Abstract: Electrical stimulation may be delivered to a patient's heart using a plurality of cardiac electrodes. Each electrode combination may be evaluated based on one or more first parameters and one or more second parameters. In many cases, the one or more first parameters are supportive of cardiac function consistent with a prescribed therapy and the one or more second parameters are not supportive of cardiac function consistent with the prescribed therapy. The electrode combination selected to deliver a cardiac pacing therapy may be more associated with the one or more first parameters supportive of cardiac function consistent with the prescribed therapy and less associated with the one or more second parameters inconsistent with cardiac function.

Abstract: An autonomic status indicator representative of a sympathetic/parasympathetic balance of a subject can use atrioventricular (AV) delays measured during recovery from (or in response to) elevated atrial pacing while the subject is at rest.

Abstract: A method and device for detecting arrhythmias in a patient that includes electrodes positioned subcutaneously within the patient, a microprocessor, coupled to the electrodes, determining one of a sequence of the sensing of cardiac signals by the electrodes and a duration between the sensing of cardiac signals by the electrodes, and control circuitry delivering a therapy in response to one of the determined sequence and the determined duration.

Abstract: Techniques are described for detecting lead-related conditions for implantable electrical leads. In some of the described embodiments, an implantable electrical lead assembly is provided with a coupling member for connecting a conductor and associated insulator(s) to an electrode/sensing element. The implantable medical device controls and performs a measurement of an electrical property of the electrical lead during periods when the conductor is decoupled from the electrode/sensing element. An indication of a lead-related condition is derived based on the measured electrical property. The lead-related condition may be associated with an insulator of a lead body of the electrical lead.

Abstract: An implantable device for providing electrical stimulation of cervical vagus nerves for treatment of chronic cardiac dysfunction with leadless heart rate monitoring is provided. A stimulation therapy lead includes helical electrodes configured to conform to an outer diameter of a cervical vagus nerve sheath, and a set of connector pins electrically connected to the helical electrodes. A neurostimulator includes an electrical receptacle into which the connector pins are securely and electrically coupled. The neurostimulator also includes a pulse generator configured to therapeutically stimulate the vagus nerve through the helical electrodes in alternating cycles of stimuli application and stimuli inhibition that are tuned to both efferently activate the heart's intrinsic nervous system and afferently activate the patient's central reflexes by triggering bi-directional action potentials.

Abstract: Systems and methods are provided for graphically configuring leads for a medical device. According to one aspect, the system generally comprises a medical device and a processing device, such as a programmer or computer, adapted to be in communication with the medical device. The medical device has at least one lead with at least one electrode in a configuration that can be changed using the processing device. The processing device provides a graphical display of the configuration, including a representative image of a proposed electrical signal to be applied by the medical device between the at least one electrode of the medical device and at least one other electrode before the medical device applies the electrical signal between the at least one electrode and the at least one other electrode. In one embodiment, the graphical display graphically represents the lead(s), the electrode(s), a pulse polarity, and a vector.

Abstract: Energy delivered from an implantable medical device to stimulate tissue within a patient's body is controlled. An electrical signal used to stimulate the tissue is changed from a first energy state to a second energy state during a magnetic resonance imaging (MRI) scan. The energy delivered is maintained at the second energy state after the MRI scan. A capture threshold of the tissue is then measured, and the energy delivered to the tissue is adjusted based on the measured capture threshold of the tissue.

Abstract: An apparatus comprises a cardiac signal sensing circuit, a pacing therapy circuit, and a controller circuit. The controller circuit includes a safety margin calculation circuit. The controller circuit initiates delivery of pacing stimulation energy to the heart using a first energy level, changes the energy level by at least one of: a) increasing the energy from the first energy level until detecting that the pacing stimulation energy induces stable capture, or b) reducing the energy from the first energy level until detecting that the stimulation energy fails to induce capture, and continues changing the stimulation energy level until confirming stable capture or the failure of capture. The safety margin calculation circuit calculates a safety margin of pacing stimulation energy using at least one of a determined stability of a parameter associated with evoked response and a determined range of energy levels corresponding to stable capture or intermittent failure of capture.

Abstract: Methods and systems are disclosed for determining whether a patient is a responder to cardiac resynchronization therapy. The beginning and ending of the intrinsic ventricular depolarization are determined through signals measured from one or more electrodes implanted in the patient's heart. An interval between the beginning and ending of the intrinsic ventricular depolarization is computed and is compared to a threshold. The threshold may be determined empirically. The pacing parameters of a heart stimulation device, such as a pacemaker, may then be configured, for example, by setting the paced atrio-ventricular delay based on whether the patient responds positively to cardiac resynchronization therapy.

