Double-counting of intracardiac electrogram during biatrial pacing.
BACKGROUND
Biatrial pacing has a significant problem with memory function that misinterprets normal sinus rhythm as atrial tachyarrhythmias and in addition estimation of the atrial pacing thresholds (biatrial and uniatrial pacing thresholds) is sometimes difficult because of small P waves.


RESULTS
The intracardiac electrograms recorded by a pacemaker in 10 patients (age, 66.7+/-10.7 (SD) years) with implanted biatrial pacemakers were analyzed. Atrial sensing within the atrial refractory period after atrial pacing was counted in 6 of the 10 patients (timing of the double counting was 143+/-64 ms) when pacing failed in the left or right atrium. Atrial sensing within the atrial refractory period after atrial pacing disappeared when biatrial pacing was successfully performed. Atrial double-counts depend on interatrial conduction delay. The memory function of implanted pacemaker devices misinterpreted normal sinus rhythm as atrial tachyarrhythmias because of atrial double-counts. On the other hand, the biatrial pacing threshold was easily recognized using this phenomenon.


CONCLUSIONS
The memory function of pacemaker devices is unreliable because of atrial double-counting during sinus rhythm in patients with biatrial pacing. However, the biatrial pacing threshold is easily checked using this phenomenon.
Kobayashi
Tsukasa
T
Second Department of Internal Medicine, Yokohama City University School of Medicine, Japan. tishika@med.yokohama-cu.ac.jp
Ishikawa
Toshiyuki
T
Sumita
Shinichi
S
Yamakawa
Youhei
Y
Ohkusu
Yasuo
Y
Matsusita
Kohei
K
Matsumoto
Katsumi
K
Nakagawa
Tsuyoshi
T
Nakazawa
Ichirou
I
Mochida
Yasuyuki
Y
Ebina
Toshiaki
T
Uchino
Kazuaki
K
Kimura
Kazuo
K
Umemura
Satoshi
S
D000368:Aged; D001281:Atrial Fibrillation; D002304:Cardiac Pacing, Artificial / Q000592:standards*; D004562:Electrocardiography; D004868:Equipment Failure; D019544:Equipment Failure Analysis; D005260:Female; D005500:Follow-Up Studies; D006329:Heart Conduction System; D006801:Humans; D008297:Male; D008838:Microcomputers; D008875:Middle Aged; D019919:Prosthesis Implantation; D013612:Tachycardia, Ectopic Atrial