US20150196769A1 - Methods and systems for improved communication between medical devices - Google Patents

Abstract

At least one of a first medical device and a second medical device may be implanted within a patient while the second medical device may optionally be proximate but external to the patient. At least one of the medical devices has an antenna having at least two electrodes and at least one of the medical devices has an antenna having at least three electrodes. The medical devices can communicate via conducted communication through the patient's tissue between a first pair of electrodes and a second pair of electrodes. At least one of the pairs of electrodes can be selected in accordance with the signal strength of the communication vector between the first and second pairs of electrodes.

Description

RELATED APPLICATIONS
• This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/926,101 filed Jan. 10, 2014 entitled “METHODS AND SYSTEMS FOR IMPROVED COMMUNICATION BETWEEN MEDICAL DEVICES”, which application is incorporated herein by reference in its entirety.
TECHNICAL FIELD
• The present disclosure generally relates to communication between medical devices, and more particularly, to methods and systems for improved communication between medical devices.
BACKGROUND
• Pacing instruments can be used to treat patients suffering from various heart conditions that may result in a reduced ability of the heart to deliver sufficient amounts of blood to a patient's body. These heart conditions may lead to rapid, irregular, and/or inefficient heart contractions. To help alleviate some of these conditions, various devices (e.g., pacemakers, defibrillators, etc.) can be implanted in a patient's body. Such devices may monitor and provide electrical stimulation to the heart to help the heart operate in a more normal, efficient and/or safe manner. In some cases, a patient may have multiple devices that operate together to detect and/or treat various conditions.
SUMMARY
• The present disclosure generally relates to communication between medical devices, and more particularly, to methods and systems for improved communication between medical devices. For example, a first medical device and a second medical device may be implanted within a patient, or the first medical device may be implanted within the patient and the second medical device may be proximate but external to the patient. At least one of the medical devices may have an antenna with at least two electrodes, and at least one of the medical devices may have an antenna with at least three electrodes. The medical devices may communicate by transmitting signals from two of the electrodes of the transmitting medical device to at least two electrodes of the receiving medical device. It is contemplated that the medical devices may communicate via radiofrequency (RF) communication, inductive coupling, conducted communication, or any other suitable communication technique.
• It will be appreciated that the relative signal strength between any two pairs of electrodes, such as a first pair of electrodes belonging to the transmitting medical device and a second pair of electrodes belonging to the receiving medical device, may depend in part on the orientation of the receiving electrodes relative to the electromagnetic field produced by the transmitting electrodes. The system may be configured to select a particular pair of electrodes for the transmitting medical device and/or the receiving medical device in order help improve the signal strength of communication between the devices. The different combination of electrodes that may be used for communication between medical devices can each be referred to a “communication vector”. In some instances, various communication vectors may be tested, and the communication vector that produces the highest relative signal strength and/or signal-to-noise ratio may be selected for subsequent communication. Various communication vectors may be re-tested periodically, upon command, when the relative signal strength and/or signal-to-noise ratio falls below a threshold, when the relative signal strength and/or signal-to-noise ratio changes by a threshold, and/or at any other suitable time as desired.
• An example method of communicating between a first medical device having a first antenna and a second medical device having a second antenna is disclosed. The first medical device is implanted within a patient and the second medical device is proximate to the patient, and the first antenna and/or the second antenna has at least three electrodes and the other antenna has at least two electrodes. The example method comprises:
• selecting a first electrode pair of the antenna that has at least three electrodes;
• at least one of sending and receiving a conducted communication signal through tissue of the patient between the first electrode pair of the antenna that has at least three electrodes and two of the electrodes of the other antenna;
• selecting a second electrode pair of the antenna that has at least three electrodes, wherein the second electrode pair is different from the first electrode pair; and
• sending a conducted communication signal through tissue of the patient between the second electrode pair of the antenna that has at least three electrodes and two electrodes of the other antenna.
• Alternatively or additionally to any of the embodiments above, the method may further include:
• monitoring a measure related to a signal to noise ratio of the conducted communication signal using the first electrode pair;
• if the measure related to a signal to noise ratio of the conducted communication signal using the first electrode pair falls below a threshold, then:
• • selecting the second electrode pair of the antenna that has at least three electrodes; and
  • sending the conducted communication signal through tissue of the patient between the second electrode pair of the antenna that has at least three electrodes and the two electrodes of the other antenna.
• Alternatively or additionally to any of the embodiments above, the method may further include:
• determining a first measure related to a signal to noise ratio of the conducted communication signal using the first electrode pair;
• determining a second measure related to a signal to noise ratio of the conducted communication signal using the second electrode pair; and
• selecting the first electrode pair or the second electrode pair for subsequent communication based on the first measure and the second measure.
• Alternatively or additionally to any of the embodiments above, the second medical device may be implanted within the patient but spaced from the first medical device.
• Alternatively or additionally to any of the embodiments above, the second medical device may be disposed outside of the patient and the second antenna is positioned on a skin surface of the patient.
• Alternatively or additionally to any of the embodiments above, the antenna that has at least three electrodes may comprise three electrodes that are arranged in a triangular configuration.
• Alternatively or additionally to any of the embodiments above, the antenna that has at least three electrodes may comprise four electrodes that are arranged in a rectangular configuration.
• Alternatively or additionally to any of the embodiments above, the antenna that has at least three electrodes may comprise four electrodes that are arranged in a kite configuration.
• Another example method of communicating between a first medical device having a first antenna with at least two electrodes and a second medical device having a second antenna with at least three electrodes comprises:
• testing communication vectors between the at least two electrodes of the first antenna and each of a plurality of pairs of electrodes of the at least three electrodes of the second antenna;
• selecting a communication vector based on signal strengths of each of the communication vectors; and
• at least one of sending and receiving a conducted communication between the first medical device and the second medical device using the selected communication vector.
• Alternatively or additionally to any of the embodiments above, the first medical device may comprise an implanted medical device and the second medical device may comprise an external device.
• Alternatively or additionally to any of the embodiments above, the first medical device may comprise an external device and the second medical device may comprise an implanted medical device.
• Alternatively or additionally to any of the embodiments above, the first medical device may comprise a first implanted medical device and the second medical device may comprise a second implanted medical device.
