家兔离体心脏组织的不应期及房室结的滤波特性

一般认为房室结具有滤波特性，即它能阻止过快或过于提前的心房冲动传到心室。本实验旨在研究家兔离体心脏组织的不应期及房室结的滤波牧场生（ｎ＝１８）。实验中发现：（１）在短基础周期（２００－３００ｍｓ）房室结的相对不应期最长，而在长基础周期（６００，７００ｍｓ）希浦系（ＨｉｓＰｕｒｋｉｎｊｅ ｓｙｔｅｍ）的相对不应期最长；（２）在多种基础周期下，大多数心脏（１６／１８）房室结有效不应期小于心房功能不应期

REFRACTORY PERIODS OF CARDIAC TISSUES AND THE FILTERING PROPERTIES OF THE ATRIOVENTRICULAR NODE IN THE ISOLATED RABBIT HEART

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 (RP) of cardiac tissues and the FP of the AVN were investigated in isolated rabbit hearts (n=18). It was found that: (1) The relative RP of AVN was the longest at shorter basic cycle lengths (BCL) (200 - 300 ms) while the relative RP of His-Purkinje system (HPS) was the longest at longer BCL (600, 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 curve was smooth at BCL from 200 to 700 ms.The present results suggest that AVN in the isolated perfused rabbit heart do not have the FP and any dual atrioventricular Pathways in a physiological sense.