Abstract: An apparatus comprises a cardiac signal sensing circuit, a physiologic sensor circuit configured to provide a physiologic sensor signal representative of mechanical cardiac activity, a therapy circuit, and a control circuit. The control circuit includes a cardiac depolarization detection circuit, a tachyarrhythmia detection circuit, and a timer circuit. A time interval between a mechanical cardiac event and a detected fiducial electrical cardiac event is monitored. The control circuit is configured to correct the monitored time interval for variation with heart rate to form a corrected electromechanical time interval, initiate anti-tachyarrhythmia therapy when the corrected electromechanical time interval satisfies a specified time interval threshold value during a detected episode of tachyarrhythmia, and withhold anti-tachyarrhythmia therapy otherwise.

Abstract: Cardiac electrostimulation energy is delivered to a heart chamber of a subject according to a normal pacing mode using a set of implantable pacing electrodes. When a threshold test for the heart chamber is initiated and a sensing electrode independent from the set of pacing electrodes is unavailable for the heart chamber, cardiac electrostimulation energy is delivered to the subject according to a threshold test mode. The threshold test mode includes sensing a cardiac activity signal from a subject using a set of sensing electrodes that includes an electrode common to the set of pacing electrodes, and changing the electrostimulation energy and sensing a resulting cardiac activity signal using the set of sensing electrodes to determine the optimum electrostimulation energy for capture of the heart chamber.

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

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

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

Abstract: An apparatus comprises a control circuit that initiates a normal pacing mode for delivery of electrostimulation energy to the heart chamber. In response to an indication to initiate a threshold test, the control circuit determines an electrode configuration used to deliver the electrostimulation energy in the normal pacing mode, selects a first threshold test mode when a sensing electrode independent from the set of pacing electrodes is unavailable for the heart chamber, wherein a cardiac activity signal is sensed using a set of sensing electrodes that includes an electrode common to the set of pacing electrodes, and selects a second threshold test mode when a sensing electrode independent from the set of pacing electrodes is available for the heart chamber, wherein the cardiac activity signal is sensed using a set of sensing electrodes that excludes an electrode common to the set of pacing electrodes.

Abstract: Cardiac electrostimulation energy is delivered to a heart chamber of a subject according to a normal pacing mode using a set of implantable pacing electrodes. When a threshold test for the heart chamber is initiated and a sensing electrode independent from the set of pacing electrodes is unavailable for the heart chamber, cardiac electrostimulation energy is delivered to the subject according to a threshold test mode. The threshold test mode includes sensing a cardiac activity signal from a subject using a set of sensing electrodes that includes an electrode common to the set of pacing electrodes, and changing the electrostimulation energy and sensing a resulting cardiac activity signal using the set of sensing electrodes to determine the optimum electrostimulation energy for capture of the heart chamber.

Abstract: Cardiac resynchronization therapy is delivered to a heart using an extended bipolar electrode configuration in accordance with programmed pacing parameters including a non-zero intraventricular delay. The extended bipolar electrode configuration comprises a left ventricular electrode defining a cathode of the extended bipolar electrode configuration and a right ventricular electrode defining an anode of the extended bipolar electrode configuration. A pace pulse is delivered to the left ventricular electrode and anodal stimulation of the right ventricle is detected based on the sensed response to the pace pulse.

Abstract: An apparatus comprises a cardiac signal sensing circuit, a physiologic sensor circuit configured to provide a physiologic sensor signal representative of mechanical cardiac activity, a therapy circuit, and a control circuit. The control circuit includes a cardiac depolarization detection circuit, a tachyarrhythmia detection circuit, and a timer circuit. A time interval between a mechanical cardiac event and a detected fiducial electrical cardiac event is monitored. The control circuit is configured to correct the monitored time interval for variation with heart rate to form a corrected electromechanical time interval, initiate anti-tachyarrhythmia therapy when the corrected electromechanical time interval satisfies a specified time interval threshold value during a detected episode of tachyarrhythmia, and withhold anti-tachyarrhythmia therapy otherwise.

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

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

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

Abstract: Cardiac resynchronization therapy is delivered to a heart using an extended bipolar electrode configuration in accordance with programmed pacing parameters including a non-zero intraventricular delay. The extended bipolar electrode configuration comprises a left ventricular electrode defining a cathode of the extended bipolar electrode configuration and a right ventricular electrode defining an anode of the extended bipolar electrode configuration. A pace pulse is delivered to the left ventricular electrode and anodal stimulation of the right ventricle is detected based on the sensed response to the pace pulse.