• Alternatively or additionally to any of the embodiments above, selecting a communication vector may comprise selecting the communication vector with the strongest signal strength.
• Alternatively or additionally to any of the embodiments above, selecting a communication vector may comprise not selecting the communication vector with the weakest signal strength.
• An example communications system is also disclosed. The example communications system comprises:
• a first medical device in communication with a first antenna having at least two electrodes; and
• a second medical device in communication with a second antenna having at least three electrodes;
• wherein at least one of the first medical device and the second medical device is configured to:
• • test communication vectors between the at least two electrodes of the first antenna and at least two pairs of the at least three electrodes of the second antenna;
  • select a communication vector from the tested communication vectors; and
  • at least one of send and receive a conducted communication along the selected communication vector.
• Alternatively or additionally to any of the embodiments above, the at least three electrodes may comprise three electrodes that are arranged in a triangular configuration.
• Alternatively or additionally to any of the embodiments above, the at least three electrodes may comprise four electrodes that are arranged in a rectangular configuration.
• Alternatively or additionally to any of the embodiments above, the at least three electrodes may comprise four electrodes that are arranged in a kite configuration.
• Alternatively or additionally to any of the embodiments above, at least one of the first medical device and the second medical device may be implanted within a patient.
• Alternatively or additionally to any of the embodiments above, the first medical device is a leadless cardiac pacemaker (LCP).
• The above summary is not intended to describe each embodiment or every implementation of the present disclosure. Advantages and attainments, together with a more complete understanding of the disclosure, will become apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE FIGURES
• The disclosure may be more completely understood in consideration of the following description of various illustrative embodiments in connection with the accompanying drawings, in which:
• FIG. 1 illustrates a block diagram of an exemplary medical device that may be used in accordance with various examples of the present disclosure;
• FIG. 2 illustrates an exemplary leadless cardiac pacemaker (LCP) having electrodes, according to one example of the present disclosure;
• FIG. 3 shows an illustrative system that includes several medical devices in accordance with the present disclosure;
• FIG. 4 is a diagram of an illustrative electromagnetic field that may be generated by an electrode pair;
• FIG. 5 is a diagram of a portion of the electromagnetic field ofFIG. 4, illustrating different geometric arrangements of electrodes relative to the electromagnetic field;
• FIG. 6 is a schematic diagram of a medical device having an illustrative antenna with three electrodes in accordance with various examples of the present disclosure;
• FIG. 7 is a schematic diagram of a medical device having an illustrative antenna with four electrodes in accordance with various examples of the present disclosure;
• FIG. 8 is a schematic diagram of an illustrative arrangement of four electrodes in accordance with various examples of the present disclosure;
• FIG. 9 is a schematic diagram of another illustrative arrangement of four electrodes in accordance with various examples of the present disclosure;
• FIG. 10 shows an illustrative system in accordance with an example of the present disclosure;
• FIG. 11 is a flow diagram of an illustrative method for communicating between medical devices;
• FIG. 12 is a flow diagram showing another illustrative method for communicating between medical devices;
• FIG. 13 is a flow diagram showing yet another illustrative method for communicating between medical devices; and
• FIG. 14 is a flow diagram showing another illustrative method for communicating between medical devices.
• While the disclosure is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit aspects of the disclosure to the particular illustrative embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure.
DETAILED DESCRIPTION
• The following description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The description and the drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the disclosure.
• A normal, healthy heart induces contraction by conducting intrinsically generated electrical signals throughout the heart. These intrinsic signals cause the muscle cells or tissue of the heart to contract. This contraction forces blood out of and into the heart, providing circulation of the blood throughout the rest of the body. However, many patients suffer from cardiac conditions that affect the contractility of their hearts. For example, some hearts may develop diseased tissues that no longer generate or conduct intrinsic electrical signals. In some examples, diseased cardiac tissues conduct electrical signals at differing rates, thereby causing an unsynchronized and inefficient contraction of the heart. In other examples, a heart may generate intrinsic signals at such a low rate that the heart rate becomes dangerously low. In still other examples, a heart may generate electrical signals at an unusually high rate. In some cases such an abnormality can develop into a fibrillation state, where the contraction of the patient's heart is almost completely de-synchronized and the heart pumps very little to no blood.
• Many medical device systems have been developed to assist patients who experience such abnormities. For example, systems have been developed to sense intrinsic cardiac electrical signals and, based on the sensed electrical signals, determine whether the patient is suffering from one or more arrhythmias. Such systems may also include the ability to deliver electrical stimulation to the heart of the patient in order to treat the detected arrhythmias. In one example, some medical device systems include the ability to identify when the heart is beating at too low of a rate, termed bradycardia. Such systems may deliver electrical stimulation therapy, or “pacing” pulses, that cause the heart to contract at a higher, safer rate. Some medical device systems are able to determine when a heart is beating at too fast of a rate, termed tachycardia. Such systems may further include one or more anti-tachycardia pacing (ATP) therapies. One such ATP therapy includes delivering electrical stimulation pulses to the heart at a rate faster than the intrinsically generated signals. Although this may temporarily cause the heart to beat faster, such a stimulation protocol may cause the heart to contract in response to the delivered pacing pulses as opposed to the intrinsically generated signals. The ATP therapy may then slow down the rate of the delivered pacing pulses, thereby reducing the heart rate to a lower, safer level.
• Other medical device systems may be able to detect fibrillation states and asynchronous contractions. For example, based on the sensed signals, some systems may be able to determine when the heart is in a fibrillation state. Such systems may further be configured to treat such fibrillation states with electrical stimulation therapy. One such therapy includes deliver of a relatively large amount of electrical energy to the heart (a “defibrillation pulse”) with the goal of overpowering any intrinsically generated signals.
• Such a therapy may “reset” the heart, from an electrical standpoint, which may allow for normal electrical processes to take over. Other medical systems may be able to sense that intrinsically generated signals are generated at differing times or that the heart conducts such signals at differing rates. These abnormalities may result in an unsynchronized, inefficient cardiac contraction. The system may further include the ability to administer one or more cardiac resynchronization therapies (CRTs). One such CRT may include delivering electrical stimulation to the heart at differing locations on and/or within the heart. Such methods may help the disparate parts of the heart to contract near simultaneously, or in a synchronized manner if the system delivers the electrical stimulation to the disparate locations at differing times. The present disclosure relates generally to systems and methods for coordinating detection and/or treatment of abnormal heart activity using multiple implanted devices within a patient. In some instances, a medical device system may include a plurality of devices for detecting cardiac arrhythmias and delivering electrical stimulation therapy. For example, illustrative systems may include devices such as subcutaneous cardioverter-defibrillators (S-ICD), external cardioverter-defibrillators, implantable cardiac pacemakers (ICP), leadless cardiac pacemakers (LCPs), and/or diagnostic only devices (devices that may sense cardiac electrical signals and/or determine arrhythmias but do not deliver electrical stimulation therapies).
