Abstract: Intermittent delivery of ventricular pacing pulses synchronized to occur during an atrial diastole time period can be used to provide atrial stretch therapy and augment the production and release of atrial natriuretic hormone.

Abstract: An implantable cardiac device includes a sensor for sensing patient activity and detecting phrenic nerve activation. A first filter channel attenuates first frequencies of the sensor signal to produce a first filtered output. A second filter channel attenuates second frequencies of the accelerometer signal to produce a second filtered output. Patient activity is evaluated using the first filtered output and phrenic nerve activation caused by cardiac pacing is detected using the second filtered output.

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: Systems and Methods for predicting patient health and patient relative well-being within a patient management system are disclosed. A preferred embodiment utilizes an implantable medical device comprising an analysis component and a sensing component further comprising a three-dimensional accelerometer, a transthoracic impedance sensor, a cardio-activity sensor, an oxygen saturation sensor and a blood glucose sensor. Some embodiments of a system disclosed herein also can be configured as an Advanced Patient Management System that helps better monitor, predict and manage chronic diseases.

Abstract: An implantable cardiac device is configured and programmed to assess a patient's cardiopulmonary function by evaluating the patient's minute ventilation response. Such evaluation may be performed by computing a minute ventilation response slope, defined as the ratio of an incremental change in minute ventilation to an incremental change in measured activity level. The minute ventilation response slope may then be compared with a normal range to assess the patient's functional status.

Abstract: An implantable cardiac device includes a sensor for sensing patient respiration and detecting phrenic nerve activation. A first filter channel attenuates first frequencies of the sensor signal to produce a first filtered output. A second filter channel attenuates second frequencies of the respiration signal to produce a second filtered output. Patient activity is evaluated using the first filtered output and phrenic nerve activation caused by cardiac pacing is detected using the second filtered output.

Abstract: Methods and systems are provided to control a configuration of a neural stimulation (NS) system having an NS device coupled to an NS lead. The methods and systems change between configurations of the NS system and collect cardiac signals from a patient that are representative of cardiac rhythms experienced by the patient over a period of time and in connection with multiple NS configurations. The methods and systems derive, from the cardiac signals, characteristic values for at least one physiologic characteristic indicative of at least one of normal and abnormal cardiac rhythms in connection with the multiple NS configurations; and select, from the multiple NS configurations, an NS operating configuration to be used by the NS system based on the characteristic values.

Abstract: Various system embodiments comprise a stimulator adapted to deliver a stimulation signal for a heart failure therapy, a number of sensors adapted to provide at least a first measurement of a heart failure status and a second measurement of the heart failure status, and a controller. The controller is connected to the stimulator and to the number of sensors. The controller is adapted to use the first and second measurements to create a heart failure status index, and control the stimulator to modulate the signal using the index. Other aspects and embodiments are provided herein.

Abstract: Methods and devices for analyzing posture-induced changes to physiological parameters of a patient (e.g., ejection time, heart rate, etc.) to provide an assessment of one or more conditions of the patient.

Abstract: A triggered mode pacing system enables dual chamber sensing. The system also determines whether a cardiac event is initially sensed in a first cardiac chamber or a second cardiac chamber. The system then triggers an output to the second cardiac chamber in response to sensing the cardiac event in the first cardiac chamber when the cardiac event was determined to have been initially sensed in the first cardiac chamber.

Abstract: Cardiac monitoring and/or stimulation methods and systems employing dyspnea measurement. An implantable cardiac device may sense transthoracic impedance and determine a patient activity level. An index indicative of pulmonary function is implantably computed to detect an episode of dyspnea based on a change, trend, and/or value exceeding a threshold at a determined patient activity level. Trending one or more pulmonary function index values may be done to determine a patient's pulmonary function index profile, which may be used to adapt a cardiac therapy. A physician may be automatically alerted in response to a pulmonary function index value and/or a trend of the patient's pulmonary index being beyond a threshold. Computed pulmonary function index values and their associated patient's activity levels may be stored periodically in a memory and/or transmitted to a patient-external device.

