet valve164, apermanent magnet166, afirst coil168, and asecond coil170. Thesolenoid pump148 is coupled to theelectronics146, the therapeuticsubstance reservoir outlet152, and theneedle154. Thesolenoid pump148 is configured for pumpingtherapeutic substance136 from the reservoir142 throughneedle154 at a programmed rate.
• Thepump cylinder156 has aninlet enclosure172, anoutlet enclosure174, atherapeutic substance inlet176, and aninfusion needle154. Theinlet enclosure172 transitions thepump cylinder156 to thetherapeutic substance inlet176. Theoutlet enclosure174 transitions thepump cylinder156 to theinfusion needle154. Thetherapeutic substance inlet176 is coupled to a therapeuticsubstance reservoir outlet152 and coupled to theinlet enclosure172 on thepump cylinder156. Some embodiments can include apiston seal178 positioned between thepump cylinder156 and thepump piston158 to reducetherapeutic substance136 flow between thepump piston158 and thepump cylinder156 and provide other functions. Thepiston seal178 can be configured to serve as a guide for the biasingelement160 and to cushion thepump piston158 at the end ofpump piston158 retraction for the intake stroke. Thepiston seal178 is manufactured from a resilient material with good sealing qualities such as synthetic rubber, PTFE, silicone, and the like.
• Thepump piston158 is moveable within thepump cylinder156 and has apiston inlet end180, apiston outlet end182, and apiston fluid path184. Thepump piston158 forms aninlet chamber186 between thepump piston158 and theinlet enclosure172 and apumping chamber188 between thepump piston158 and theoutlet enclosure174. Theinlet chamber186 contains thetherapeutic substance136 that is displaced when thepump piston158 retracts. Thepumping chamber188 contains thetherapeutic substance136 that is displaced when thepump piston158 is actuated. Thepiston fluid path184 is configured to provide fluid communication between theinlet chamber186 and thepumping chamber188 that is controlled by theinlet valve162. Thepiston fluid path184 can take a wide variety of forms such as a central fluid path, a side fluid path, a partial central and partial side fluid path, and the like.
• The biasingelement160 is positioned in the pumpcylinder inlet chamber186 between thepump piston158 and theinlet enclosure172. The biasingelement160 exerts force on thepump piston158 to expulsetherapeutic substance136 through theinfusion needle154. In some embodiments, the biasingelement160 exerts substantially the sole force on thepump piston158 to expulsetherapeutic substance136 through theinfusion needle154. The biasingelement160 also provides force to maintain thepump piston158 in an actuated position until retracted to seal theinlet valve162 against theoutlet enclosure174 to provide redundant protection against unintended flow oftherapeutic substance136 to the patient. The biasingelement160 can be one or more of a wide variety of biasing structures that are selected to provide the desired biasing force on thepump piston158. The desired force of the biasingelement160 in a particular embodiment is the force required to overcome any frictional losses during thepump piston158 expulsion stroke and to generate pressure to open theoutlet valve164. Some specific embodiments of the biasingelement160 include a spring, a coil spring, and the like.
• Theinlet valve162 is carried on the pumppiston outlet end182. Theinlet valve162 can be a variety ofinlet valves162 such as a flapper valve, annular flapper valve, ball valve, reed valve, duckbill valve, poppet valve, and the like. Theoutlet valve164 is carried in theoutlet enclosure174 and coupled to theinfusion needle154. Theoutlet valve164 improvessolenoid pump148 safety by substantially preventing unintended flow oftherapeutic substance136 when the reservoir142 pressure is greater than the infusion site134 pressure. Theoutlet valve164 improvessolenoid pump148 accuracy by maintaining sufficient back pressure to keep theinlet valve162 closed duringtherapeutic substance136 expulsion through theinfusion needle154 so that additiontherapeutic substance136 is not infused when the reservoir142 pressure is greater than the infusion site134 pressure. Theoutlet valve164 can be a variety ofoutlet valves164 such as a flapper valve, ball valve, reed valve, duckbill valve, poppet valve, and the like. An outlet valve embodiment is shown inFIG. 15.
• Some embodiments of thesolenoid pump148 can include ananti-cavitation valve190 positioned in fluid communication with thetherapeutic substance inlet176. Theanti-cavitation valve190 substantially preventstherapeutic substance136 in theinlet chamber186 from flowing back through thetherapeutic substance inlet176 duringpump piston158 retraction. Since thetherapeutic substance136 cannot flow backwards, pressure in theinlet chamber186 increases as thepump piston158 retracts causing thetherapeutic substance136 to flow through thepiston fluid path184 without causing thepump chamber188 pressure to drop low enough to cause dissolved gasses to come out of solution. Also by substantially preventing the back flow oftherapeutic substance136 through thetherapeutic substance inlet176 duringpump piston158 retraction,piston pump158 efficiency is improved because wastedtherapeutic substance136 flow is minimized. Theanti-cavitation valve190 can be a wide variety ofanti-cavitation valves190 such as a flapper valve, annual flapper valve, ball valve, reed valve, duckbill valve, poppet valve, and the like. In addition to displacingtherapeutic substance136 that operates theinlet valve162,outlet valve164, andanti-cavitation valve190, thepump piston158 carries apermanent magnet166.
• Thepermanent magnet166 is at least a firstpermanent magnet166 having afirst pole192 and asecond pole194. Thepermanent magnet166 is carried by thepump piston158 and acted on by the magnetic fields created by the coils167 that include at least thefirst coil168 and at least thesecond coil170. When thefirst coil168 andsecond coil170 are energized, the coils167 produce an electromagnetic axial force that acts on thepermanent magnet166 to impart motion to thepump piston158. In some embodiments, there can be more than onepermanent magnet166 such as a firstpermanent magnet166, a secondpermanent magnet196, a thirdpermanent magnet198 and so forth. Also in some embodiments, there can be more than afirst coil168 andsecond coil170 such as athird coil171 and so fourth. When using more than onepermanent magnet166, like poles are positioned adjacent to one another, and there are N-1 operationalpermanent magnets166 where N is the number of coils167 in the range from about 3 to 10. Thepermanent magnet166 is manufactured from a hard ferromagnetic material such as samarium cobalt, neodymium, ceramic, alnico, and the like. Since thepermanent magnet166 material is typically not therapeutic substance compatible or biocompatible, thepermanent magnet166 is typically isolated from thetherapeutic substance136 by thepiston fluid path184 and thepump piston158 sealed is by thepiston inlet end180 andpiston outlet end182. Positioned in operating relationship to thepermanent magnet166 are thefirst coil168 and thesecond coil170. Analternative solenoid pump148 embodiment using two coils167 is shown inFIGS. 12-13.
• FIGS. 16-19 show block diagram of some of the permanentmagnet solenoid pump148permanent magnet166 and coil167 embodiments. There is at least afirst coil168 configured around thepump cylinder156 positioned adjacent to thefirst pole192 of thepermanent magnet166, and at least asecond coil170 configured around thepump cylinder156 positioned adjacent to thesecond pole194 of thepermanent magnet166. Thefirst coil168 and thesecond coil170 can be reversed in relation to thepermanent magnet166, so thefirst coil168 is adjacent to thesecond pole194 and thesecond coil170 is adjacent to thefirst pole192. Other embodiments of the permanentmagnet solenoid pump148 can have more than afirst coil168 andsecond coil170 such as athird coil171 or N operational coils where N is an integer in the range from about 3 to 10. When thesolenoid pump148 is configured with N coils there will be N-1 operationalpermanent magnets166. The following discussion will use the term coil167 to refer afirst coil168 and asecond coil170, or N coils andpermanent magnet166 to refer to a firstpermanent magnet166 or N-1 permanent magnets.
• The coils167 are typically wound in opposite directions, so current flows in opposite directions to generate opposing magnetic fields. Alternatively, the coils167 can be wound in the same direction and the voltage polarity applied to the coils167 can be opposing to cause current to flow in opposite directions to generate opposing magnetic fields. The coils167 are configured to create a force in one direction for onepermanent magnet pole192 and in the same direction for the otherpermanent magnet pole194. The coils167 are energized forpump piston158 retraction toward theinlet enclosure172 to fill thepump chamber188 from theinlet chamber186. Since the coils167 are not typically compatible with therapeutic substances or biocompatible, the coils167 are typically isolated from thetherapeutic substance136 by thepump cylinder156 and isolated from the patient138 by thehousing141. Thepump cylinder156 is manufactured from any therapeutic substance compatible material that meets design requirements such as titanium, tantalum, stainless steel, plastic, ceramic, and the like. Thepermanent magnet166 and coils167 can be inserted into thepump cylinder156 along with thepump piston158 and then theinlet enclosure172 andoutlet enclosures174 can be welded to isolate thepermanent magnet166 and coils167 from thetherapeutic substance136. The coil's167 electromagnetic axial force can be enhanced with a magneticallypermeable yoke200 andpole pieces202.
• The magneticallypermeable yoke200 andpole pieces202, although not required for operation, enhance the electromagnetic axial force created by the coils167. The magneticallypermeable yoke200 is placed around the coils167 to improve magnetic efficiency. The magneticallypermeable yoke200 also shields thepermanent magnet166 from external high magnetic fields, until the magneticallypermeable yoke200 becomes saturated, to protect thepermanent magnet166 from demagnetization. The external high magnetic field can be created by equipment such as Magnetic Resonance Imaging (MRI) equipment, magnetic security equipment, and the like. Thepole pieces202 can be positioned adjacent to one or more of the permanent magnet's166 poles. For example, afirst pole piece204 can be carried on thepump piston158 between thepermanent magnet166 and theinlet enclosure172 to improve magnetic coupling. Asecond pole piece206 can be carried on thepump piston158 between thepermanent magnet166 and theoutlet enclosure174 to improve magnetic coupling.