• FIG. 1 illustrates a block diagram of an exemplary medical device100 (referred to hereinafter as, MD100) that may be used in accordance with various examples of the present disclosure. In some cases, theMD100 may be used for sensing intrinsic cardiac activity, determining occurrences of arrhythmias, and delivering electrical stimulation in response to determining an occurrence of an arrhythmia. In some instances,MD100 can be implanted within a patient's body, at a particular location (e.g., in close proximity to the patient's heart), to sense and/or regulate the cardiac activity of the heart. In other examples,MD100 may be located externally to a patient to sense and/or regulate the cardiac activity of the heart. In one example, cardiac contractions generally result from electrical signals that are intrinsically generated by a heart. These electrical signals conduct through the heart tissue, causing the muscle cells of the heart to contract.MD100 may include features that allowMD100 to sense such electrical signals and/or other physical parameters (e.g. mechanical contraction, heart sounds, blood pressure, blood-oxygen levels, etc.) of the heart. Such electrical signals and/or physical properties may be considered “cardiac activity.”MD100 may include the ability to determine occurrences of arrhythmias based on the sensed cardiac activity. In some examples,MD100 may be able to deliver electrical stimulation to the heart in order to treat any detected arrhythmias. For example,MD100 may be configured to deliver electrical stimulation, pacing pulses, defibrillation pulses, and/or the like in order to implement one or more therapies, such as bradycardia therapy, ATP therapy, CRT, defibrillation, or other electrical stimulation therapies.
• FIG. 1 is an illustration of an examplemedical device100. Theillustrative MD100 may include asensing module102, apulse generator module104, aprocessing module106, atelemetry module108, and abattery110, all housed within ahousing120.MD100 may further include leads112, andelectrodes114 attached tohousing120 and in electrical communication with one or more of themodules102,104,106, and108 housed withinhousing120.Leads112 may be connected to and extend away fromhousing120 ofMD100.
• In some examples, leads112 are implanted on or within the heart of the patient.Leads112 may contain one ormore electrodes114 positioned at various locations onleads112 and distances fromhousing120. Some leads112 may only include asingle electrode114 while other leads112 may includemultiple electrodes114. Generally,electrodes114 are positioned onleads112 such that when leads112 are implanted within the patient, one ormore electrodes114 are in contact with the patient's cardiac tissue. Accordingly,electrodes114 may conduct intrinsically generated electrical signals to leads112.Leads112 may, in turn, conduct the received electrical signals to one ormore modules102,104,106, and108 ofMD100. In a similar manner,MD100 may generate electrical stimulation, and leads112 may conduct the generated electrical stimulation toelectrodes114.Electrodes114 may then conduct the electrical signals to the cardiac tissue of the patient. When discussing sensing intrinsic signals and delivering electrical stimulation, this disclosure may consider such conduction implicit in those processes.
• Sensing module102 may be configured to sense the cardiac electrical activity of the heart. For example,sensing module102 may be connected toleads112 andelectrodes114 throughleads112 andsensing module102 may be configured to receive cardiac electrical signals conducted throughelectrodes114 and leads112. In some examples, leads112 may include various sensors, such as accelerometers, blood pressure sensors, heart sound sensors, blood-oxygen sensors, and other sensors which measure physiological parameters of the heart and/or patient. In other examples, such sensors may be connected directly tosensing module102 rather than to leads112. In any case,sensing module102 may be configured to receive such signals produced by any sensors connected tosensing module102, either directly or through leads112.Sensing modules102 may additionally be connected toprocessing module106 and may be configured to communicate such received signals toprocessing module106.
• Pulse generator module104 may be connected toelectrodes114. In some examples,pulse generator module104 may be configured to generate an electrical stimulation signals to provide electrical stimulation therapy to the heart. For example,pulse generator module104 may generate such a signal by using energy stored inbattery110 withinMD100.Pulse generator module104 may be configured to generate electrical stimulation signals in order to provide one or multiple of a number of different therapies. For example,pulse generator module104 may be configured to generate electrical stimulation signals to provide bradycardia therapy, tachycardia therapy, cardiac resynchronization therapy, and fibrillation therapy. Bradycardia therapy may include generating and delivering pacing pulses at a rate faster than the intrinsically generated electrical signals in order to try to increase the heart rate. Tachycardia therapy may include ATP therapy as described herein. Cardiac resynchronization therapy may include CRT therapy also described herein. Fibrillation therapy may include delivering a fibrillation pulse to try to override the heart and stop the fibrillation state. In other examples,pulse generator104 may be configured to generate electrical stimulation signals to provide electrical stimulation therapies different than those described herein to treat one or more detected arrhythmias.
• Processing module106 can be configured to control the operation ofMD100. For example,processing module106 may be configured to receive electrical signals fromsensing module102. Based on the received signals,processing module106 may be able to determine occurrences of arrhythmias. Based on any determined arrhythmias,processing module106 may be configured to controlpulse generator module104 to generate electrical stimulation in accordance with one or more therapies to treat the determined one or more arrhythmias.Processing module106 may further receive information fromtelemetry module108. In some examples,processing module106 may use such received information in determining whether an arrhythmia is occurring or to take particular action in response to the information.Processing module106 may additionally controltelemetry module108 to send information to other devices.
• In some examples,processing module106 may include a pre-programmed chip, such as a very-large-scale integration (VLSI) chip or an application specific integrated circuit (ASIC). In such embodiments, the chip may be pre-programmed with control logic in order to control the operation ofMD100. By using a pre-programmed chip,processing module106 may use less power than other programmable circuits while able to maintain basic functionality, thereby increasing the battery life ofMD100. In other examples,processing module106 may include a programmable microprocessor. Such a programmable microprocessor may allow a user to adjust the control logic ofMD100, thereby allowing for greater flexibility ofMD100 than when using a pre-programmed chip. In some examples,processing module106 may further include a memory circuit andprocessing module106 may store information on and read information from the memory circuit. In other examples,MD100 may include a separate memory circuit (not shown) that is in communication withprocessing module106, such thatprocessing module106 may read and write information to and from the separate memory circuit.
