Truncus arteriosus with unilateral absence of a pulmonary artery. Criteria for operability and surgical results.

In 15 of 126 (12%) patients with truncus arteriosus who were catheterized at the Mayo Clinic from 1967 through 1975, natural agenesis of one pulmonary artery was present. Ten truncus patients with either natural or acquired absence of one pulmonary artery have undergone definitive operation. The criteria for operability, based on a calculation of pulmonary resistance, are different in patients with single pulmonary artery than in patients with two pulmonary arteries. Study revealed that, if the calculated pulmonary resistance in the patient with single pulmonary artery is halved, this new value provides a more reliable assessment of the reactivity of the pulmonary arteriolar bed than does the total calculated pulmonary resistance value. Follow-up information suggests that the patient with single pulmonary artery may be at potentially high risk of continued progression of pulmonary vascular disease after surgical correction, possibly because of the postoperative obligatory increased flow through the single pulmonary arteriolar bed as a result of the entire cardiac output passing through it. Surgical correction of truncus arteriosus during infancy, before significant pulmonary vascular disease has developed, appears to be particularly desirable in this subgroup of patients with single pulmonary artery.