Septal Defect and Severe Pulmonary Hypertension Correlation with Response of Pulmonary Arterial Pressure

SUCCESS in the surgical treatment of children who have large ventricular septal defects is dependent in part on the proper selection of patients for operation. The patients most deser-ving of such correction are those who have severe pulmonary hypertension, and it is in these that the decision to offer surgical intervention may present the greatest problems. The factors influencing the increase in pulmonary arterial pressure deserve critical analysis. Elevated pulmonary arterial pressure in patients with large ventricular septal defects is, to a great extent, the result of 2 factors, namely increased pulmonary blood flow or increased pulmonary vascular resistance; both factors are present in some instances. -in those patients without pulmonary vascular disease but with a high pulmonary blood flow in relationship to systemic blood flow and witlh only slightly increased pulmonary vascular resistance, the pulmonary arterial pressure may be equal or nearly equal to the systemic pressure. In those who have complicating pulmonary vascular disease in whom the pulmonary resistance is increased and the pulmonary blood flow is not increased in relationship to systemic flow, the pulmonary and systemic pressures may be equal or nearly equal. If the increased pulmonary arterial pressure is prinmarily the result of increased pulmonary blood flow from a left-to-right shunt, surgical closure of the defect will result in a decrease in pulnmonary arterial pressure. If the in-