• Telemetry module108 may be configured to communicate with devices such as sensors, other medical devices, or the like, that are located externally toMD100. Such devices may be located either external or internal to the patient's body. Irrespective of the location, external devices (i.e. external to theMD100 but not necessarily external to the patient's body) can communicate withMD100 viatelemetry module108 to accomplish one or more desired functions. For example,MD100 may communicate sensed electrical signals to an external medical device throughtelemetry module108. The external medical device may use the communicated electrical signals in determining occurrences of arrhythmias.MD100 may additionally receive sensed electrical signals from the external medical device throughtelemetry module108, andMD100 may use the received sensed electrical signals in determining occurrences of arrhythmias.Telemetry module108 may be configured to use one or more methods for communicating with external devices. For example,telemetry module108 may communicate via radiofrequency (RF) signals, inductive coupling, optical signals, acoustic signals, conducted communication signals, or any other signals suitable for communication. Communication techniques betweenMD100 and external devices will be discussed in further detail with reference toFIG. 3 below.
• Battery110 may provide a power source toMD100 for its operations. In one example,battery110 may be a non-rechargeable lithium-based battery. In other examples, the non-rechargeable battery may be made from other suitable materials know in the art. Because, in examples whereMD100 is an implantable device, access toMD100 may be limited, it is necessary to have sufficient capacity of the battery to deliver sufficient therapy over a period of treatment such as days, weeks, months, or years. In other examples,battery110 may a rechargeable lithium-based battery in order to facilitate increasing the useable lifespan ofMD100.
• In general,MD100 may be similar to one of a number of existing medical devices. For example,MD100 may be similar to various implantable medical devices. In such examples,housing120 ofMD100 may be implanted in a transthoracic region of the patient.Housing120 may generally include any of a number of known materials that are safe for implantation in a human body and may, when implanted, hermetically seal the various components ofMD100 from fluids and tissues of the patient's body.
• In some examples,MD100 may be an implantable cardiac pacemaker (ICP). In such an example,MD100 may have one or more leads, for example leads112, which are implanted on or within the patient's heart. The one or more leads112 may include one ormore electrodes114 that are in contact with cardiac tissue and/or blood of the patient's heart.MD100 may also be configured to sense intrinsically generated cardiac electrical signals and determine, for example, one or more cardiac arrhythmias based on analysis of the sensed signals.MD100 may further be configured to deliver CRT, ATP therapy, bradycardia therapy, defibrillation therapy and/or other therapy types vialeads112 implanted within the heart.
• In some instances,MD100 may be a subcutaneous cardioverter-defibrillator (S-ICD). In such examples, one ofleads112 may include a subcutaneously implanted lead. In some cases,MD100 may be configured to sense intrinsically generated cardiac electrical signals and determine one or more cardiac arrhythmias based on analysis of the sensed signals.MD100 may further be configured to deliver one or more defibrillation pulses in response to determining an arrhythmia.
• In still other examples,MD100 may be a leadless cardiac pacemaker (LCP—described more specifically with respect toFIG. 2). In such examples,MD100 may not include leads112 that extend away fromhousing120. Rather,MD100 may includeelectrodes114 coupled relative to thehousing120. In these examples,MD100 may be implanted on or within the patient's heart at a desired location, and may be configured to deliver CRT, ATP therapy, bradycardia therapy, and/or other therapy types viaelectrodes114.
• In some instances,MD100 may be a diagnostic-only device. In some cases,MD100 may be configured to sense, or receive, cardiac electrical signals and/or physical parameters such as mechanical contraction, heart sounds, blood pressure, blood-oxygen levels, etc.MD100 may further be configured to determine occurrences of arrhythmias based on the sensed or received cardiac electrical signals and/or physical parameters. In one example,MD100 may do away withpulse generation module104, asMD100 may not be configured to deliver electrical stimulation in response to determining an occurrence of an arrhythmia. Rather, in order to respond to detected cardiac arrhythmias,
• MD100 may be part of a system of medical devices. In such a system,MD100 may communicate information to other devices within the system and one or more of the other devices may take action, for example delivering electrical stimulation therapy, in response to the receive information fromMD100. The term pulse generator may be used to describe any such device that is capable of delivering electrical stimulation therapy to the heart, such as an ICD, ICP, LCP, or the like. In some instances, theMD100 may be a neural stimulation device, or any other medical device, as desired.
• In some example,MD100 may not be an implantable medical device. Rather,MD100 may be a device external to the patient's body, and may include skin-electrodes that are placed on a patient's body. In such examples,MD100 may be able to sense surface cardiac electrical signals (e.g. electrical signals that are generated by the heart or device implanted within a patient's body and conducted through the body to the skin) In such examples,MD100 may still be configured to deliver various types of electrical stimulation therapy. In other examples, however,MD100 may be a diagnostic-only device, a neurostimulator, and/or other implantable medical devices.
• FIG. 2 is an illustration of an exemplary leadless cardiac pacemaker (LCP)200. In the example shown,LCP200 may include all of the modules and components ofMD100, except thatLCP200 may not include leads112. As can be seen inFIG. 2,LCP200 may be a compact device with all components housed withinLCP200 or directly onhousing220. As illustrated inFIG. 2,LCP200 may includetelemetry module202,pulse generator module204,processing module210, andbattery212. Such components may have a similar function to the similarly named modules and components as discussed in conjunction withMD100 ofFIG. 1.
• In some examples,LCP200 may includeelectrical sensing module206 andmechanical sensing module208.Electrical sensing module206 may be similar tosensing module102 ofMD100. For example,electrical sensing module206 may be configured to receive electrical signals generated intrinsically by the heart.Electrical sensing module206 may be in electrical connection withelectrodes214, which may conduct the intrinsically generated electrical signals toelectrical sensing module206.Mechanical sensing module208 may be configured to receive one or more signals representative of one or more physiological parameters of the heart. For example,mechanical sensing module208 may include, or be in electrical communication with one or more sensors, such as accelerometers, blood pressure sensors, heart sound sensors, blood-oxygen sensors, and other sensors which measure physiological parameters of the patient. Although described with respect toFIG. 2 as separate sensing modules, in some examples,electrical sensing module206 andmechanical sensing module208 may be combined into a single module.
• In at least one example, each ofmodules202,204,206,208, and210 illustrated inFIG. 2 may be implemented on a single integrated circuit chip. In other examples, the illustrated components may be implemented in multiple integrated circuit chips that are in electrical communication with one another. All ofmodules202,204,206,208, and210 andbattery212 may be encompassed withinhousing220.Housing220 may generally include any material that is known as safe for implantation within a human body and may hermetically sealmodules202,204,206,208, and210 andbattery212 from fluids and tissues whenLCP200 is implanted within a patient.
• As depicted inFIG. 2,LCP200 may includeelectrodes214, which can be secured relative tohousing220 but exposed to the tissue and/or blood surrounding theLCP200. As such,electrodes214 may be generally disposed on either end ofLCP200 and may be in electrical communication with one or more ofmodules202,204,206,208, and210. In some examples,electrodes214 may be connected tohousing220 only through short connecting wires such thatelectrodes214 are not directly secured relative tohousing220. In some examples,LCP200 may additionally include one ormore electrodes214′.Electrodes214′ may be positioned on the sides ofLCP200 and increase the number of electrodes by whichLCP200 may sense cardiac electrical activity and/or deliver electrical stimulation.Electrodes214 and/or214′ can be made up of one or more biocompatible conductive materials such as various metals or alloys that are known to be safe for implantation within a human body. In some instances,electrodes214 and/or214′ connected toLCP200 may have an insulative portion that electrically isolates theelectrodes214 from, adjacent electrodes, thehousing220, and/or other materials.
