Abstract: An implantable medical device includes a local clock generator for generating a system clock signal. The local clock generator is periodically calibrated to maintain accuracy of the generated system clock signal. A clocking circuit is coupled to the local clock generator to provide the calibration factor for calibrating the local clock generator. The implantable medical device receives an accurate clock signal that is transmitted from an external device and the accurate clock signal is provided to the clocking circuit. The system clock signal is also provided to the clocking circuit and a computation is performed to derive the calibration factor.

Abstract: A method and device for measuring and controlling stimulation current, for example in an implantable device, are disclosed. A series capacitor (Cb) is disposed along the conduction path, and the voltage (Uc) across the capacitor measured, so as to provide a direct measurement of the delivered stimulation current.

Abstract: In general, the disclosure is directed to techniques for identification and remediation of oversensed cardiac events using far-field electrograms (FFEGMs). Identification of oversensed cardiac events can be used in an ICD to prevent ventricular fibrillation (VF) detection, and thereby avoid delivery of an unnecessary defibrillation shock. Alternatively, or additionally, identification of oversensed cardiac events can be used in an ICD to support delivery of bradycardia pacing during an oversensing condition. In some cases, bradycardia pacing delivered in response to detection of oversensed cardiac events may include pacing pulses from multiple vectors to provide redundancy in the event the oversensing may be due to a lead-related condition.

Abstract: A remote external interface for an implantable cardiac function management device is configured to be communicatively coupled to the implantable cardiac function management device via a network to a local external interface and via telemetry between the local external interface and the implantable cardiac function management device. The remote external interface includes a communication circuit and a processor circuit. The communication circuit is configured to communicate with the implantable cardiac function management device. The processor circuit is configured to perform an analysis of physiologic data received from the implantable cardiac function management device in response to operation of the implantable cardiac function management device using a plurality of therapy control parameter sets. The processor circuit can be further configured to select a particular therapy control parameter set using the analysis.

Abstract: Generally, the disclosure is directed one or more methods or systems of cardiac pacing employing a right ventricular electrode and a plurality of left ventricular electrodes. Pacing using the right ventricular electrode and a first one of the left ventricular electrodes and measuring activation times at other ones of the left ventricular electrodes. Pacing using the right ventricular electrode and a second one of the ventricular electrodes and measuring activation times at other ones of the left ventricular electrodes. Employing sums of the measured activation times to select one of the left ventricular electrodes for delivery of subsequent pacing pulses.

Abstract: A programmer for cardiac implantable medical devices, including an accelerated test mode of the operating parameters. The programmer includes a user interface (10) that is used to define the tests to be performed on the implant and display the results thereof. These tests includes: ventricular and atrial sensing sensitivity, ventricular and atrial lead impedance, and ventricular and atrial capture threshold. Each test step involves (i) a predetermined setting of the operating mode, pacing rate and atrio-ventricular delay of the implantable device, (ii) collection of the operating data of the implantable device according said predetermined settings, and (iii) processing and display of thus collected data. There further exists one test step of time compression along which at least some of the ventricular and atrial tests for a same parameter are executed simultaneously during a common step, preferably the tests of sensing sensitivity and lead impedance.

Abstract: Polarization signals, which represent voltages measured at a pacemaker electrode, are not constant and may drift. Polarization signal drift, which often precedes undesirable pace polarization artifacts, is more significant when the pacemaker is inhibited from providing an electrical stimulation to the patient's heart. The present invention provides an implantable system and methods for stabilization of a polarization signal. Electrical pulses may be applied to stabilize a polarization signal. In one implementation of the invention, polarization signal stabilization may be used as part of process to terminate tachycardia.

Abstract: An instrument that utilizes body contact electrodes evaluates the quality of the connections made between the electrodes and the body. An electrode contact quality evaluation circuit performs the quality evaluation, such as by determining contact impedances for the electrodes. The corresponding contact quality of each electrode is conveyed to the user.

