US20090198295A1 - Intravascular Medical Device - Google Patents

Abstract

An implantable medical device is configured so that all of the major components including a housing and attached leads are disposed within the vasculature of a patient. A tether extends from the housing of the device to an implant location where the tether is secured to tissue outside of the vasculature. In this manner, an intravascular medical device may be implanted at a location remote from final placement, delivered via the vasculature and anchored at the initial entry point.

Description

CROSS REFERENCE TO RELATED APPLICATIONS
• This application is a continuation of U.S. application Ser. No. 11/342,734 filed on Jan. 30, 2006 and entitled “Intravascular Medical Device”.
BACKGROUND
• 1. Field of the Invention
• The present invention relates to medical devices and in particular, implantable medical devices.
• 2. Description of the Related Art
• Medical devices related to managing, treating and providing therapy for cardiac conditions have changed and improved dramatically since their inception. Cardiac pacing, as an example, originally required an external pulse generator that itself required external power. While providing life sustaining therapy, patients were tethered to the power source and of course, power failures could prove catastrophic. Portable, battery powered external pulse generators were developed and provided the patient with the ability to be ambulatory; however, the pulse generator had to be carried by the patient. Furthermore, pacing leads were exposed through the patient's tissue and extreme care had to be exercised to minimize the risk of infection or inadvertent withdrawal.
• Subsequently, fully implantable, battery powered pulse generators were provided in a hermetically sealed housing. This housing was rather large and was typically implanted in the abdomen of the patient, with leads extending to the heart. The size of such a device often made it rather uncomfortable and the implantation procedure was relatively invasive.
• As technology improved, implantable medical devices (IMDs) have become continuously smaller, while offering increased longevity, reliability and many more features and therapies. Epicardial leads that were attached to an external wall of the heart were replaced with endocardial leads that are implanted transvenously, thus becoming minimally invasive. With these smaller devices, the housing was no longer placed in the abdomen but instead was implanted subcutaneously or sub-muscularly, often in the pectoral region. A “pocket” is formed underneath the skin or muscle sufficiently large to receive the housing of the IMD. The exposed or proximal ends of the leads are then connected to the housing and the incision is closed. While now routine, this is still a surgical procedure that requires skill and the appropriate medical facilities.
• In general, patients are comfortable with these implanted devices and have a full range of motion, without interference or hindrance. Some patients feel the housing in the “pocket,” which may be physically and/or psychologically uncomfortable. Physically, some patients may press against the housing during certain physical activities making the housing noticeable. Even if not a hindrance or painful, simply “feeling” the presence of the device may remind that patient that they have a medical implant and/or medical condition and this alone may be troubling to that patient. Some patients develop a habit of pressing against the pocket and hence against the IMD and often rotating or twisting the IMD. Typically, IMDs that have one or more leads will have any excess lead length coiled under (or around) the housing of the IMD. Thus, frequent patient manipulation may cause portions of the lead(s) to twist or rub, potentially damaging the lead body or pulling the lead out of contact with the targeted tissue. This is sometimes referred to as “twiddlers syndrome.”
• As the size and capability of IMDs has greatly improved, use of these devices has naturally expanded. This results in greater knowledge and acceptance among the patient population as well as within the medical community. As a result, caregivers are using IMDs with more frequency and for new and diverse purposes. For example, pacemakers are used in patients with various bradyarrhythmias. In such a patient, the heart's intrinsic pacing function fails or is deficient and the IMD provides electrical stimulation to maintain the proper heart rhythm. Such therapy is well known and is referred to above with the early, external pulse generators. Recently, the medical community has been using pacing technology in patient's whose heart rhythm is actually normal. Heart failure patients often have normal rhythm and conduction; however, this disease causes the heart to enlarge. As a result the left and right ventricles are unsynchronized when they contract even though the depolarization waveform triggering such a contraction was “timed” properly. Using cardiac resynchronization therapy (CRT), the left and right ventricles are paced, leading to a mechanical “resynchronization” of the left and right ventricular contractions. This not only leads to better immediate hemodynamic performance, but the heart itself often remodels itself (reducing in size) leading to an improvement in the disease state.
• Not only are new therapies and treatments developing, implantable devices are now being used to collect sensor data for a variety of purposes. For example, implantable loop recorders (ILRs) are implanted subcutaneously and record cardiac data, unobtrusively, for extended periods of time. This allows robust medical data to be collected that, as a practical matter, may be otherwise unattainable.
• These are merely two examples that illustrate the ever increasing trend to beneficially use implantable medical devices with greater frequency and for a wide variety of purposes that extend well beyond cardiac care. This presents a challenge to some caregivers who might want to use a given device for their patient but do not have the necessary surgical qualifications to actually implant the device. While such a patient may always be referred to another doctor, this adds cost and burden, some patients may not follow through, and some caregivers may simply opt for other treatments in order to maintain their relationship with the patient.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a schematic illustration of selected internal components of an intravascular medical device (IVMD) consistent with the teachings of the present invention.
• FIG. 2 is a schematic illustration of the IVMD including a tether and a lead.
• FIG. 3 illustrates an electrode incorporated into the tether.
• FIG. 4 illustrates an IVMD having multiple leads.
• FIG. 5 is a sectional view of a housing of the IVMD.
• FIGS. 6A-6B illustrate an IVMD having a lead and the tether coupled to a common end of the housing.
• FIGS. 7A-7 illustrate a system for deploying the lead and housing.
• FIGS. 8A-8D illustrate an IVMD having a tether with a lumen.
• FIGS. 9A-9D illustrate an IVMD having a tether with a lumen coaxial with a lumen through the housing and an attached lead.
• FIGS. 9A-9D illustrate multiple lumens.
• FIG. 10 illustrates a housing having multiple housing portions.
• FIGS. 11A-11B illustrate multiple housing components with a common tether.
• FIGS. 12A-12D illustrate a mechanism to attach a stylet to a housing component.
• FIGS. 13A13B illustrate an IVMD with multiple housing portions.
• FIG. 14 illustrates an IVMD having multiple housing potions and multiple tethers.
• FIG. 15 illustrates an interaction of a stylet with both tethers ofFIG. 14.
• FIG. 16 illustrates an IVMD with multiple housing portions.
• FIG. 17 illustrates an implanted IVMD.
• FIG. 18 illustrates the anatomical relationship between the subclavian vein and the clavicle.
• FIG. 19 illustrates the anatomical location of the cephalic vein.
• FIG. 20 illustrates an IVMD implanted in the superior vena cava having an auxiliary support member further anchoring the lead.
• FIG. 21A-21J illustrate the insertion and anchoring of an IVMD.
• FIGS. 22A-22B illustrate a tether anchor.
• FIG. 23 is a flowchart describing a process for implanting an IVMD.
DETAILED DESCRIPTION
