Relation of symptoms to contractility and defect size in infants with ventricular septal defect

Abstract

Forty-two infants with a ventricular septal defect (VSD) (21 asymptomatic and 21 symptomatic) were compared with 17 control infants to determine if symptoms of congestive heart failure (i.e., tachypnea/poor growth) were due to depressed contractility or defect size, or both. Echocardiographic indexes of defect size, left ventricular performance (shortening fraction), preload (left ventricular end-diastolic dimension), after-load (left ventricular end-systolic wall stress) and contractility (the relation between velocity of circumferential fiber shortening and wall stress) were measured. Clinical assessment included measurement of weight and respiratory rate. Pulmonary and systemic blood flow were assessed in 17 symptomatic and 3 asymptomatic patients by cardiac catheterization. Although there was no significant difference in age, the symptomatic group had significantly lower weight (5.5 ± 2.9 vs 7.3 ± 2.3 kg, p < 0.05) and a higher respiratory rate (53 ± 14 vs 43 ± 6 breaths/min, p < 0.05), compared with control subjects. The mean pulmonary to systemic blood flow ratio in the symptomatic group was 2.9:1. Preload indexed for body surface area was significantly higher in the groups with a VSD compared with control subjects (asymptomatic, 8.5 ± 1.7 cm/m 2; symptomatic, 9.1 ± 1.7 cm/m 2; control subjects, 6.8 ± 1.1 cm/m 2; p < 0.05). Shortening fraction, afterload and contractility were not significantly different among all groups. A defect size >0.5 cm (or defect size indexed for body surface area >1.8 cm/m 2) was predictive of the presence of symptoms. It is concluded that contractility is normal in infants with a VSD. Symptoms may be related to pulmonary congestion. Perhaps VSD size can be used to predict patient course.