• To implantLCP200 inside patient's body, an operator (e.g., a physician, clinician, etc.), may need to affixLCP200 to the cardiac tissue of the patient's heart. To facilitate fixation,LCP200 may include one or more anchors216.Anchor216 may be any one of a number of fixation or anchoring mechanisms. For example,anchor216 may include one or more pins, staples, threads, screws, helix, tines, and/or the like. In some examples, although not shown,anchor216 may include threads on its external surface that may run along at least a partial length ofanchor216. The threads may provide friction between the cardiac tissue and the anchor to help fixanchor216 within the cardiac tissue. In other examples,anchor216 may include other structures such as barbs, spikes, or the like to facilitate engagement with the surrounding cardiac tissue.
• The design and dimensions ofMD100 andLCP200, as shown inFIGS. 1 and 2, respectively, can be selected based on various factors. For example, if the medical device is for implant on the endocardial tissue, such as is sometimes the case of an LCP, the medical device can be introduced through a femoral vein into the heart. In such instances, the dimensions of the medical device may be such as to be navigated smoothly through the tortuous path of the vein without causing any damage to surrounding tissue of the vein. According to one example, the average diameter of the femoral vein may be between about 4 millimeters (mm) to about 8 mm. For navigation to the heart through the femoral vein, the medical device can have a diameter of less than8 mm In some examples, the medical device can have a cylindrical shape having a circular cross-section. However, it should be noted that the medical device can be made of any other suitable shape such as rectangular, oval, etc. A flat, rectangular-shaped medical device with a low profile may be desired when the medical device is designed to be implanted subcutaneously.
• WhileIMD100 andLCP200 are described as suitable example medical devices, it is contemplated that the present disclosure is applicable more broadly to communication between any two (or more) medical devices.
• FIG. 3 is a schematic illustration of amedical device system300. As illustrated,medical device system300 includes afirst MD310, asecond MD320 and athird MD330. Each ofMD310,MD320 andMD330 can represent any of a variety of different medical devices that are configured to deliver electrical stimulation, pacing pulses, defibrillation pulses, or the like in order to implement one or more therapies, such as ATP therapy, CRT, or other electrical stimulation therapies, or are diagnostic only or other medical devices, as desired. Each ofMD310,MD320 andMD330 can include leads or be leadless. It will be appreciated that while three medical devices are shown inFIG. 3,system300 may include just one or two medical devices, or may include four or more medical devices, depending on the particular application.
• In some embodiments, each ofMD310,MD320 andMD330, if present, may be implanted and/or positioned proximate the patient. In some embodiments,MD310 may be implanted,MD320 may be external to the patient andMD330 may be optional.MD320 may include a skin patch including two or more electrodes. In some cases, one or more ofMD310,MD320 andMD330 may be a medical device programmer or communicator that is configured to communicate with and/or program one or more implanted medical device. For example,MD320 may be a medical device programmer or communicator that is configured to communicate with and/or program one or more implanted medical device - such asMD310 andMD330. In some embodiments,MD310 may be implanted within the patient andMD320 and/orMD330 may also be implanted within the patient but be spaced apart fromMD310 and from each other.
• As illustrated,MD310 includes afirst electrode312 and asecond electrode314.MD320 includes afirst electrode322, asecond electrode324 and athird electrode326.MD330 includes afirst electrode332, asecond electrode334, athird electrode336 and afourth electrode338. In this example,MD310 has asingle electrode pair315 that can be used to sense, pace and/or communicate with another medical device.MD320 has afirst electrode pair325 betweenfirst electrode322 andsecond electrode324, asecond electrode pair327 betweensecond electrode324 andthird electrode326, and athird electrode pair329 betweenfirst electrode322 andthird electrode326 that can each be used, either individually or in combination, to sense, pace and/or communicate with another medical device.MD330 has afirst electrode pair333 betweenfirst electrode332 andsecond electrode334, asecond electrode pair335 betweensecond electrode334 andthird electrode336, athird electrode pair337 betweenthird electrode336 andfourth electrode338, afourth electrode pair339 betweenfirst electrode332 andfourth electrode338, afifth electrode pair331 betweenfirst electrode332 andthird electrode336 and asixth electrode pair341 betweensecond electrode334 andfourth electrode338 that can each be used, either individually or in combination, to sense, pace and/or communicate with another medical device.
• It will be appreciated that the relative signal strength received at a particular electrode pair can be a function of, at least in part, the relative orientation of the electrode pair relative to the electromagnetic field that is being generated by a transmitting electrode pair.FIG. 4 is a stylized or idealizedelectromagnetic field400 generated by an electrode pair, which includes acathode electrode410 and ananode electrode420. This is a stylizedelectromagnetic field400 as it would appear in a homogenous conducting medium. As the patient's tissue near and around medical devices is not homogenous, the actual electromagnetic field would vary from that shown. Theelectromagnetic field400 can be considered as includingequipotential lines430 and electric field lines440.FIG. 5 provides anenlarged portion500 illustrating the effects of electrode orientation relative to theequipotential lines430 and the electric field lines440.
• In the illustration ofFIG. 5, it is assumed that a medical device includes afirst electrode510, asecond electrode520 and athird electrode530. A first electrode pair vector A may be considered as existing betweenfirst electrode510 andsecond electrode520. A second electrode pair vector B may be considered as existing betweenfirst electrode510 andthird electrode530. A third electrode pair vector C may be considered as existing betweensecond electrode520 andthird electrode530. It will be appreciated that the relative signal strength between one of electrode pair vectors A, B and C will be influenced by the angle between the receiving antenna (one of the electrode pair vectors A, B and C) and the local electric field produced by the transmitting antenna (cathode410 andanode420 as shown inFIG. 4). As can be seen, the received signal will be the signal strength times the cosine of theangle0 between the corresponding electrode pair vector A, B or C and the electric field lines440. The electrode pair vectors each represent a pair of electrodes of the medical device. A particular one the electrode pairs A, B, or C selected for communication, in combination with an electrode pair of the transmitting antenna (e.g. cathode410 andanode420 as shown inFIG. 4) can be considered a “communication vector”.
• As illustrated, electrode pair vector A forms an angle OA that is90 degrees. As the cosine of90 degrees is zero, electrode pair vector A (betweenfirst electrode510 and second electrode520) would not receive a signal. Electrode pair vector B forms an angle AB that is 15 degrees. The cosine of 15 degrees is 0.97, and thus electrode pair vector B would receive a signal that is 97% of the strength of the signal at that location. Electrode pair vector C forms an angle Ac that is 45 degrees. The cosine of 45 degrees is 0.71, and thus electrode pair vector C would receive a signal that is 71% of the strength of the signal at that location. It will be appreciated, therefore, that by having several electrode pairs, or electrode pair vectors, to choose from may facilitate thedevices MD310,MD320 andMD330 of system300 (FIG. 3) in selecting an electrode pair or electrode pair vector that helps increase the relative signal strength and/or signal-to-noise ratio for communication therebetween. The angles shown inFIG. 5 are illustrative only, as in practice the medical device that includeselectrodes510,520 and530 may have any particular orientation with respect to electromagnetic field400 (FIG. 4), and the orientation may change over time as the patient breathes, the heart pumps, or the patient otherwise moves. It is contemplated that a medical device may have two, three, four or more electrodes that can be utilized in pairs to help improve communication between medical devices.