• FIG. 1 illustrates an exemplary intravascular medical device (IVMD)10. TheIVMD10 is an implantable medical device that includes a hermetically sealedhousing12 containing components18 to control, power, and operate the device. Thehousing12 is shaped and configured to reside entirely within the vasculature anatomy or within a given organ (e.g., the heart, lungs, kidney, pancreas, etc.) via the vasculature. In one embodiment, thehousing12 has an approximate diameter of 6-7 French. TheIVMD10 may have any number of functional areas including sensing, diagnostic, communications and therapy delivery. In the illustrated example, theIVMD10 includes cardiac sensing, pacing and defibrillation as well as the ability to communicate with an external device through telemetry.
• Thehousing12 includes aproximal header16 and adistal header16. The operative components18 include apower source20, such as a battery. One ormore capacitors22 are provided that allow charge to be accumulated for rapid discharge to deliver a defibrillation or cardioversion pulse. Apulse generator26 is coupled to thepower source20 and provides electrical stimuli for cardiac pacing.
• Amicroprocessor24, memory36 (flash, EEPROM, ROM, RAM, DRAM, harddisk, etc.), analog to digital converter (A/D)30,analog signal processor28, and digital signal processor (DSP)32 are positioned within thehousing12. An externally actuatedswitch42 is provided and may take the form of a reed switch that is closed by a magnet. Such aswitch42 may be used to initiate a telemetry session withIVMD10.
• Alternatively, communication may be initiated directly by an RF signal or other appropriate transmission medium. Atelemetry module34 provides the ability to transmit and receive data. Areservoir35 is optionally included. The reservoir may provide a supply of a deliverable drug (e.g., insulin), genetic material, or biologic. TheIVMD10 may provide for the release of the material on a given schedule or based upon sensed need. Some materials, such as insulin, may be dispersed as needed but are predictably used; that is, the likelihood of delivery over a given time period is high. Other material may be delivered on an acute basis. For example, a dose of a blood thinner, coagulant, anti-coagulant, or adrenaline is provided and released when necessitated.
• Anaccelerometer40 may be utilized to provide an indication of patient activity for a rate response function and/or a relative position indicator; that is, physical position of the patient (e.g., prone). Finally, asensor array50 is illustrated. Thesensor array50 may sense any number of parameters such as temperature, pressure, velocity or other fluid flow characteristics, impedance, motion or size (e.g., ultrasound for wall motion and/or chamber size), oxygenation, glucose, or the level of any sensed chemical substance. It should be appreciated that while illustrated as contained within thehousing12, thesensor array50 may have appropriate external portions not shown. For example, if used as a pressure sensor, a transducing membrane will form a part ofhousing12 or part of a lead coupled with thehousing12, either physically or through telemetric connection (e.g., a body bus). Likewise, any additional component(s) forsensor array50 will be included in this manner, as required. Cardiac data (e.g., electrogram (EGM)) will be sensed via one or more leads as explained below. In addition, thehousing12 may include one or more electrodes incorporated into the structure of the housing12 (i.e., an active “can”).
• As indicated thepower source20 may be a single use battery. Alternatively, the battery may be rechargeable. As such, anoptional recharging module25 is illustrated. Therecharging module25 may receive power from an external source, such as directed RF energy, which is converted and used to recharge thebattery20. The RF energy may be collected via one or more antenna as discussed below, by using thehousing12 as an antenna, or by incorporating a receiver into thehousing12. Alternatively, or in addition, therecharging module25 may use other mechanisms to generate power. In one embodiment, heat from within the patient is converted into current. In another embodiment, chemical energy from cells proximate the implant location is converted into electrical energy by the chargingmodule25. The chargingmodule25 may convert body motion into electrical energy. Such motion may come from multiple sources including without limitation gross patient movement (walking, exercising, etc.), lung motion (breathing), cardiac contractions, vasculature contraction (pulsitile blood flow), or fluid flow. The length of the unit provides the ability to harness mechanical power at one or more flexation points. Such flexation points may occur along the tether and/or in-between housing components. In this context, mechanical motion is converted into electrical energy by various mechanisms such as movement of a magnetic member within a coil. The chargingmodule25 may also used photovoltaic conversion to generate electrical current. A light collected placed sufficiently close to the surface of the patient's tissue will receive enough ambient light to provide power. Various other techniques are available to recharge the battery and are considered to be within the spirit and scope of the present invention. The following documents are herein incorporated by reference in their entirety: U.S. Pat. No. 6,242,827, issued to Wolf et al. on Jun. 5, 2001; U.S. Pat. No. 6,768,246, issued to Pelrine et al. on Jul. 27, 2004; US Published Application 2004/0073267, published on Apr. 15, 2004; and US Published Application 2004/0158294 published on Aug. 12, 2004.
• Themodule25 has been described in conjunction with a traditionalrechargeable battery20 as a mechanism to recharge that battery. It should be appreciated that to conserve space, thetraditional battery20 may be eliminated or greatly reduced in size (due to a decrease in reliance upon the battery). That is, the various mechanisms described to generate electrical energy from sources around theIVMD10 may be used to directly power theIVMD10, without first storing that energy in a battery. This concept is applicable to any of the various forms theIVMD10. In one embodiment, providing power directly from module23 is utilized when the IVMD has low or minimal power consumption requirements (e.g., periodic sensing). Thus, power is generated for internal operations and when communication is desired, external power is provided for e.g., telemetry functions, through inductive coupling or RF power transmission. Of course, theIVMD10 may be completely dependant upon such power conversion for all of its functionality. Finally, as indicated, a smaller battery or capacitor may be provided to collect some amount of energy prior to use; either to mitigate against fluctuation in the source (e.g., movement stops for a period of time) or to provide an even power supply to mitigate against power fluctuations; that is, to provide a relatively stable DC source.
• FIG. 2 illustrates a lead60 coupled with thedistal header16. One or more electrodes are incorporated into thelead60. As illustrated, lead60 includes ahelical affixation member64 that allows penetration into tissue to secure the distal portion of thelead60 at a specific site. Thehelical affixation member64 may serve as an electrode and/or the distal end of thelead60, proximal to thehelical member64, acts as an electrode. Acoil electrode62 is positioned proximal to the distal end of thelead60 so that when implanted, the coil electrode creates a defibrillation vector through an appropriate cardiac path with another electrode of theIVMD10. The length of thelead60 and the relative position of the electrodes are selected based upon the type of therapies, sensing and diagnostics provided and the implant location of thehousing12. Thelead60 may have other functions instead of or in addition to electrical stimulation or sensing. For example, a number of non-electrical parameters (e.g., pressure, temperature, velocity, chemical presence/concentration, etc.) may be sensed by providing an appropriate sensor. Thelead60 may have a delivery device to deliver drugs, genetic material, or biologics from thereservoir35. Such a delivery device may include aneedle65afor delivery into tissue; a disbursingtip65b(e.g., a porous surface for release into a fluid supply or against a larger surface area); or a variety of other delivery mechanisms.