Abstract: A medical device includes a pulse generator, a lead, and an electrode. The lead includes an electrode and a lead conductor connecting the pulse generator with the electrode via first and second conductive paths. The medical device includes first and second switches. The first switch is disposed along the first conductive path and includes an open state in the presence of a magnetic field and a closed state in the absence of the magnetic field. The second switch is disposed along the second conductive path and includes an open state when a voltage applied across the second switch is at or below a threshold voltage and a closed state when the voltage applied across the second switch exceeds a threshold voltage.

Abstract: A lead connection system includes a connector housing. A plurality of lead retainers disposed in the connector housing are configured and arranged to removably attach to a proximal end of one of a received plurality of leads. The plurality of lead retainers include at least one of a slidable drawer and at least one pivotable hinged panel. A plurality of connector contacts are configured and arranged for making electrical contact with one or more of the terminals of one or more of the plurality of received leads. A single connector cable has a distal end that is electrically coupled to the plurality of connector contacts and a proximal end that is configured and arranged for insertion into a trial stimulator. A cable connector is electrically coupled, via the connector contacts, to at least one terminal of each of the received plurality of leads.

Abstract: One embodiment of the present invention relates to an implantable medical device (“IMD”) that can be programmed from one operational mode to another operational mode when in the presence of electro-magnetic interference (“EMI”). In accordance with this particular embodiment, the IMD includes a communication interface for receiving communication signals from an external device, such as a command to switch the IMD from a first operation mode to a second operation mode. The IMD further includes a processor in electrical communication with the communication interface, which is operable to switch or reprogram the IMD from the first operation mode to the second operation mode upon receiving a command to do so. In addition, the IMD includes a timer operable to measure a time period from when the processor switches the IMD to the second operation mode.

Abstract: A device senses cardioelectrical signals using a right atrial (RA) lead, which might include far-field R-waves as well as near-field P-waves. The device concurrently senses events using a proximal electrode of an LV lead, which can sense both P-waves and R-waves as substantially near-field events. Suitable templates are then applied to the signals sensed via the proximal LV electrode to identify the origin of the signals (e.g. atrial vs. ventricular) so as to properly classify the corresponding events sensed in the RA as near-field or far-field events. In this manner, far-field oversensing is conveniently detected.

Abstract: A programming-device user interface may include multiple levels of abstraction for programming treatment settings. A stimulation zone-programming interface may be at a highest level of abstraction and may include idealized stimulation zones. A field strength-programming interface may be at a middle level of abstraction and may include electromagnetic field-strength patterns generated by the stimulation zones, and/or electrode settings, and a depiction of how the electromagnetic fields interact with each other. An electrode-programming interface may be at a lowest level of abstraction and may depict treatment settings at an electrodes-view level. These interfaces may include a display of a stimulatable area of the patient's body. The display may include a depiction of leads and/or the underlying physiology, such as a depiction of a portion of a spine. Algorithms map treatment settings from one level of abstraction to settings at one or more other levels of abstraction.

Abstract: A method for monitoring a biological cardiac pacemaker is provided. The method may include stimulating a heart at a region selected for implantation of a biological pacemaker and sensing at least one electrical signal indicative of a cardiac depolarization originating in the region selected for implantation of the biological pacemaker. The method may further include sensing at least one subsequent electrical signal produced by the heart and determining if the subsequent electrical signal originated in the region selected for the biological pacemaker or another region of the heart. In an alternative embodiment, the method may include determining a template time difference between two points on cardiac complexes sensed in two or more different cardiac locations during normal sinus rhythm. The method may further include determining a time difference between two points on a subsequent cardiac complex sensed in two or more different cardiac locations.

Abstract: An implantable device for providing electrical stimulation of cervical vagus nerves for treatment of chronic cardiac dysfunction with leadless heart rate monitoring is provided. A stimulation therapy lead includes helical electrodes configured to conform to an outer diameter of a cervical vagus nerve sheath, and a set of connector pins electrically connected to the helical electrodes. A neurostimulator includes an electrical receptacle into which the connector pins are securely and electrically coupled. The neurostimulator also includes a pulse generator configured to therapeutically stimulate the vagus nerve through the helical electrodes in alternating cycles of stimuli application and stimuli inhibition that are tuned to both efferently activate the heart's intrinsic nervous system and afferently activate the patient's central reflexes by triggering bi-directional action potentials.

