Disappearance of Ventricular Arrhythmia Caused by Coronary Occlusion during Retrograde Bleeding through Collaterals

Ventricular irregularities and their relations to collateral circulation were studied on acute occlu-sion of the left anterior descending coronary artery of do, g, heart. The size of the collateral circula-tion existing in normal hearts was estimated by measuring retrograde pressure and blood flow from the occluded artery. Two essentially different types of ventricular arrhythmias were observed in the early and later stages after acute occlu-sion. The mortality in the early stage resulting from ventricular fibrillation was 39.5%. The frequency of extrasystole in this stage was inversely related to the magnitude of collateral circulation. The arrhythmia in the later stage disappeared and reverted to regular sinus rhythm during a period of backward bleeding for measuring retrograde flow. The backward bleeding not only brought back a regular rhythm, but also improved left ventricular performance. Some arrhythmogenic substances originated from ischemic tissue probably take part in the genesis of the arrhythmia in the later stage.