Left ventricular performance in the natural history and after corrective surgery of isolated ventricular septal defect.

Left ventricular performance by determination of the systolic time intervals, was analyzed in 34 patients with isolated ventricular septal defect and unidirectional left-to-right shunt. Fourteen of them (group I) with mean pulmonary flow/systemic flow ratio 2.19 +/- 0.3 SD, underwent corrective surgery; the other 20 patients (group II) with mean pulmonary flow/systemic flow ratio 1.43 +/- 0.3 SD were not operated; all the patients were followed up for at least 10 years. The measurements were obtained from simultaneous high speed photographic recordings of electrocardiogram, external carotid pulse and phonocardiogram. The analysis of data in group I showed a significant prolongation of pre-ejection period and an abbreviation of left ventricular ejection time; the degree of abbreviation was related to the magnitude of the shunt. The above abnormalities persisted after corrective surgery, and only several years after the operation these parameters became normal. Instead, the systolic time intervals were always normal in group II during the whole follow-up period. The most likely explanation for the observed abnormalities in ventricular septal defect in group I is that the depressed contractility of the left ventricle, which is secondary to the important volume overload, persists after corrective surgery. Septal construction abnormalities, before and after ventricular septal defect repair, may be another contributing factor in abnormal systolic time intervals.