Abstract: A method, system, and apparatus for performing a lead condition assessment and/or a lead orientation determination associated with an implantable medical device (IMD). A first impedance is determined. The first impedance relates to the impedance relative to a first electrode and a portion of the IMD. A second impedance is determined. The second impedance relates to the impedance relative to a second electrode and the portion of the IMD. The first impedance is compared with the second impedance to determine an impedance difference. A determination is made whether the impedance difference is outside a predetermined tolerance range. Furthermore, artifact measured during impedance measurements or test pulses may be compared to assess lead orientation. An indication of a lead condition error is provided in response to determining that the impedance difference is outside the predetermined tolerance range.

Abstract: A method and system of post-processing of sensing data generated by a medical device that includes transmitting a plurality of stored sensing data generated by the medical device to an access device, the stored sensing data including sensed atrial events and sensed ventricular events. The access device determines, in response to the transmitted data, instances where the medical device identified a cardiac event being detected in response to the sensing data, and determines, in response to the transmitted sensing data, whether one of the sensed ventricular events and the sensed atrial events is initiating conduction of a heart associated with the stored sensing data.

Abstract: Embodiments of the present invention relate to monitoring a patient's atrial stretch, heart failure (HF) condition, and/or risk of atrial fibrillation (AF), as well as methods for estimating a change in at least one of a patient's left atrial pressure (LAP), pulmonary capillary wedge pressure (PCWP), and right pulmonary artery pressure (RPAP). Embodiments of the present invention also relate to selecting a pacing energy level. Such embodiments involve determining atrial evoked response metrics when a patient's atrium is paced, and monitoring changes in such metrics.

Abstract: Methods and devices are described that allow estimation of an electrostimulation capture threshold, such as a dedicated bipolar pacing vector threshold. In an example, an equal-energy assumption between first and second pacing vectors can be used to estimate an electrostimulation capture threshold of a second pacing vector from a measured electrostimulation capture threshold of the first pacing vector and impedances of the first and second pacing vectors. In an example, a relationship between first and second pacing vectors can be determined from measured data, and a parameter of the relationship can be used with a measurement of an electrostimulation capture threshold of the first pacing vector to estimate an electrostimulation capture threshold of the second pacing vector.

Abstract: Methods and devices for classifying a cardiac pacing response involve using a first electrode combination for pacing and a second electrode combination for sensing a cardiac signal following pacing. The cardiac response to pacing may be classified using the sensed cardiac signal. One process involves using the sensed cardiac signal to detect the cardiac response as a fusion/pseudofusion beat. Another process involves using the sensed cardiac signal to classify the cardiac response to pacing as one of at least three cardiac response types.

Abstract: A failure detection and warning system for monitoring a medical device wherein the system includes means structured to passively or actively detect faults occurring in the medical device being monitored, and wherein the fault includes an unprogrammed and/or undesired shut off of the medical device being monitored or an unprogrammed and/or undesired shut-off of the output of the medical device being monitored by the system.

Abstract: The disclosure described techniques for associating therapy adjustments with intended patient posture states. The techniques may include receiving a patient therapy adjustment to a parameter of a therapy program that defines electrical stimulation therapy delivered to the patient, identifying a posture state of the patient, and associating the patient therapy adjustment with the posture state when the patient therapy adjustment is within a range determined based on stored adjustment information for the identified posture state.

Abstract: A multi-function defibrillator having an improved mode selection switch (200). When the switch is rotated to select the desired mode of operation, such as defibrillation, cardio-version, pacing, or monitoring, the positioning of those modes related to the Off position (205) is based on the time-criticality of the corresponding therapy. The most time-critical therapy is located closest to the Off position, and the least time-critical therapy is located furthest away from the Off position.

Abstract: An active medical device such as pacemaker, defibrillator and/or resynchronizer with automatic optimization of atrioventricular delay is disclosed. The active medical device is adapted for analyzing a signal delivered by a hemodynamic sensor such as an endocardial acceleration sensor, whose variation according to the AVD is represented by a sigmoid function. An optimal AVD is searched by: applying a reference AVD (XC), at least one left AVD (XL, XLL) and at least one right AVD (XR, XRR); measuring the corresponding hemodynamic parameters (Y1, Y2, Y3, Y4, Y5); evaluating the second derivative of the function at the respective points (XC, Y3; XL, Y2, XR, Y4) of the characteristic corresponding to the reference AVD, to the left AVD and to the right AVD; estimating from these values of second derivatives, the position of an intermediate point of the characteristic for which the second derivative is zero or minimum, and determining the corresponding AVD for that intermediate point as the optimal AVD.

