Abstract: An implantable medical device and associated method perform ECG morphology monitoring. A subcutaneous ECG signal and a posture signal are sensed in a patient. A cardiac condition is detected in response to the ECG signal and the posture signal. In one embodiment, multiple ECG morphology templates corresponding to each of a number of different patient postures are acquired and stored for use in detecting a cardiac condition.

Abstract: Methods and devices for identification of intrinsic ventricular activity occurring within a ventricular signal. Ventricular signal morphology is analyzed to determine if the signal contains intrinsic ventricular activity while delivering pacing pulses separated by nearly constant time intervals. Furthermore, an extension of a pacing interval is specified based on whether or not the signal contains autonomous intrinsic ventricular activity. In this manner, the pacing interval is only extended when it is likely for autonomous intrinsic ventricular activity to occur.

Abstract: An implantable medical device and associated method perform ECG morphology monitoring. A subcutaneous ECG signal and a posture signal are sensed in a patient. A cardiac condition is detected in response to the ECG signal and the posture signal. In one embodiment, multiple ECG morphology templates corresponding to each of a number of different patient postures are acquired and stored for use in detecting a cardiac condition.

Abstract: The invention is directed to methods and apparatus for automatically changing from bi-ventricular pacing, in which an implantable medical device (IMD) applies pacing stimuli to both ventricles of a heart during a cardiac cycle, to single-ventricle pacing, in which the IMD paces one ventricle and inhibits pacing of the other. An IMD applying the techniques of the invention automatically changes from bi-ventricular pacing to single-ventricle pacing, or vice versa, as a function of the reliability of left ventricular pacing. Exemplary techniques for determining the reliability of left ventricular pacing include impedance measurement, capture testing, capture threshold testing, or any combination thereof.

Abstract: A medical device is directed to techniques for removing polarization artifacts from electrical activity signals in order to detect presence of an evoked response. More specifically, a medical device receives a signal that represents electrical activity within a heart of a patient following delivery of a stimulation pulse to the heart and reconfigures a filter state of a filter from an initial filter state to remove the polarization artifact from the electrical activity signal in order to determine whether a cardiac event, such as an evoked response has occurred. The medical device may, for example, when the filter of the medical device is a digital filter, recalculate the values of digital filter components using the present input value of the electrical activity signal as a direct current (DC) input value of the digital filter.

Abstract: In general, the invention is directed to identification of intrinsic ventricular activity occurring within a ventricular signal. In particular, the invention involves the analysis of ventricular signal morphology to determine if the signal contains intrinsic ventricular activity while delivering pacing pulses separated by nearly constant time intervals. Furthermore, the invention specifies an extension of a pacing interval based on whether or not the signal contains intrinsic ventricular activity. In this manner, the pacing interval is only extended when it is likely for intrinsic ventricular activity to occur.

Abstract: Method and device for determining capture status of a heart chamber that receives a pulse from an implantable pulse generator (IPG). Signal processing can be used to improve the reliability of capture detection by transforming the sensed response signal into a set of morphological characteristics. Analysis of selected morphological characteristics serves to distinguish signals indicative of capture from signals indicative of loss of capture.

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: The invention is directed to techniques for removing polarization artifacts from electrical activity signals in order to detect presence of an evoked response. More specifically, a medical device receives a signal that represents electrical activity within a heart of a patient following delivery of a stimulation pulse to the heart and reconfigures a filter state of a filter from an initial filter state to remove the polarization artifact from the electrical activity signal in order to determine whether a cardiac event, such as an evoked response has occurred. The medical device may, for example, when the filter of the medical device is a digital filter, recalculate the values of digital filter components using the present input value of the electrical activity signal as a direct current-(DC) input value of the digital filter.

Abstract: The invention is directed to methods and apparatus for automatically changing from bi-ventricular pacing, in which an implantable medical device (IMD) applies pacing stimuli to both ventricles of a heart during a cardiac cycle, to single-ventricle pacing, in which the IMD paces one ventricle and inhibits pacing of the other. An IMD applying the techniques of the invention automatically changes from bi-ventricular pacing to single-ventricle pacing, or vice versa, as a function of the reliability of left ventricular pacing. Exemplary techniques for determining the reliability of left ventricular pacing include impedance measurement, capture testing, capture threshold testing, or any combination thereof.

Abstract: In general, the invention is directed to techniques for determining capture status of a heart chamber that receives a pulse from an implantable pulse generator (IPG). Digital signal processing (DSP) can be used to improve the reliability of capture detection by transforming the sensed response signal into a set of morphological characteristics. Analysis of selected morphological characteristics serves to distinguish signals indicative of capture from signals indicative of loss of capture.

Abstract: In general, the invention is directed to identification of intrinsic ventricular activity occurring within a ventricular signal. In particular, the invention involves the analysis of ventricular signal morphology to determine if the signal contains intrinsic ventricular activity while delivering pacing pulses separated by nearly constant time intervals. Furthermore, the invention specifies an extension of a pacing interval based on whether or not the signal contains intrinsic ventricular activity. In this manner, the pacing interval is only extended when it is likely for intrinsic ventricular activity to occur.