Late Results After Surgical Closure of Ventricular Septal Defect in Children

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Abstract
Twenty-two children, who were operated on for ventricular septal defects (VSD) at 3-11 years of age, were studied 2-11 years postoperatively with respect to signs of residual shunt, cardiomegaly, physical capacity and pulmonary resistance at various rates of perfusion. There was evidence of residual shunt in one of the patients at follow-up. This was also the only patient who had persisting cardiomegaly in the group. Exercise tests were as a rule within normal limits. Total pulmonary resistance (TPR) decreased in all instances and was abnormally elevated in 6 patients at the follow-up. as compared to 12 at the pre-operative study. Total pulmonary resistance index (TRP1) was abnormally elevated in 8 patients, as compared to 10 at the pre-operative study. Whereas TPR decreased from an average pre-operative level of 7.9 to 4.2, TPR1 average remained virtually unchanged. The two most hyper-resistive patients were found to have identically high resistance indices at the follow-up investigation, indicating little effect on the obstructive vascular lesion. During provoked increase of pulmonary blood flow TPR fell further in nearly all patients. The presure/flow characteristics of the pulmonary circulation in patients with normal resting vascular resistance (PVR) followed closely the regression line of a normal material. Conversely the 5 patients with elevation of PVR at test demonstrated a uniformly steep pressure/flow relationship, indicating a rigid vascular basin in these patients. It is suggested that some of the discrepancies that exist in relation to the effect of surgical closure of VSD may be related to the fact that for the most part a growing population is under study. The “natural” history of pulmonary haemodynamics in the growing individual constitutes a potential error for the long-term evaluation of the effect of VSD closure on pulmonary vascular resistance. It is recommended that resistance figures based on body-size-related flow indices are used and that particularly when the postoperative investigation reveals a moderately hyperresistive patient or a “borderline” case, the resistive characteristics of the pulmonary circulation be studied at various flow rates. Our results support the opinion that the VSD patient should be operated on before a markedly obstructive vascular lesion has developed since there is little evidence to suggest a reversibility of the disease.