Abstract: The invention relates to medical devices such as pacemakers, pulse generators, cardioverter-defibrillators and the like and more particularly relates to modular and reconfigurable medical system platforms and methods of designing, testing, controlling and implementing diverse therapies, diagnostics, physiologic sensors and related instrumentation using said medical system platforms. Methods, systems and devices provide a new design platform for implantable and external medical devices such as pacemakers, defibrillators, neurostimulators, heart monitors, etc. A real-time, highly flexible system of software and hardware modules enables both prototypes and products to respond to patient and customer needs with greater design and manufacturing efficiency. Certain embodiments integrate a general-purpose processor with interface circuitry to provide a standard platform for implementing new and conventional therapies with software models rather than custom circuitry.

Abstract: An implantable medical device can include a hermetically-sealed implantable housing, an exposed first conductor located on or near the housing, and at least one insulated second conductor located near the exposed first conductor. In an example, the implantable medical device can include an isolation test circuit to provide a test stimulus to the exposed first conductor and configured to measure a portion of the test stimulus coupled to the second conductor.

Abstract: An implantable heart stimulating device for indicating congestive heart failure (CHF) has a processor and a sensor combination that senses at least two heart events during one heart cycle at different locations of the heart. The processor is supplied with signals from the sensor combination relating to the sensed events, and determines therefrom at least one heart time interval between the sensed events in the same heart cycle. The processor determines a CHF indicator value representing a degree of CHF based on a variability measure calculated from at least two heart time intervals from at least two different heart cycles. The processor determines the CHF indicator value in relation to previous CHF indicator values.

Abstract: Various configurations of systems that employ leadless electrodes to provide pacing therapy are provided. In one example, a system that provides multiple sites for pacing of myocardium of a heart includes wireless pacing electrodes that are implantable at sites proximate the myocardium using a percutaneous, transluminal, catheter delivery system. Each of the electrodes contains a source of electrical energy for pacing the myocardium and is adapted to receive electromagnetic energy from a source outside the myocardium. The system also includes a source adapted for placement outside the myocardium and that uses locally measured electrocardiograms to synchronize pacing of the heart by sending electromagnetic commands to the electrodes to pace the myocardium surrounding the electrodes. Also disclosed is various configurations of such systems, wireless electrode assemblies, and delivery catheters for delivering and implanting the electrode assemblies.

Abstract: An implantable medical device (IMD) receives an input associated with the presence of an environment having an external source that generates an interfering signal, such as an MRI device. The IMD adjusts a first set of one or more sensing parameters of a sensing module of the IMD in response to receiving the input associated with the presence of the environment. In this manner, the IMD operates in accordance with the adjusted sensing configuration in the presence of the interfering signal in an attempt to obtain a more detailed representation of the signal including noise caused by the interfering signal. The IMD analyzes the signals sensed using the first set of adjusted sensing parameters to determine if further adjustment is desired. If desired, the IMD adjusts a second set of one or more sensing parameters of the sensing module based on the analysis.

Abstract: Systems, devices and methods are provided for displaying statistical distributions of cardiac events. A device embodiment comprises circuitry adapted to communicate with a medical device that is adapted to acquire data regarding cardiac events occurring at two or more cardiac sites, and display means for displaying a histogram of the data as two or more statistical distributions for the two or more cardiac sites. The histogram includes a number of histogram bins. At least one of the histogram bins includes both a representation for at least a portion of a statistical distribution of a cardiac event for a first cardiac site and a representation for at least a portion of a statistical distribution of a cardiac event for a second cardiac site. Other embodiments are provided herein.

Abstract: An implantable medical device for delivering electrical cardiac therapy includes a first implantable housing containing a battery. There is also a second implantable housing separate from the first implantable housing and containing at least one of: electronic circuitry adapted to evaluate and initiate electrical cardiac therapy, a storage capacitor and an electrode structure comprising a sensing electrode, a pacing electrode and a therapy electrode. There is a method of providing electrical cardiac therapy by implanting a first housing containing a battery into a first implantation site within the body. Then, implant a second housing separate from the first housing into a second implantation site within the body. The second housing contains at least one of: electronic circuitry adapted to evaluate and initiate electrical cardiac therapy; a storage capacitor and an electrode structure comprising a sensing electrode, a pacing electrode and a therapy electrode.