• Thelead60 is connected to thedistal header16. The connection may be a permanent, integral formation. That is, thelead60 andhousing12 are fabricated to form an integral unit or thelead60 is permanently affixed to thehousing12. Alternatively, thelead60 is separable from thehousing12, as explained below. As used throughout, the designations proximal anddistal header14,16 are used to indicate particular portions of thehousing12. It should be appreciated, that these portions may include a header in the traditional sense of an implantable medical device. That is, a separate portion from the remainder of the housing that includes various connection mechanisms (e.g., for receiving a lead connector pin). Alternatively, the terminology may simply refer to a given end or portion of thehousing12 to facilitate description.
• Aflexible tether70 extends from and is securely coupled to theproximal header14. At aproximal end74, thetether70 has an anchoring point. In the illustrated embodiment, a T-shapedanchor member76 is attached to thetether70 at the anchoring point. Theanchor member76 includes one ormore suture ports78 extending through themember76. As indicated,IVMD10 is implanted transvenously and theentire housing12 resides within the vasculature or within an organ accessed via the vasculature. Thetether70 extends from the implanted location of thehousing12, through the vasculature and is anchored at or near the vasculature incision or puncture created for implantation. Thus, thetether70 will fully or partially maintain the position of theIVMD10. For example, if implanted in the superior vena cava, with apacing lead60 extending from thehousing12 into a cardiac chamber, blood flow and gravity (generally) will provide force against thehousing12 in a direction towards the heart. With the anchor point fixed, thehousing12 is prevented from traveling towards the heart and is thus secured. While suturing has been discussed, other methods of attaching or anchoring thetether70 and/or theanchor76 may be utilized.
• Theanchoring point74 allows for subsequent identification and access to theIVMD10. That is, if the IVMD is replaced or modified, theanchoring point74 is located and theIVMD10 can be accessed or removed via thetether70 along the same vasculature pathway. As such, theanchoring point74 may optionally include a radiopaque marker, may be constructed of a biocompatible metal, or having other identifying mechanisms to aid in determining the location of theanchor point74 at a later time via X-ray, MRI, or other imaging techniques. Alternatively, theanchor point74 may be positioned sufficiently close to the surface of the patient's skin that its location may be felt by applying pressure to the area.
• Thetether70 is intended to secure the position of theIVMD10 during the life of the implant. Accordingly, the tether material is constructed of a suitably strong, flexible, biocompatible material. The length of thetether70 may include a drug eluting surface along the entire exterior, a portion of the exterior, or multiple distinct drug eluting surfaces may be provided. In some embodiments, thetether70 may be used to temporarily secure theIVMD10 until another anchoring mechanism is enacted (e.g., fibrotic growth). In yet another alternative embodiment, theIVMD10 is intended to degrade within the body or pass harmlessly out of the body. For example,IVMD10 may be a chemical sensor and thetether70 secures theIVMD10 at an appropriate location within the vasculature, counteracting the forces of pulsitile blood flow. Eventually, the sensor will dissolve and in such an embodiment, thetether70 could likewise dissolve. Of course, thetether70 provides a convenient mechanism to remove any such device thus providing for temporary implantation of a variety of medical devices, including pacemakers and defibrillators.
• Thetether70 is provided with an excess length. After implantation of thelead60 andhousing12, the desired length oftether70 is determined. This final length should include enough excess to allow for normal movement of thehousing12 within the vasculature as well as any variations that will occur due to patient movement, positioning, growth or other physiological variations. Thetether70 is then cut at the appropriate location and anchored into place. The T-shapedanchor member76, if used, is attached to thecut tether70, either by suturing, mechanically clamping or using any other secure coupling mechanism.
• As indicated, excess tether length is provided at the proximal end of thetether70 with an expectation that this excess will trimmed or remain unused. This allows for flexibility during implantation and minimizes the need to have multiple pre-configured devices to accommodate different patient sizes and implant locations. Conversely, a distal portion of thetether70 will reliably remain intact. Thus, this portion of thetether70 may be used to provide additional structure or functionality.
• As illustrated inFIG. 2, anantenna72 extends from thehousing12 and may be contained within or affixed to an outer portion of thetether70. Including theantenna72 within thetether70 provides a hermitic enclosure for theantenna72 and any exposed feedthrough. The length, size, shape and configuration of theantenna72 may vary from the illustrated embodiment and may extend for a relatively long length as compared to traditional implantable medical devices. Theantenna72 may be used for communication and/or as an RF collector to receive power to recharge thepower source20. Furthermore, while oneantenna structure72 is illustrated, multiple antennas may be provided to facilitate different types of communication; to have a different antenna for transmission versus reception; to provide a separate power collector, to provide low and high power communication formats, to provide redundancy or for any number of reasons. One or more antennas may also be included in thelead body60.
• FIG. 3 illustrates an alternative embodiment, wherein adistal portion80 of thetether70 functions as a lead having anelectrode82 for sensing or stimulation. That is, theelectrode82 is electrically coupled to thehousing12 via thedistal portion80 of thetether70. This electrical coupling may be completely internal to and distinct from thetether70 so that the mechanical properties of thetether70 may be relied upon without adding stress or strain to what would be considered a lead body. Theelectrodes62 and82 may be positioned to facilitate defibrillation across the vector defined. In another embodiment, theelectrode82 acts as a pacing electrode. In yet another embodiment,element82 is a sensor such as a pressure sensor. Theantenna72 ofFIG. 2 is not illustrated, though such an antenna may also be provided when thetether70 includes one or more electrodes and/or sensors. The structure of thetether70 may vary over its length. Thedistal portion80 is not intended to be severed. The proximal portion, in one embodiment, is intended to be severed; thus, atransition point84 may be present. Thetether70 may have different materials and different construction from one portion to another or may have a unitary construction throughout.
• FIG. 4 illustrates anembodiment having lead60 and lead100 extending from the distal header15. Thesecond lead100 is illustrated as having atined tip110 for securement as well as atip electrode112 andring electrode114.FIG. 4 is meant to illustrate that multiple leads may depend from thedistal header16 and a variety of electrode and attachment (e.g., tines, helical tip) configurations may be employed. The use of two such leads is not meant to be limiting and any number of additional leads may be provided. Though not illustrated, one or more additional electrodes may be present ontether70, as illustrated inFIG. 3.
• FIG. 5 illustrates a sectional view ofhousing12. In particular,multiple connection ports150,152,154 and156 are illustrated in the proximal anddistal headers14,16.Port150 includes acavity160 shaped to receive a male connecting pin from, e.g., a lead. Aset screw162 is positioned to advance into thecavity160 and engage the connecting pin, thus securing the pin in place. Access to theset screw162 is gained through a set screw opening165 that may include a self sealing material, such as silicone to reduce fluid entry into the set screw opening after implantation. The configuration ofport150 is repeated in each of the illustratedports152,154 and156. More or fewer ports may be provided as necessary and alternative configurations may be employed. When used to received and secure alead60, the lead pin will make contact with one or more electrical connectors disposed withincavity160. Thetether70 may also include a connector pin thus allowing for connection to thehousing12 in the same manner as a lead. Of course, if thetether70 includes electrode(s), antennas or other components appropriate electrical contact is made via the pin and cavity. In the absence of such components, the tether is simply mechanically secured within theport154,156. As indicated, thetether70 may be integrally formed with theproximal header14, thus appropriate access toports154,156 (if provided) is facilitated by the configuration of thetether70 or by providing access through a portion of thetether70.
