犬心房功能不应期与房室结有效不应期对比研究

Comparative study on atrial functional refractory period and atrioventricular nodal effective refractory period in the dog

为进一步了解房室传导的电生理特性 ,对 8只犬在体条件下的心房功能不应期 (AFRP)和房室结有效不应期(AVNERP)进行对比研究。采用心房期前刺激法 ,记录静注美托洛尔阻断心脏β受体前后不同基础周期条件下的电生理参数 ,绘制成房室传导曲线。分析发现静注美托洛尔前后各个基础周期条件下 ,8只犬 AVNERP均不能测出 ;相同基础周期条件下 ,美托洛尔用药前后房室传导曲线有明显变化 ,AFRP也明显延长 (P<0 .0 5 )。结果提示不同种属间心肌不应期存在差异 ,犬 AVNERP始终小于

In order to observe further electrophysiologic characteristics of atrioventricular (AV) conduction,We compared atrial functional refractory peroid (AFRP) and atrioventricular nodal effective refractory period (AVNERP) in 8 dogs. AV condution was assessed by atrial extrastimulus technique using at least two basic cycle lengths. The electophysiologic parameters were recorded before and after administering intravenous Metoprolol to block the β receptor in the heart, and plotted into the AV conduction curve. As a result,the AVNERP could not be measured in any dog. AV conduction curve showed significant changes before and after the administration of Metoprolol at equivalent basic cycle length,AFRP also showed significant prolongation. It domonstrated that the refractory periods of cardiac conduction are obvious difference in different species. The properties that AVNERP is permanently shorter than AFRP in the dog may be functional manifestation of its physiologic characteristics.