Abstract: A medical device having a unit in communication with ancillary components wherein the unit and the ancillary components each have a sensory output through which communication with a user of the medical device may be accomplished and to which the user's attention directed. In one aspect, the medical device is an AED unit with associated pads, which are an ancillary component electrically connected to the AED unit. In this illustrative example, the unit has a unit sensory output (e.g., a speaker or a display), and the pads, and/or their associated packaging, have an ancillary sensory output (e.g. a speaker or display). Programming in the AED unit controls output to the sensory outputs such that the user's attention is directed between the unit and the ancillary components.

Abstract: A method is provided of tissue ablation during a tissue ablation procedure. Ablation energy is applied by using a tissue ablation device to create an ablation at a tissue site. An ablation endpoint at the tissue site is detected by using an ablation endpoint device with one or more sensors that are positioned to monitor the ablation. The one or more sensors are selected from at least one of, a piezoelectric and a silicon MEMS sensor. Upon detecting the ablation endpoint, delivery of ablation energy to the tissue site ceases.

Abstract: A method is provided of tissue ablation during a tissue ablation procedure. Ablation energy is applied by using a tissue ablation device to create an ablation at a tissue site. An ablation endpoint at the tissue site is detected by using an ablation endpoint device with one or more sensors that are positioned to monitor the ablation. The one or more sensors are selected from at least one of, a piezoelectric and a silicon MEMS sensor. Upon detecting the ablation endpoint, delivery of ablation energy to the tissue site ceases.

Abstract: Systems and methods for determining the coronary sinus vein branch location of a left ventricle electrode are disclosed. The systems and methods involve detecting the occurrence of electrical events within the patient's heart including sensing one or more of the electrical events with the electrode and then analyzing the electrical events to determine the electrode's position. The determination of electrode position may be used to automatically adjust operating parameters of a VRT device. Furthermore, the determination of electrode position may be made in real-time during installation of the electrode and a visual indication of the electrode position may be provided on a display screen.

Abstract: Vector selection is automatically achieved via a thoracic or intracardiac impedance signal collected in a cardiac function management device or other implantable medical device that includes a test mode and a diagnostic mode. During a test mode, the device cycles through various electrode configurations for collecting thoracic impedance data. At least one figure of merit is calculated from the impedance data for each such electrode configuration. In one example, only non-arrhythmic beats are used for computing the figure of merit. A particular electrode configuration is automatically selected using the figure of merit. During a diagnostic mode, the device collects impedance data using the selected electrode configuration. In one example, the figure of merit includes a ratio of a cardiac stroke amplitude and a respiration amplitude. Other examples of the figure of merit are also described.

Abstract: Techniques are provided for use by implantable medical devices such as cardiac resynchronization therapy (CRT) devices for detecting pulmonary edema based on transthoracic impedance sensed using cardiac pacing/sensing leads, wherein detection can be performed while lead maturation occurs. Briefly, the implantable device determines whether the leads are within an initial post-implant interval following implant during which lead maturation generally occurs. The device then detects pulmonary edema or related medical conditions within the patient based on transthoracic impedance using a set of detection parameters adjusted for use during the post-implant interval. Thus, rather than “blanking” impedance data during lead maturation, the device instead detects and processes impedance during this period to identify possible episodes of pulmonary edema so that appropriate measures can be undertaken, such as delivery of warnings or titration of appropriate medications.

Abstract: An implantable device for facilitating control of electrical stimulation of cervical vagus nerves for treatment of chronic cardiac dysfunction is provided. A stimulation therapy lead includes helical electrodes configured to conform to an outer diameter of a cervical vagus nerve sheath, and a set of connector pins electrically connected to the helical electrodes. A neurostimulator includes an electrical receptacle into which the connector pins are securely and electrically coupled. The neurostimulator also includes a pulse generator configured to therapeutically stimulate the vagus nerve through the helical electrodes in alternating cycles of stimuli application and stimuli inhibition that are tuned to both efferently activate the heart's intrinsic nervous system and afferently activate the patient's central reflexes by triggering bi-directional action potentials.

