title: Electrocardiographic features of atrial depolarization during pacing of right atrial appendage.
abstract: Identification of atrial capture during pacing from right atrial appendage is frequently difficult. Electrocardiograms of forty five patients implanted with AAI/DDD pacemakers (thirty unipolar, fifteen bipolar) were analysed to characterize the specific morphology of paced P waves. Compared to sinus P waves, atrial pacing resulted in atrial depolarization of lower amplitude (0.16 +/- 0.05 mv vs 0.11 +/- 0.032 mv, P less than 0.005) but increased duration (0.07 +/- 0.009 sec vs 0.08 +/- 0.017 sec, P less than 0.005). P wave morphology was similar in unipolar and bipolar pacing units. It was positive in lead I (80%), II (71.11%), III (80%) and aVF (75.55%). In lead aVL, paced P waves were usually diphasic with an initial negative deflection (35.55%). Precordial leads showed paced atrial depolarization of small amplitude and did not help in identification of atrial capture. In unipolar pacing P waves were best seen in lead III because of small pacing spike in this lead. Lead II was suitable for identification of paced P waves in bipolar pacing. Thus careful examination of standard ECG leads for paced P waves of low amplitude, prolonged duration and specific morphology can help in confirming atrial capture following pacing stimulus from right atrial appendage.
authors.affiliation: Department of Cardiology, G.B. Pant Hospital, New Delhi.
authors.forename: N
authors.initials: N
authors.lastname: Pandit
authors.forename: K K
authors.initials: KK
authors.lastname: Sethi
authors.forename: J C
authors.initials: JC
authors.lastname: Mohan
authors.forename: R
authors.initials: R
authors.lastname: Arora
authors.forename: M
authors.initials: M
authors.lastname: Khalilullah
mesh_terms: D000328:Adult; D000368:Aged; D016280:Atrial Function, Right / Q000502:physiology*; D001283:Atrioventricular Node / Q000503:physiopathology*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D006327:Heart Block / Q000503:physiopathology* / Q000628:therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D012804:Sick Sinus Syndrome / Q000503:physiopathology* / Q000628:therapy; D012849:Sinoatrial Node / Q000503:physiopathology*