Abstract: An active implantable medical device such as a cardiac prosthesis for the treatment of a heart failure by controlled adjustment of the atrioventricular and interventricular delays. The device provides atrioventricular and/or biventricular stimulation, a sensor delivering at least one hemodynamic parameter correlated with time intervals representative of the succession of the systolic and diastolic phases, and circuits to adjust the AV delay and/or VV delay. The device determines (12) during one cardiac cycle several parameters such as the left ventricular pre-ejection interval LPEI, the left ventricular ejection time LVET, the diastolic filling time FT and the conduction time PR. The device compares (14, 18) these parameters with at least one predetermined criterion. If a condition is met, the device readjusts (16) the AV delay and/or VV delay to maximize the ventricular filling and ejection.

Abstract: A modular external defibrillator system in embodiments of the teachings may include one or more of the following features: a base containing a defibrillator to deliver a defibrillation shock to a patient, (b) one or more pods each connectable to a patient via patient lead cables to collect at least one patient vital sign, the pods operable at a distance from the base, (c) a wireless communications link between the base and a selected one of the two or more pods to carry the at least one vital sign from the selected pod to the base, the selection being based on which pod is associated with the base.

Abstract: A system and method for painlessly calculating an estimated defibrillation threshold, such as by using an implantable medical device and a controller. The estimated defibrillation threshold can be calculated using a delivered first energy to a first thoracic location, an electric field detected at a second thoracic location, and an electric field detected between a third thoracic location and a fourth thoracic location. The estimated defibrillation threshold represents an energy that, when delivered at the first thoracic location, can create an electric field strength in a target region of the heart that meets or exceeds a target electric field strength.

Abstract: In general, the disclosure describes techniques for detecting lead related conditions, such as lead fractures or other lead integrity issues. As described herein, lead related conditions are identified by detecting delivered energy and electrical path impedance during delivery of a therapeutic electrical to a patient. If one or both of the delivered energy and impedance traverse respective thresholds, a lead related condition may exist. The energy delivered during the electrical signal may be compared to the amount of energy the electrical signal was programmed to deliver to determine if the delivered energy is less than a threshold percentage of the programmed energy of the electrical signal. The impedance of the electrical path through which the therapeutic electrical signal is delivered may be compared to a threshold impedance value to determine if the impedance detected during the electrical signal is greater than the threshold.

Abstract: A system and method for painlessly calculating an estimated defibrillation threshold, such as by using an implantable medical device and a controller. The estimated defibrillation threshold can be calculated using a delivered first energy to a first thoracic location, an electric field detected at a second thoracic location, and an electric field detected between a third thoracic location and a fourth thoracic location. The estimated defibrillation threshold represents an energy that, when delivered at the first thoracic location, can create an electric field strength in a target region of the heart that meets or exceeds a target electric field strength.

Abstract: A device and method for defrosting a defibrillation electrode are provided. This includes an automated external defibrillator that is capable of defrosting one or more frozen electrodes. The device is includes a portable housing containing a battery powered energy source and a controller as well as at least a pair of electrodes which are operably coupled to the housing. The electrodes are designed for attachment to the chest of a patient in need of resuscitation and contain a conductive interface medium that has temperature dependent properties. A controller is configured to selectively heat the conductive interface medium by applying limited electrical impulses and raise the electrode temperature to a desired temperature range.

Abstract: Methods and devices for testing lead impedance in an implantable cardiac stimulus device. A resistor is placed in series with the lead impedance, and a predetermined or known voltage is applied to the resistor and lead impedance. The voltage across the resistor is measured, and it is then determined whether the lead impedance falls within an acceptable range.

Abstract: An exemplary method includes configuring a coil electrode as a cathode, calling for delivery of energy to an electrode configuration that includes the coil cathode wherein the energy exceeds one joule, configuring a coil electrode as an anode and, within 10 seconds of the calling, calling for delivery of energy to an electrode configuration that includes the coil anode wherein the energy exceeds one joule. Such an exemplary method may aim to induce fibrillation and to defibrillate tissue. Various other exemplary methods are disclosed as well as various exemplary devices, systems, etc.

Abstract: The present invention relates to a system and method for determining the impedance of an electrode at the electrode-body interface. The electrode-body impedance of one of the electrodes may be calculated using the voltage difference between that electrode and a plurality of other electrodes, and the voltage and impedance of an alternating current generator in communication with the electrodes.