• When thepump piston158 is fully positioned toward theinlet enclosure172, themaximum pump chamber188 volume is created. Thepump chamber188 has apump chamber188 volume comprising a stroke volume and a dead volume. The stroke volume is in the range from about 0.5 micro liters to about 5.0 micro liters. The sum of aninlet valve162 opening pressure and theoutlet valve164 opening pressure exceeds the maximum pressure of the reservoir142 less the infusion site134 pressure to substantially prevent free flow oftherapeutic substance136 to the patient. The dead volume is less than half the stroke volume in the range from about 0.25 micro liters to about 2.5 micro liters. The solenoid pump's148 small dead volume compared to the stroke volume improves the solenoid pump's148 capability to pass air because of the low vacuum pressure that is typically generated in thepump chamber188. Theinlet valve162 andoutlet valve164 opening pressures are selected to prevent unintended infusion under extreme operating conditions. Unintended infusion is substantially prevented by selecting theinlet valve162 opening pressure and theoutlet valve164 opening pressure so the sum of these pressures is greater than the maximum pressure difference between the reservoir142 and the infusion site134. For example, unintended infusion is prevented when the reservoir142 pressure is high and the ambient pressure (typically the same as the infusion site134 pressure) is low that can occur when the reservoir142 is full and the patient is exposed to high temperature at high altitude.
• The solenoid pump's148 ability to pass air and operate accurately is a function of the solenoid pump's148 compression ratio, thereservoir outlet152 pressure, theinfusion needle154 pressure, andoutlet valve164 cracking (opening) pressure. For adiabatic systems with ideal gases, the compression ratio in thepump chamber188 can be expressed as$\begin{array}{cc}{\mathrm{CR}}_{\mathrm{pc}}=\frac{V_{\mathrm{pc}\mathrm{final}}}{V_{\mathrm{pc}\mathrm{initial}}}& \left(\mathrm{Equation}1\right)\end{array}$
  where CR_pcis the compression ratio in thepump chamber188, V_{pc final}is the final volume in thepump chamber188 calculated by (stroke volume+pump chamber dead volume) where stroke volume=piston area×piston stroke, and V_{pc initial}is the initial volume in thepump chamber188 also known as the pump chamber dead volume which is also the pump chamber volume remaining after thepump piston158 has expulsed the stroke volume. The compression ratio in theinlet chamber186 can be expressed as$\begin{array}{cc}{\mathrm{CR}}_{\mathrm{ic}}=\frac{V_{\mathrm{ic}\mathrm{final}}}{V_{\mathrm{ic}\mathrm{initial}}}& \left(\mathrm{Equation}2\right)\end{array}$
  where CR_icis the compression ratio in theinlet chamber186 and V_icis the volume in theinlet chamber186, V_{ic final}=(stroke volume+inlet chamber dead volume), and V_{ic initial}=(inlet chamber dead volume). From these relationships, it is apparent thatpump chamber188 pressure will be decreasing andinlet chamber186 pressure will be increasing as thepump piston158 retracts. Fortherapeutic substance136 to flow into thepump chamber188 when gas bubbles are present, the pressure in thepump chamber188 during thepump piston158 stroke must drop substantially below theinlet chamber186 pressure. Fortherapeutic substance136 to flow out of thepump chamber188, the expulsion pressure must be greater than theinfusion needle154 pressure.Therapeutic substance136 flows through theoutlet valve164 when P_pc≧P_a+P_ovc, where P_pcis the pressure in thepump chamber188, P_ais the ambient pressure at theinfusion outlet154, and P_ovcisoutlet valve164 cracking (opening) pressure. By selecting theappropriate outlet valve164 cracking pressure the risk of unintentional infusion can be substantially eliminated.
• The permanentmagnet solenoid pump148 is designed to be energy efficient consuming less than about 3.0 Joules per milliliter (J/ml) at about 137,895 pascals (20 pounds/square inch) back pressure. Thesolenoid pump148 is about 5% to 10% efficient in terms of electrical energy input and fluid work output. The energy efficiency of thesolenoid pump148 to a large degree determines energy efficiency of the therapeuticsubstance delivery patch130 and the size ofpower source144 needed. For example, doublingsolenoid pump148 efficiency can theoretically result in nearly a 50% reduction in energy consumption and a 50% reduction in the size ofpower source144. Additionally, thesolenoid pump148 can be a wide variety of sizes. The design of thesolenoid pump148 permits small sized configuration such as less than about 20.0 mm long by about 6.0 mm in diameter with a total volume less than about 0.5 cc. The small size of thesolenoid pump148 also permit having a small therapeuticsubstance delivery patch130 that can be more inconspicuously attached to a patient's skin such as under clothes, including on arms, legs, torso or other areas.
Operation (Patch130 Embodiment)
• FIG. 20 shows a flowchart of a method for operating a therapeuticsubstance delivery patch130 having a permanentmagnet solenoid pump148 embodiment. Thetherapeutic substance136 is supplied from a therapeutic substance reservoir142 to atherapeutic substance inlet176. Thesolenoid pump148 generally operates by retracting apump piston158 and then actuating thepump piston158 while operating valves to delivertherapeutic substance136 through aninfusion needle154 at a programmed rate. This operation is repeated a predetermined number of times at predetermined intervals to deliverytherapeutic substance136 at the programmed rate. For example, asolenoid pump148 with a stroke volume of 2.0 micro liters would typically be operated from a maximum of about 10 cycles per second (Hz) to achieve an infusion rate of 1.2 milliliters per minute to a minimum of about 1.0 cycle per hour to achieve an infusion rate of about 48 micro liters per day.
• Retracting thepump piston158 is initiated when afirst coil68 for current flow in a first direction is energized112 and asecond coil170 for current flow in an opposite direction are energized212 to create a electromagnetic axial force. Thepump piston158 is retracted214 when the electromagnetic axial forces acts on apermanent magnet166 carried on thepump piston158. While thepump piston158 is retracting, aninlet valve162 is opened216 and abiasing element160 is loaded. Apump chamber188 is filled withtherapeutic substance136 through theinlet valve162 while thepump piston158 is being retracted214. In an embodiment having apiston seal178, duringpump piston158 retraction thepiston seal178 can also be configured to dampen the shock when thepump piston158 reaches its fully retracted position. By dampening this shock, thepiston seal178 can reduce some wear and noise that occurs when thepump piston158 reaches its fully retracted position. In embodiments having ananti-cavitation valve190, theanti-cavitation valve190 preventstherapeutic substance136 in theinlet chamber186 from flowing back to the therapeutic substance reservoir142 when thepump piston158 retracts. Theanti-cavitation valve190 helps maintainhigher pump chamber188 pressures duringpump piston158 retraction, which makes it easier to pass air bubbles.
• Duringpump piston158 retraction assuming there isanti-cavitation valve190 and both theinlet chamber186 and pumpchamber188 are filled withtherapeutic substance136, the pressure in theinlet chamber186 will increase rapidly due to the incompressibility of liquids which will cause thetherapeutic substance136 to flow through thepiston fluid path184 into thepump chamber188 without causing thepump chamber188 pressure to decrease to the level that would cause gasses to come out of solution. After thepump piston158 is retracted, operation of thesolenoid pump148 continues when thepump piston158 is actuated.
• Actuating the pump piston is initiated when thefirst coil168 for current flow in the first direction is de-energized222, and thesecond coil170 for current flow in the opposite direction is de-energized222 to collapse the electromagnetic axial force. As the electromagnetic axial force collapses, the biasingelement160 is unloaded, and thepump piston158 is actuated by the biasingelement160 driving thepump piston158 toward theoutlet enclosure174. While thepump piston158 is being actuated226, pressure generated in thepumping chamber188 opens theoutlet valve164. Theopen outlet valve164 permits a stroke volume to be expulsed through theinfusion needle154 while thepump piston158 is actuated226. Thetherapeutic substance136 discharged through theinfusion needle154 is delivered at a programmed rate. In some embodiments during pump piston actuation226, thepiston seal178 substantially preventstherapeutic substance136 from flowing around thepump piston158 back into theinlet chamber186. The previously discussed method embodiment elements are presented in a general sequence that is intended to be limiting only when a particular element is required to be sequence in a certain way for the entire method embodiment to be practical. Pump piston actuation226 can be mathematically characterized.
• During piston actuation226 to expulsetherapeutic substance136, when thepump chamber188 volume is decreasing and theinlet chamber186 volume is increasing the following relationships exist. The final pressure in thepump chamber188 can be express as$\begin{array}{cc}{P}_{\mathrm{pc}\mathrm{final}}=\frac{P_{\mathrm{pc}\mathrm{initial}}}{{\mathrm{CR}}_{\mathrm{pc}}}& \left(\mathrm{Equation}3\right)\end{array}$
  where P_{pc final}is the final pressure in thepump chamber188, P_{pc initial}is the initial pressure in thepump chamber188, and CR_pcis the compression ratio in thepump chamber188. The final pressure in theinlet chamber186 can be expressed as$\begin{array}{cc}{P}_{\mathrm{ic}\mathrm{final}}=\frac{P_{\mathrm{ic}\mathrm{initial}}}{{\mathrm{CR}}_{\mathrm{ic}}}& \left(\mathrm{Equation}4\right)\end{array}$
  where P_{ic final}is the final pressure in theinlet chamber186, P_{ic initial}is the initial pressure in theinlet chamber186, and CR_icis the compression ratio in thepump chamber188.Therapeutic substance136 flows through theoutlet valve164 when P_{pc final}≧P_a+P_ovc(Equation 5) where P_icis the initial pressure in theinlet chamber186, P_ais the ambient pressure at the pump outlet, and P_ovcisoutlet valve164 cracking (opening) pressure. The above relationships assume that there is ananti-cavitation valve190, there is no air in thepump chamber188, and since liquids are essential incompressible P_icdecreases as thepump piston158 is actuated.
• Thus, embodiments of thesolenoid pump148 are disclosed to increase energy efficiency, increase accuracy, reduce the residential space requirement, improve therapeutic substance compatibility, and provide many other improvements. One skilled in the art will appreciate that the present invention can be practiced with embodiments other than those disclosed. The disclosed embodiments are presented for purposes of illustration and not limitation, and the present invention is limited only by the claims that follow.
