Izumi K
Mouridai Clinic, Kanagawa, Japan.
Mater Med Pol. 1990 Jul-Sep;22(3):168-72.
Atrial parasystole arising from two different ectopic atrial foci, namely, double atrial parasystole, showed intermittent trigeminy due to 3:1 exit block, in which both the ectopic atrial rates were around the sinus rate. Atrial trigeminy showing positive P waves in leads II and III continued, then intermittent atrial parasystole with negative P waves in leads II and III took over. The double atrial parasystole was considered to be interspersed with reentrant atrial beats. Other possible mechanisms to cause a disruptive influence on the trigeminy of the atrial parasystole with positive P waves in leads II and III are: (a) concealed intraatrial reentry with resetting by the sinus impulse; and (b) delayed capture by the impulse of the third preceding sinus beat, and the subsequent 3:1 exit block. On the other hand, the atrial parasystole with negative P waves in leads II and III tended to show long interectopic intervals, in which some of the parasystolic beats exhibited a coupling to the third preceding sinus beat. This suggested prompt resetting by the sinus impulse and the ensuing 3:1 exit block.
起源于两个不同异位心房灶的房性并行心律，即双重房性并行心律，因3:1传出阻滞而呈现间歇性三联律，其中两个异位心房率均接近窦性心律。在II导联和III导联中显示正向P波的房性三联律持续存在，随后在II导联和III导联中出现负向P波的间歇性房性并行心律取而代之。双重房性并行心律被认为夹杂着折返性房性搏动。对II导联和III导联中出现正向P波的房性并行心律三联律产生干扰影响的其他可能机制为：(a) 隐匿性房内折返并由窦性冲动重置；(b) 被前一个窦性搏动的冲动延迟夺获，随后出现3:1传出阻滞。另一方面，II导联和III导联中出现负向P波的房性并行心律往往表现为较长的异位间期，其中一些并行心律搏动与前一个窦性搏动三联律相关。这提示由窦性冲动迅速重置并随后出现3:1传出阻滞。