• FIGS. 6A and 6B illustrate an alternative multiple lead configuration. In this embodiment, lead60 is coupled with thedistal header16. Asecond lead100′ is coupled with theproximal header14 as is thetether70. In some applications, it may be desirable to have thesecond lead100′ extend in the same direction as thetether70, and as such, connection to theproximal header14 is straight forward. Alternatively, and as illustrated, thelead100′ is extended in the same direction as the first lead60 (i.e., distal to the housing12). When coupled with theproximal header14, thelead100′ is bent to achieve this configuration. While this is non-problematic for thelead100′, movement of thehousing12 via the tether70 (e.g., retracting the housing12) may be more difficult. To permit and facilitate such movement, thelead100′ is bent to provide sufficient excess so that thehousing12 may move relative to thelead100′ without affecting the tip placement. It should be appreciated thelead60, extending from thedistal header16 also includes a certain amount of excess to address normal movement ofhousing12 caused by pulsitile blood flow as well as some movement caused by withdrawal or retraction of thetether70.
• The curvature in the lead100′ may simply be imparted during implant, with thehousing12 remaining separate from thelead100′ other than at theproximal header14. Alternatively, as illustrated inFIG. 6B, aguide member180 may be provided on an outer portion of thehousing12. Thelead100′ passes through theguide member180 maintaining thelead100′ in close proximity to the housing despite the imparted curvature and any resulting bias. In addition, by appropriately sizing theguide member180 and providing a material with a low coefficient of friction (e.g., parylene, silicone) on theguide member180 and/or thelead100′, thehousing12 may be slid relative to thelead100′.
• For clarity, lead60 is not shown inFIG. 6B. It should be appreciated that more than one lead may be coupled to theproximal header14 in the manner illustrated. Furthermore, even if a single lead is employed, that lead may be coupled as illustrated by thelead100′ inFIGS. 6A and 6B. This would allow all connections to be made at one end of thehousing12 while still permitting lead advancement in a direction opposite to that of thetether70.
• FIGS. 7A and 7B illustrate a system including a device that will aid in positioning any of the illustrated leads as well as thehousing12. A steerable stylet (or catheter)200 has ahandle portion202 at a proximal end that includes controls that cause the stylet to flex or bend to facilitate intravascular navigation. A releasable clampingmember210 is positioned at or near a distal end of thestylet200. The clamping member is illustrated schematically inFIG. 7B as a sectional taken about the line A-A ofFIG. 7A. Upon actuation of thehandle portion202, the clampingmember210 opens and closes pivotingarms212 so thatlead100′ (or tether70) is gripped or released. In this manner, thelead100′ is directed to a target location and the clampingmember210 is opened, releasing thelead100′. It should be appreciated that thestylet200 could be navigated as an over the wire catheter, thus following a previously positioned guidewire. The clamping of thelead100′ would remain the same; however, the stylet/catheter200 would be guided by the guide wire as opposed to being navigated independently. As indicated, such a device may be used to position leads coupled with either theproximal head14 or thedistal header16 and may be used to position thehousing12. To position thehousing12, the clamping member may be secured to a portion of an attached lead or to thetether70. Implantation in this manner will be facilitated if the clamping occurs relatively close to thehousing12. Alternatively, a lead extending from thedistal header16 may be gripped at any position distal to thehousing12, so that advancement of the lead withstylet200 advances thehousing12 as well.
• FIGS. 8A-8D illustrate another embodiment wherein asteerable stylet250 is used to position thehousing12.FIG. 8C is a sectional view taken about the line A-A inFIG. 8A andFIG. 8D is a sectional view taken about the line B-B inFIG. 8A. In this embodiment, thetether70 has alumen254 sized to receive thestylet250. While the T-anchor76 is illustrated as being coupled with thetether70, it should be appreciated that the T-anchor76 may be attached afterwards and hence is not utilized with thestylet250 or the T-anchor76 includes a throughbore that aligns with thelumen254, thereby permitting passage of thestylet250. In this embodiment, anabutment252 is provided on an exterior of thehousing12, as part ofproximate header14. Thus, as thestylet250 extends through thelumen254, the tip of thestylet250 will eventually reach and strike theabutment252. Continued advancement of thestylet250 will cause advancement of thehousing12 within a vasculature pathway. If advanced too far, thetether70 may be retracted, thus retracting thehousing12. As such, thehousing12 may be implanted at a target location by using thestylet250 for forward advancement of thehousing12 and thetether70 for any necessary retraction. Leads (not shown in these figures) may be implanted with thestylet200 previously described or similar mechanisms, if utilized.FIG. 8C also illustrates how the antenna72 (if included) is positioned outside of the path defined bylumen254, which is congruent withabutment252.
• FIGS. 9A-9D are similar toFIGS. 8A-8D. In this embodiment, thelumen254 extends through thehousing12 as well as thelead60. Thus, thestylet250 may be advanced all the way through thetether70, thehousing12 and thelead60 until it abuts an end of thelead60. Thus, navigation of thestylet250 will direct the distal end of e.g., lead60 which pulls thehousing12, ultimately positioning that component as well.
• FIGS. 9E-9H illustrate an embodiment havingmultiple lumens254a,254bthroughtether70,housing12 and lead(s)60, with the second lead not illustrated. In this manner thestylet250 can be directed through aspecific lumen254a,254, to engage a particular lead separately from another lead. As should be apparent, more than twolumens254a,254bmay be provided to permit more than two leads or other appendages to be directly manipulated by thestylet250. Further, the size, spacing and configuration of thelumens254 may be varied. In an alternative arrangement, more lumens are provided through thehousing12 and coupled with a corresponding lead than are provided through thetether70. That is, thestylet250 is directed through a lumen in thetether70 and into a larger opening within theproximal header14. The tip of thestylet250 is then manipulated to manually select from a plurality of lumens each extending from this opening through thehousing12 to a particular lead.
• While direct manipulation of thestylet250 to select a desired lumen within thehousing12 is one option, alternative arrangements are available. For example, the tip of thestylet250 may be sized or shaped to specifically engage only one lumen through the opening in theproximal header14. For each such lumen engaged, the tip may be exchanged or adifferent stylet250 may be utilized. As an example, the largest tip may be inserted through the common lumen in thetether70 and will only access the largest sub-lumen passing through thehousing12. While occluding this larger opening, the next smaller tip may be utilized, and again a specific sub-lumen provides the only passage.