Detailed System Example (IMD312 and Patch320)
• A detailed system example different from the examples provided above including an implantedmedical device30 and therapeuticsubstance delivery patch32 utilized in conjunction with delivery of therapy by the implantedmedical device30 is provided in conjunction withFIGS. 21-27.
• FIG. 21 is an illustration of an implantable medical device,IMD30, adapted for use to communicate with an externally mounted therapeuticsubstance delivery patch32. The IMD implanted in patient10 includesIMD312.IMD312 is a pacemaker, implanted cardioverter/defribillator (ICD) or combined pacemaker/ICD device. In accordance with conventional practice in the art,IMD312 is housed within a hermetically sealed biologically inert outer casing which may itself be conductive so as to serve as an indifferent electrode in the IMD's pacing cardioversion/sensing circuit. One or more pacemaker leads collectively identified withreference number314 are electrically coupled toNID312 in a conventional manner and extend into the patient'sheart316 viavein318. Disposed generally near the distal end ofleads314 are one or more exposed conductive electrodes for receiving electrical cardiac signals and/or for delivering electrical pacing and/or cardioversion/defibrillation stimuli toheart316. As will be appreciated by those of ordinary skill in the art, leads314 may be implanted with distal ends situated in the atrium and/or ventricle ofheart316.
• In this embodiment of the invention,patch32 ispatch320. As depicted inFIG. 21,patch320 is linked viatelemetry transmission321 toIME312.
• FIG. 22 is a variation ofFIG. 21 in whichprogrammer322 is shown in communication with implantedmedical device312 andpatch320. Specifically,programming unit322 is in telemetry or wireless communication with implantedmedical device312 andpatch320 via uplink anddownlink communication channels323 and323′, respectively.Programmer322 described herein with reference toFIG. 21 is disclosed in more detail in U.S. Pat. No. 5,345,362 issued to Thomas J. Winkler entitled “Portable Computer Apparatus with Articulating Display Panel” which patent is hereby incorporated herein by reference in its entirety.
• FIG. 23 is another embodiment of the present invention wherein data is communicated using various media to transfer information fromIMD312 andpatch320 via programmer, IRM orequivalent device322. As discussed hereinabove data fromIMD312 andpatch320 is uplinked todevice322 from which it may be directed to aPC324 orserver326 using, for example, a modem, an ISDN line, fiber optic, cable, infrared, bluetooth-enabled or equivalent direct or wireless communication systems.Server326 is also accessible directly to qualified users atstation328. Further,server326 may be accessible viaInternet330 toremote users332.
• With this exemplary communication network, caregivers, physicians and other qualified personnel may be able to access and review or reprogram the operations ofIMD312 and patch320 remotely. For example,user328 may use a LAN1 or other secure lines to accessserver326 from which either current or stored data relating to the operation ofIMD312 andpatch320 could be obtained for evaluation and adjustment, or remote patient monitoring. Similarly, remote users atstation332 may be able to access operational and functional data ofIMD312 andpatch320 viaInternet330.
• One of the aspects of this embodiment of the present invention is the use of a transdermallyoperable patch320. It is similar to the electrotransport drug delivery system disclosed in Design Patent No. 384,745 to Lattin et al. Further, a similar device is disclosed in U.S. Pat. No. 5,995,869 to Cormier et al. Additionally, electrotransport delivery device with voltage boosting circuit is disclosed in U.S. Pat. No. 6,035,234 to Riddle et al. And an electrotransport device and method of setting the output using the same drug delivery device is disclosed in U.S. Pat. No. 6,086,572 to Johnson et al. which patent applications are incorporated herein by reference in their entireties. Any of these therapeutic substance delivery patches as well as others may be used within the scope of the present invention.
• The present invention implements a highly adaptable communication link between the implanted device and the drug delivery device disclosed in the prior art. The communication system as indicated hereinabove without limitation could be telemetry or as substantially described in U.S. Pat. Nos. 5,683,432 and 5,843,139, or an equivalent medical device communication system such as the one disclosed in U.S. Pat. No. 4,987,897 to Funke which patent is herein incorporated by reference in its entirety. Accordingly, the present invention provides a closed-loop drug delivery system that operates in data communications with an implanted device to attenuate the impact of shock and other discomfort resulting from IMD therapy.
• Referring now toFIG. 24, a fully implantableatrial cardioverter system312 embodying the present embodiment of the invention in association with a schematically illustratedhuman heart316 in need of atrial fibrillation monitoring and potential cardioversion of theatria516,518 and anexternal programmer322 are shown. Theatrial cardioverter system312 is capable of the sequential initiation of delivery of a pain alleviating analgesic at therapeutic levels followed by delivery of atrial cardioversion electrical energy pulses or shocks of sufficient amplitude and duration to effectively cardiovert theheart316 in atrial fibrillation. The portions of theheart316 illustrated inFIG. 23 are the right ventricle (RV)512, theleft ventricle514, the right atrium (RA)516, theleft atrium518, the superior vena cava (SVC)520, theCS521 including the coronary sinus (CS) ostium oropening524, the left ventricular free wall526 and theinferior vena cava527.
• Thesystem330 generally includes anenclosure532, for hermetically sealing the internal circuit elements, battery, telemetry antenna, abipolar RV lead534, and a RA-CS lead536. Theenclosure532 and leads534 and536 are arranged to be implanted beneath the skin of a patient so as to render theatrial cardioverter system330 fully implantable.
• TheRV lead534 preferably comprises an endocardial bipolarlead having electrodes538 and540 arranged for establishing electrical contact with theright ventricle512 of theheart316. Theelectrodes538 and540 permit bipolar sensing of ventricular depolarizations or R-waves in theright ventricle512. As illustrated, thelead534 is preferably fed through theSVC520, theright atrium516, and then into theright ventricle512 to lodge theelectrodes538,540 in the apex thereof as illustrated.
• The RA-CS lead536 generally includes a tip orCS cardioverting electrode544 and a proximal ring orRA cardioverting electrode546 as shown in U.S. Pat. No. 5,165,403, for example. As illustrated, the RA-CS lead536 is flexible and arranged to be passed down thesuperior vena cava520, into theright atrium516, into thecoronary sinus ostium524. TheCS electrode544 is advanced into thecoronary sinus channel521 of the heart near the left side thereof so that the first ortip electrode544 is within thecoronary sinus channel521 either within thecoronary sinus522 adjacent theleft ventricle514 and beneath theleft atrium518 or most preferably within the great cardiac vein523 adjacent theleft ventricle514 and beneath theleft atrium518. Theelectrodes544 and546 are spaced apart such that when theCS electrode544 is positioned as described above, theRA electrode546 is in theright atrium516. TheCS electrode544 together with theRA electrode546 provides bipolar sensing of heart activity in theatria516 and518.
• TheCS electrode544 and theRA electrode546 also provide for the delivery of defibrillating electrical energy to the atria. Because theCS electrode544 is located beneath theleft atrium518 near theleft ventricle514 and theRA electrode546 is within theright atrium516, the cardioverting electrical energy, when applied between these electrodes will be substantially confined to theatria516 and518 of theheart316. As a result, the electrical energy applied to theright ventricle512 andleft ventricle514 when the atria are cardioverted or defibrillated will be minimized. This greatly reduces the potential for ventricular fibrillation of the heart to be induced as a result of the application of cardioversion electrical energy of the atria of the heart.
• Further electrode systems and cardioversion pathways have been disclosed and are suitable for use in the practice of the present invention. One such atrial cardioversion electrode system is disclosed in the article “Safety and Feasibility of Transvenous Cardioversion in Atrial Tachycardia”, by Blanc et al., published in Cardiac Pacing, edited by Gomez, Future Pub. Co., 1985, pp 1526-1529. This electrode system employs a single lead with electrodes located in the right atrium and in the pulmonary artery. Delivery of atrial cardioversion shocks between an RV electrode and a subcutaneous electrode is disclosed in U.S. Pat. No. 5,292,338. Delivery of atrial defibrillation pulses between a coronary sinus electrode and a subcutaneous electrode is also disclosed in U.S. Pat. No. 5,314,430.
• A further suitable atrial cardioversion electrode system is disclosed in U.S. Pat. No. 5,549,642 incorporated herein by reference in its entirety. The electrode system disclosed therein includes an RA/SVC electrode (alone or optionally coupled to a subcutaneous electrode) and a CS electrode. The elongated RA/SVC electrode appears to provide atrial defibrillation thresholds in the range of about 1.0 Joule or less across a substantial portion of the patient population which represents a substantial improvement over the RA or SVC to CS/great vein electrode system employed in the above-referenced '403 patent.
• Any of the above atrial cardioversion electrode systems and associated atrial and/or ventricular leads may be used in the practice of the present invention. However, even an approximately 1.0 joule cardioversion shock can be painful to a substantial portion of the population, particularly since atrial fibrillation episodes repeat frequently, requiring frequent cardioversion.
• Within theenclosure532, thesystem330 includes aventricular sense amplifier550 coupled to theRV lead534 to receive electrical signals in the ventricle across thebipolar electrode pair538,540 and an R-wave detector552 to detect the R-waves therefrom. Theventricular sense amplifier550 and the R-wave detector552 form a first detecting means that senses R-waves in the electrogram transmitted to ventricular sense amplifier by theRV lead534. The R-wave detector552 is of the type well known in the art, which provides an output pulse upon the occurrence of an R-wave being sensed during a cardiac cycle of the heart. The delivery of the atrial defibrillation shock or pulse is timed from the R-wave employing the ventricular timer564 as described below.
