Effect on coronary flow of atrial contraction.

J V Reid, C I Bhagat
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Abstract

The transient decrease in coronary conductance and flow that is seen when the atria contract has been studied in 6 anaesthetized, open-chest dogs in heart block, paced via epicardial pacemaker leads. Left circumflex and anterior descending coronary flows were recorded via Doppler ultrasonic flow probes; aortic and left ventricular pressures and electrocardiogram were recorded simultaneously. The transient conductance and flow decrease in diastole were found from linear regression to be consistent with the left ventricular pressure rise caused by atrial contraction, in the case of the anterior descending coronary artery, which also showed no decrease in peak systolic conductance or flow when atria and ventricles contracted simultaneously. Circumflex conductance and flow were decreased by an atrial contraction to an extent greater than could be accounted for by the rise in left ventricular diastolic pressure. Peak circumflex flow and conductance were also decreased in systole, by 12 per cent, when atrial and ventricular contractions were exactly synchronous so that the atria could not discharge into the ventricles. The systolic effect and the excessive diastolic effect are ascribed to compression of atrial branches of the circumflex artery. This artrial compression mechanism accounted for 37-75 per cent of the effect of an atrial contraction on conductance in diastole. Values from 5 dogs of systolic and diastolic conductance changes due to atrial compression were linearly related. Calculation of atrial flow by applying this percentage to the transient flow decrease indicated that 17 per cent of circumflex diastolic flow was atrial, and that this percentage stayed constant throughout diastole.

心房收缩对冠状动脉血流的影响。
我们研究了6只麻醉开胸犬在心脏传导阻滞时,经心外膜起搏器导联起搏时冠状动脉传导和血流的短暂性下降。多普勒超声血流探头记录左旋和前降冠状动脉血流;同时记录主动脉压、左心室压及心电图。线性回归发现,在冠状动脉前降支的情况下,舒张期瞬时电导和血流下降与心房收缩引起的左室压力升高一致,心房和心室同时收缩时,收缩峰值电导和血流也没有下降。心房收缩导致的回转电导和血流减少,其程度大于左室舒张压升高所导致的程度。在收缩期,当心房和心室收缩完全同步时,心房不能向心室放电,峰值回流流量和电导也减少了12%。收缩作用和过度舒张作用是由于弯曲动脉的心房分支受到压迫。在舒张期心房收缩对传导的影响中,这种到达的压缩机制占37- 75%。5只犬心房受压引起的收缩和舒张电导变化值呈线性相关。通过将此百分比应用于瞬时流量减少的心房流量计算表明,17%的回旋舒张期流量是心房流量,并且该百分比在整个舒张期保持不变。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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