Abstract: A medical device includes an energy storage device, a plurality of electrodes, a memory, a switching circuit, and a processing module. The energy storage device stores electrical energy for delivery of defibrillation therapy to a heart. The memory stores N therapy configurations, each of the N therapy configurations defining which of the plurality of electrodes are used to deliver defibrillation therapy and further defining a waveform to be applied during delivery of defibrillation therapy. The switching circuit is configured to connect the plurality of electrodes to the energy storage device.

Abstract: A method for detecting potential failures by a lead of an implantable medical device is provided. The method includes sensing a first signal over a first channel between a first combination of electrodes on the lead and sensing a second signal from a second channel between a second combination of electrodes on the lead. The method determines whether at least one of the first and second signals is representative of a potential failure in the lead and identifies a failure and the electrode associated with the failure based on which of the first and second sensed signals is representative of the potential failure. Optionally, when the first and second sensed signals are both representative of the potential failure, the method further includes determining whether the first and second sensed signals are correlated with one another. When the first and second sensed signals are correlated, the method declares an electrode common to both of the first and second combinations to be associated with the failure.

Abstract: A system for monitoring trends in lead impedance includes collecting data from various sources in an implantable medical device system. Lead impedance, non-physiologic sensed events percentage of time in mode switch, results of capture management operation, sensed events, adversion pace counts, refractory sense counts and similar data are used to determine the status of a lead. A set of weighted sum rules are implemented by a software system to process the data and provide displayable information to health care professionals via a programmer. The lead monitoring system includes a patient alert system for patients to seek help in the event a serious lead condition is identified.

Abstract: The invention relates to a service unit (30) having an interface (54) for receiving data from a personal medical device, an analysis unit (52) connected to the interface (54) for analyzing data received from the personal medical device (10), and an aftercare appointment determination unit (54) for determining a particular next aftercare appointment at least on the basis of data received from a particular personal medical device (10).

Abstract: A system comprising an implantable medical device that comprises a memory circuit, a radiation detector circuit configured to detect a condition correlative to a high-energy radiation level that exceeds a background radiation level, and a controller circuit. The control circuit checks memory locations for errors using a first rate of error checking per time period during a normal operation mode and, in response to the radiation detector circuit indicating a high-energy radiation level, initiates a memory scrubbing mode, wherein the memory scrubbing mode has an increased rate of error checking substantially all memory locations per time period in the memory circuit to check for any errors and correct any such errors.

Abstract: This document discusses, among other things, systems and methods for automatic electrode integrity management. Interelectrode impedance is measured for various electrode combinations of an implantable cardiac function management device. The impedance data is processed, such as at an external remote server, to determine whether an electrode is failing or has failed, to select an alternate electrode configuration, to alert a physician or patient, to predict a time-to-failure such as by using population data, or to reprogram electrode configuration or other device parameters of the implantable cardiac function management device.

Abstract: A method and system for recording changes to programmable parameters in an implantable pulse generator. An executable program is stored in an implantable pulse generator. A parameter log is maintained in the implantable pulse generator, where the parameter log is used to record changes to the state of one or more programmable parameters of the executable program. When a change is detected in the state, from a first state to a second state, of the one or more programmable parameters the first state of the one or more programmable parameters changed to the second state are recorded in the parameter log. The parameter log is retrievable to allow for analysis of when and how changes took place to the executable program.

Abstract: Methods, systems, and devices for signal analysis in an implanted cardiac monitoring and treatment device such as an implantable cardioverter defibrillator. In illustrative examples, sensed data including detected events is analyzed to identify likely overdetection of cardiac events. In some illustrative examples, when overdetection is identified, data may be modified to correct for overdetection, to reduce the impact of overdetection, or to ignore overdetected data.

Abstract: An IMD may transition to an MRI mode automatically in response to detecting one or more conditions indicative of the presence of a strong magnetic field. Large static magnetic fields, such as those produced by an MRI device, may interact with the blood of a patient as it flows through the magnetic field to produce a voltage, a phenomenon referred to as the magnetohydrodynamic (MHD) effect. The voltage produced by the MHD effect is proportional to the strength of the magnetic field. As such, the voltage produced by blood flow in the strong magnetic field of an MRI device may result in a change in a characteristic of an electrogram (EGM). The IMD may detect the change in the characteristic of the EGM caused by the MHD effect and transition to operation in the MRI mode in response to at least the change in the EGM.