• The lead and electrode systems in certain embodiments of the above-referenced '338, '403 and '430 and '642 patents include an RV defibrillation electrode positioned on an RV lead inserted into the right ventricle and a pair of ventricular sense electrodes. Alternatively, in the atrial cardioversion system depicted inFIG. 24, common ventricular pacing leads having bipolar screw-in ventricular electrodes of this type may be employed as pace/sense electrodes538,540.
• Anatrial sense amplifier554 is coupled to the RA-CS lead536 to receive electrical signals or P-waves across theright atrium516. Theatrial sense amplifier554 forms a second detecting means for detecting P-wave atrial activity of the heart picked up by theCS electrode544 andRA electrode546 of the RA-CS lead536. The P-wave output signal of theatrial sense amplifier554 is coupled to an analog todigital converter560 which converts the analog signal representative of the atrial activity of the heart to digital samples for further processing to determine if atrial fibrillation is present and if the atrial cardioversion shock is effective in converting the atria to a normal atrial rate.
• Theenclosure532 of theatrial cardioverter system330 further include amicrocomputer562 that is preferably implemented in a manner disclosed in the above-referenced '338 patent and further as described hereinafter with respect to the flow diagram ofFIG. 27. The implementation of themicrocomputer562 in accordance with this embodiment of the present invention results in a plurality of functional stages and RAM/ROM582 for storing operating algorithms and programmable parameters as well as accumulated operating data for subsequent telemetry out to theexternal programmer322.
• The circuitry includes the ventricular timer564 for timing various intervals that recur in each QRST cycle as well as the R-wave synchronization time interval, aninterval set stage566 for selecting time intervals to be timed out in the ventricular timer564, a delay timer565 for timing out further delay times set in interval setstage566 for the delivery of the pain alleviating therapy, an optionalpatient warning device567 and warning setregister563, a cardioversion energylevel set stage569, anatrial fibrillation detector570, a chargedelivery control stage572, an analgesicdelivery control stage590, and a computation stage580.
• Themicrocomputer562 is arranged to operate in conjunction with RAM/ROM memory582 which may be coupled to themicrocomputer562 by a multi-bit address bus and a bi-directional multiple-bit data bus. This permits themicrocomputer562 to address desired memory locations within the memory for executing write or read operations. During a write operation, themicrocomputer562 stores data, such as time intervals or operating parameters in the memory582 at the addresses defined by multiple-bit data bus. During a read operation, themicrocomputer562 obtains data from the memory at the storage locations identified by the multiple-bit addresses provided over the address bus and receives the data from the memory582 over the bi-directional data bus. Data related to the detections of atrial fibrillation and the deliveries of the therapies may be recorded in the RAM memory582 for interrogation and telemetry out to theexternal programmer322 in a manner well known in the art.
• Detection of atrial fibrillation may be accomplished inatrial fibrillation detector570, in conjunction with computation stage580, ofmicrocomputer562 from the digitized P-waves detected byatrial sense amplifier554 using any of the various atrial fibrillation detection methodologies known to the art. Generally, atrial fibrillation may be detected in response to an extended series of high rate (e.g. 240 BPM or greater) atrial depolarizations or P-waves. If greater specificity for atrial fibrillation is desired, analysis of regularity of rate waveform morphology may also be employed.
• Termination of atrial fibrillation may be detected in response to a decrease in the rate of atrial depolarizations and/or an increase in their regularity.
• Appropriate detection methodologies are disclosed in the article “Automatic Tachycardia Recognition”, by Arzbaecher et al., published in PACE, Vol. 7, May-June 1984, part II, pages 541-547 and in PCT Application No. US92/02829, Publication No. WO 92/18198 by Adams et al., both incorporated herein by reference in their entireties. In the PCT application, careful synchronization of the high voltage atrial defibrillation pulse to the ventricles to avoid induction of ventricular tachycardia or fibrillation is also discussed.
• In addition, in the context of devices which automatically detect the occurrence of atrial fibrillation, the patient may optionally be warned of the detection of atrial fibrillation to be ready for the delivery of the atrial cardioversion shock through operation of thewarning device567. In this alternate variation of the embodiment of the invention, a warning may be provided to the patient of the diagnosis of atrial fibrillation and the commencement of delivery of the pain alleviation drug therapy. The warning may be effected in the manner described in U.S. Pat. No. 5,332,400 incorporated herein by reference in its entirety, but is preferably effected by energizing a piezoelectric crystal oscillator that oscillates at an audible frequency intense enough for the patient to hear it and take precautions, if necessary. The patient may also optionally be provided with alimited function programmer322 for use in communicating a command to themicrocomputer562 to prevent delivery of the cardioversion shock until the patient feels the effects of the pain alleviation therapy, at which time the patient may employ theprogrammer322 to enable delivery of the cardioversion shock, subject to re-verification of the presence of the atrial fibrillation.
• In this regard, thesystem330 also includes the warning setregister563, the delay timer565, and thewarning device567 that are utilized for generating the warning alarm for the patient when theatrial fibrillation detector570 determines that the atria are in fibrillation. Thewarning device567 may constitute an audible alarm sounding piezoelectric crystal oscillator for warning the patient that atrial fibrillation has been detected and that cardioverting electrical energy will be applied to the patient's atria.
• If aprogrammer322 is provided, it may also optionally include a patient activated command signal to initiate the delivery of the pain alleviating and cardioversion therapies in response to symptomatic atrial fibrillation. In this context as well, the ability to use theprogrammer322 to delay the delivery of the cardioversion pulse until the patient has felt the effects of the pain alleviating therapy is believed valuable.
• After the fibrillation detection warning is delivered to the patient, or after the patient requests cardioversion therapy by means of theprogrammer322, register563 is set to indicate that the patient has received the fibrillation detection warning or has requested therapy. Immediately thereafter, the delay timer565 starts timing the warning delay period and initiates communication todrug delivery system320 via RF transmitter592 andantenna594. The delay period defines a time interval from when the patient receives the warning or requests therapy to when the patient should first expect to receive the cardioverting electrical energy. The delay time is preferably programmable between one minute and twenty minutes to afford sufficient time to permit the pain alleviating therapy to take effect and for the patient to prepare for receiving the atrial cardioverting electrical energy. A second warning may optionally be given slightly before delivery of the cardioversion pulse, if desired. If the patient does not perceive the analgesic effect of the pain alleviating therapy during the warning delay, the patient may use theprogrammer322 to reset the delay timer565 to delay delivery of the cardioversion pulse until timer565 expires. Alternatively, the programmer may instead allow the patient to delay delivery of the pulse until the patient perceives the analgesic effect, and allow delivery of the cardioversion therapy only following a patient initiated enable signal to the implanted device indicating that therapy may be delivered. As yet another alternative, the programmer may be employed to simply abort the therapy during the warning delay, which may be especially useful if therapy was initially requested by the patient, and the patient's symptoms have subsided.
• A warning system as described above, including apparatus specifically dedicated to providing the warning may not be necessary if the patient can independently feel the analgesic take effect.
• FIG. 5 illustrates a representative electrotransport delivery device that may be used in conjunction with the present invention.Device320 comprises anupper housing346, acircuit board assembly348, alower housing356,anode electrode357,cathode electrode359,anode reservoir362,cathode reservoir364 and skin-compatible adhesive367.Upper housing346 haslateral wings345, which assist in holdingdevice320 on a patient's skin.Upper housing346 is preferably composed of an injection moldable elastomer (e.g., ethylene vinyl acetate). Printedcircuit board assembly348 comprises anintegrated circuit349 coupled todiscrete components352,antenna354 andbattery350.Circuit board assembly348 is attached tohousing346 by posts (not shown inFIG. 25) passing throughopenings343aand343b,the ends of the posts being heated/melted in order to heat stake thecircuit board assembly348 to thehousing346.Lower housing356 is attached to theupper housing346 by means of adhesive367, theupper surface372 of adhesive367 being adhered to bothlower housing356 andupper housing346 including the bottom surfaces ofwings345.
• Shown (partially) on the underside ofcircuit board assembly348 is abutton cell battery350. Other types of batteries may also be employed topower device320.
• Thedevice320 is generally comprised ofbattery350,electronic circuitry349,352,354,electrodes357,359, andhydrogel drug reservoirs362,364, all of which are integrated into a self-contained unit. The outputs (not shown inFIG. 25) of thecircuit board assembly348 make electrical contact with theelectrodes359, and357 throughopenings358,358′ in thedepressions360,360′ formed inlower housing356, by means of electrically conductiveadhesive strips366,366′.Electrodes357 and359, in turn, are in direct mechanical and electrical contact with thetop sides368,368′ ofdrug reservoirs362 and364. The bottom sides370′,370 ofdrug reservoirs362,364 contact the patient's skin through theopenings365′,365 inadhesive367.