• As described, theIVMD10 may include multiple leads with each of these leads attached or coupled with thehousing12. Due to the size and implant location ofIVMD10, particular configuration of thehousing12 may make attachment of more than two leads cumbersome. In fact, in embodiments, the use of more than one lead may be cumbersome. In such a case, the present invention provides for the use ofmultiple IVMDs10, each having one or two leads. Theseparate IVMDs10 are in wireless communication so that their activities are synchronized. For example, one IVMD may provide atrial pacing and another may provide ventricular pacing. Themultiple IVMDs10 may be completely independent and simply communicate to one another to synchronize timing. Alternatively, oneIVMD10 may act to control the functions of one or more other IVMDs. Themultiple IVMDs10 may be implanted through the same entry point and reside in the same anatomical location or proximate one another (e.g., both within the superior vena cava but offset from one another). Alternatively, the multiple IVMDs may be implanted from different locations and reside remotely from one another, while retaining wireless communication.
• FIG. 10 illustrates an embodiment whereinhousing12 is separated into twocomponents12a,12b.Thehousing components12a,12bare operatively coupled together with aflexible interconnect300, which may include one or more wires, cables or fibers for electrical or data communication. Alternatively, theflexible interconnect300 may be a solely a mechanical coupling with eachhousing component12a,12boperating independently. For example, each may have separate functions. Alternatively, thehousing components12a,12bare mechanically coupled and communicate in a wireless medium such as RF. Due to their close proximity, they may also be inductively coupled both for data communication and power transmission functions. Thus, theflexible interconnect300 will mechanically connect theseparate housing components12a,12band may provide electrical, data and/or power couplings. As such, theflexible interconnect300 will act liketether70′ as betweenhousing component12aandhousing component12b.That is, securing the proximal end oftether70′ will ultimately retrainhousing component12bthrough theflexible interconnect300.
• FIG. 10 also schematically illustrates asimplified tether70′ as compared to thetether70 illustrated in previous embodiments.Simplified tether70′ is a generally linear, flexible member such as wire or cord and may be monofilament or multi-filar. Thesimplified tether70′ could be secured to an anchor member such as the T-anchor76, which is then secured to tissue. Alternatively, thesimplified tether70′ could be sutured directly to tissue.
• FIGS. 11A and 11B illustrate another embodiment includingmultiple housing components12aand12b.As shown,housing component12aincludes thelead60 extending from adistal end16. Thetether70 extends in an opposite direction from theproximal end14. A threadedreceptacle310 is axially aligned with a lumen254 (FIGS. 8-9) through thetether70. Thesecond housing component12bincludes a throughbore320 sized to receive thetether70. Thus, thehousing component12bmay be added to or removed from thecomponent12asubsequent to implantation ofcomponent12a.
• Thehousing component12aincludes one ormore receiving channels314a,314bthat receive corresponding connector pins312a,312b.The engagement of connector pins312 within channels314 allows for a mechanical coupling as well as optionally providing for electrical connection through one or all of the connections. The connector pins312 are provided with biasedprotrusions316a,316breceived withindetents318a,318b;thus, locking the connectors pins312 into the channels314 when full inserted. Initial insertion as well as subsequent release of the connector pins312 may require retraction of theprotrusions316 internally via a mechanism that is not illustrated; thus, providing a secure locking mechanism. Alternatively, the spring bias of theprotrusions316 may be overcome by applying sufficient force in an axial direction. Thus, a locking action is formed that will maintain the connection of the twohousing components12aand12bwhile implanted, but does not require additional components for engagement and/or disengagement. It should be appreciated that the size, shape, location, and configuration of the pins312 and channels314 may be varied in numerous ways while remaining within the spirit and scope of the present invention.
• InFIG. 11B,housing component12ais coupled withhousing component12b.Also illustrated is astylet322 having a threaded, taperedtip326. Thestylet326 is inserted through thelumen254 with thetether70. Thestylet326 is advanced until thetip326 reaches the threadedreceptacle310. Rotation of thestylet326 then causes the threadedtip326 to engage thereceptacle310. Once so engaged, liner movement of thestylet322 will correspondingly move thehousing component12a(and12bif coupled as illustrated). Furthermore, once fully engaged, rotation of the stylet in a clockwise (with standard threading) direction will rotate thehousing component12a.Use of thestylet322 in this manner allows for greater positional control of thehousing12awithin the vasculature. While retraction of thetether70 allows for gross movements, the engagedstylet322 permits more precise movement which facilitates the attachment or detachment ofhousing component12b,among other things.
• In one embodiment, thestylet322 is advanced through thetether70 and threaded into thereceptacle310. Thehousing receptacle12bis then advanced over thetether70 using another stylet (see e.g.,FIG. 13B) to push thehousing12b.When thehousing components12a,12bare proximate one another,stylet322 is used (alone or in combination with tether70) to holdhousing component12ain place and rotatehousing component12ato align withhousing component12b.When so aligned, thehousing components12a,12bare joined. It should be appreciated that engagement mechanisms may be provided betweenhousing member12a,12bthat do not require specific alignment. That is, a retaining clip, channel or other member may extend about the circumference of the header of one housing component and a corresponding component may extend circumferentially (fully or partially) about the corresponding header of the other housing component; thus, relative rotational positioning between the two housing components is irrelevant to engagement so long as general axial alignment is provided. For example, rather than having channel314 discretely received a single pin312, the channel314 may extend circumferentially around the proximal planar face of thehousing component12a.Thus, the pin(s)312 may be received anywhere along this channel314. Relative rotation is permitted even whenprotrusions316 and detent318 (which may also be circumferential) are utilized. Alternatively, the detent(s)318 may remain discrete and rotation of thehousing components12a,12bwill cause engagement.
• FIGS. 12A-12D illustrate another embodiment ofstylet322.FIGS. 12A-12C are side sectional views of a tip portion of thestylet322. Initial engagement of the threadedtip326 may be made more difficult since thehousing component12ais relatively free to rotate when implanted. Thestylet322 in the present embodiment includes anouter sheath350 and aninner rod member352. The threaded tapered tip324 retracts and extends from theouter sheath350.
• One or more pins340 extend from theouter sheath350, with twosuch pins340a,340billustrated. The pins340 are sized to easily engage openings342 (with342aand342billustrated). It should be appreciated that more openings342 may be provided than pins340 to again ease initial engagement. As illustrated inFIGS. 12A and 12D, thetip326 is initially retracted within thesheath350 and thestylet322 is spaced fromhousing12. Thestylet322 is advanced until the pins340 engage the openings342, as shown inFIG. 12B. Rotation of thestylet322 may be necessary to achieve this engagement. Again, the fit of the pin340 to the opening342 need not be particularly tight. Subsequent rotation of thestylet322 will cause the pins340 to abut a surface of the openings342. Subsequently, therod352 may be advanced via control at ahandle360 and rotated so thattip326 is threaded into thereceptacle310, thus achieving a secure engagement so that subsequent manipulation of thestylet322 will directly control thehousing12.
