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Hemodynamic correlates of clinical severity in isolated ventricular septal defect
1Department of Pediatrics, Children's Memorial Hospital, Northwestern University Medical School, Chicago, Illinois 60614.
Insights
Clinical severity in ventricular septal defect is linked to oxygen delivery, not shunt size. Key factors include oxygen consumption, hemoglobin, and cardiac index, influencing heart rate and growth failure.
Area of Science:
- Pediatric Cardiology
- Cardiovascular Physiology
Background:
- Ventricular septal defect (VSD) is a common congenital heart defect.
- Clinical assessment of VSD severity often relies on factors related to the left-to-right shunt.
- The role of tissue oxygen delivery in VSD severity is less understood.
Purpose of the Study:
- To investigate whether clinical severity in VSD is more closely related to variables of tissue oxygen delivery or left-to-right shunt.
- To identify key physiological parameters influencing clinical severity in young children with VSD.
Main Methods:
- Cardiac catheterization data from 40 children under 3 years old with VSD were analyzed.
- Clinical severity indicators included medication use (digoxin, diuretics), heart rate, and growth failure.
- Oxygen transport variables and left-to-right shunt assessments were independently evaluated.
Main Results:
- Children requiring digoxin and diuretics showed higher heart rates and lower superior vena cava oxygen saturation.
- Heart rate variation was significantly explained by oxygen consumption, hemoglobin, cardiac index, and pulmonary vascular resistance.
- Growth failure was primarily associated with the left ventricular forward stroke index.
Conclusions:
- Tissue oxygen delivery variables, including oxygen consumption, hemoglobin, cardiac index, forward stroke index, and vena cava oxygen saturation, are crucial in assessing VSD clinical severity.
- These findings suggest a shift in focus from shunt size to oxygen delivery in managing VSD.
- Understanding these physiological determinants can improve clinical evaluation and treatment strategies for VSD.
Abstract:
To test the hypothesis that the clinical assessment of severity in ventricular septal defect would be more related to variables which define tissue oxygen delivery than variables which define the left-to-right shunt, cardiac catheterization data from 40 children < 3 years of age were assessed. Variables which were considered indicative of clinical severity included the need for digoxin and diuretics, resting heart rate, and severity of growth failure. Variables measured at cardiac catheterization, including those which related to oxygen transport, and assessment of left-to-right shunt, were considered independently. Patients receiving digoxin and diuretics were more tachycardic (142 +/- 18 vs. 111 +/- 26 beats/min, p < 0.001) and had lower superior vena cava oxygen saturation (64 +/- 6 vs. 69 +/- 5%, p < 0.01). Variation in heart rate (r2 = 0.46) was best explained by oxygen consumption, hemoglobin concentration, cardiac index, and pulmonary vascular resistance. Variation in growth failure (r2 = 0.15) was related only to the left ventricular forward stroke index. These data suggest that variables related to oxygen delivery, including oxygen consumption, hemoglobin concentration, cardiac index, forward stroke index, and superior vena cava oxygen saturation, are the major contributors to the clinical assessment of severity in ventricular septal defect.