• Device320 optionally has a feature, which allows the patient to self-administer a dose of drug by electrotransport. Upon depression ofpush button switch342, the electronic circuitry oncircuit board assembly348 delivers a predetermined DC current to the electrode/reservoirs357,362 and359,364 for a delivery interval of predetermined length. Thepush button switch342 is conveniently located on the top side ofdevice320 and is easily actuated through clothing. A double press of thepush button switch342 within a short time period, e.g., three seconds, is preferably used to activate the device for delivery of drug, thereby minimizing the likelihood of inadvertent activation of thedevice320. Preferably, the device transmits to the user a visual, tactile and/or audible confirmation of the onset of the drug delivery interval by means ofLED344 becoming lit, TENs-like stimulation viaelectrodes357 and359 and/or an audible sound signal from, e.g., a “beeper”. Drug is delivered through the patient's skin by electrotransport, e.g., on the arm or body, over the predetermined delivery interval.
• Anodic electrode357 is preferably comprised of silver andcathodic electrode359 is preferably comprised of silver chloride. Bothreservoirs362 and364 are preferably comprised of polymeric gel materials.Electrodes357,359 andreservoirs362,364 are retained bylower housing356.
• A liquid drug solution or suspension is contained in at least one of thereservoirs362 and364. Drug concentrations in the range of approximately 1×10⁻⁴M to 1.0 M or more can be used, with drug concentrations, in the lower portion of the range being preferred. Typically, the reservoir containing the drug will also contain the selected countersensitizing agent, in an amount and concentration effective to provide the flux necessary to reduce or prevent sensitization of the skin or mucosa.
• FIG. 26 shows a simplified schematic block diagram ofdrug delivery system320integrated circuit349.Microprocessor372 under control of a program contained in RAM/ROM374 (interconnected via bi-directional bus379) receives commands fromIMD312 throughreceiver378 andantenna354. Upon a command to initiate drug delivery, themicroprocessor372 initiates drug delivery through drugdelivery control block380, which initiates iontophoretic drug delivery through two electrodes (not shown).Timer377 times the length of time for drug delivery under control of intervals stored in RAM/ROM374 previously programmed via programmer322 (not shown inFIG. 26). Upontimer377 time out, a signal is sent toIMD312 fromtransmitter block376 andantenna354 using the same telemetry system described herein above.
• The infusion of various analgesic drugs or agents (or, simply “analgesics”) including opiates (i.e. morphine sulfate, hydromorphone) and non-opiates (i.e. alpha-2 adrenergic agonists and neuron specific calcium channel blocking agents) have demonstrated rapid and effective analgesia following administration. Dependent upon the specific analgesic administered, it is also reported that the onset of pain suppression occurs in a couple of minutes to one hour, and the duration of analgesia may range from 4-24 hours. The delay in analgesia onset is not problematic, since rapid cardioversion is not necessary for atrial fibrillation as opposed to ventricular fibrillation. Time to analgesia can be utilized by thesystem330 to re-verify the continuation of atrial fibrillation, charge storage capacitors to deliver the cardioversion shock, and ensure ventricular sensing to allow cardioversion shock synchronization with the R-wave of the cardiac cycle.
• A first alternative embodiment of the invention may employ thedrug delivery system320 for delivery of a cardioversion or defibrillation threshold reducing agent such as D-sotalol, Procainamide or Quinidine as an alternative to, or in conjunction with, delivery of the pain alleviating therapy discussed above. The reduction of defibrillation threshold in such case would provide the possibility of a reduced amplitude, less painful cardioversion pulse. The delivery of a threshold reducing agent thus can be employed as a pain alleviating therapy or as part of a pain alleviating therapy. In a more complex embodiment, two separate drug delivery systems might be employed to allow delivery of the threshold reducing agent alone or in conjunction with an analgesic.
• A second alternative embodiment of the invention may employ thedrug delivery system320 for delivery of diuretic and blood pressure regulating agents such as Thiazide diuretics (hydrochlorothiazide, chlorthalidone), usually adequate for mild heart failure, loop diuretics (furosemide, bumetanide, ethacrynic acid) reserved for severe volume overload or thiazide-resistant edema. Additionally, ACE inhibitors have been shown to prevent or slow the progression of heart failure in patients with symptomatic and asymptomatic left ventricular dysfunction. Currently, four agents are used for the treatment of CHF (Congestive Heart Failure): captopril, enalapril, lisinopril, and quinapril. The implementation ofID312 of this embodiment would use the Medtronic Chronicle™ CHF monitoring system such as described in U.S. Pat. Nos. 5,535,752 and 6,155,267, incorporated herein by reference in their entireties. TheIMD312, as described in the '267 patent, would monitor chronic data representative of at least one physiological parameter. The chronic data is monitored to detect changes in state of the at least one physiological parameter. Data associated with detected changes in state is stored withinIMD312. The detection of changes in state of the at least one physiological parameter is performed by establishing a baseline (e.g., a center reference line and upper and lower control limits), and then determining if the chronic data being monitored satisfies predetermined, preprogrammed conditions (e.g., conditions based on the center reference line and the upper and lower control limits) indicative of a change in state of the at least one physiological parameter. If data occurs outside of these predetermined limits, theIMD312 sends telemetry signals todrug delivery system320 to initiate the delivery of the appropriate drug as described herein above.
• A third alternative embodiment may utilize thedrug delivery system320 as the patient activator/programmer322 by incorporating the features and function as described in U.S. Pat. No. 5,987,356 incorporated herein by reference in its entirety.
• FIG. 27 depicts a flow chart of an operation of the system shown inFIG. 24 in accordance with the present invention. At step S100, which continues at all times (except during the delivery of atrial cardioversion shock), atrial activity of the heart is sensed. Atstep102, the atrial fibrillation detection algorithm is invoked inatrial fibrillation detector570. If it is detected, then in step S104, theIMD330 transmits a signal to thedrug delivery system320 viadrug delivery control590, RF transmitter592 andantenna594 to initiate delivery at S105 of a programmed bolus of the pain alleviating drug fromdrug dispenser320.
• Thecharge delivery control572 may be commanded to start charge up of the charge storage capacitors, but it is preferred to delay capacitor charge up until the end of the delay for the analgesic to take effect and commence capacitor charge up during the analgesic time course, that is, the time period that the analgesia effect is expected to continue. At S107 thepatch520 transmits a confirmation of drug delivery completion back to theIMD312. Optional warning steps for the patients to show the status of the detection, drug delivery and cardioverter status may be included but are not shown in the flow chart ofFIG. 7.
• A delay timer565 is loaded and enabled to time out the delay for the analgesia effect to take place in steps S106 and S108. During this delay, the continuation of the atrial fibrillation episode may be verified in steps S100 and S102 and the algorithm may optionally be halted at that point. However, since atrial fibrillation bouts reoccur and since the bolus of pain alleviating drug is already delivered, reconfirmation at the end of the delay times is sufficient to determine whether or not to deliver the cardioversion shock therapy.
• When the delay timer565 times out in step S108, the delay timer565 is reset for the analgesic time course and is started in step S110. The atrial fibrillation detection is re-verified in step S112 during the analgesic time course. If it only re-verified after the analgesic time course times out, then it is necessary to repeat steps S104-S114 until it is re-verified during an analgesic time course.
• Then, in step S116, acharge delivery control572 is commanded to enable the storage capacitor charge circuit574 to charge the high voltage output capacitors up to the cardioversion energy set inlevel stage569. Themicrocomputer562 then sets a synchronization time interval in interval setstage566 from an R-wave detected by R-wave detector552. The ventricular timer564 then provides a blanking signal to the ventricular andatrial sense amplifiers550 and554. Both operations may be performed in step S118. Re-verification of continued atrial fibrillation may also be performed between steps S116 and S118.
• At the expiration of the synchronization time interval in ventricular timer564, a command is applied through the charge delivery control to operate a discharge circuit576 to discharge the atrial cardioversion shock viaelectrodes544 and546. After the atrial cardioversion shock is delivered, the atrial and ventricular sense amplifiers are again enabled, and the presence or absence of atrial fibrillation is again tested in step S112. If the episode is terminated, then the algorithm loops back to step S100.
• If the episode is not terminated, the steps ofFIG. 27 may be repeated. After a certain number of attempts, the available therapies may be exhausted. Whether or not the therapies are successful, the patient will likely have been advised to contact the attending physician. The event history of the episodes and delivered therapies are recorded in RAM582 for subsequent telemetry out and analysis by the physician in a manner well known in the art in order to assist in reprogramming therapies.
• Thus, the methodological sequence to provide the pain alleviating therapy to counter the pain induced by delivery of atrial cardioversion energy includes the initial detection of atrial fibrillation, optional warning to the patient, drug infusion therapy to produce analgesia, time out to allow analgesia to take effect and the charge storage capacitors to be charged, reverification of atrial fibrillation, delivery of the cardioversion energy, and verification that successful atrial defibrillation has taken place. Should successful atrial cardioversion not take place, the steps ofFIG. 27, would be reinitiated, except that analgesic drug delivery would not be repeated unless the analgesic time course time had timed out in order to prevent drug overdose.
• Depending on the analgesic employed, it may also be desirable to include a further timer to inhibit delivery of a further analgesic bolus timed from the previous delivery for a further time delay to prevent drug overdose. Such a timer may take into account the cumulative amount of analgesic delivered over a set time period.