Abstract: A system and method for recording sensing and pacing events in a cardiac rhythm management device. The method may be particularly useful in assessment of pacing parameters for ventricular resynchronization therapy.

Abstract: One aspect of this disclosure relates to a system for dynamic battery management in implantable medical devices. An embodiment of the system includes two or more devices for measuring battery capacity for an implantable medical device battery. The embodiment also includes a controller connected to the measuring devices. The controller is adapted to combine the measurements from the measuring devices using a weighted average to determine battery capacity consumed. According to various embodiments, at least one of the measuring devices includes a coulometer. At least one of the measuring devices includes a capacity-by-voltage device, according to an embodiment. The system further includes a display in communication with the controller in various embodiments. The display is adapted to provide a depiction of battery longevity in units of time remaining in the life of the implantable medical device battery, according to various embodiments. Other aspects and embodiments are provided herein.

Abstract: Methods and implantable devices that address response to, or avoidance of, likely non-cardiac voltages including after potentials from external or internal stimulus. Also, methods of operation in implantable medical devices, the methods configured for identifying saturation of input circuitry and mitigating the effects of such saturation. Also, implantable cardiac stimulus or monitoring devices that include methods for identifying saturated conditions and mitigating the effects of such saturation.

Abstract: A self-diagnostic system for an implantable cardiac device such as a pacemaker, cardioverter, or resynchronization device which utilizes a subcutaneous ECG channel is described. The subcutaneous ECG channel allows the device to, in real time and independent of the standard pacing and sensing circuitry, verify the presence of pacing spikes, chamber senses, and other device outputs and hence establish and verify device integrity.

Abstract: A lead system for an implantable medical device and applications for the lead system. Also includes therapeutic systems, devices, and processes for detecting and treating disordered breathing and treating cardiac and breathing issues together with an implantable device.

Abstract: A system and method for managing locally-initiated medical device interrogation is presented. An interface is provided over which to retrieve patient data recorded and transiently staged by a medical device monitoring physiological measures of a patient. The patient data is periodically retrieved by interfacing to and interrogating the medical device per a pre-defined schedule through the interface. Further retrieval of the patient data is permitted independent of the pre-defined schedule. The system stores remotely-specifiable criteria specified by a caregiver and controls patient-initiated patient data retrieval in accordance with the criteria.

Abstract: Systolic timing intervals are measured in response to delivering pacing energy to a pacing site of a patient's heart. An estimate of a patient's acute response to cardiac resynchronization therapy (CRT) for the pacing site is determined using the measured systolic timing intervals. The estimate is compared to a threshold. The threshold preferably distinguishes between acute responsiveness and non-responsiveness to CRT for a patient population. An indication of acute responsiveness to CRT for the pacing site may be produced in response to the comparison.

Abstract: An implantable medical device (IMD) having a therapy circuit for delivering atrial pacing and a control circuit for detecting a return to sinus rhythm. The control circuit determines the duration of an atrial arrhythmia preceding the return to sinus rhythm, and controls the therapy circuit to deliver transient atrial pacing based on the atrial arrhythmia duration.

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: Generally, the disclosure is directed one or more methods or systems of cardiac pacing employing a right ventricular electrode and a plurality of left ventricular electrodes. Pacing using the right ventricular electrode and a first one of the left ventricular electrodes and measuring activation times at other ones of the left ventricular electrodes. Pacing using the right ventricular electrode and a second one of the ventricular electrodes and measuring activation times at other ones of the left ventricular electrodes. Employing sums of the measured activation times to select one of the left ventricular electrodes for delivery of subsequent pacing pulses.