Abstract: The present invention relates generally to a therapeutic pulse generator system used to provide energy efficient stimulation/pacing by causing controlled cellular depolarization based on pre-measured charge transfer. This is accomplished by periodic electrical characterization of the electrode-tissue interface. Each channel of stimulation is programmed individually enabling the clinician to customize the therapeutic protocol. Energy efficiency may also be further improved through the use of a multi-channel lead in which the amount of energy required for each subsequent channel may be set to be less than the previous channel. The total energy required for multi-channel stimulation/pacing has also been shown to be less than that required by a single channel for the same therapeutic benefit.

Abstract: A device tests a circuit that is a source of alternating current by measuring at least one electrical parameter of the circuit to determine whether the circuit is able to provide adequate energy for defibrillation by an external defibrillator. The device may test the circuit by applying a load to the circuit, and measuring one or more electrical parameters when the load is applied to the circuit. The device may be the external defibrillator itself, or a separate testing device. In some embodiments in which an external defibrillator tests a circuit, the defibrillator modifies a value of at least one therapy delivery parameter for a subsequent delivery of one or more defibrillation pulses based on the measured electrical parameter value measured. By modifying a therapy delivery parameter, the defibrillator may deliver defibrillation pulses at an energy level that is supportable by the circuit.

Abstract: A neural stimulation system automatically corrects or adjusts the stimulus magnitude (stimulation energy) in order to maintain a comfortable and effective stimulation therapy. Because the changes in impedance associated with the electrode-tissue interface can indicate obstruction of current flow and positional lead displacement, lead impedance can indicate the quantity of electrical stimulation energy that should be delivered to the target neural tissue to provide corrective adjustment. Hence, a change in impedance or morphology of an impedance curve may be used in a feedback loop to indicate that the stimulation energy needs to be adjusted and the system can effectively auto correct the magnitude of stimulation energy to maintain a desired therapeutic effect.

Abstract: A process for determining whether the location of a stimulation electrode meets a selected heart performance criteria includes providing stimulation to the heart through the electrode and obtaining an impedance measurement during stimulation delivery using an impedance sensing vector formed by electrodes that do not include the stimulation electrode. The impedance measurements are processed, either alone or in combination with an electrogram, also obtained during stimulation, to obtain a measure of hemodynamic performance.

Abstract: A method includes sensing a cardiac electrogram (EGM) signal of a patient via one or more electrodes on at least one implantable medical lead. An asystolic EGM signal is detected from the patient, and a lead integrity test of the at least one implantable medical lead is initiated in response to the asystolic EGM signal.

Abstract: A system and method for determining complex intercardiac impedance to detect various cardiac functions are disclosed involving a signal generator means for providing an adjustable direct current signal, a modulator for modulating the adjustable direct current signal to produce a modulated signal, at least one electrode for propagating the modulated signal across a myocardium, at least one sensor for detecting an outputted modulated signal from the myocardium, and at least one circuit to reduce the influence of process noise (aggressors) in the outputted modulated signal. The at least one circuit comprises an amplifier, a demodulator, and an integrator. The amplitude and phase of the final outputted modulated signal indicate the complex impedance of the myocardium. Changes in the complex impedance patterns of the myocardium provide indication of reduced oxygen and blood flow to the myocardium.

Abstract: Electrical crosstalk between two implantable medical devices or two different therapy modules of a common implantable medical device may be evaluated, and, in some examples, mitigated. In some examples, one of the implantable medical devices or therapy modules delivers electrical stimulation to a nonmyocardial tissue site or a nonvascular cardiac tissue site, and the other implantable medical device or therapy module delivers cardiac rhythm management therapy to a heart of the patient.

Abstract: A nondefibrillating and nonfibrillation-inducing energy is delivered at a first internal thoracic location. A first resulting electrical signal is detected at a second internal thoracic location in or near a target region of a heart. A first defibrillation threshold is estimated using the nondefibrillating and nonfibrillation-inducing energy, the first resulting electrical signal, and a target electric field strength. The defibrillation threshold represents an energy that when delivered at the first internal thoracic location creates an electric field strength in the target region of the heart that meets or exceeds the target electric field strength.