Abstract: Systems and methods for sleep state classification involve detecting conditions related to sleep, including at least one condition associated with rapid eye movement (REM) sleep. Additionally, a condition modulated by the sleep-wake status of the patient may be detected. A medical system that is partially or fully implantable incorporates sensors and circuitry for detecting and processing the sleep-related signals. A sleep state processor classifies the patient's sleep state based on the sleep-related signals. Sleep state classification may be used in connection with the delivery of sleep state appropriate therapy, diagnostic testing, or patient monitoring.

Abstract: Techniques are provided for assessing left atrial pressure (LAP) based on atrial electrocardiac signal parameters, particularly intra-atrial conduction delay (IACD) and P-wave duration. In one example, a pacemaker or other implantable device senses an intracardiac electrogram (IEGM) or a subcutaneous electrocardiogram (ECG), from which IACD and P-wave duration are derived. The device tracks changes, if any, in the parameters. A significant increase in either IACD or P-wave duration is associated with an increase in LAP. In some examples, conversion factors are calibrated for use with a particular patient to relate IACD and/or P-wave duration values to LAP values to provide an estimate of actual LAP. The conversion factors are pre-calibrated using LAP measurements obtained using a wedge pressure sensor. In other examples, IACD and P-wave duration are instead used to confirm the detection of an elevation in LAP initially made using impedance signals. Other confirmation parameters are described as well.

Abstract: An implantable device monitors and treats heart failure, pulmonary edema, and hemodynamic conditions and in some cases applies therapy. In one implementation, the implantable device applies a high-frequency multi-phasic pulse waveform over multiple-vectors through tissue. The waveform has a duration less than the charging time constant of electrode-electrolyte interfaces in vivo to reduce intrusiveness while increasing sensitivity and specificity for trending parameters. The waveform can be multiplexed over multiple vectors and the results cross-correlated or subjected to probabilistic analysis or thresholding schemata to stage heart failure or pulmonary edema. In one implementation, a fractionation morphology of a sensed impedance waveform is used to trend intracardiac pressure to stage heart failure and to regulate cardiac resynchronization therapy. The waveform also provides unintrusive electrode integrity checks and 3-D impedancegrams.

Abstract: A method of synchronizing a heart rate parameter of multiple users includes generating a pacing signal at a specific frequency, measuring a physiological parameter of each of the multiple users, presenting to each user an output based upon the measured physiological parameter of the respective user, and presenting to each user an output based upon the generated pacing signal. The measured physiological parameter could include heart rate variability. In one embodiment, the step of presenting to each user an output based upon the generated pacing signal, include presenting a first user with a first output, and presenting a second user with a second output, where the second output is out of phase with the first output.

Abstract: A method for use by an active medical device includes using a stimulation device and an endocardial acceleration sensor to obtain a plurality of hemodynamic parameters associated with at least three atrioventricular delays. The method further includes using the plurality of hemodynamic parameters to find a second derivative associated with the atrioventricular delays. The method further includes using interpolation to estimate an atrioventricular delay which will reduce the second derivative associated with the atrioventricular delays. The method further includes using the estimated atrioventricular delay in a subsequent stimulation.

Abstract: The invention relates to systems, devices, and methods for detecting infections associated with implantable medical devices. In an embodiment, the invention includes a method of detecting infection in a patient including measuring a physiological parameter using a chronically implanted sensor at a plurality of time points and evaluating the physiological parameter measurements to determine if infection is indicated. In an embodiment, the invention includes an implantable medical device including a first chronically implantable sensor configured to generate a first signal corresponding to a physiological parameter and a controller disposed within a housing, the controller configured to evaluate the first physiological parameter signal to determine if an infection is indicated. Other embodiments are also included herein.

Abstract: Methods and/or devices for modifying the sampling rate for measuring a patient's intrinsic AV conduction time during cardiac therapy. For example, the sampling rate for measuring a patient's intrinsic AV conduction time may be modified (e.g., decrease or increased) based on one or more monitored physiological parameters, such as activity level and/or heart rate.

Abstract: Implantable systems, and methods for use therewith, enable the monitoring of a patient's electromechanical delay (EMD) and arterial blood pressure. Paced cardiac events are caused by delivering sufficient pacing stimulation to cause capture. A cardiogenic impedance (CI) signal, indicative of cardiac contractile activity in response to the pacing stimulation being delivered, is obtained. One or more predetermined features of the CI signal are detected, and a value indicative of the patient's EMD is determined by determining a time between a delivered pacing stimulation and at least one of the detected one or more features of the CI signal. The value indicative of EMD can be used to more accurately determine metrics indicative of pulse arrival time (PAT), which can be used to estimate arterial blood pressure.