• In addition, it may be desirable to provide the patient with the option of usingprogrammer322 to temporarily program the delivery of an increased quantity of analgesic, if the desired analgesia effect is not achieved at the permanently programmed setting. A time and date record of such patient programmed increases may be kept in the system memory for review by the physician, and the repetitive use of the programmer may be inhibited.
• A physiologic monitoring system consisting of an implantable therapeutic device (e.g., pacemaker or ICD) and an externally-applied external monitor incorporating: 1) electrodes for detecting the electrical behavior of the implanted device, 2) a controller, 3) a power source, and 4) a radio transmitter for sending information to an external receiving system. The external monitoring system is constantly monitoring the therapeutic electrical output of the implantable device and decoding the electrical behavior according to pre-set algorithms to uniquely infer what the implanted device is sensing. The radio transmitter in the external monitor ten sends the decoded data to an external receiver, which subsequently sends it on to a patient monitoring system. This invention allows an external monitor to receive physiologic data without using telemetry simply by monitoring the easily-detected electrical therapy (e.g., pacing or high voltage cardioversion/defibrillation delivered by the implanted device.
• Implanted devices like pacemakers and ICDs are constantly sensing their associated physiological environment. For example, pacemakers and ICD's are always sensing native electrical activity in the atria and ventricles, associated data such as activity or respiration, and derived parameters such as presence or absence of capture, lead integrity problems, and the like. In order to know what an implanted device is sensing, radio telemetry, typically in the 175 KHz range, is widely used to interrogate the memory in the device. This requires a sophisticated instrument such as a programmer which is capable of interacting with the implanted device along with computational capabilities to decode the data in the telemetry stream. Another method of determining what the device is sensing is to use a “Patient Alert” type feature, where the device actually generates an audible tone when certain sensed conditions are fulfilled (such as a lead problem). This requires the patient to listen for the tone, decide what the tone means, and contact a health care worker.
• The following are examples of detection by the electrodes: 1) Detection of arrhythmias, 2) Detection of device malfunction, such as lead failure or misprogramming, 3) Detection of underlying physiologic parameters such as hemodynamics and other sensed parameters.
• The therapeutic electrical output of a therapeutic implantable device like a pacemaker or an ICD is easily detectable from the skin surface using ECG electrodes and a standard ECG preamplifier which are well known in the art. The therapeutic electrical output from a pacemaker consists of pacing pulses in the 1-5 volt range, which can be detected by skin electrodes as several millivolt signals. The high voltage defibrillation output from an implantable defibrillator consists of ramp waveforms in the hundreds of volts range, which again can be easily detected as several volt signals on the skin surface. The therapeutic electrical output of a therapeutic implantable device occurs as a response to a set of sensed conditions. It is frequently possible to create a 1-1 mapping between a specific type of therapeutic electrical output and the sensed conditions that leads to that output, based on the characteristics of the specific implanted device and the way it is programmed. As a very simple example, ventricular pacing in a VVI pacemaker occurs when no intrinsic ventricular electrical signal is detected by the pacemaker during a pre-set time interval. Therefore, detecting a regular set of ventricular pacing stimuli can be taken as evidence that there are no intrinsic ventricular depolarizations occurring, without having to measure intrinsic ventricular activity independently. Implantable therapeutic devices have evolved considerably in complexity from VVI pacing, and there are now specific therapeutic algorithms built into most devices which occur in response to a particular set of sensed conditions. For example, Rate Drop Response is a particular type of pacing which is easily recognized by a rapid start of regular pacing, at a relatively high rate (such as 120 bpm), followed by a gradual fallback in pacing rate over the next several minutes. This particular algorithm is activated by a specific set of trigger criteria, including a fall in the intrinsic ventricular rate through a specific rate window over a specific time window. Therefore, the specific therapeutic electrical “signature” generated by the Rated Crop Response algorithm, which is easily detectable at the skin surface, allows the external device to determine that a specific type of intrinsic rate change occurred and to send this information to a patient monitoring system. Similarly, an ICD may be programmed to deliver a burst of autodecremental anti-tachycardia pacing (ATP) if a ventricular arrhythmia of a certain rate is detected. The external monitor can easily detect the specific pattern of auto-decremental ATP as a “signature” of a ventricular arrhythmia and, similarly, identify this arrhythmia and send the detection to an external patient monitoring system. There are many other examples of unique therapeutic electrical “signatures” which can be used by the external monitoring system to generate a specific diagnosis. In addition to detecting physiologic conditions such as arrhythmias, this device could also detect potential malfunctions or problems with the implanted device. For example, ventricular safety pacing occurs in response to a sensed beat during a pacemaker refractory period. The safety pace is easily recognizable by its characteristic coupling interval from the previous pace. Frequent ventricular safety pacing sometimes indicates a lead insulation problem. Therefore, the detection of frequent ventricular safety pacing could initiate a transmission of “possible ventricular lead problem.” If the monitor also detected intrinsic electrical activity of the heart (e.g. easily detected ORS complexes), relationships between the therapeutic electrical output of the device and the detected intrinsic rhythm could add additional richness to the detection scheme. For example, a dissociation between ventricular pacing spikes and intrinsic ventricular beats could indicate loss of capture. Detecting this pattern could generate the message “possible loss of capture.” Another potential use is to detect underlying physiologic conditions that the implanted device responds to. For example, future implantable therapeutic devices may incorporate hemodynamic sensors or ischemia sensors. It is conceivable that the implanted device may respond with a specific therapeutic electrical intervention, based on the data from these sensors. For example, an implantable pacemaker may be programmed to undergo a certain type of pacing rate fallback if ischemia is detected. This specific behavior could be decoded as indicative of sensed ischemia. Referring toFIG. 1, electrodes are applied to the patient (at left) and connected to the EKG preamplifier on the external monitoring system. The EKG preamplifier sends the amplified signal to the Algorithm Decoder. The Algorithm Decoder typically contains either an Analog to Digital Converter (ACD) or an analog sense amplifier with comparator circuitry in order to detect therapeutic electrical signals. The output from the ADC or comparator is then sequentially fed to the Algorithm Decodeer circuitry, which compares the incoming signal with a set of patterns stored in the Algorithm Storage RAM. The Algorithm Storage RAM contains the specific therapeutic patterns tat are used to decode the therapeutic electrical signals into specific patterns. This RAM would be customized for the specific implantable device and the specific programming; for example, VT at a certain rate might be programmed to cause the implantable device to initiate a specific type of ATP. This information would then be loaded into the Algorithm Storage RAM. The diagram shows how the radio transmitter could also function as a receiver to program the Algorithm Storage RAM. The Algorithm Storage RAM would also contain a PLA that translates each detected therapeutic electrical pattern into a simple signal that is then sent to the radio transmitter for transmission to the receiving system. As in the example above, autodecremental ATP in response to a detected VT might generate a “10001000” radio signal, while a defibrillation shock might general a “11111111” radio signal, which the receiver would decode into the appropriate sensed rhythm. In the example given above, other conditions such as excess ventricular safety pacing, dissociation between pacing and intrinsic beats, or a specific rate fallback behavior indicating ischemia would also generate unique identifying codes. Also noted in the diagram is a controller, which would typically consist of a microprocessor and its associated software or microcode required to operate the entire device. In addition, the figure demonstrates a power source (e.g., battery, which could be rechargeable), which supplies power to all of the electronics in the monitor.
• One embodiment method includes: 1) Using the therapeutic electrical output of an implanted device to discern sensed conditions that initiated the therapeutic electrical intervention. 2) Having an external cutaneous device detect the therapeutic electrical output of an implanted device that allows the external device to discern the sensed conditions of the implanted device. 3) Use of an algorithm decoder to translate therapeutic electrical stimuli into specific sensed conditions based on the specific characteristics of the implanted device and its associated programming. 4) Use of a radio link to download specific algorithm information into the algorithm decoder. 5) Detecting implantable device malfunction through external decoding of therapeutic electrical interventions. 6) Detecting underlying physiologic states (e.g., ischemia) through external decoding of therapeutic electrical interventions.
• Thus, embodiments of the Implantable Medical Device And Patch System And Method Of Use are disclosed. One skilled in the art will appreciate that the present invention can be practiced with embodiments other than those disclosed. The disclosed embodiments are presented for purposes of illustration and not limitation, and the present invention is limited only by the claims that follow.