Abstract: An implantable medical device (IMD) may include a lead circuit including a first node configured to be coupled to a first lead that may be coupled to a first target tissue and including a second node configured to be coupled to a second lead that may be coupled to a second target tissue. The IMD may include an impedance unit that may determine at least one characteristic of coupled energy associated with the lead circuit, where the coupled energy may be produced by a source external to the IMD. The impedance unit may provide an impedance between the first node and the second node, where the impedance is selected based at least in part on a characteristic of the coupled energy. The impedance is selected to reduce the coupled energy or a negative effect associated with functionality of the IMD induced by the coupled energy.

Abstract: This disclosure provides a pacing technique that reduces the effect of oversensing caused by noise on pacing therapy. The IMD delivers a pacing pulse subsequent to sensing an electrical signal on the lead when the sensed electrical signal coincides with an independently detected noise signal and the sensed electrical signal occurs during a period of time of an expected intrinsic cardiac signal. The IMD may, in some instances, trigger delivery of the pacing pulse during the escape interval instead of waiting for the escape interval to expire. Pacing in accordance with the techniques of this disclosure may allow for improved therapy during an MRI procedure by decreasing the risk associated with inappropriate pacing inhibition as well as decreasing the risk associated with pacing during the vulnerable period of the cardiac cycle.

Abstract: A method of left ventricular pacing including automated adjustment of a atrio-ventricular (AV) pacing delay interval and intrinsic AV nodal conduction testing. It includes—upon expiration or reset of a programmable AV Evaluation Interval (AVEI)—performing the following: temporarily increasing a paced AV interval and a sensed AV interval and testing for adequate AV conduction and measuring an intrinsic atrio-ventricular (PR) interval for a right ventricular (RV) chamber. In the event that the AV conduction test reveals an AV conduction block condition then a pacing mode-switch to a bi-ventricular (Bi-V) pacing mode occurs and the magnitude of the AVEI is increased.

Abstract: A method and apparatus implementing the method, which is not dependent on monitoring the electrical impedance of the lead, detects imminent structural failure of an electrical lead in an implanted medical device, such as an implantable cardioverter-defibrillator (ICD) or a pacemaker. The approach is to monitor directly the mechanical load loss of the lead (a measure of the loss of structural integrity of the lead) rather than, as in the prior art, to infer it from the electrical impedance.

Abstract: Various aspects of the present subject matter relate to a method. According to various method embodiments, cardiac activity is detected, and neural stimulation is synchronized with a reference event in the detected cardiac activity. Neural stimulation is titrated based on a detected response to the neural stimulation. Other aspects and embodiments are provided herein.

Abstract: In some aspects, a method includes measuring unipolar signals at one or more electrodes in response to electrical activity in a heart cavity. The method also includes determining, based at least in part on Laplace's equation, bipolar physiological information at multiple locations of an surface based on the measured unipolar signals and positions of the one or more electrodes with respect to the surface.

Abstract: A method and system of post-processing of sensing data generated by a medical device that includes transmitting a plurality of stored sensing data generated by the medical device to an access device, the stored sensing data including sensed atrial events and sensed ventricular events. The access device determines, in response to the transmitted data, instances where the medical device identified a cardiac event being detected in response to the sensing data, and determines whether there is an abrupt onset of the cardiac event in response to the transmitted data.

Abstract: An implantable medical device for optically sensing action potential signals in excitable body tissue. The device includes an elongated tubular lead body carrying an optical fiber extending from a proximal lead end to a distal lead end to position the optical fiber at a target site. The lead body additionally carries a conduit for dispensing a voltage-sensitive fluorescent dye into tissue surrounding the target site. The optical fiber transmits excitation light to the fluorescent dye to cause the dye to fluoresce with varying intensity as the transmembrane potentials of local tissue cells vary due to passing depolarization wavefronts. The optical fiber transmits the fluorescence signal to the device to generate an action potential signal or fiducial points of an action potential signal for use in accurately measuring and characterizing electrical activity of excitable tissue.

Abstract: A method for detecting potential failures by a lead of an implantable medical device is provided. The method includes sensing a first signal over a first channel between a first combination of electrodes on the lead and sensing a second signal from a second channel between a second combination of electrodes on the lead. The method determines whether at least one of the first and second signals is representative of a potential failure in the lead and identifies a failure and the electrode associated with the failure based on which of the first and second sensed signals is representative of the potential failure. Optionally, when the first and second sensed signals are both representative of the potential failure, the method further includes determining whether the first and second sensed signals are correlated with one another. When the first and second sensed signals are correlated, the method declares an electrode common to both of the first and second combinations to be associated with the failure.