Abstract: The health state of a subject is automatically evaluated or predicted using at least one implantable device. In varying examples, the health state is determined by sensing or receiving information about at least one physiological process having a circadian rhythm whose presence, absence, or baseline change is associated with impending disease, and comparing such rhythm to baseline circadian rhythm prediction criteria. Other chronobiological rhythms beside circadian may also be used. The baseline prediction criteria may be derived using one or more past physiological process observation of the subject or population of subjects in a non-disease health state. The prediction processing may be performed by the at least one implantable device or by an external device in communication with the implantable device. Systems and methods for invoking a therapy in response to the health state, such as to prevent or minimize the consequences of predicted impending heart failure, are also discussed.

Abstract: An implantable medical device that includes an elongated lead body having an outer surface and an opening along the outer surface, a first sensor positioned along the lead body and configured to receive acoustic signals through the opening of the first lead body and generate an electrical signal representative of sounds produced at a targeted location along a patient's cardiovascular system, and a processor configured to detect change in an S-T segment of sensed cardiac signals, and receive the acoustic signal and determine whether the sensed cardiac signals correspond to one of acute myocardial infarct and myocardial ischemia in response to the detected change.

Abstract: The present invention relates generally to methods and systems for optimizing stimulation of a heart of a patient. Hemodynamical index signals reflecting a mechanical functioning of a heart of a patient are recorded at different hemodynamical states. Corresponding hemodynamical reference signals at corresponding hemodynamical states are recorded. At least one hemodynamical index parameter is extracted from the recorded hemodynamical index signals. The at least one hemodynamical index parameter is a measure of the mechanical functioning of the heart and a hemodynamical index model is created, wherein the hemodynamical index model is based on the at least one hemodynamical index parameter and a comparison between output results from the hemodynamical index model and corresponding hemodynamical reference signals. From this hemodynamical index model, a hemodynamical index can be derived, which then can be used in determining patient customized cardiac pacing settings of the cardiac stimulator.

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: Pacing left and right ventricles of the heart for delivery of heart failure therapy involves measuring right ventricular (RV) pressure and a left ventricular (LV) pressure, and computing a parameter developed from one or both of the RV and LV pressure measurements. The parameter is indicative of a degree of left and right ventricular synchronization. At least one parameter of a heart failure pacing therapy is adjusted based on the parameter to improve synchronization of the right and left ventricles.

Abstract: A method of controlling the operation of a pulsatile heart assist device (14) in a patient (10). The method consisting of utilizing sounds produced by the heart (12) to control the operation of the heart assist device (14).

Abstract: A pacing system computes optimal cardiac resynchronization pacing parameters using intrinsic conduction intervals. In various embodiments, values for atrio-ventricular delay intervals are each computed as a function of an intrinsic atrio-ventricular interval and a parameter reflective of an interventricular conduction delay. Examples of the parameter reflective of the interventricular conduction delay include QRS width and interval between right and left ventricular senses.

Abstract: Methods for determination of timing for electrical shocks to the heart to determine shock strength necessary to defibrillate a fibrillating heart. The timing corresponds the window of most vulnerability in the heart, which occurs during the T-wave of a heartbeat. Using a derivatized T-wave representation, the timing of most vulnerability is determined by a center of the area method, peak amplitude method, width method, or other similar methods. Devices are similarly disclosed embodying the methods of the present disclosure.

Abstract: Methods and systems to modulate timing intervals for pacing therapy are described. For each cardiac cycle, one or both of an atrioventricular (A-V) timing interval and an atrial (A-A) timing interval are modulated to oppose beat-to-beat ventricular (V-V) timing variability. Pacing therapy is delivered using the modulated timing intervals.