Claims (48)

1. A method of administering a therapeutic substance to a patient having an implanted medical device, wherein the implanted medical device generates a signal, the method comprising:

attaching a patch containing the therapeutic substance to the patient so that the patch is in contact with the skin of the patient;

generating a signal from the implanted medical device; and

administering the therapeutic substance from the patch to the patient in response to the signal generated by the medical device.

2. The method according toclaim 1 wherein the medical device further comprises a sensor, the method further comprising:

sensing a physiologic characteristic of the patient by the medical device wherein the signal generated by the medical device represents the physiologic characteristic.

3. The method according toclaim 2 wherein the physiologic characteristic is selected from the group consisting of temperature, blood oxygen saturation, activity level, lung wetness, glucose level, thoracic impedance, EKG, heart rate, respiration rate, EMG, EEG, blood pressure, intra cerebral ventricular (ICV) pressure, and position of the patient.

4. The method according toclaim 1 wherein the signal generated by the medical device represents operational information of the medical device.

5. The method according toclaim 1 wherein the attaching a patch containing the therapeutic substance to the skin of the patient comprises adhering the patch to the skin.

6. The method according toclaim 1 wherein the patch is a transdermal drug delivery patch.

7. The method according toclaim 6 wherein the transdermal drug delivery patch comprises an iontophoretic transdermal drug delivery patch.

8. The method according toclaim 6 wherein the transdermal drug delivery patch comprises a sonophoretic transdermal drug delivery patch.

9. The method according toclaim 6 wherein the transdermal drug delivery patch utilizes a laser to assist in transmission of the drug through the skin of the patient.

10. The method according toclaim 1 wherein the administering the therapeutic substance to the patient in response to the signal generated by the medical device comprises administering the therapeutic substance through a needle attached to the patch.

11. The method according toclaim 1 wherein administering the therapeutic substance to the patient in response to the signal generated by the implanted medical device comprises directing the therapeutic substance into an implanted catheter access port wherein the catheter access port delivers the drug to a selected location in the body.

12. The method according toclaim 11 wherein the selected location comprises the brain.

13. The method according toclaim 11 wherein the selected location comprises the spinal cord.

14. The method according toclaim 11 wherein the selected location comprises the vascular system.

15. The method according toclaim 11 wherein the selected location comprises the heart.

16. The method according toclaim 1 wherein the step of administering the therapeutic substance to the patient in response to the signal generated by the medical device comprises administering a drug to the patient.

17. The method according toclaim 1 wherein the step of administering the therapeutic substance to the patient in response to the signal generated by the medical device comprises administering a biologic agent to the patient.

18. The method according toclaim 1 wherein the step of administering the therapeutic substance to the patient in response to the signal generated by the medical device includes delivery of a therapeutic substance selected from the group consisting of anti-arrhythmic drugs, diuretic drugs, vasodilators, muscle relaxants, pain relieving drugs, analgesics, anti-clotting drugs, blood thinners, anti-seizure drugs, gene therapeutic substances, naturitic peptides, insulin, or any other therapeutic substance whose administration would be improved if the delivery could be optimally timed to the receipt of information from an implantable medical device.

19. The method according toclaim 1 wherein the medical device is selected from the group consisting of a nerve stimulator, brain stimulator, muscle stimulator, infusion pump, drug delivery device, monitoring device, cochlear implant, oxygen sensing device, pacemaker, defibrillator, cardioverter, pacemaker/cardioverter/defibrillator (PCD), left ventricular assist device and total artificial heart device.

20. A method of administering a therapeutic substance to a patient having an implanted medical device that is adapted to take an action on the patient, the method comprising:

attaching a patch containing the therapeutic substance to the patient so that the patch is in contact with the skin of the patient and a sensor for sensing a physiologic reaction to the action taken by the medical device;

sensing with the sensor the physiologic reaction to the action taken by the implanted medical device; and

administering the therapeutic substance to the patient in response to the reaction sensed by the sensor.

21. The method according toclaim 20 wherein the medical device has an active mode and an inactive mode relating to at least one activity of the medical device, wherein the step of sensing with the sensor the patient's physiologic reaction to the action taken by the medical device comprises determining whether the medical device is in the active or inactive mode.

22. A method of administering an therapeutic substance to a patient having an implanted medical device that is adapted to take an action on the patient, the method comprising:

attaching a patch containing the therapeutic substance to the patient so that the patch is in contact with the skin of the patient and a sensor for sensing the action taken by the medical device;

sensing with the sensor the action taken by the implanted medical device; and

administering the therapeutic substance to the patient in response to the action sensed by the sensor.

23. The method according toclaim 22 wherein the medical device has an active mode and an inactive mode relating to at least one activity of the medical device, wherein the step of sensing with the sensor the action taken by the medical device comprises determining whether the medical device is in the active or inactive mode.