• FIGS. 13A and 13B illustrate another embodiment utilizingmultiple housing components12a,12b.In this embodiment, thetether70 is coupled withhousing component12aandhousing component12bis slid over thetether70. A stylet/catheter400 is provided that includes alumen410 sized to receive thetether70. Thus, thestylet400 is also slid overtether70 and is used to pushhousing component12binto engagement withhousing component12a.Though not separately shown, it should be appreciated that thestylet400 may be releasably secured tohousing component12bso that advancement, retraction and rotation of thehousing component12bis facilitated. The manner in which stylet400 is releasably secured tohousing component12bmay vary and may include without limitation any of the coupling arrangements discussed herein.
• FIG. 14 illustrates an embodiment of amulti component housing12, wherein thedistal housing component12bincludes asupplemental tether450. Thesupplemental tether450 may be permanent or temporary. In either case, thetether450 may be used to retracthousing component12bwhile a device such asstylet400 is used to advance thehousing component12b.When permanent, thesupplemental tether450 may be separately sutured at a distal end for securement or may simply be affixed to thetether70.
• FIG. 15 is an embodiment similar to that ofFIG. 14. In this embodiment, thestylet400 includes an outwardly extendingtab460. As thestylet400 is rotated (in either direction), thetab460 will engage thesecondary tether450, causing thehousing component12b,to rotate with thestylet400. Thus, thestylet400 is used to advance and rotate thehousing component12b,without any other coupling required and thesecondary tether450 is used to retract thehousing component12b.
• More than two housing components may be coupled together to form or modify theIVMD10. As previously indicated, different parts of the same device may be separated between housing components. Alternatively or in addition, subsequent housing components may be added to provide additional therapies, diagnostics, capabilities or power. For example, anIVMD10 may be implanted with a single use (i.e., non-rechargeable) battery. At a later point, another housing component may be added that includes a power supply to replace the depleted or soon to be depleted single use battery. Thus, the useful lifetime of a given device may be extended with a relatively minor procedure. AnIVMD10 may initially be implanted having pacing functions and a later module may be added that provides defibrillation therapies.FIG. 16 illustrates one embodiment ofIVMD10 having four joinedhousing components12a,12b,12cand12d.It should be appreciated that any number may be joined using any combination of the embodiments discussed herein. It should further be appreciated that each such component need not have the same size and shape. This will depend upon the components included in any given section ofhousing12 and may take advantage of variations in the vasculature anatomy.
• TheIVMD10 may also be accessed post implant to add components (as discussed above) or to exchange components. That is, rather than simply adding ahousing component12 having anadditional battery20, ahousing portion12 having thebattery20 is first removed over thetether70 and anew housing portion12 is added. In this manner, the lead(s)60 may remain in place, while other portions of the device are removed, replaced or otherwise manipulated. To that end, it should be appreciated that thedistal header16 may take the form of a full orpartial housing component12 that remains in place and is tethered to allow other housing components to be manipulated. Alternatively, thetether70 may be coupled with a distal portion of the lead(s) or lead connector. Thus, theentire housing12 may be added/removed while the lead(s) remains implanted and tethered. Finally, it should be appreciated that the IVMD may provide a variety of functions including sensing, diagnostics and/or therapy. Thus, accessing theIVMD10 via thetether70 allows for other components to be exchanged without removing the entirety of the device. For example, chemical sensors may become depleted of a source material or catalyst and replaced in this manner. Similarly, longer term drug eluting member or drug reservoirs may be replaced. Such reservoirs may contain traditional pharmaceuticals and/or genetic materials or biologics. TheIMVD10 may be used to deliver such agents (e.g., gene therapy) to a target tissue location. When necessary, theIVMD10 is re-supplied without requiring complete extraction or the implantation of another device.
• FIG. 17 illustrates anIVMD10 implanted within thesubclavian vein504 and extending into thesuperior vena cava506 of aheart500. Thelead60 is illustrated as being an atrial pacing lead and adistal tip64 is affixed within theright atrium502. Multiple additional leads may be included. Thetether70 extends from theproximal header14 of thehousing12 through thesubclavian vein504. Theproximal end74 of thetether70 exits thesubclavian vein504 at aninitial entry point600. Theproximal end74 is secured to tissue surrounding theinitial entry point600, by e.g., the T-shapedanchor76 which is sutured to the tissue. As pulsitile blood flow, directed towards theheart500, and patient movement will cause movement of thehousing12, a sufficient amount of slack material is provided along the length of thetether70.
• The position ofhousing12 illustrated inFIG. 17 is non-limiting. If desired, thehousing12 may be positioned closer to theinitial entry point600, thereby increasing the length of thelead60. Conversely, thehousing12 may be positioned closer to or even within theheart500, increasing the length of thetether70 and decreasing the necessary length of thelead60.FIG. 18 illustrates the position of theheart500 relative to thesubclavian vein504 as well as theclavicle620. In some embodiments, it may be desirable to position thehousing12 within thesuperior vena cava506 below (towards the heart500) theclavicle620. This avoids any potential for “subclavian crush” wherein leads or components within the vasculature are compressed between the clavicle and the first rib (not illustrated). The size and nature of a givenIVMD10 will determine whether this is or is not a concern. Due to its size, shape and material properties, this will generally not affect thetether70. Furthermore, implantation via thesubclavian vein504 is only one entry site and others may be utilized.
• As illustrated inFIG. 17, theinitial entry point600 may be positioned quite distant relative to the location of thehousing12.FIG. 19 illustrates the position of thecephalic vein660 which flows into thesubclavian vein504 and is accessible along thearm665 of the patient. Thus, theinitial entry point600 may be made in thecephalic vein660 with thetether70 then anchored to tissue in thearm665.
• After implantation, it may be necessary or desirable to access theIVMD10. Theproximal end74 of thetether70 is located and, e.g., thesubclavian vein504 is accessed. Thehousing12 may be moved or removed/explanted via thetether70 and any associated leads60 can likewise be moved, explanted, tested or otherwise manipulated. In addition, components may be added or replaced onhousing12 without requiring removal. As identification of theproximal end74 of thetether70 facilitates such procedures, theproximal end74 may include a radiopaque marker for identification with various imaging technologies, such as X-ray imaging or fluoroscopy. Of course, the entirety of thetether70 may likewise be radiopaque. Alternatively, or in addition thereto, theproximal end74 may be felt by applying pressure in the area. The configuration and anchoring of theproximal end74 will determine whether this is possible and a balance is selected between patient perception of the proximal end, and the ability to locate thetether70 manually, and the ease or pressure required to locate the tether manually70. As yet another alternative, the subclavian vein504 (or any vein/artery with a tether70) is accessed via a new puncture distal to theproximal end74. Thetether70 is then located and manipulated. This may involve severing thetether70 and if appropriate, reattaching or re-anchoring thetether70.
• As illustrated inFIG. 17, theIVMD10 is secured at two locations; the first being where theproximal end74 of thetether70 is sutured and the second where thelead60 is affixed to the atrial wall. In some embodiments, the nature of the lead60 (or the absence thereof) may permit the distal end of that lead60 or thehousing12 to move freely and remain unsecured. For example, lead60 may include a pressure sensor or temperature sensor. While such sensors may still include an attachment mechanism, it is possible to permit them to remain unattached. In addition to having thetether70 anchored and having one or more leads60 anchored, the flow of blood is directed towards the heart; which generally assists with maintaining the position ofhousing12 as this flow generates force against the anchored portion of thetether70. This represents a relatively simple implantation procedure in that additional retention mechanisms are not required.
