Changes in Canine cardiac function after the ligation of septal artery

Abstract

Electrocardiographic and hemodynamic observations were performed on 12 adult mongrel dogs in which the septal artery had been ligated experimentally in order to investigate the influence of a ventricular septal injury on the cardiac function. The results obtained are summarized as follows.
1) Severe arrhythmia, such as ventricular tachycardia, was recorded in all the dogs just after the ligation of the septal artery and 40 percent of these dogs died after showing ventricular fibrillation within 30 minutes after the ligation.
2) An hour after the ligation of the septal artery was observed left ventricular failure which was indicated by a fall in aortic pressure and left ventricular systolic pressure, an elevation in left ventricular end-diastolic pressure, a decrease in peak positive dP/dt (the maximal rate of rise of left ventricular pressure), and a prolongation in left ventricular ejection time. Moreover, left ventricular failure was enhanced to some extent 3 months after the ligation.
3) Abnormal deviations of S-T segment, variation of T wave, prolongation of Q-T interval, and left bundle branch block (in one dog) were presented as electrocardiographic findings during the acute phase. They were supported by vectorcardiographic findings, but disappeared during the chronic phase.
4) Pathological examination of the heart 3 months after the ligation showed that ischemic areas were localized to some restricted regions of the ventricular septum.
From these results, it is presumed that the ischemia and/or infarct of the ventricular septum may have exerted harmful influences on the cardiac function, even though areas involved in these changes are restricted to a small extent and the electrocardiography reveals no distinct abnormalities.