Automatic assessment of atrial pacing threshold in current medical practice.

AIMS: The aim of this study was to validate the ambulatory automatic atrial threshold monitoring algorithm by comparing the measurements assessed by the automatic system and those evaluated manually by the physician at discharge, 2- and 8-month follow-up sessions. METHODS AND RESULTS: This is an observational multicentric prospective study of 352 patients implanted with EnPulse(®) DR pacemakers. Mean age was 76.3 ± 9.4 years. Indications of pacing were atrio-ventricular block (AVB) (64%) and sinus dysfunction (SD) or brady-tachy syndrome (36%). The automatic atrial threshold monitoring function was maintained at nominal programming state with daily measurement scheduled at 1:00 am. Ambulatory automatic atrial threshold assessment was possible for 91.5% of patients at discharge, 97.3% at 2 months, and 95.7% at 8 months. Causes of the unsuccessful attempts to perform automatic atrial threshold were atrial arrhythmias or permanent atrial and ventricular pacing. Feasibility is significantly better for AVB indication than SD indication due to more frequent occurrence of atrial fibrillation (AF). At each stage, there is a strict correlation between the automatic measurements and those conducted manually by the physician with a P < 0.001. CONCLUSION: Feasibility of ambulatory automatic atrial threshold is good. Results of the study show excellent correlation between the two methods for atrial threshold: there is no statistical difference between manual and automatic measurements during follow-up.

Effect of a pacing mode preserving spontaneous AV conduction on ventricular pacing burden and atrial arrhythmias.

BACKGROUND: Using dual-chamber pacemakers with new algorithms: Manage Ventricular Pacing (MVP™), minimizes unnecessary ventricular pacing (VP). This function operates in AAI/R mode with backup VP during AV block. AIM: The aim of "Generation MVP" study was to assess the VP burden and atrial arrhythmias (AA) burden according to indication of pacing and MVP™ function programming of AdaptaDR implantable pacemaker (Medtronic Inc., Minneapolis, MN, USA). METHODS: The multicenter observational "Generation MVP" study included 220 patients aged 75.9 ± 11 years (men = 52%) implanted for sinus node dysfunction (SND; n = 115) or atrio-ventricular block (AVB; n = 105). Programming MVP function has been left to the physician's discretion. Percentage of VP and AA burden (percentage of time spent in AA) stored in memories were assessed at 2 and 10 months. RESULTS: 220 patients were followed at 2 months (174 MVP [On], 46 MVP [off]) and at 10 months (165 MVP [On], 55 MVP [off]). Median percentage of VP is significantly lower when MVP is programmed [On] versus [off] at 2 and 10 months follow-up for SND and AVB indications of pacing (P < 0.001). Finally, programming MVP function is performed at middle term (10 months) for 84% of patients with SND and 65% of patients with AVB: median percentage of VP is as low as 0.6% for patients with SND and 12% for patients with AVB versus 95% for SND and 99% for AVB when MVP function is programmed [off](P < 0.001). Median AA burden was significantly lower when MVP function was programmed [On] versus [off] at 2 months (8.7% vs 28%; P < 0.001) and 10 months (1% vs 22%; P < 0.001). CONCLUSION: In this study programming MVP function decreases percentage of VP at 2 and 10 months for patients paced for SND or AVB. Moreover median AA burden is reduced when MVP function was programmed [On] vs [off] at two follow-ups.

Atrioventricular nodal reentrant tachycardia diagnosed by pacemaker electrograms.

Electrograms stored by pacemakers or implantable defibrillators enable the diagnosis of numerous atrial or ventricular arrhythmia episodes. We present the case of a patient implanted with a DDD pacemaker for sinus node dysfunction who experienced episodes of tachycardia. Atrioventricular nodal reentrant tachycardia was diagnosed by real-time analysis of electrograms during and at the onset of the tachycardia episodes. Electrophysiological study confirmed the diagnosis and led to radical treatment of the tachycardia by radiofrequency ablation of the slow pathway.

Cardiac resynchronization therapy using a VDD lead.

In heart failure patients with normal sinus node function, cardiac resynchronization therapy can be achieved with only two leads, one VDD type, and one left ventricular. This reduces the number of venous punctures, implanted leads, and possibly operation and fluoroscopic times and complication rates. We present two cases and discuss the advantages and limits of such a procedure.

Cross-ventricular pacemaker-mediated tachycardia by myopotential induction during biventricular pacing.

BACKGROUND: Patients in permanent atrial fibrillation treated for heart failure and ventricular asynchrony can be implanted with conventional dual chamber pacemakers (DDD) pacemakers used in the biventricular mode. The left ventricular lead is connected to the atrial channel. CASE REPORT: We report the case of a patient who developed ventriculo-ventricular pacemaker-mediated tachycardia (PMT) induced by myopotential sensing in the atrial channel, inhibiting left ventricular pacing. CONCLUSION: In the absence of specifically designed pacemakers, the use of DDD pacemakers in the biventricular mode requires certain precautions, such as anti-PMT mode activation, disabling automatic sensitivity, and lengthening the postventricular atrial refractory period (PVARP), or mode switch to DVIR.