• As indicated, thesubclavian vein504 andsuperior vena cava506 are not the only potential implant locations. A variety of other locations will be able to utilize blood flow and gravity in combination with thetether70 to secureIVMD10. Of course,IVMD10 may be implanted in other locations wherein this effect is not available or sufficient. In addition, there may be other reasons to further secure various portions ofIVMD10. In one embodiment, retractable members are provided that expand against a vessel wall to secure theIVMD10. The retractable members are collapsed for subsequent movement or explanation. Such structures are illustrated in published PCT application WO 2004/110263 which is herein incorporated by reference.
• FIG. 20 illustrates anIVMD10 implanted in substantially the same position as illustrated inFIG. 17. In this embodiment, anexpansion member700 is expanded within thesuperior vena cava506.Expansion member700 presses thelead60 against an interior wall of the vessel, further securing thelead60 in place.Expansion member700 may be a self expanding member made from shape-memory material or from material having a spring force that is restrained by e.g., a catheter until deployed. Alternatively,expansion member700 is mechanically expanded by a balloon catheter or similar deployment mechanism. The use of such a member is generally not required when both ends of the IVMD are secured and blood flow is not pulling against an implanted lead. Such an expansion member may be useful when thelead60 is otherwise unsecured orIVMD10 is positioned in a location where blood flow or other forces might negatively affect the implant. It should be appreciated that theexpansion member700 may be used for one or more leads, thehousing12, thetether70 or any combination thereof.
• FIGS. 21A-21J schematically illustrate implantation of theIVMD10. InFIG. 21A, aneedle810 is used to percutaneously pierce and enter avessel802, such as for example the subclavian vein or cephalic vein. Theneedle810 passes through theskin800; in some cases access to thevein802 may require piercing muscle or other tissue. Care is taken with the percutaneously puncture so that the needle does not pass entirely through thevessel802 and into theunderlying tissue804.
• With theneedle810 positioned within thevessel802, aguidewire815 is passed through theneedle810 and into the vessel, as shown inFIG. 21B. While retaining theguidewire815 in place, theneedle810 is withdrawn as illustrated inFIG. 21C. Adeployment catheter820 is inserted (FIG. 21D) into thevessel802 over theguidewire815. A dilation catheter may be used to expand the original puncture or the tissue may be cut if the opening is insufficient. Depending upon the configuration of theIVMD10, theguidewire815 and/or thedeployment catheter820 may be directed to the final implant location for a lead and/or for the housing of theIVMD10. Alternatively, if a stylet or other external mechanism is utilized, thedeployment catheter820 need only provide access to thevessel802 and the length of penetration is selected as desired.
• TheIVMD10 passes through thecatheter820 and enters thevessel802. Again, multiple embodiments have been presented and the order of entry of certain components will vary accordingly. In this example, thelead60 is directed first towards the implant site by e.g., a stylet directed through the lead or a stylet gripping an external portion of the lead; neither of which are illustrated in this figure. Trailing thelead60 is thehousing12 followed by thetether70. When thehousing12 and lead60 are positioned, thetether70 will include an excess amount exiting the incision site as illustrated inFIG. 21F. If additional intravascular securement mechanisms are utilized, they are deployed and configured. Thetether70 is cut (FIG. 21G) at severpoint830 with a sufficient amount of excess provided so that upon anchoring, enough slack remains to allow expected movement of theIVMD10 within the vasculature. The cut tether now has a newproximal end840.
• The newproximal end840 is secured. As discussed, there are multiple methods to attach thetether70. As illustrated, the T-anchor76 is mechanically attached to the new proximal end840 (FIG. 21H). The T-anchor76 is then secured withsutures850 to tissue proximate the incision site (FIG. 21I). The puncture or incision through thevessel802 will heal around thetether70 and if necessary, this process may be aided by additional suturing or other techniques. The T-anchor76 will remain below thesurface860 of theskin800, with the actual depth/distance from thesurface860 determined by the medical practitioner, the depth of the incision, and the site of implant. It should be appreciated that theanchor76 may be affixed to skin tissue, muscle or even the vasculature wall. The final position of theanchor76 may therefore be subcutaneous or submuscular. As illustrated inFIG. 21J, theanchor76 may be secured some distance from thevessel802. This may require an additional minor incision, but allows the anchor point to be selected disparate from the puncture through thevessel802.
• FIGS. 22A and 22B are side elevational sectional views that illustrate an external vasculature anchor900 (EV anchor). As previously discussed, the T-anchor76 is sutured or otherwise attached to tissue external to thevessel802. TheEV anchor900 is configured for direct attachment to an external wall of thevessel802. TheEV anchor900 has anarcuate attachment pad902 with atether connection rod904 depending therefrom. A tether attachment opening906 is provided at a distal end of therod904 so that thetether70 is coupleable to therod904. The rod90 penetrates the vessel802 (though the drawings are not meant to be to scale) and serves as the anchor for thetether70. Thearcuate attachment pad902 is large in comparison to therod904 so that the force generated against thevessel802 is dispersed over a larger surface area.
• TheEV anchor900 includes an interiorconcave surface910 that is placed in contact with the vessel wall. Thissurface910 is subdivided into afirst region915 proximate the rod and the remainder of thesurface920. Various drug eluting or traditional coatings may be applied to theinterior surface910. For example, in thefirst region915, where therod904 enters thevessel802, adhesives, steroids, coagulants or other materials are provided to facilitate the closure and healing of the puncture. Thesecond region920 may be utilized for more adhesion or simply mechanical support. Theattachment pad902 is meant to generally conform to the shape of the exterior wall of thevessel802. To that end, thepad902 may be flexible or malleable. Furthermore, while illustrated as extending about less the half the circumference of thevessels802, it should be appreciated that thepad902 may extend about a greater portion of thevessel802 and may completely surround thevessel802.
• FIG. 23 is a flowchart with an overview of the steps for implanting theIVMD10 consistent with the teachings of the present invention and as described in greater detail above. The appropriate point of entry (e.g., subclavian vein) is identified and a percutaneous puncture is made (1000). If necessary, this opening is enlarged and any necessary catheter, guidewire or stylet is utilized to insert, deliver and attach the housing, leads and any other intravascular components of the IVMD10 (1010). Thetether70 extends from the now deliveredhousing12 to the entry site and excess tether is cut and discarded (1020). Finally, the tether is secure external to the vessel so as to anchor the IVMD10 (1030).
• While various embodiments have been shown and described, the present invention is not meant to be limited by these embodiments. Furthermore, the embodiments may be combined in numerous ways without departing from the teachings of the present invention, even when not specifically illustrated. Variations and modifications may be made without departing from the spirit and scope of the present invention.