Abstract: A medical device and associated method for controlling a cardiac pacing therapy sense a first cardiac signal including events corresponding to cardiac electrical events and a second cardiac signal including events corresponding to cardiac hemodynamic events. A processor is enabled to measure a cardiac conduction time interval using the first cardiac signal and control a signal generator to deliver a pacing therapy. A pacing control parameter is adjusted to a plurality of settings during the pacing therapy delivery. A hemodynamic parameter value is measured from the second cardiac signal during application of each of the control parameter settings. The processor identifies an optimal setting from the plurality of settings and solves for a patient-specific equation defining the pacing control parameter as a function of the cardiac conduction time interval.

Abstract: Techniques are provided for use with an implantable cardiac stimulation device equipped with a multi-pole left ventricular (LV) lead and a right ventricular (RV) lead for identifying suitable pacing vectors. In one example, RV-LV delay times are measured while using different electrodes of the LV lead as cathodes for sensing. The LV electrode having the longest RV-LV delay time is identified and LV capture thresholds and diaphragmatic stimulation thresholds are measured for pacing vectors that employ that LV electrode as a cathode. Assuming at least one vector employing the selected LV electrode is found to have acceptable thresholds, the vector is selected for use in delivering pacing therapy with the selected LV electrode. If none of the pacing vectors employing the selected LV electrode has acceptable thresholds, another LV electrode is selected and the procedure is repeated. Examples with a multi-pole RV lead are also described.

Abstract: A system, operatively connectable both to a cardiac-rhythm-management (CRM) subject, and to a CRM device associated with that subject, and an associated method, operable, in relation to received-and-processed, real-time, CRM-subject-specific, simultaneous ECG and heart-sound information, and other information including measurement time markers where available, for blocking, under all circumstances during the ventricular relative refractory period lying within each of successive CRM-subject cardiac cycles occupying a span of such cycles, the ventricular pacing activity of the subject-associated CRM device—the beginning and ending of such blocking in each cardiac cycle being system-defined to lie preferably, and respectively, (a) within the real-time, ventricular depolarization window in the cycle, and (b) at the time of the real-time, S2 heart-sound, plus or minus any user-defined time-delta.

Abstract: Methods for timing pacing pulses in an implantable single chamber pacemaker create a simulated, or virtual chamber in order to apply dual chamber-type algorithms and modes. For example, a virtual atrium may be constructed based on information provided by the ventricle, that is, the timing of actual intrinsic ventricular events, and the timing of paced ventricular events, both of which may be sensed as ventricular depolarization by electrodes of the implanted system.

Abstract: Devices and methods for sleep detection involve the use of an adjustable threshold for detecting sleep onset and termination. A method for detecting sleep includes adjusting a sleep threshold associated with a first sleep-related signal using a second sleep-related signal. The first sleep-related signal is compared to the adjusted threshold and sleep is detected based on the comparison. The sleep-related signals may be derived from implantable or external sensors. Additional sleep-related signals may be used to confirm the sleep condition. A sleep detector device implementing a sleep detection method may be a component of an implantable pulse generator such as a pacemaker or defibrillator.

Abstract: Various systems, methods, devices and arrangements are implemented for use in pacing of the heart. One implementation is directed to methods and systems for determining a pacing location in the right ventricle of a heart and near the His bundle. A pacing signal is delivered to the location in the right ventricle. The pacing signal produces a capture of a left ventricle. Properties of the capture are monitored. Results of the monitored capture are used to assess the effectiveness of the delivered pacing signal as a function of heart function. The heart function can be, for example, at least one of a QRS width, fractionation and a timing of electrical stimulation of a late activation site of a left ventricle relative to the QRS.

Abstract: An implantable device and method for monitoring S1 heart sounds with a remotely located accelerometer. The device includes a transducer that converts heart sounds into an electrical signal. A control circuit is coupled to the transducer. The control circuit is configured to receive the electrical signal, identify an S1 heart sound, and to convert the S1 heart sound into electrical information. The control circuit also generates morphological data from the electrical information. The morphological data relates to a hemodynamic metric, such as left ventricular contractility. A housing may enclose the control circuit. The housing defines a volume coextensive with an outer surface of the housing. The transducer is in or on the volume defined by the housing.

Abstract: A medical system comprises a plurality of electrodes; at least one sensor configured to output at least one signal based on at least one physiological parameter of a patient; and a processor. The processor is configured to control delivery of stimulation to the patient using a plurality of electrode configurations. Each of the electrode configurations comprises at least one of the plurality of electrodes. For each of the electrode configurations, the processor is configured to determine a first response of target tissue to the stimulation based on the signals, and a second response of non-target tissue to the stimulation based on the signals. The processor is also configured to select at least one of the electrode configurations for delivery of stimulation to the patient based on the first and second responses for the electrode configurations. As examples, the target tissue may be a left ventricle or vagus nerve.