Abstract: A cardiac rhythm management device predicts defibrillation thresholds without any need to apply defibrillation shocks or subjecting the patient to fibrillation. Intravascular defibrillation electrodes are implanted in a heart. By applying a small test energy, an electric field near one of the defibrillation electrodes is determined by measuring a voltage at a sensing electrode offset from the defibrillation electrode by a known distance. A desired minimum value of electric field at the heart periphery is established. A distance between a defibrillation electrodes and the heart periphery is measured, either fluoroscopically or by measuring a voltage at an electrode at or near the heart periphery. Using the measured electric field and the measured distance to the periphery of the heart, the defibrillation energy needed to obtain the desired electric field at the heart periphery is estimated. In an example, the device also includes a defibrillation shock circuit and a stimulation circuit.

Abstract: An automatic external defibrillator electrode package includes a coded conductive label that uniquely identifies the type of automatic electrode contained therein. Pins on the defibrillator body make electrical contact with the conductive label when the package is attached to the defibrillator. These pins sense the shape of the conductive label to ascertain the electrode type, thereby enabling the AED to automatically set the proper operating mode.

Abstract: A medical device includes a rechargeable lithium-ion battery for providing power to the medical device. The lithium-ion battery includes a positive electrode comprising a current collector and an active material comprising a material selected from the group consisting of LiCoO2, LiMn2O4, LiNixCoyNi(1?x?y)O2, LiAlxCoyNi(1?x?y)O2, LiTixCoyNi(1?x?y)O2, and combinations thereof. The lithium-ion battery also includes a negative electrode having a current collector and an active material including a lithium titanate material. The current collector of the negative electrode includes a material selected from the group consisting of aluminum, titanium, and silver. The battery is configured for cycling to near-zero-voltage conditions without a substantial loss of battery capacity.

Abstract: Approaches for estimating capture thresholds for alternate pacing vectors of multi-electrode pacing devices are described. Capture thresholds of at least one initial pacing vector is measured. The impedance of the initial pacing vector and at least one alternate pacing vector is measured. The initial and alternate pacing vectors have an electrode in common. The common electrode has the same polarity in both the initial and the alternate pacing vectors. The capture threshold for the alternate pacing vector may be estimated based on the measured capture threshold of the initial pacing vector, the measured the impedance of the initial pacing vector, and the measured impedance of the alternate pacing vector.

Abstract: Methods and systems are directed to selecting from a variety of capture verification modes. A plurality of capture verification modes, including a beat by beat capture detection mode and a capture threshold testing mode without intervening beat by beat capture detection is provided. An efficacy of at least one of the capture verification modes is evaluated and, based on the evaluation, a capture verification mode is selected.

Abstract: A defibrillator for external application to a patient. The defibrillator includes a power storage unit for supplying a defibrillation shock. The power storage unit has a capacitor unit encompassing at least one capacitor. In order to adjust a defibrillation treatment to different patients, the defibrillator advantageously comprises several different capacitor units which have a capacity adapted to various patient impedances and are or can be coupled in a replaceable manner to the defibrillator.

Abstract: A cardiac rhythm management device predicts defibrillation thresholds without any need to apply defibrillation shocks or subjecting the patient to fibrillation. Intravascular defibrillation electrodes are implanted in a heart. By applying a small test energy, an electric field near one of the defibrillation electrodes is determined by measuring a voltage at a sensing electrode offset from the defibrillation electrode by a known distance. A desired minimum value of electric field at the heart periphery is established. A distance between a defibrillation electrodes and the heart periphery is measured, either fluoroscopically or by measuring a voltage at an electrode at or near the heart periphery. Using the measured electric field and the measured distance to the periphery of the heart, the defibrillation energy needed to obtain the desired electric field at the heart periphery is estimated. In an example, the device also includes a defibrillation shock circuit and a stimulation circuit.

Abstract: An apparatus and method for delivering an external shock pulse receive pacing pulses generated by a first device and a shock pulse generated by a second device. An output of the apparatus is coupled to patient electrodes and the apparatus controls delivery of the received pacing pulses to the output and delivery of the received shock pulse to the output. A control module, pacing control and shock control included in the apparatus cooperatively control delivery of the received shock pulse to the output at a predetermined delay after one of the received pacing pulses.

Abstract: The invention presents an apparatus and techniques for determining whether a medical electrode, such as a defibrillation electrode coupled to an automated external defibrillator, is in a condition for replacement. The determination can be made as a function of one or more data. In one exemplary embodiment, the determination is a function of one or more measurements of an impedance of a hydrogel bridge in a test module. In another exemplary embodiment, the determination is a function of one or more environmental condition data from one or more environmental sensors.