Abstract: A medical device, programmer, or other computing device may determine values of one or more activity and, in some embodiments, posture metrics for each therapy parameter set used by the medical device to deliver therapy. The metric values for a parameter set are determined based on signals generated by the sensors when that therapy parameter set was in use. Activity metric values may be associated with a postural category in addition to a therapy parameter set, and may indicate the duration and intensity of activity within one or more postural categories resulting from delivery of therapy according to a therapy parameter set. A posture metric for a therapy parameter set may indicate the fraction of time spent by the patient in various postures when the medical device used a therapy parameter set. The metric values may be used to evaluate the efficacy of the therapy parameter sets.

Abstract: Example techniques for communicating between two medical devices are described. One medical device may be an implantable medical device. Another medical device may be a lead-borne implantable medical device. The lead-borne implantable medical device may be referred to as a satellite. The implantable medical device may measure impedance of a path including at least two electrodes, at least one of which is on the lead, using an impedance measurement module. In some example implementations of this disclosure, the implantable medical device may also use the impedance measurement module to communicate with the satellite on the lead.

Abstract: A method for operating an implantable medical device to obtain substantially synchronized closure of the mitral and tricuspid valves based on sensed heart sounds includes sensing an acoustic energy; producing signals indicative of heart sounds of the heart of the patient over predetermined periods of a cardiac cycle during successive cardiac cycles; calculating a pulse width of such a signal; and iteratively controlling a delivery of the ventricular pacing pulses based on calculated pulse widths of successive heart sound signals to identify an RV interval or VV interval that causes a substantially synchronized closure of the mitral and tricuspid valve. A medical device for optimizing an RV interval or VV interval based on sensed heart sounds implements such a method and a computer readable medium encoded with instructions causes a computer to perform such a method.

Abstract: Techniques are provided for estimating defibrillation impedance of an implantable cardioverter/defibrillator (ICD). Briefly, at least two low-voltage resistance values are measured at different voltages using a pair of stimulation electrodes connected to the ICD. High-voltage defibrillation impedance is then estimated by the ICD based on a weighted combination of the measured resistance values. In one example, a set of weight coefficients, calculated during an initial calibration procedure, are applied to the measured resistance values to produce the estimate of the high-voltage defibrillation impedance. The weight coefficients are updated whenever a defibrillation shock is delivered, based on actual defibrillation impedance values measured during the shock.

Abstract: A method of detecting cardiac signals in a medical device that includes decomposing a cardiac signal using a wavelet function at a plurality of scales to form a corresponding wavelet transform, determining approximation coefficients in response to the plurality of scales, reconstructing a first wavelet representation of the wavelet transform using predetermined approximation coefficients of the determined approximation coefficients, and evaluating the detected cardiac signals in response to the reconstructing.

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: In general, this disclosure is directed to techniques and circuitry to determine characteristics of an implantable lead associated with an implantable medical device (IMD). The implantable lead may be designed to be MRI-safe by having one or more components that attenuate frequencies associated with an MRI that, if left unreduced, may interfere with the performance of the lead and/or cause harm to the tissue in which the lead is implanted. The circuitry may transmit a signal through the lead and receive a response signal. The device may determine the lead characteristics by comparing the transmitted signal with the received signal. In addition to determining whether the lead is MRI-safe, the techniques of this disclosure may be also utilized to determine whether the lead is faulty.

Abstract: Controller, system and method for an implantable medical device having a plurality of electrodes, said implantable device being capable of delivering a therapeutic stimulation to a patient. An electrode interface is operatively coupled between a plurality of electrodes and a control module. The control module uses an electrode interface to obtain a plurality of measurements of impedance values for a plurality of selected pairs of individual ones of the plurality of electrodes. A user interface displays an indicia, indicative of operability of a group of at least one of said plurality of electrodes, based on a comparison of said plurality of measurements to a predetermined range, said indicia being a qualitative representation of operability of said group of at least one of said plurality of electrodes.

