起搏随访及程控上海.ppt

* Hysteresis allows the sensed intrinsic rate to decrease to a value below the programmed lower rate before pacing resumes. Hysteresis provides the capability to maintain the patients own heart rhythm as long as possible, while pacing at a faster rate if the intrinsic rhythm falls below the hysteresis rate. The hysteresis rate is always the lower rate limit. The lower rate limit is initiated by a paced event, while the hysteresis rate is initiated by a non-refractory sensed event. In the example above, the lower rate limit is 60 ppm (1000 ms), while the hysteresis rate is 50 ppm (1200 ms). The patient is paced at 60 ppm until an intrinsic event occurs, and an interval of 1200 ms is started. This patient did not have another sensed event, so a ventricular pace was delivered. However, if another sensed event had occurred, the pacemaker would again have extended the interval to 1200 ms. * The Post-Ventricular Atrial Refractory Period (PVARP) is the period of time after a ventricular pace or sense when the atrial channel is in refractory. In other words, atrial senses outside of blanking that occur during this period are seen (and marked 揂R) on the marker channel), but do not initiate an AV interval. The purpose of PVARP is to avoid allowing retrograde P waves, far-field R waves, or premature atrial contractions to start an AV interval which would cause the pacemaker to pace in the ventricle at a high rate. The refractory period after a ventricular event (paced or sensed) is designed to avoid restarting of the V-A interval due to a T wave. Ventricular sensed events occurring in the noise sampling portion of the ventricular refractory period are seen (and marked 揤R?on the marker channel) but will not restart the V-A interval. The atrial channel is refractory following a paced or sensed event during the AV interval. This allows atrial senses occurring in the AV interval to be seen but not restart another AV interval . * * Search AV 周期性的测量 AV间期及调节PAV/SAV鼓励自身的传导. S