초록 ▼

A special type of AV/PV hysteresis is provided in a dual-chamber pacemaker. A long AV delay is initially provided, thereby affording as much opportunity as possible for natural AV conduction to occur. Such long AV delay is automatically shortened should AV block occur. Periodic scanning for the retu

A special type of AV/PV hysteresis is provided in a dual-chamber pacemaker. A long AV delay is initially provided, thereby affording as much opportunity as possible for natural AV conduction to occur. Such long AV delay is automatically shortened should AV block occur. Periodic scanning for the return of AV conduction (absence of AV block) is performed so that the AV delay can be returned to its long value as soon as possible. In one embodiment, the pacemaker "learns" the natural conduction time (AR interval) of the patient and thereafter uses such learned natural conduction time as a reference against which subsequently measured AR intervals are compared to better distinguish conducted ventricular contractions from ectopic, pathologic, or other nonconducted ventricular contractions (e.g., PVC's). If the measured AR interval is approximately the same as the "learned" AR interval, then the R-wave at the conclusion of the measured AR interval is presumed to be a conducted R-wave that signals the return of AV conduction, and the AV delay is lengthened back to its original value. If, on the other hand, the measured AR interval is significantly different than the "learned" natural conduction time, then the R-wave at the conclusion of the measured AR interval is presumed to be a nonconducted R-wave, and the AV delay is kept short. In other embodiments, other techniques are used to distinguish a conducted R-wave from a nonconducted R-wave.

대표청구항 ▼

[ What is claimed is:] [1.] An improved method of ventricular support in a dual-chamber implantable electronic pacemaker, the electronic pacemaker including timing means for generating timed intervals, sensing means for sensing P-waves and R-waves, and pulse generating means for generating A-pulses

[ What is claimed is:] [1.] An improved method of ventricular support in a dual-chamber implantable electronic pacemaker, the electronic pacemaker including timing means for generating timed intervals, sensing means for sensing P-waves and R-waves, and pulse generating means for generating A-pulses and V-pulses, the method comprising:(a) initiating a long atrioventricular interval (AVI) in response to a first atrial event, the first atrial event comprising either an stimulated A-pulse or a sensed P-wave;(b) detecting whether an R-wave is sensed during the long AVI initiated in response to the first atrial event;(c) generating a first V-pulse following the long AVI initiated in response to the first atrial event whenever an R-wave is not sensed during the long AVI;(d) initiating a ventricular support response whenever an R-wave is not sensed during the long AVI initiated in response to the first atrial event, the ventricular support response comprising:initiating a short AVI in response to a second atrial event, andgenerating a second V-pulse following the short AVI initiated in response to the second atrial event;(e) detecting, whenever the ventricular support response is initiated, whether the ventricular support response continues to be needed by scanning for the recurrence of an R-wave, the scanning for the recurrence of an R-wave comprising:initiating the long AVI in response to a third atrial event, anddetecting whether an R-wave is sensed during the long AVI initiated in response to the third atrial event; and(f) terminating the ventricular support response whenever an R-wave is sensed during the long AVI initiated in response to the third atrial event.