Therapy and Prevention Congenital Ileart Disease

Early surgery for forms of hypoplastic right heart syndrome may increase right ventricular size but could leave the patient with a residual right-to-left atrial shunt. Previous attempts to assess the capability of the right ventricle to accept systemic venous return have relied on angiographic estimates of tricuspid valve and right ventricular sizes. Since the minimum adequate sizes have not been established, we used a more physiologic technique of temporarily occluding the interatrial communication with a balloon-tipped catheter at cardiac catheterization in six consecutive patients. Five patients tolerated complete occlusion, although the tricuspid valve anulus diameter was less than the fifth percentile in all, and right ventricular volume was less than the fifth percentile in four. These five underwent surgical closure of an interatrial communication without evidence of postoperative systemic venous hypertension. Attempted occlusion in the sixth patient caused profound systemic venous hypoxia and surgical closure was not attempted. Temporary balloon occlusion may improve selection of patients for definitive operation. Circulation 68, No. 5, 1081-1086, 1983. INITIAL SURGICAL MANAGEMENT of patients with pulmonary atresia and intact ventricular septum consists of establishing adequate pulmonary blood flow and achievement of right ventricle-to-pulmonary artery continuity. 1-3 This approach has been associated with an increase in right ventricular dimensions in some patients.4' Despite right ventricular growth there is often a residual right-to-left shunt at the atrial level as a result of "resistance" to right ventricular inflow.5Factors that may be responsible for this include anatomic abnormalities such as tricuspid stenosis, tricuspid regurgitation, or a small right ventricular chamber, as well as functional abnormalities such as diminished right ventricular contractility or decreased right ventricular compliance from hypertrophy, fibrosis, or a previous ventriculotomy.5 8 Because of symptoms from hypoxia and the risk of paradoxical embolus and brain abscess, these patients must be considered for separation of systemic and pulmonary circulations. If the resistance to right ventricular inflow is too great, From the Department of Pediatrics, University of Minnesota, Minneapolis. Supported in part by the Dwan Family Funds, Minneapolis, and grant HL 28241 from the National Heart, Lung and Blood Institute. Dr. Lock is an Established Investigator of the American Heart Association. Address for correspondence: John L. Bass, M.D., Box 94 Mayo Building, University of Minnesota, Minneapolis, MN 55455. Received June 2, 1983; accepted June 30, 1983. Vol. 68, No. 5, November 1983 however, marked elevation of right atrial pressure may follow closure of the interatrial communication. Selection of patients for separation of pulmonic and systemic circulations may be difficult. This decision generally depends on angiographic measurements of the tricuspid valve diameter,5 estimates of right ventricular volume, and the anatomy of the right ventricle. Neither the minimum tricuspid valve diameter ndr the right ventricular volume that will accommodate total systemic blood flow has been established,9 and these methods do not assess the functional capacity of the right ventricle. We therefore sought a more direct and physiologic method of assessing right ventricular capability and applied the technique of temporary occlusion of the atrial septal defect with a balloon-tipped catheter. We also compared temporary atrial septal defect occlusion with conventional angiographic evaluation of the right ventricle.