• FIG. 6 illustrates a medical device (MD)600 that includes afirst electrode610, asecond electrode620 and athird electrode630. A total of threeelectrode pair vectors640,650 and660 may be formed using the three electrodes ofMD600.MD600 may represent an implanted medical device or an external medical device.MD600 may, in some cases, represent an external patch that is secured to the skin of a patient, and may communicate with an implanted medical device such as a leadless cardiac pacemaker (LCP). As illustrated,electrodes610,620 and630 are equally spaced forming an equilateral triangle. In some embodiments,electrodes610,620 and630 may instead be unequally spaced, thereby forming a non-equilateral triangle.
• FIG. 7 illustrates a medical device (MD)700 that includes afirst electrode710, asecond electrode720, athird electrode730 and afourth electrode740. InFIG. 7, a total of6electrode pair vectors750,752,754,756,758 and760 may be formed using the electrodes ofMD700.MD700 may represent an implanted medical device or an external medical device.MD700 may, for example, represent an external patch that is secured to the skin of a patient. As illustrated,electrodes710,720,730 and740 are spaced aboutMD700 in a kite pattern. In some embodiments,electrodes710,720,730 and740 may instead be spaced aboutMD700 in a variety of different patterns. It will be appreciated that the relative angles between pairs ofelectrodes710,720,730 and740 may be varied by altering the relative dimensions, i.e., length and/or width of the spacings between the electrodes ofMD700.
• FIGS. 8 and 9 provide additional examples of possible electrode pair vector angles in medical devices having4 electrodes arranged in a rectilinear configuration (FIG. 8) or in a kite like configuration (FIG. 9). It will be appreciated that these are illustrative only, as the angles inFIG. 8 may be altered by changing the relative length and width of a square or rectangle extending through the four electrodes. Similarly, the angles inFIG. 9 may be altered by changing the relative length and width of a kite-shape extending through the four electrodes.
• It can be seen that having two electrodes can provide a situation in which there can be no or substantially no signal strength at the location of a receiving antennae, depending on orientation of the receiving antennae relative to the emitted electric field. Having three electrodes provides three possible electrode pair vectors that can be selected, whereby selecting the electrode pair vector with the greatest signal strength, may help improve the signal strength received by the receiving antennae. Having four electrodes provides six possible electrode pair vectors that can be selected. In some cases, and to provide even more vectors, two or more of the electrodes may be effectively shorted together so that the shorted electrodes collectively act as an electrode. For example, and specifically with respect toFIG. 7,electrodes730 and740 may be effectively shorted together and may act as a single electrode (e.g. anode), andelectrode710 orelectrode720 may act as the other electrode (e.g. the cathode). This is just one example.
• In some instances, the medical devices described herein, includingMD100,LCP200,MD310,MD320,MD330,MD600 orMD700 may be programmed or otherwise configured to test various communication vectors and to select the appropriate communication vector for communication. In some embodiments, the strongest communication vector may be selected. In some embodiments, the weakest communication vector may be excluded from use. In some embodiments, depending on the purpose of the communication, several communication vectors may be used in combination.
• In some instances, one vector may be used during a first part of a single communication and a second vector may be used during a second part of the communication. This may occur when, for example, a device programmer or an S-ICD is communicating with a LCP. The LCP may be moving during each beat of the heart, and the angles between the various electrodes may change over time. In some cases, it may be advantageous to use a first vector to start communication, and then as the LCP moves, switch to a second vector to complete the communication.
• Alternatively, or in addition, communication may be simultaneously performed using two or more vectors. This may provide one or more redundant communication paths, so that if one communication path becomes less effective or drops out, then the redundant communication path(s) can be used. For example, and specifically with respect toFIG. 7, communication may be simultaneously performed using afirst vector754 extending betweenelectrodes730 and740 and asecond vector758 extending betweenelectrodes720 and740. Then, if communication using thefirst vector754 becomes less effective or drops out, the system can still communicate using thesecond vector758. In some cases, communication may be performed simultaneously using both vectors, and the system may select the communication path with the highest signal strength, the communication path that provided successful transmission, and/or may use any other criteria for selecting from the two or more communication paths. In some cases, a communication may be performed using multiple vectors, and the results may be compared. If there is no difference in the results, then either result may be used. If there is a difference, other criteria may be used to help identify the correct result. For example, a parity bit and/or checksum may be used to identify which transmissions were successful. If no transmissions were successful, a signal may be sent notifying the sender to repeat the transmission using a different vector or set of vectors.
• FIG. 10 provides an illustrative medical system in which anLCP782 is shown fixed to the interior of the left ventricle of aheart788 and anLCP784 is shown fixed to the interior of the right ventricle ofheart788. In some embodiments, there may be additional LCPs implanted inheart788. In other cases, there may only be one LCP, such asLCP784. In some embodiments, one or more LCPs may be fixed to the exterior of theheart788. InFIG. 10, anexample SICD786 is shown. Theexample SICD786 includes a lead790 bearing one ormore electrodes792,794 and796. In some embodiments, thelead790 may include more than three electrodes. In some cases, oncelead790 has been implanted,electrodes792,794 and796 may be considered as being aligned vertically proximate the patient's sternum. Optionally, an additional electrode may be disposed on a horizontal (once implanted) portion oflead790. It will be appreciated that as illustrated,SICD786 may be considered as having a total of four electrodes, as the housing ofSICD786 may also function as an electrode. In some instances, lead790 may be positioned subcutaneouslyadjacent heart788. In some cases, the illustrative medical system may include an external patch such asMD700 previously discussed with respect toFIG. 7 for connecting to, for example, an external medical device.
• In some cases, there may be a desire for communication between two or more ofLCP782,LCP784,SICD786 and/or anMD700. It will be appreciated, for example, that for communication between theLCP782 andMD700, there may be a total of four (or more) electrodes onMD700 and two to four (or more) electrodes onLCP782, and thus many different communication vectors may be tested and selected as discussed previously. In some cases, particularly in conducting communication betweenSICD786 and any of the other devices shown, it will be appreciated thatelectrodes792,794 and796 are arranged in a largely linear fashion near a distal end oflead790. Accordingly, in some cases, selecting between these three electrodes for use in a communication vector with anLCP872 or784 may not substantially change the geometry of the vector and thus may not substantially improve the communication vector. In some embodiments, communication withSICD786 may benefit from also considering one or more can electrodes, such as can electrode797 of theSICD786. When so provided, the SICD may have fourdifferent electrodes792,794,796 and797, and eachLCP782 and784 may have two to four (or more) electrodes. This may provide many vectors to choose from with a variety of different vector geometries. Alternatively, or in addition, theSICD electrodes792,794 and796 may be arranged in a non-linear manner, such as in a cross-pattern.
