Using devices with a variable postventricular atrial refractory period for cardiac resynchronization

Trapped p waves causing loss of physiological left bundle branch pacing

OBJECTIVE

We present the case of a 75-year-old woman with severe aortic stenosis and moderate left ventricular dysfunction, who underwent elective transcatheter aortic valve replacement. After the procedure, the patient developed a left bundle branch block and a long PR interval. For this reason, a dual chamber pacemaker with pacing in the left bundle branch area was implanted. On device interrogation, we confirmed the presence of functional atrial undersensing causing loss of ventricular electric resynchronization. This case highlights the importance of recognizing this problem and, by means of device reprogramming and pharmacological intervention, suggests a stepwise approach to solve it.

Logic Analysis of Arrhythmia Triggered by Pacemaker Special Functions - An Educational Presentation

Dual-chamber pacemaker is a fully automatic pacemaker with the function of simulating human physiological pacing. It regulates pacing by programming different refractory periods and various special functions, which are closely related to arrhythmia. After in-depth understanding of these special functions, regular electrocardiogram follow-up analysis is required to provide individualized optimal program control and so is appropriate the administration of the pacemaker’s special functions to better provide optimal clinical guidance for patients with arrhythmia.

Dissimilar ventricular rhythms: implications for ICD therapy

Sensing of left ventricular (LV) activity in some devices used for cardiac resynchronization therapy (CRT) was designed primarily to prevent the delivery of an LV stimulus into the LV vulnerable period. Such a sensing function of the LV channel is not universally available in contemporary CRT devices. Recordings of LV electrograms may provide special diagnostic data unavailable solely from the standard right ventricular electrogram and corresponding marker channel. We used the LV sensing function of Biotronik CRT defibrillators to find 3 cases of dissimilar ventricular rhythms or tachyarrhythmias. Such arrhythmias are potentially important because concomitant slower right ventricular activity may prevent or delay implantable cardioverter-defibrillator therapy for a life-threatening situation involving a faster and more serious LV tachyarrhythmia. Dissimilar ventricular rhythms may not be rare and may account for cases of unexplained sudden death with a normally functioning implantable cardioverter-defibrillator and no recorded terminal arrhythmia.