Abstract: Methods and apparatus for accurately and painlessly measuring the impedance between defibrillation electrodes implanted in a patient utilize a high current test pulse delivered with a sufficiently high current to produce an accurate measurement of the defibrillation electrode impedance while limiting the duration of the test pulse such that the pain sensing cells in the patient do not perceive the test pulse. In one embodiment, the test pulse is generated from the high voltage transformer without storing energy in the high voltage capacitors and is delivered to the defibrillation electrodes in the patient utilizing the high voltage switching circuitry.

Abstract: The invention is a method of automatically adjusting an electrode array to the neural characteristics of an individual patient. By recording neural response to a predetermined input stimulus, one can alter that input stimulus to the needs of an individual patient. A minimum input stimulus is applied to a patient, followed by recording neural response in the vicinity of the input stimulus. By alternating stimulation and recording at gradually increasing levels, one can determine the minimum input that creates a neural response, thereby identifying the threshold stimulation level. One can further determine a maximum level by increasing stimulus until a predetermined maximum neural response is obtained.

Abstract: Systems and methods provide baroreflex activation to treat or reduce pain and/or to cause or enhance sedation or sleep. Methods involve activating the baroreflex system to provide pain reduction, sedation, improved sleep or some combination thereof. Systems include at least one baroreflex activation device, at least one sensor for sensing physiological activity of the patient, and a processor coupled with the baroreflex activation device(s) and the sensor(s) for processing sensed data received from the sensor and for activating the baroreflex activation device. In some embodiments, the system is fully implantable within a patient, such as in an intravascular, extravascular or intramural location.

Abstract: Electrobiological stimulation is carried out transcranially by applying high frequency squarewave bursts exhibiting no d.c. term across the cranial region. Such stimulation is commenced employing ramp generators and positive and negative voltage converters which evolve the requisite baseform and burst frequencies having a voltage waveform which is square in nature. Both voltage and current are sensed and subjected to comparator logic in conjunction with predetermined thresholds and windows. Overcurrent detection and overvoltage detection is provided in hard wired fashion to assure rapid shutdown response. D.C offset detection is provided along with waveform balance tests to further assure the safety of the system. Diagnostic procedures as well as therapeutic procedures may be carried out with a system version which provides for the application of a stimulus in conjunction with safety monitoring and controller based development of stimulating waveforms, all of which exhibits no d.c. term.

Abstract: This document discusses, among other things, a system and method for painlessly calculating an estimated defibrillation threshold, such as by using an implantable medical device and a controller. The estimated defibrillation threshold can be calculated using a delivered first energy to a first thoracic location, an electric field detected at a second thoracic location, and an electric field detected between a third thoracic location and a fourth thoracic location. The estimated defibrillation threshold represents an energy that, when delivered at the first thoracic location, can create an electric field strength in a target region of the heart that meets or exceeds a target electric field strength.

Abstract: An exemplary method includes detecting fibrillation, measuring impedance of a defibrillation circuit that includes myocardial tissue, determining one or more defibrillation shock parameters based at least in part on the impedance, delivering a defibrillation shock using the one or more defibrillation shock parameters and, if the shock was unsuccessful, adjusting a membrane time constant and determining one or more new defibrillation shock parameters based at least in part on the adjusted membrane time constant. Various other exemplary methods are disclosed as well as various exemplary devices, systems, etc.

Abstract: An external defibrillator is described which maintains the durations of phases of a multiphasic shock waveform within or below desired limits. As the duration of a waveform increases for patients of increased patient impedance, the durations of the phases of a multiphasic shock waveform also increase. Before a maximum duration limit is exceeded, the defibrillator adds another phase to the multiphasic waveform which brings the durations of the phases within the desired range or below a maximum duration limit. Both the number of shock phases and the individual phase durations can be controlled in response to measured patient impedance.

Abstract: An exemplary method includes detecting fibrillation, measuring impedance of a defibrillation circuit that includes myocardial tissue, determining one or more defibrillation shock parameters based at least in part on the impedance, delivering a defibrillation shock using the one or more defibrillation shock parameters and, if the shock was unsuccessful, adjusting a membrane time constant and determining one or more new defibrillation shock parameters based at least in part on the adjusted membrane time constant. Various other exemplary methods are disclosed as well as various exemplary devices, systems, etc.

