The effect of atrial dilatation on reperfusion arrhythmias: development of supraventricular tachycardias on reperfusion with atrial stretching.

Abstract

Unlabelled: The study was aimed at investigating the effect of atrial dilatation on the genesis of supraventricular tachyarrhythmias following myocardial reperfusion. Experiments were carried out in 26 mongrel dogs under pentobarbital narcosis with artificial ventilation. Electrophysiological study was performed for studying the arrhythmic condition of the heart. Investigations were carried out: (i) in normal condition, (ii) during atrial stretching (balloon dilatation of the left atrium), (iii) in reperfusion following myocardial ischemia, (iv) in reperfusion combined with atrial stretching. On reperfusion the irritability of the atrium increased moderately (on atrial extrastimuli in 3 dogs non-sustained atrial tachycardia, in 7 dogs repeated atrial responses could be induced). Reperfusion with atrial stretching, however, very markedly enhanced the atrial vulnerability, and in 19 dogs atrial tachycardia appeared spontaneously. Comparison of the effect of atrial stretching to that of atrial stretching + reperfusion showed that the reperfusion significantly augmented the arrhythmia-inducing effect of atrial stretching.

Clinical investigations: Aortocoronary bypass operations were followed by development of supraventricular tachycardia in 41 out of 428 operated cases. Atrial dilatation was detected in 37 cases, mostly before the appearance of atrial tachycardia. The data seem to prove that atrial dilatation has an important part in the pathogenesis of supraventricular tachyarrhythmias following reperfusion of myocardial ischemia.