Clinical problems of postoperative pulmonary vascular disease.

The younger the patient with a large left to right shunt at the time of operation, the greater the likelihood that pulmonary vascular resistance will fall to normal thereafter. In older patients, the degree to which the pulmonary vascular resistance is elevated before operation is a critical factor determining operability and prognosis. Patients at particularly high risk for the development of significant pulmonary vascular obstruction early in life are those with certain forms of cyanotic congenital heart disease, such as complete transposition of the great arteries with ventricular septal defect and patent ductus arteriosus, and truncus arteriosus. Other conditions in which pulmonary vascular obstruction appears to progress rapidly include large ventricular septal defect, complete atrioventricular canal defect and left to right shunt lesions in an environment of high altitude or associated with unilateral pulmonary arterial absence of the Down's syndrome. In this report the framework is reviewed for recognizing that important pre- and postnatal modifiers of the pulmonary vascular bed may be lesion-dependent. Thus, the growth and development of the pulmonary vascular bed during fetal and early postnatal life, as well as the morphologic alterations described in detail by Heath and Edwards, are likely to determine the ultimate intensity and magnitude of pulmonary vascular obstruction. Commentary is also provided concerning the management of patients with high pulmonary vascular resistance during pregnancy and delivery, their response to exercise, and the possibility of medical treatment designed to reduce pulmonary vascular resistance, and perhaps prolong life and enhance its quality.