Abstract: In general, the disclosure relates to techniques for calculating mean impedance values and impedance variability values to detect a possible condition with a lead or device-lead pathway or connection. In one example, a device may be configured to determine an impedance value for an electrical path based on a plurality of measured impedance values for the electrical path, wherein the electrical path comprises a plurality of electrodes, and to determine an impedance variability value based on at least one of the plurality of measured impedance values. The device may be further configured to determine a threshold value based on the determined impedance value and the impedance variability value, compare a newly measured impedance value for the electrical path to the threshold value, and indicate a possible condition of the electrical path based on the comparison.

Abstract: A method for operating an implantable medical device includes delivering a plurality of pacing pulses to an atria of a patient's heart and monitoring intrinsic atrial activity to detect intrinsic atrial contractions between one or more of the plurality of pacing pulses. The method further includes detecting atrial undersensing as a function of the detection of intrinsic atrial contractions.

Abstract: Various techniques for disabling a first implantable medical device (IMD) by modulation of therapeutic electrical stimulation delivered by a second medical device are described. One example method includes delivering therapeutic electrical stimulation from a more recently implanted second IMD at a higher average rate than the previously implanted first IMD so that only the more recently implanted IMD will administer therapy, and modulating stimulation by the more recently implanted IMD in order to send a disable command to the previously implanted IMD.

Abstract: A system and method for passively testing a cardiac pacemaker in which sensing signal amplitudes and lead impedance values are measured and stored while the pacemaker is functioning in its programmed mode. The amplitude and impedance data may be gotten and stored periodically at regular intervals to generate a historical record for diagnostic purposes. Sensing signal amplitudes may also be measured and stored from a sensing channel which is currently not programmed to be active as long as the pacemaker is physically configured to support the sensing channel. Such data can be useful in evaluating whether a switch in the pacemaker's operating mode is desirable.

Abstract: Response to cardiac resynchronization therapy is predicted for a given stimulation site so that an atrioventricular delay of an implantable device administering cardiac resynchronization therapy may be set to a proper amount. The first deflection of ventricular depolarization is measured, such as through a surface electrocardiogram or through an intracardiac electrogram measured by a lead positioned in the heart at the stimulation site. The maximum deflection of the ventricular depolarization is then measured by the lead positioned at the stimulation site. The interval of time between the first deflection and the maximum deflection of the ventricular depolarization is compared to a threshold to determine whether the stimulation site is a responder site. If the interval is larger than the threshold, then the site is a responder and the atrioventricular delay of the implantable device may be set to less than the intrinsic atrioventricular delay of the patient.

Abstract: A noise-suppressing electrocardiograph (ECG) adapter having a first end, a second end, and a noise-suppression element is presented, together with an ECG noise-suppressing system and related methods. In an embodiment, the noise-suppressing ECG adapter includes a housing having at least one first connector disposed at a first end of the housing adapted to electrically couple with an ECG lead set, and at least one second connector adapted for coupling to an input of an ECG device. The adapter includes a noise suppression element. The noise suppression element includes a ferromagnetic element having an opening defined therein. In an embodiment the noise suppression element is internal to the adapter. In another embodiment, the noise suppression element is tethered externally to the adapter and configured to clamp around at least a portion of an ECG leadwire.

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: According to some methods, for example, preprogrammed in a microprocessor element of an implantable cardiac pacing system, at least one of a number of periodic pacing threshold searches includes steps to reduce an evoked response amplitude threshold for evoked response signal detection. The reduction may be to a minimum value measurable above zero, for example, as determined by establishing a ‘noise floor’. Alternately, amplitudes of test pacing pulses and corresponding post pulse signals are collected and reviewed to search for a break, to determine a lower value to which the evoked response threshold may be adjusted without detecting noise. Subsequent to reducing the threshold, if no evoked response signal is detected for a test pulse applied at or above a predetermined maximum desirable pulse energy, an operational pacing pulse energy is set to greater than or equal to the maximum desirable in conjunction with a reduction in pacing rate.

