[Atrial sensing and atrioventricular synchrony in single lead VDD pacemakers. Can the appearance of atrial undersensing be predicted?].
Single-lead VDD-pacing is an alternative to DDD-systems in patients with AV-block and normal sinus node function. Atrial sensing plays a central role in these pacemakers. AV-synchrony, incidence of atrial arrhythmias and the occurrence of sinus node disease were investigated in 108 patients with VDD-pacemakers followed over a mean period of 24.8 months after implantation. Determinants influencing the occurrence of atrial undersensing were especially focused on. Mean atrial potential and sensing threshold were reduced within the first 2 weeks after implantation (p < 0.01). Intermittent atrial undersensing occurred in 25.9% of patients and was observed in 82.1% of these patients within the first 2 weeks after implantation. Positioning the atrial dipole in the low right atrium showed a significantly higher incidence of atrial undersensing (42% in comparison to 24% in the other positions). In a multivariate analysis including intra- and postoperative measurements as well as characteristics of the pacemakers and leads, it was the only parameter significantly (p < 0.02) correlated to the occurrence of atrial undersensing. Atrial fibrillation was observed in 4.6% of patients, a sinus node disease became evident in 2.7% of patients; 92.6% of patients remained in the AV-synchronous mode. Intermittent atrial undersensing is common in single-lead VDD-pacemakers and difficult to provide during implantation. The atrial dipole should not be positioned in the low right atrium and highest atrial sensitivity should generally be programmed. Nevertheless, VDD-pacing achieves an AV-synchrony comparable to DDD-pacemakers.
Wiegand
U K
UK
Klinik für Kardiologie, Medizinische Universität zu Lübeck.
Schneider
R
R
Bode
F
F
Brandes
A
A
Taubert
G
G
Potratz
J
J
D000368:Aged; D000369:Aged, 80 and over; D001283:Atrioventricular Node / Q000503:physiopathology*; D002311:Cardiomyopathy, Dilated / Q000503:physiopathology / Q000628:therapy; D003327:Coronary Disease / Q000503:physiopathology / Q000628:therapy; D015716:Electrocardiography, Ambulatory / Q000295:instrumentation*; D004567:Electrodes, Implanted; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005080:Exercise Test / Q000295:instrumentation; D005260:Female; D006327:Heart Block / Q000503:physiopathology / Q000628:therapy*; D006349:Heart Valve Diseases / Q000503:physiopathology / Q000628:therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D012849:Sinoatrial Node / Q000503:physiopathology; D012984:Software