Abstract: A medical device system and method that includes sensing a heart sound signal from a first external sensor, determining whether a pulmonary hypertension signature is detected in response to the sensed heart sound signal, sensing a lung sound signal from a second external sensor, determining whether a heart failure signature is detected in response to the sensed lung sound signal, and determining therapy parameters in response to determining whether a pulmonary hypertension signature is detected and determining whether a heart failure signature is detected.

Abstract: The present invention relates generally to methods for implantable medical devices and more particularly to methods for optimizing stimulation of a heart of a patient. The method comprises: determining recommended pacing settings including recommended AV delays and/or recommended W delays based on IEGM data. Further, at least one hemodynamical parameter is determined based on measured at least one hemodynamical signal. Reference pacing settings are determined including reference AV delays and/or reference W delays based on said hemodynamical parameters. An AV delay correction value and a W delay correction value are calculated as a difference between recommended AV and/or VV delays and reference AV and/or W delays, respectively. The correction values are used for updating recommended AV and/or VV delays, respectively.

Abstract: A maximum pacing rate limiter for use in adaptive rate pacing in conjunction with a cardiac rhythm management system for a heart. The maximum pacing rate limiter may function to measure an interval, termed the ERT interval, between a paced ventricular evoked response and a T-wave. The maximum pacing rate limiter may further function to maintain the ERT interval at less than a certain percentage of the total cardiac cycle. In one disclosed embodiment, a maximum pacing rate limiter calculates an ERT rate based on the detected paced ventricular evoked response and the T-wave, and the pacing rate limiter module further communicates the minimum of the ERT rate and an adaptive-rate sensor indicated rate to a pacemaker.

Abstract: The present invention provides methods for detecting phrenic nerve stimulation. A pacing module is instructed to deliver pacing pulses having a predetermined pulse amplitude and/or width within the refractory period of the left ventricle. The pacing pulses are repeatedly delivered during a number of cardiac cycles and wherein the pacing pulses are delivered at different delays relative to an onset of the refractory period of the left ventricle in different cardiac cycles. Impedance signals are measured in time windows synchronized with the delivery of pacing pulses in the refractory period of the left ventricle using at least one electrode configuration. At least one impedance signal is gathered from each time window, aggregated impedance signals are created using the impedance signals from the different time windows, and the aggregated impedance signals are analyzed to detect PNS.

Abstract: Systems and methods to monitor cardiac mechanical vibrations using information indicative of lead motion are described. In an example, a system including an implantable medical device can include an excitation circuit configured to provide a non-tissue stimulating, non-therapeutic electrical excitation signal to a portion of an implantable lead. A receiver circuit can be configured to obtain information indicative of a mechanical vibration of the implantable lead due at least in part to one or more of an impact of at least a portion of the heart to the implantable lead, or friction contact between the implantable lead and cardiac tissue. The system can include a processor circuit configured to determine one or more of a lead mechanical status, or information indicative of valvular activity using the information indicative of the mechanical vibration of the implantable lead.

Abstract: The present invention provides implantable medical devices for detecting phrenic nerve stimulation. A pacing module is configured to deliver pacing pulses having a predetermined pulse amplitude and/or width within the refractory period of the left ventricle. The pacing pulses are repeatedly delivered during a number of cardiac cycles, and the pacing pulses are delivered at different delays relative to an onset of the refractory period of the left ventricle in different cardiac cycles. An impedance measurement module is configured to measure impedance signals in time windows synchronized with the delivery of pacing pulses in the refractory period of the left ventricle. A phrenic nerve stimulation, PNS, detection module is configured to gather at least one impedance signal from each time window, create aggregated impedance signals using the impedance signals from the different time windows, and analyze the aggregated impedance signals to detect PNS.

