Study of load-independent index of left ventricular myocardial contractility in infants with isolated ventricular septal defect and congestive heart failure

ABSTRACT

Twenty-nine infants with isolated VSD [15 symptomatic and 14 asymptomatic] and with age ranged from 5 to 14 months were compared with 15 control infants, to determine if symptoms of congestive heart failure were due to depressed contractility or defect size or both. We found that the symptomatic infants had a significant increased heart rate and respiratory rate [P < 0.01] and a significant lower systolic blood pressure [P < 0.05] than the other groups. The symptomatic patients had non significant increased ESD, EDD and End-systolic stress [ESS] than other groups of the study but there was no significant difference between the three groups as regards fractional shortening [FS] and velocity of circumferential fiber shortening [VCFc]. We found that the left ventricular contractility in the symptomatic patients was not depressed as the predicted VCFc was lower than the measured VCFc, at any given ESS. The ESS/VCFc curve slope of the symptomatic patients [-0.005] was less than asymptomatic patients [-0.009] and the control infants [-0.012] and shifted to the right, due to increased LV preload and wall stress as the symptomatic patients had a significant bigger VSD and a significant increased pulmonary/ systemic flow ratio [Qp/Qs] than asymptomatic patients [P < 0.01]. It is concluded that the left ventricular contractility in patients with VSD and CHF was not depressed and their symptoms may be related to increased pulmonary flow due to increased left- to -right shunt through a big VSD