LEFT-VENTRICULAR MECHANICS AFTER CLOSURE OF VENTRICULAR SEPTAL-DEFECT- INFLUENCE OF SIZE OF THE DEFECT AND AGE AT SURGICAL REPAIR

To evaluate the influence of the size of the defect and the age of sur gical repair on left ventricular mechanics, including geometry, shape, diastolic and systolic function as well as myocardial contractility, we used cross-sectional echo-Doppler to study 20 patients (12 males, 8 females) who had undergone successful surgical closure of a ventricul ar septal defect. The patients were divided in two groups, corrected e arly and late, on the basis of the degree of left-to-right shunting (r atio of pulmonary to systemic output of greater or less than 2.5/1) an d the age at the surgical repair (older or younger than 2 years of age ). The group undergoing early correction included 11 patients, mean ag e 7.1+/-1.8 years (range 4.2-11.8 years), having surgery at mean age o f 1.3 +/- 0.6 years for a large ventricular septal defect (mean ratio of pulmonary to systemic output of 3.1/1; range 3.4-2.7/1) with a mean postoperative follow-up 4.6+/-1.9 years. The group of nine patients u ndergoing late correction had a mean age of 11.3 +/- 4.9 years (range 6.7-17.2 years), with a later surgical repair (mean age 4.7+/-2.7 year s) for a moderate-sized ventricular septal defect (mean pulmonary/syst emic output ratio 2.1/1; range 2.3-1.7) and a mean postoperative follo w-up of 7 +/- 4.2 years. Each group of surgically repaired patients wa s compared with a control group matched for age, body surface area and gender. No significant differences were found between the normal cont rols and those undergoing early correction for any assessed functional index regarding left ventricular geometry (normalized volumes and-mas s for body surface area, mass/volume and thickness/radius ratios), sha pe (long axis-short axis ratio), diastolic (mitral and pulmonary venou s flow patterns) and systolic (fractional shortening and rate-correcte d mean velocity of circumferential fibre shortening) function. In addi tion, the data points for each patient for the rate-corrected mean vel ocity of circumferential fibre shortening to end-systolic stress relat ionship were within the 95% confidence limits of normal, suggesting no rmal left ventricular contractility. On the other hand, the patients u ndergoing surgery at a later age showed a persistent increase of the n ormalized left ventricular end-diastolic volume and mass, with an high er mass/volume ratio and reduced end-systolic stress compared with nor mal controls. Furthermore, left ventricular shape (long axis-short axi s ratio) was abnormal at end-diastole but with its normal values at en d-systole. Our: data suggest that, in the presence of a large ventricu lar septal defect, early successful surgical repair <2 years of age re sults in complete recovery of left ventricular mechanics in the postop erative follow-up. In contrast, surgical closure at > 2 years of age, even for a moderately sized ventricular septal defect, deleteriously a ffects postoperative left ventricular geometry and shape. Since prolon ged volume overload may be detrimental to myocardial function, earlier surgical repair should be recommended.