Abstract: In general, the invention is directed to techniques for capture testing of a capture threshold in cooperation with measurement of other cardiac parameters. Physiological or non-physiological parameters may indicate a possible change in the capture threshold, and a significant change in a cardiac parameter may trigger more frequent monitoring of the capture threshold. In addition, measurement of cardiac parameters in relation to measurement of the capture threshold may be useful in diagnosing problems and forecasting possible loss of capture.

Abstract: A neural stimulation system automatically corrects or adjusts the stimulus magnitude (stimulation energy) in order to maintain a comfortable and effective stimulation therapy. Because the changes in impedance associated with the electrode-tissue interface can indicate obstruction of current flow and positional lead displacement, lead impedance can indicate the quantity of electrical stimulation energy that should be delivered to the target neural tissue to provide corrective adjustment. Hence, a change in impedance or morphology of an impedance curve may be used in a feedback loop to indicate that the stimulation energy needs to be adjusted and the system can effectively auto correct the magnitude of stimulation energy to maintain a desired therapeutic effect.

Abstract: A method of screening for breast cancer, comprising: testing a plurality of asymptomatic women by measuring at least one electrical impedance characteristic on at least one breast, said asymptomatic woman being classified as belonging to a first group having a first risk factor for breast cancer; and re-classifying some of the women as belonging to a second group having a second risk factor greater than the first risk factor, based on the at least one impedance characteristic, wherein the second group has a risk factor of at least twice that of the first group, but less than 15 times that of the first group; and wherein fewer than 60% of those in the first group that have breast cancer are reclassified into the second group.

Abstract: An implantable medical device operates to promote intrinsic ventricular depolarization according to a pacing protocol. The medical device monitors the AV interval and adjusts the Ventricular Pacing Protocol if the AV interval exceeds a threshold when the cardiac rate is elevated.

Abstract: A system and method for monitoring and controlling the therapy of a cardiac rhythm abnormality victim at a remote site by proving immediate access to a medical professional at a central station. The method comprises the steps of: (1) providing a plurality of electrodes for receiving cardiac signals generated by the victim and for the application of electrical pulses to the victim at a remote site; (2) transmitting the signals from the remote site to a central station; (3) receiving the signals at the central station and displaying them for the medical professional; (4) selecting whether to delivery defibrillation or pacing therapy to the victim based on the medical professional's analysis of the signals (5) transmitting the selection results to the remote site; and (6) receiving the selection results at the remote site and applying the selected therapy to the victim.

Abstract: A method for determining a cardiac shock strength, for example the programmed first-therapeutic shock strength of an implantable cardioverter defibrillator (ICD), including the steps of sensing a change in a T-wave of an electrogram with respect to time such as the maximum of the first derivative of a T-wave of an electrogram; delivering a test shock by (i) delivering a test shock at a test-shock strength and at a test-shock time relating to the maximum of the first derivative of the T-wave with respect to time; and (ii) sensing for cardiac fibrillation. If fibrillation is not sensed, test-shock delivery is repeated at the same test-shock strength and at specific, different test-shock times relating to the maximum of the first derivative of the T-wave. If fibrillation is still not sensed, the shock strength is decreased and test shocks are repeated at the same specific test shock times relative to the maximum of the first derivative of the T-wave.

Abstract: A portable defibrillator includes a self-test circuit in which electrical energy is discharged from one or a bank of capacitors to a charge receiving circuit which recycles the energy to a rechargeable battery to prolong the original battery charge. A charge receiving circuit may contain a relatively high Ohmic value/low Wattage resistor such that the discharge occurs over a relatively long period of time, rendering a heat sink unnecessary. The resistor may be a single high value resistor or a network of plural smaller value resistors. Optional switching of the discharge electrical energy during a self-test either recycles it to the rechargeable battery or discharges it through the resistor. The self-test may be carried out on a bank of capacitors in rotation, discharging energy from one capacitor into the next such that all capacitors are charged and discharged from substantially a single power input.

Abstract: The invention is directed to techniques for estimating a deformation factor of one or more capacitors in an implantable medical devices (IMD), and techniques for reforming such capacitors. An estimate of the ideal charge time is extrapolated from a first measured charge interval associated with charging the capacitor(s) to a first energy level. The actual charge time to associated with charging the capacitor(s) to a second energy level, e.g., the fully charged state, is measured. The deformation factor is calculated as a ratio of the actual charge interval to the second energy level to the ideal charge time. In some cases, the calculated deformation factor is used to adjust the timing of a future scheduled reformation of the capacitor(s).