24. A method of administering an therapeutic substance to a patient having an implanted medical device that is adapted to take an action on the patient, the method comprising:

attaching a patch containing the therapeutic substance to the patient so that the patch is in contact with the skin of the patient and a sensor for determining if the medical device has taken an action on the patient;

determining with the sensor whether the medical device has taken an action on the patient; and

administering the therapeutic substance to the patient in response to the determination carried out in the determining step.

25. The method according toclaim 24 wherein the determining step comprises sensing a parameter relevant to whether the medical device has taken an action on the patient or a physiologic reaction of the patient expected in response to the action, and inferring whether the medical device has taken the action.

26. A method of administering a therapeutic substance to a patient having an implanted blood pressure monitor, wherein the implanted blood pressure monitor generates a signal, the method comprising:

attaching a patch containing the therapeutic substance to the patient so that the patch is in contact with the skin of the patient;

generating a signal from the implanted blood pressure monitor representing the blood pressure of the patient; and

administering the therapeutic substance from the patch to the patient in response to the signal generated by the medical device.

27. The method according toclaim 26 wherein the therapeutic substance is selected from the group consisting of diuretic drugs, beta blockers, and vasodilators.

28. A method of administering a therapeutic substance to a patient having an epileptic seizure or in anticipation or prediction of an epileptic seizure, the patient having an implanted neurostimulator including deep brain stimulation leads, wherein the implanted neurostimulator generates a signal, the method comprising:

attaching a patch containing the therapeutic substance to the patient so that the patch is in contact with the skin of the patient;

generating a signal from the implanted neurostimulator representing the electric potentials in the brain of the patient; and

administering the therapeutic substance from the patch to the patient in response to the signal generated by the implanted neurostimulator.

29. The method according toclaim 28 wherein the therapeutic substance is selected from the group consisting of Phenytoin and Conantonkin-G.

30. A method of administering a therapeutic substance to a patient having diabetes, the patient having an implanted glucose monitor, wherein the implanted glucose monitor generates a signal, the method comprising:

attaching a patch containing the therapeutic substance to the patient so that the patch is in contact with the skin of the patient;

generating a signal from the implanted glucose monitor representing glucose level; and

administering the therapeutic substance from the patch to the patient in response to the signal generated by the implanted glucose monitor.

31. The method according toclaim 30 wherein the therapeutic substance is selected from the group consisting of insulin and glucagons.

32. A method of administering a narcotic antagonist to a patient receiving opioids, the patient having an implanted medical device capable of sensing respiration rate, wherein the implanted medical device generates a signal, the method comprising:

attaching a patch containing the narcotic antagonist to the patient so that the patch is in contact with the skin of the patient;

generating a signal from the implanted medical device representing respiration rate; and

administering the narcotic antagonist from the patch to the patient in response to the signal generated by the implanted medical device.

33. The method according toclaim 32 wherein the opioid comprises morphine and the narcotic antagonist comprises naloxone.

34. The method according toclaim 32 wherein the opioid comprises fentanyl and the narcotic antagonist comprises naloxone.

35. The method according toclaim 32 wherein the opioid comprises sufentanil and the narcotic antagonist comprises naloxone.

36. The method according toclaim 32 wherein the opioid comprises hydromorphone and the narcotic antagonist comprises naloxone.

37. A method of administering an antiarrythmic drug to a patient, the patient having an implanted medical device capable of sensing heart rate, wherein the implanted medical device generates a signal, the method comprising:

attaching a patch containing the antiarrythmic drug to the patient so that the patch is in contact with the skin of the patient;

generating a signal from the implanted medical device representing heart rate; and

administering the antiarrythmic drug from the patch to the patient in response to the signal generated by the implanted medical device.

38. A drug delivery patch capable of administering a therapeutic substance to a patient based on information received from an implanted medical device, the patch comprising:

a housing configured for attachment to the patient so that the housing contacts the patient's skin;

a therapeutic substance reservoir coupled to the housing, the therapeutic substance reservoir having a reservoir outlet;

a power source carried in the housing;

electronics carried in the housing and coupled to the power source, the electronics comprising a telemetric receiver capable of receiving a signal generated from the implanted medical device; and

a pump coupled to the electronics and coupled to the reservoir outlet, the pump configured for pumping a therapeutic substance from the therapeutic substance reservoir through an infusion outlet at a programmed rate based on the signal received from the implanted medical device.

39. A therapeutic substance delivery patch capable of administering a therapeutic substance to a patient based on information received from an implanted medical device, the patch comprising:

a housing including reservoir means for containing the therapeutic substance;

attachment means for attaching the patch to the patient so that the patch is in contact with the patient's skin;

communication means for receiving a signal from the implanted medical device representing a physiologic condition of the patient;

control means for controlling the functions of the patch through a control signal wherein the control signal is based at least in part on the signal from the implanted medical device; and

delivery means for delivering a metered amount of the therapeutic substance to the patient in response to the control signal.

40. The therapeutic substance delivery patch according toclaim 39 wherein the therapeutic substance is selected from the group consisting of antiarrythmic drugs; diuretic drugs; beta blockers; vasodilators; muscle relaxants; pain relieving drugs; analgesics; anti-clotting drugs; blood thinners; anti-seizure drugs; naturitic peptides; and narcotic antagonists.

41. The therapeutic substance delivery patch according toclaim 39 wherein the therapeutic substance is selected from the group consisting of amiodarone; bumentanide; conantonkin-G; flecainide; ibutilide; isosorbide; furosemide; metaprolol; naloxone; nitroglycerine; phenytoin; procainamide; propranolol; insulin; glucagons; and sotalol.

42. The therapeutic substance delivery patch according toclaim 39 wherein the attachment means comprises an adhesive applied to the housing.

43. A therapeutic substance delivery patch capable of administering a therapeutic substance to a patient based on information sensed from an implanted medical device, the patch comprising:

a housing including reservoir means for containing the therapeutic substance;

attachment means for attaching the patch to the patient so that the patch is in contact with the patient's skin;

sensing means for sensing an action taken by the implanted medical device;

control means for controlling the functions of the patch through a control signal wherein the control signal is based at least in part on the sensed action; and

delivery means for delivering a metered amount of the therapeutic substance to the patient in response to the control signal.

44. A therapeutic substance delivery patch capable of administering a therapeutic substance to a patient based on sensed physiologic information, the patch comprising:

a housing including reservoir means for containing the therapeutic substance;

attachment means for attaching the patch to the patient so that the patch is in contact with the patient's skin;

sensing means for sensing a physiologic reaction to an action taken by the implanted medical device;

control means for controlling the functions of the patch through a control signal wherein the control signal is based at least in part on the sensed reaction; and

delivery means for delivering a metered amount of the therapeutic substance to the patient in response to the control signal.

45. The therapeutic substance delivery patch according toclaim 44 wherein the sensing means comprises a sensor capable of sensing conditions selected from the group consisting of galvanic skin resistance, temperature, oxygen saturation, blood pressure, activity level of patient, lung wetness, glucose level, thoracic impedance, EKG, heart rate, respiration rate, EMG, EEG, ICV pressure, and position of patient.

46. A therapeutic substance therapy system for delivery of a therapeutic substance into a human body comprising:

(a) an implanted medical device capable of generating a telemetric signal;

(b) a therapeutic substance delivery patch attached to the patient so that the patch is in contact with the skin of a patient, the therapeutic substance delivery patch comprising:

(i) a telemetric receiving antenna for receiving the telemetric signal from the implanted medical device;

(ii) a reservoir capable of holding the therapeutic substance; and

(iii) means for delivering the agent into the body.

47. A therapeutic substance therapy system for delivery of a therapeutic substance into a human body comprising:

(a) an implanted medical device capable of generating an electric therapy signal, the electric therapy signal provided to the patient for therapeutic reasons;

(b) a therapeutic substance delivery patch attached to the patient so that the patch is in contact with the skin of a patient, the therapeutic substance delivery patch comprising:

(i) a sensor for sensing the electric therapy signal;

(ii) a reservoir capable of holding the therapeutic substance; and

(iii) means for delivering the agent into the body based at least in part on the sensed electric therapy signal.

48. A therapeutic substance therapy system for delivery of a therapeutic substance into a human body comprising:

(a) an implanted medical device capable of generating an electric therapy signal, the electric therapy signal provided to the patient for therapeutic reasons wherein the electric therapy signal results in a physiologic reaction;

(b) a therapeutic substance delivery patch attached to the patient so that the patch is in contact with the skin of a patient, the therapeutic substance delivery patch comprising:

(i) a sensor for sensing the physiologic reaction to the electric therapy signal;

(ii) a reservoir capable of holding the therapeutic substance; and

(iii) means for delivering the agent into the body based at least in part on the sensed physiologic reaction to the electric therapy signal.

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