Systolic time intervals in patent ductus arteriosus before and after corrective surgery

Systolic time intervals (STI) were analyzed in 11 patients with isolated patent ductus arteriosus (PDA) and unidirectional left-to-right shunt, before, shortly after (within 2 months) and a long time (at least 10 years) after the corrective surgery. The measurements were obtained from simultaneous high speed photographic recordings of electrocardiogram, external carotid pulse and phonocardiogram. Before the operation, the left ventricular ejection time (LVET) was significantly prolonged (p less than 0.01) and this abnormality was correlated with Qp/Qs (r = 0.74, p less than 0.01). Shortly after the operation, the LVET was shorter than normal, and became normal only a long time after. It is concluded that the most likely explanation for these abnormalities is: 1) before the operation, the increased stroke volume of the left ventricle secondary to the shunt, and 2) after corrective surgery, the depressed contractility of the left ventricle secondary to the long-standing volume overload which tends to persist after the corrective surgery.