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Refractory periods of cardiac tissues and the filtering properties of the atrioventricular node in the isolated rabbit heart

Zhang Lingling, Niu Weizhen, Liu Beiying, Jiao Xiaohui, Liu Ping

Department of Physiology, Zhangjiakou Medical College. Zhangjiakou 075029, Hebei；China

Abstract

It is generally believed that the atrioventricular node (AVN) possesses filtering properties (FP) capable of preventing excess atrial impulses or earlier atrial premature beat from reaching the ventricle. In the present study, the refractory periods (RF) of cardiac tissues and the FP of the AVN were investigated in siolated rabbit hearts (n=18). It was found that: (1) relative RP of AVN was the longest at shorter basic cycle lengths (BCL) (200--300ms) while the relative RP of His--Purkinje system (HPS) was the longest at longer BCL (400, 700 ms). (2) The effective RP of AVN was shorter than the functional RP of the atrium in most cases (16/18) at any BCL. (3) During rapid atrial pacing at cycle length of 140 ms in 7 cases, AVN maintained 1:1 conduction. (4) the atrioventricular nodal conduction ncurve was smooth at BCL from 200 to 700 ms.

Key words: Atrioventricular node;Filtering properties;Refractory period;Dual A-V pathways;Rabbit

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Citing This Article：

Zhang Lingling, Niu Weizhen, Liu Beiying, Jiao Xiaohui, Liu Ping. Refractory periods of cardiac tissues and the filtering properties of the atrioventricular node in the isolated rabbit heart. Acta Physiol Sin 1995; 47 (2): (in Chinese with English abstract).