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: An implantable medical device, IMD, (100) conducts CRT settings searches at multiple CRT settings search periods during an optimization time period by testing different candidate CRT settings and selecting the optimal CRT setting based on output signals of a hemodynamic sensor (240). The respective optimal CRT settings determined during the optimization time period are employed in order to predict at least one future optimal CRT setting that can be used by the IMD (100) following the end of the optimization time period. The IMD (100) then generates and applies pacing pulses to a subject's (5) heart (10) according to a CRT setting of the at least one future optimal CRT setting. The embodiments therefore enable efficient cardiac resynchronization therapy without any sensor readings after the end of the optimization time period and can therefore provide cardiac resynchronization therapy even if the hemodynamic sensor (240) becomes inoperable.

Abstract: A neural stimulation system senses autonomic activities and applies neural stimulation to sympathetic and parasympathetic nerves to control autonomic balance. The neural stimulation system is capable of delivering neural stimulation pulses for sympathetic excitation, sympathetic inhibition, parasympathetic excitation, and parasympathetic inhibition.

Abstract: An adaptive dual chamber pacemaker and/or cardioverter defibrillator for delivering ventricular stimulation to the heart correlated with hemodynamic performance of the heart, including a hemodynamic sensor for monitoring the hemodynamic performance of the heart, an atrial electrode and a ventricular electrode for sensing ventricular and atrial signals, and a learning module having a spiking neural network processor for learning to associate the ventricular-atrial intervals sensed by the electrodes with the hemodynamic performance sensed by the hemodynamic sensor, calculating ventricular-atrial intervals, replacing the ventricular-atrial intervals calculated from the sensed ventricular and atrial signals with the learned associated ventricular-atrial intervals, and causing delivery according to the learned associated ventricular-atrial intervals of a ventricular stimulation to the heart during atrial fibrillation episodes.

Abstract: Techniques are provided for use by an implantable medical device for optimizing the amount of ventricular dyssynchrony induced within a patient during protective pacing. In one example, the device analyzes intracardiac electrogram signals to detect an ischemic event within the heart. The device then delivers pacing stimulus in accordance with adjustable pacing parameters to induce ventricular dyssynchrony within the heart and adjusts the pacing parameters within a range of permissible values to achieve a preferred degree of ventricular dyssynchrony within the patient, so long as there is no significant reduction in left ventricular pumping functionality. Preferably, the pacing parameters are adjusted to maximize or otherwise optimize the degree of dyssynchrony induced within the patient. If a significant reduction in LV pumping functionality is detected, the dyssynchrony-inducing pacing is preferably suspended to avoid any deterioration in the condition of the heart.

Abstract: Systems and methods using a heart valve and an implantable medical device, such as for event detection and optimization of cardiac output. The cardiac management system includes a heart valve, having a physiological sensor. The physiological sensor is adapted to measure at least one of an intrinsic electrical cardiac parameter, a hemodynamic parameter or the like. The system further includes an implantable electronics unit, such as a cardiac rhythm management unit, coupled to the physiological sensor of the heart valve to receive physiological information. The electronics unit is adapted to use the received physiological information to control delivery of an electrical output to the subject.

Abstract: Various techniques are disclosed for facilitating selection of at least one vector from among a plurality of vectors for pacing a chamber of a heart. In one example, a method includes presenting, by a computing device, a plurality of criteria by which each of the plurality of vectors may be prioritized, selecting at least one criterion from among a plurality of criteria by which each of the plurality of vectors may be prioritized, measuring the at least one selected criterion for each of the plurality of vectors, and automatically prioritizing, by the computing device, the plurality of vectors based on the measurement of the at least one selected criterion.

Abstract: A system to measure intracardiac impedance includes implantable electrodes and a medical device. The electrodes sense electrical signals of a heart of a subject. The medical device includes a cardiac signal sensing circuit coupled to the implantable electrodes, an impedance measurement circuit coupled to the same or different implantable electrodes, and a controller circuit coupled to the cardiac signal sensing circuit and the impedance measurement circuit. The cardiac signal sensing circuit provides a sensed cardiac signal. The impedance measurement circuit senses intracardiac impedance between the electrodes to obtain an intracardiac impedance signal. The controller circuit determines cardiac cycles of the subject using the sensed cardiac signal, and detects tachyarrhythmia using cardiac-cycle to cardiac-cycle changes in a plurality of intracardiac impedance parameters obtained from the intracardiac impedance signal.