Abstract: An implantable medical device applies an electric signal over two electrodes and measures the resulting electric signal over a candidate pair of neighboring electrodes on a lead for a first heart ventricle or over a candidate electrode of the lead and a case electrode. An impedance signal is determined for each candidate pair or electrode based on the applied signal and the measured resulting signal. A time difference between start of contraction in a second ventricle and the timing of local myocardial contraction as identified from the impedance signal at the site of the candidate pair or electrode is determined for each candidate pair or electrode. An optimal pacing electrode is selected to correspond to one of the electrodes of the candidate pair having the largest time difference or the candidate electrode having largest time difference.

Abstract: Generally, the disclosure is directed one or more methods or systems of cardiac pacing employing a right ventricular electrode and a plurality of left ventricular electrodes. Pacing using the right ventricular electrode and a first one of the left ventricular electrodes and measuring activation times at other ones of the left ventricular electrodes. Pacing using the right ventricular electrode and a second one of the ventricular electrodes and measuring activation times at other ones of the left ventricular electrodes. Employing sums of the measured activation times to select one of the left ventricular electrodes for delivery of subsequent pacing pulses.

Abstract: According to various method embodiments for pacing a heart and avoiding unwanted stimulation of a phrenic nerve during cardiac pacing, a desired pacing time for delivering a cardiac pace is determined, and a desired nerve traffic inhibition time to inhibit nerve traffic in the phrenic nerve is determined using the desired pace time. The cardiac pace is delivered at the desired pacing time and nerve traffic in the phrenic nerve is inhibited at the desired nerve traffic inhibition time.

Abstract: Generally, the disclosure is directed one or more methods or systems of cardiac pacing employing a right ventricular electrode and a plurality of left ventricular electrodes. Pacing using the right ventricular electrode and a first one of the left ventricular electrodes and measuring activation times at other ones of the left ventricular electrodes. Pacing using the right ventricular electrode and a second one of the ventricular electrodes and measuring activation times at other ones of the left ventricular electrodes. Employing sums of the measured activation times to select one of the left ventricular electrodes for delivery of subsequent pacing pulses.

Abstract: A two-dimensional refractory period is defined in conjunction with the detection of cardiac events. Detection parameters associated with the two-dimensional refractory period may define a period of time during which a sensed cardiac signal is blanked or may define a period of time during which a given sensing threshold applies. The two-dimensional refractory period may be employed in atrial sensing to selectively blank far-field T-waves while enabling P-wave detection. The two-dimensional refractory period may be employed in ventricular sensing to selectively blank near-field T-waves while enabling detection of the QRS complex. The detection parameters associated with the two-dimensional refractory period may be adapted based on characteristics of previously detected cardiac signals.

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: Medical device implants for stimulating the nervous system of a recipient are disclosed. Embodiments include a cochlear implant with electrodes for delivering charge to the cochlea of the recipient and stimulation circuitry for delivering the charge to the electrodes. The medical devices include a transfer line which carries power and/or communication signals, the transfer line being in contact with tissue of the recipient when the medical device implant is implanted. A leakage capture conductor and/or sensing electrode is located or locatable proximate the insulated conductor.

Abstract: A processor-based method for use with an active implantable medical device for cardiac pacing, resynchronization, and/or defibrillation includes forming a plurality of first and second endocardial acceleration vectors using a plurality of endocardial acceleration signals acquired using stimulation to cause capture and a spontaneous rhythm of the patient in the absence of ventricular pacing, respectively. An at least two dimension space is created using the first and second endocardial acceleration vectors, including two subspaces corresponding to the presence and absence of capture, respectively. Ventricular capture is tested for after acquiring a new endocardial acceleration signal. The testing includes forming a new endocardial acceleration signal based on the new vector. Presence or absence of capture is determined for the new signal based on the position of the new vector relative to the two subspaces.

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.