Claims (20)

1. An intravascular medical device (IVMD) comprising:

an intravascular housing having a proximal end and a distal end;

a circuit configured to operate the IVMD contained within the housing;

a first lead coupled with the distal end and having a fixation member at a distal end of the lead; and

an elongated tether coupled with the proximal end of the housing.

2. The IVMD ofclaim 1 further comprising:

an electrode disposed along the tether and electrically coupled to the housing through the tether.

3. The IVMD ofclaim 1, further comprising:

an antenna coupled to the circuit through the proximal end of the housing and attached to the tether.

4. The IVMD ofclaim 3, wherein the antenna is disposed within the tether.

5. The IVMD ofclaim 1, wherein the tether further comprises a tether lumen extending through an entirety of the tether.

6. The IVMD ofclaim 5, wherein the housing further comprises a housing lumen extending through the housing wherein the housing lumen is coaxially aligned with the tether lumen.

7. The IVMD ofclaim 6, wherein the lead further comprises a lead lumen extending through at least a portion of the first lead and the lead lumen is coaxially aligned with the housing lumen.

8. The IVMD ofclaim 1, further comprising a second lead coupled with the distal end of the housing.

9. The IVMD ofclaim 8, further comprising:

a first tether lumen extending through the tether;

a first housing lumen extending through the housing:

a first lead lumen extending through the first lead; and

a second lead lumen extending through the second lead.

10. The IVMD ofclaim 1, further comprising a tether anchor coupleable with a proximal end of the tether.

11. The IVMD ofclaim 10, wherein the tether anchor is a T-shaped member including at least one suturing location.

12. The IVMD ofclaim 10, wherein the tether anchor is a malleable, arcuate member having a rod depending from a concave surface, wherein the proximal end of the tether is coupleable to the rod.

13. The IVMD ofclaim 1, wherein the IVMD is a pacemaker.

14. The IVMD ofclaim 1, wherein the IVMD is a defibrillator.

15. The IVMD ofclaim 1, wherein the IVMD is a pacemaker and a defibrillator.

16. The IVMD ofclaim 1, wherein the housing has a diameter of approximately 6-7 French.

17. An intravascular medical device, comprising:

a housing deployable within a vascular structure;

means for delivering a therapy;

means for securing the housing within the vasculature to a site exterior to the vasculature.

18. An intravascular medical device (IVMD) system comprising:

a housing deployable within a vasculature structure;

means for delivering therapy;

means for securing the housing within the vasculature to a site exterior to the vasculature; and

means for delivering the housing to an implant location within the vascular structure.

19. The IVMD system ofclaim 18, wherein the means for securing include a tether having a lumen and the means for delivering include a stylet configured for insertion through the lumen to direct movement of the housing.

20. The IVMD ofclaim 18, wherein the means for delivering include a stylet having means for engaging an exterior of a lead coupled with the housing.

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