• One or all of theelectrodes792,794,796,797 and theSCID786 housing may be used only for communication; alternatively one or all of theelectrodes792,794,796,797 and theSCID786 housing may also be used for other purposes such as sensing a physiological parameter (e.g. intrinsic cardiac activity, thoracic impedance) and/or delivering one or more electrical therapies (e.g. cardioversion/defibrillation shocks, cardiac paces, neural stimulation energy).
• In some cases, it will be appreciated that which specific vector or vectors are most useful for communicating between any particular pair of devices may change over time. For example,LCP782 and/orLCP784, if present, may move and change orientation somewhat with each heartbeat. As the patient breathes, and their chest rises and falls, theSICD786 and an external device such asMD700 may also move. Accordingly, in some embodiments, it may be advantageous to use a first vector for part of a communication, and then as one or more devices move relative to one another, such as with the heartbeat and/or patient respiration, switch to a second vector to continue the communication. In some cases, signal strength, error rate and/or communication parameter may be monitored over time, and the vector may be automatically switched if desired. While a first and second vector are used here an example, it is contemplated that the system may switch between more than two different vectors if desired. It is contemplated that the vectors may be switched in real or near real time, and/or may be updated from time to time, e.g. every minute, hour, day, month, each doctor visit, and/or any other suitable time.
• FIG. 11 is a flow diagram showing anillustrative method1000 that may be carried out via any of the medical devices described herein, includingMD100,LCP200,
• MD310,MD320,MD330,MD600 orMD700. Atblock1010, a first electrode pair of an antenna having at least three electrodes is selected. A communication signal, such as a conducted communication signal, may be sent through tissue of the patient between the first electrode pair of the antenna having at least three electrodes and two electrodes of another antenna, as generally seen atblock1020. Atblock1030, a second electrode pair of the antenna having at least three electrodes is selected. The second electrode pair selected being different from the first selected electrode pair. A communication signal is again sent through tissue of the patient between the first electrode pair of the antenna having at least three electrodes and two electrodes of another antenna, as generally seen atblock1040.
• FIG. 12 is a flow diagram showing anillustrative method1100 that may be carried out via any of the medical devices described herein, includingMD100,LCP200,MD310,MD320,MD330,MD600 orMD700. Atblock1110, a first electrode pair of an antenna having at least three electrodes is selected. A communication signal is sent through tissue of the patient between the first electrode pair of the antenna having at least three electrodes and two electrodes of another antenna, as generally seen atblock1120. Atblock1130, a second electrode pair of the antenna that has at least three electrodes is selected. The second electrode pair is different from the first selected electrode pair. A communication signal may be sent through tissue of the patient between the first electrode pair of the antenna having at least three electrodes and two electrodes of another antenna, as generally seen atblock1140.
• During operation, and as seen atblock1150, a measure related to a signal-to-noise ratio of the conducted communication signal using the first electrode pair may be monitored. If the measure related to the signal-to-noise ratio falls below a threshold or changes by more than a threshold, the second electrode pair of the antenna having at least three electrodes is selected, as generally shown atblock1160. Atblock1170, a communication signal may then be sent through tissue of the patient between the second electrode pair of the antenna having at least three electrodes and the two electrodes of the other antenna.
• FIG. 13 is a flow diagram showing anillustrative method1200 that may be carried out via any of the medical devices described herein, includingMD100,LCP200,
• MD310,MD320,MD330,MD600 orMD700. Atblock1210, a first electrode pair of an antenna having at least three electrodes is selected. A communication signal is sent through tissue of the patient between the first electrode pair of the antenna having at least three electrodes and two electrodes of another antenna, as generally seen atblock1220. Atblock1230, a second electrode pair of the antenna that has at least three electrodes is selected. The second electrode pair is different from the first selected electrode pair. A communication signal is sent through tissue of the patient between the first electrode pair of the antenna having at least three electrodes and two electrodes of another antenna, as generally seen atblock1240.
• During operation, and asblock1280, a first measure related to a signal-to-noise ratio of the communication signal using the first electrode pair is determined. A second measure related to a signal-to-noise ratio of the communication signal using the second electrode pair is determined, as generally indicated atblock1290. Atblock1292, the first electrode pair or the second electrode pair is selected for subsequent communication based on the first measure and the second measure.
• FIG. 14 a flow diagram showing anillustrative method1300 that may be carried out via any of the medical devices described herein, includingMD100,LCP200,MD310,MD320,MD330,MD600 orMD700. Atblock1310, communication vectors are tested between at least two electrodes of a first antenna and each of a plurality of pairs of electrodes of a second antenna that has at least three electrodes. In an embodiment, a communication vector is tested periodically, for example once per second, minute, day or month. In another embodiment, a communication vector is tested only when a communication parameter fails to meet a predetermined criteria. In some embodiments, a communication vector is tested during an office visit. In other embodiments, a communication vector is tested during an interaction between a medical device and an external system that is configured to provide device or patient data to a clinician at a remote location. A communication vector is selected based on a communication parameter of one or more of the communication vectors, as generally indicated atblock1320. The communication parameter could, for example, be an absolute signal strength, a relative signal strength and/or a signal-to-noise ratio, or any other parameter affecting or potentially affecting communication. Atblock1330, a conducted communication is sent between a first medical device and a second medical device using the selected communication vector.
• As detailed above, the medical devices referenced herein may by any suitable medical device. In some non-limiting example, themethods1000,1100,1200,1300 may be used in communication between an LCP and a medical device programmer or communicator, an LCP and an Sub-coetaneous Implantable Cardioverter Defibrillator (SICD), an LCP and a co-implanted diagnostic device, an LCP and a neurostimulator device, an LCP and another LCP, and/or between any other suitable medical devices, as desired.
• In some embodiments, any of these methods described herein could embody receiving a communication instead or, or in addition to, sending a communication signal. In some embodiments, a selection or determination of a communication vector used for sending a communication signal may be the same as a communication vector used for receiving a communication signal. In some embodiments, a selection or determination of a communication vector used for sending a communication signal may be different than a communication vector used for receiving a communication signal.
• Those skilled in the art will recognize that the present disclosure may be manifested in a variety of forms other than the specific embodiments described and contemplated herein. As one example, as described herein, various examples include one or more modules described as performing various functions. However, other examples may include additional modules that split the described functions up over more modules than that described herein. Additionally, other examples may consolidate the described functions into fewer modules. Accordingly, departure in form and detail may be made without departing from the scope and spirit of the present disclosure as described in the appended claims.

