Pulmonary Vascular Disease in Transposition of the Great Vessels and Intact Ventricular Septum

SUMMARY Eight of 135 (6%) children with d-transposition of the great vessels and with intact ventricular septum and no patent ductus arteriosus had evidence of progressive pulmonary vascular disease. Seven of 101 (7%) patients for whom histologic data was available, had Heath-Edwards grades IV or V pulmonary vascular disease, six had grade II, and 88 had either normal or grade I findings. One of 34 patients for whom histologic data was not available had hemodynamic evidence of pulmonary vascular disease at cardiac catheterization after the Mustard operation. When infants younger than 3 months old were excluded, eight of 85 (9%) had ad-vanced pulmonary vascular disease. Twenty-three patients had microthrombi in their pulmonary arteries and arterioles, and in one patient thrombi were observed before the development of pulmonary vascular disease. Clinically unrecognized pulmonary microthrombi are suggested as a possible etiologic agent in the develop-ment of pulmonary vascular disease in patients with transposition of the great vessels. Progressive pulmonary vascular disease can first be discovered after the Mustard operation, even in patients without preoperative evidence of pulmonary hypertension or elevated pulmonary vascular resistance. PULMONARY VASCULAR DISEASE is often a complication in patients with complete transposition of the great vessels,-5 particularly when there is a large ventricular septal defect6 or patent ductus arteriosus.6 In the absence of these associated defects the incidence is less, but has been reported to occur in 6-40 % of cases.5 ' 7-10 This study examines the in-cidence of progressive pulmonary vascular disease in patients with transposition of the great vessels and in-tact ventricular septum who were seen at a single in-stitution over a 22-year period, and suggests a possible etiologic factor not previously emphasized by other in-vestigators. Materials and Methods The study group (table 1) included 135 patients with transposition of the great vessels and intact ventric-ular septum or hemodynamically insignificant ventric-ular septal defect, and no patent ductus arteriosus. All patients were seen at the Willis J. Potts Children'