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Relation of symptoms to contractility and defect size in infants with ventricular septal defect
T R Kimball1, S R Daniels, R A Meyer
1Division of Cardiology, Children's Hospital Medical Center, Cincinnati, Ohio 45229.
Insights
Infants with ventricular septal defects (VSD) show normal heart contractility. Symptoms of heart failure in these infants are linked to larger defect size and pulmonary congestion, not reduced cardiac function.
Area of Science:
- Pediatric Cardiology
- Congenital Heart Disease
- Echocardiography
Background:
- Ventricular septal defects (VSD) are common congenital heart abnormalities.
- Symptoms of congestive heart failure in infants with VSD can be severe.
- The etiology of these symptoms (contractility vs. defect size) requires clarification.
Purpose of the Study:
- To investigate whether symptoms of congestive heart failure in infants with VSD are caused by depressed myocardial contractility or VSD size.
- To differentiate the roles of preload, afterload, and contractility in symptomatic VSD.
Main Methods:
- Compared 42 infants with VSD (21 asymptomatic, 21 symptomatic) to 17 control infants.
- Utilized echocardiography to assess VSD size, left ventricular performance, preload, afterload, and contractility.
- Performed clinical assessments (weight, respiratory rate) and cardiac catheterization for blood flow analysis.
Main Results:
- Symptomatic infants had lower weight and higher respiratory rates than controls.
- Left ventricular preload was significantly higher in VSD groups compared to controls.
- No significant differences in shortening fraction, afterload, or contractility were found among groups.
- VSD size >0.5 cm predicted the presence of symptoms.
Conclusions:
- Infants with VSD exhibit normal myocardial contractility.
- Symptoms of heart failure in VSD are associated with larger defect size.
- Pulmonary congestion, secondary to increased pulmonary blood flow, likely contributes to symptoms.
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), afterload (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 less than 0.05) and a higher respiratory rate (53 +/- 14 vs 43 +/- 6 breaths/min, p less than 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/m2; symptomatic, 9.1 +/- 1.7 cm/m2; control subjects, 6.8 +/- 1.1 cm/m2; p less than 0.05). Shortening fraction, afterload and contractility were not significantly different among all groups. A defect size greater than 0.5 cm (or defect size indexed for body surface area greater than 1.8 cm/m2) 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.(ABSTRACT TRUNCATED AT 250 WORDS)