Abstract: The present invention outlines structures and methods for delivering a controllable amount of energy to a patient by automatically compensating for the load impedance detected by an implantable-cardioverter defibrillator (ICD). The invention employs high speed, switching power converter technology for the efficient generation of high energy, arbitrarywaveforms. Unlike a linear amplifier, switching power converters deliver high-energy waveforms with an efficiency that is independent of the size and amplitude of the desired waveform. An ICD that uses a switching power converter to deliver the desired energy to the patient stores the energy to be delivered in a storage capacitor. The converter then transforms this energy into an arbitrarily shaped output voltage-controlled or current-controlled waveform by switching the storage capacitor in and out of the output circuit at a high rate of speed. Preferably, the waveform comprises a ramp-type waveform.

Abstract: The invention is directed to techniques for electrode placement around a heart. A harness having one or more attachment sites may be secured around the heart, and electrodes may be secured at the attachment sites as desired by the physician for the patient. The electrodes may be, for example, pacing and sensing electrodes, defibrillation electrodes, or any combination thereof. The harness holds the electrodes in place and also impedes the progress of ventricular dilation. The electrodes attached to the harness may be used for any of several purposes, such as cardiac resynchronization, selective defibrillation, measurement of impedance, pacing and cardioversion.

Abstract: A method of analysis of medical signals which uses wavelet transform analysis to decompose cardiac signals. Apparatus for carrying out the method, and cardiac apparatus adapted to employ the method are also described.

Abstract: An implantable cardiac stimulation device, such as a pacemaker or Implantable Cardioverter Defibrillator, is configured to automatically monitor the effects of antiarrhythmic drugs on cardiac electrical signals within a patient to verify the efficacy of the drugs taken. In one example, an analysis of patient cardiac electrical signals is performed by comparing the cardiac electrical signals with values representative of the effects of different classes of antiarrhythmic drugs. If the implantable device determines that the prescribed antiarrhythmic drugs have not been effective, a warning signal is generated. The warning signal is conveyed directly to the patient via a bedside monitor and to the patient's physician via remote connection to an external programmer device so that both are notified of the drug efficacy problems.

Abstract: An apparatus and method of automatically measuring the lead impedance of a high energy shock lead before delivery of high energy therapy used to treat heart arrhythmia. In one example, an impedance measurement circuit measures the impedance between electrodes in a plurality of pairs of electrodes. The measured lead electrode impedance is compared to a predetermined value to detect if the lead is shorted to another lead. If a high-energy shock electrode is shorted to another lead, a shorted lead indicator is set to a fault state. Based on the state of the shorted lead indicator, a processor prevents or allows the delivery of high energy therapy. By checking for a lead short before delivery of the therapy, all of the energy of the therapy is delivered to the patient rather than being bypassed by a shorted lead connection.

Abstract: A flat capacitor includes a case having a feedthrough hole, a capacitor stack located within the case, a coupling member having a base surface directly attached to the capacitor stack and having a portion extending through the feedthrough hole, the coupling member having a mounting hole, a feedthrough conductor having a portion mounted within the mounting hole, and a sealing member adjacent the feedthrough hole and the feedthrough conductor for sealing the feedthrough hole. Other aspects of the invention include various implantable medical devices, such as pacemakers, defibrillators, and cardioverters, incorporating one or more features of the exemplary feedthrough assembly.

Abstract: A leakage detection system for use in an implantable cardiac stimulation device, such as a cardioverter defibrillator. The leakage detection system includes a switch bank and a controller that regulates the switching arrangements of various switches. The leakage detection system causes pulse generators to generate a pulse-train waveform comprised of a sequence of pulses of opposite polarities, and to deliver these pulses in a preselected temporal relation. The controller detects the current leakage from the pulse generator to the tissues by sensing and analyzing the voltage or current of the pulse generator, leads, and electrodes. The pulsatility and alternating polarities of biphasic pulse-train waveforms increase the stimulation threshold of the motor or sensory nerves and excitable tissues.

Abstract: An implantable cardioverter/defibrillator includes an active can electrode and a high-voltage lead that can be electrically isolated from one another by opening a switch between them. The performance of the high-voltage lead and the can electrode can then be independently monitored, thus indicating which lead is inoperable, should one become inoperable. If a lead becomes inoperable, the implantable device can then reconfigure an electrical pathway such as a cardioversion and/or a defibrillation pathway by excluding the inoperable lead. By separating the high-voltage lead from the can electrode, pseudo ECG measurements can also be taken and utilized by the implantable device.