Pandit N, Sethi K K, Mohan J C, Arora R, Khalilullah M
Department of Cardiology, G.B. Pant Hospital, New Delhi.
Indian Heart J. 1991 Mar-Apr;43(2):79-82.
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.
从右心耳起搏时，心房夺获的识别常常很困难。对45例植入AAI/DDD起搏器的患者（30例单极，15例双极）的心电图进行分析，以确定起搏P波的特定形态。与窦性P波相比，心房起搏导致心房去极化幅度降低（0.16±0.05mV对0.11±0.032mV，P<0.005）但持续时间增加（0.07±0.009秒对0.08±0.017秒，P<0.005）。单极和双极起搏装置中的P波形态相似。在I导联（80%）、II导联（71.11%）、III导联（80%）和aVF导联（75.55%）中为正向。在aVL导联中，起搏P波通常呈双相，初始为负向偏转（35.55%）。胸前导联显示起搏心房去极化幅度小，无助于识别心房夺获。在单极起搏中，由于该导联起搏尖峰小，P波在III导联中最易观察到。II导联适用于识别双极起搏中的起搏P波。因此，仔细检查标准心电图导联中低幅度、延长持续时间和特定形态的起搏P波，有助于确认右心耳起搏刺激后的心房夺获。
