摘要:
During a period of time comprising a plurality of cardiac cycles, a time relationship between ventricular events and atrial detections is established. Based on the relationship, a post-ventricular atrial refractory period is defined. The period includes an absolute atrial refractory period and a segmented relative atrial refractory period, wherein the segmented relative atrial refractory period includes at least one blanking window during which atrial detections of ventricular events have or are likely to occur.
摘要:
During a period of time comprising a plurality of cardiac cycles, a time relationship between ventricular events and atrial detections is established. Based on the relationship, a post-ventricular atrial refractory period is defined. The period includes an absolute atrial refractory period and a segmented relative atrial refractory period, wherein the segmented relative atrial refractory period includes at least one blanking window during which atrial detections of ventricular events have or are likely to occur.
摘要:
A technique is provided for detecting episodes of cardiac ischemia based on an examination of the total energy of T-waves. Since cardiac ischemia is often a precursor to acute myocardial infarction (AMI) or ventricular fibrillation (VF), the technique thereby provides a method for predicting the possible onset of AMI or VF. Briefly, the technique integrates internal electrical cardiac signals occurring during T-waves and then compares the result against a running average. If the result exceeds the average by some predetermined amount, ischemia is thereby detected and a warning signal is provided to the patient. The maximum slope of the T-wave is also exploited. Techniques are also set forth herein for reliably detecting T-waves, which help prevent P-waves from being misinterpreted as T-waves on unipolar sensing channels. The T-wave detection technique may be used in conjunction with ischemia detection or for other purposes.
摘要:
Techniques for detecting tachyarrhythmia and also for preventing T-wave oversensing use signals filtered by a narrowband bradycardia filter in combination with signals filtered by a narrowband tachycardia filter. A separate wideband filter may also be used.
摘要:
A method is provided to determine pacing parameters for an implantable medical device (IMD) and collects heart sounds during the cardiac cycles. The method comprises changing a value for a pacing parameter between the cardiac cycles and analyzing a characteristic of interest from the heart sounds. The method comprises setting a desired value for the pacing parameter based on the characteristic of interest from the heart sounds. The system comprises inputs configured to be coupled to at least one lead having electrodes to sense intrinsic events and to deliver pacing pulses over cardiac cycles. The system has a sensor for collecting heart sounds during cardiac cycles and controller to control delivery of pacing pulses based on pacing parameters. The controller changes a value for at least one of the pacing parameters between the cardiac cycles and provides an analysis module to analyze a characteristic of interest from the heart sounds.
摘要:
A surface electrocardiogram (EKG) is emulated using signals detected by internal leads of an implanted device. In one example, emulation is performed using a technique that concatenates portions of signals sensed using different electrodes, such as by combining far-field ventricular signals sensed in the atria with far-field atrial signals sensed in the ventricles. In another example, emulation is performed using a technique that selectively amplifies or attenuates portions of a single signal, such as by attenuating near-field portions of an atrial unipolar signal relative to far-field portions of the same signal. The surface EKG emulation may be performed by the implanted device itself or by an external programmer based on cardiac signals transmitted thereto. A transtelephonic monitoring network is also described, wherein the emulated surface EKG (or raw data used to emulate the EKG) is relayed from an implanted device to a remote monitor, typically installed in a physician's office.
摘要:
During cross-chamber pacing, where anodal capture may not be desirable, pulses are applied between a cathode electrode in a first chamber and an anode electrode in a second chamber. A capture detector detects for capture of the second chamber by the pacing pulses. If capture of the second chamber persists, another electrode is selected as the anodal electrode. During single-chamber pacing, where anodal capture may be desirable, pulses are applied between a cathode electrode and an anode electrode associated with the same chamber. A capture detector detects for capture at both electrodes. If anodal capture is not detected, the energy of the pacing pulse is increased, until anodal capture is detected.
摘要:
Techniques for detecting tachyarrhythmia and also for preventing T-wave oversensing use signals filtered by a narrowband bradycardia filter in combination with signals filtered by a narrowband tachycardia filter. A separate wideband filter may also be used.
摘要:
An implantable medical device includes a first, short-range telemetry circuit; a second, long-range telemetry circuit; a first power system that powers the first telemetry circuit; and a second power system that powers the second telemetry circuit. The second power system includes an internal charging system and a rechargeable battery coupled to the internal charging system. The internal charging system may be configured for electromagnetic-inductive or RF-transmission coupling with an external charging system. A controller monitors the energy level of the rechargeable battery and provides an signal indicative of the level.
摘要:
An implantable medical device is provided that comprises a housing, sensors configured to be located to proximate a heart, and a sensing module to sense cardiac signals originating from the heart over a channel defined by the sensors. The cardiac signals include intrinsic R-wave events and associated intrinsic confirmation events when the heart exhibits normal sinus rhythm. The device further includes memory to store the cardiac signals sensed over a channel, and a detection module. The detection module identifies an R-wave event within the cardiac signals. The detection module captures, in the memory, a segment of the cardiac signals that precedes the R-wave event as a retrospective segment. The detection module determines whether the retrospective segment includes an intrinsic confirmation event that is associated with and occurs before the R-wave event. The detection module declares an arrhythmia based at least in part on the determination of whether the retrospective segment includes the intrinsic confirmation event is absent from the retrospective segment.