CARDIAC COMPLICATIONS OF CEREBRAL ARTERIOVENOUS FISTULA IN INFANCY

Abstract

Four infants with congenital arteriovenous malformation of the vein of Galen are discussed, in each of whom there was clinical or roentgenographic evidence of cardiac involvement secondary to the arteriovenous shunt. Infant 1 was a neonate who presented solely with signs of severe circulatory congestion. The infant died at 48 hours of age despite therapy directed at relief of congestion and improvement of cardiac function. Infant 2 presented during infancy with roentgenographic evidence of cardiomegaly secondary to cerebral arteriovenous fistula. Chest roentgenograms showed decrease in size of the cardiac image after reduction of the fistula. Partial anomalous pulmonary venous drainage was an associated finding at autopsy. Infant 3 underwent operation for complete removal of a cerebral arteriovenous aneurysm, and died 7 hours postoperatively with clinical evidence of circulatory overloaded. In Case 4 cardiovascular studies were done prior to successful reduction of cerebral arteriovenous fistula, and were repeated 4 weeks postoperatively. The shunt was demonstrated by a marked elevation of oxygen saturation of internal jugular venous blood as compared with iliac venous blood; this discrepancy was markedly diminished after operation. Cardiac output was measured by the dye-dilution technique and postoperatively showed a 50% decrease as compared with the abnormally high preoperative determination. The hemodynamic effects of arteriovenous fistula are discussed. The precise mechanisms responsible for the compensatory increase in blood volume are incompletely understood. The increased cardiac output is accomplished by means of augmented stroke volume in accordance with the Starling law of the heart. While phlebotomy may appear to be indicated in an attempt to reduce the circulatory load resulting from a large arteriovenous shunt, it also deprives the patient of a homeostatic response useful in maintaining adequate perfusion distal to the shunt. Digitalis should be administered when myocardial failure contributes to circulatory congestion.