Claims (20)

What is claimed is:

1. A method of communicating between a first medical device having a first antenna and a second medical device having a second antenna, wherein the first medical device is implanted within a patient and the second medical device is proximate to the patient, and wherein the first antenna and/or the second antenna has at least three electrodes and the other antenna has at least two electrodes, the method comprising:

selecting a first electrode pair of the antenna that has at least three electrodes;

at least one of sending and receiving a conducted communication signal through tissue of the patient between the first electrode pair of the antenna that has at least three electrodes and two of the electrodes of the other antenna;

selecting a second electrode pair of the antenna that has at least three electrodes, wherein the second electrode pair is different from the first electrode pair; and

sending a conducted communication signal through tissue of the patient between the second electrode pair of the antenna that has at least three electrodes and two electrodes of the other antenna.

2. The method ofclaim 1, further comprising:

monitoring a measure related to a signal to noise ratio of the conducted communication signal using the first electrode pair;

if the measure related to a signal to noise ratio of the conducted communication signal using the first electrode pair falls below a threshold, then:

selecting the second electrode pair of the antenna that has at least three electrodes; and

sending the conducted communication signal through tissue of the patient between the second electrode pair of the antenna that has at least three electrodes and the two electrodes of the other antenna.

3. The method ofclaim 1, further comprising:

determining a first measure related to a signal to noise ratio of the conducted communication signal using the first electrode pair;

determining a second measure related to a signal to noise ratio of the conducted communication signal using the second electrode pair; and

selecting the first electrode pair or the second electrode pair for subsequent communication based on the first measure and the second measure.

4. The method ofclaim 1, wherein the second medical device is implanted within the patient but spaced from the first medical device.

5. The method ofclaim 1, wherein the second medical device is disposed outside of the patient and the second antenna is positioned on a skin surface of the patient.

6. The method ofclaim 1, wherein the antenna that has at least three electrodes comprises three electrodes that are arranged in a triangular configuration.

7. The method ofclaim 1, wherein the antenna that has at least three electrodes comprises four electrodes that are arranged in a rectangular configuration.

8. The method ofclaim 1, wherein the antenna that has at least three electrodes comprises four electrodes that are arranged in a kite configuration.

9. A method of communicating between a first medical device having a first antenna with at least two electrodes and a second medical device having a second antenna with at least three electrodes, the method comprising:

testing communication vectors between the at least two electrodes of the first antenna and each of a plurality of pairs of electrodes of the at least three electrodes of the second antenna;

selecting a communication vector based on signal strengths of each of the communication vectors; and

at least one of sending and receiving a conducted communication between the first medical device and the second medical device using the selected communication vector.

10. The method ofclaim 9, wherein the first medical device comprises an implanted medical device and the second medical device comprises an external device.

11. The method ofclaim 9, wherein the first medical device comprises an external device and the second medical device comprises an implanted medical device.

12. The method ofclaim 9, wherein the first medical device comprises a first implanted medical device and the second medical device comprises a second implanted medical device.

13. The method ofclaim 9, wherein selecting a communication vector comprises selecting the communication vector with the strongest signal strength.

14. The method ofclaim 9, wherein selecting a communication vector comprises not selecting the communication vector with the weakest signal strength.

15. A communication system, comprising:

a first medical device in communication with a first antenna having at least two electrodes; and

a second medical device in communication with a second antenna having at least three electrodes;

wherein at least one of the first medical device and the second medical device is configured to:

test communication vectors between the at least two electrodes of the first antenna and at least two pairs of the at least three electrodes of the second antenna;

select a communication vector from the tested communication vectors; and

at least one of send and receive a conducted communication along the selected communication vector.

16. The communication system ofclaim 15, wherein the at least three electrodes comprise three electrodes that are arranged in a triangular configuration.

17. The communication system ofclaim 15, wherein the at least three electrodes comprise four electrodes that are arranged in a rectangular configuration.

18. The communication system ofclaim 15, wherein the at least three electrodes comprise four electrodes that are arranged in a kite configuration.

19. The communication system ofclaim 15, wherein at least one of the first medical device and the second medical device are implanted within a patient.

20. The communication system ofclaim 15, wherein the first medical device is a leadless cardiac pacemaker (LCP).

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