Straddling right atrioventricular valve in criss-cross atrioventricular relationship.

Two cases of complex congenital heart disease are described in which systemic and pulmonary bloodstreams crossed at the atrioventricular level. Both patients were examined clinically, echocardiographically, and by cardiac catheterization, including angiography, and both underwent cardiac surgery and had intraoperative mapping of their conduction systems. Both patients were found to have levocardia and situs solitus of viscera and atria, large ventricular septal defect, and straddling right atrioventricular valve. One patient had atrioventricular discordance but with the left ventricle anterior and alightly on the right and with pulmonary atresia and dextromalposition of the aorta. The other patient had atrioventricular concordance but with the left ventricle inferior and slightly on the left and with ventricular-arterial concordance to normally related great arteries and banded pulmonary trunk. To our knowledge, this combination including straddling right atrioventricular valve has not been reported in the literature before. In both patients the straddling atrioventricular valve was thought to preclude corrective operation at that time. A unique palliative procedure--left ventricle-to-pulmonary trunk shunt--was successful in the first case and partial debanding of the pulmonary trunk in the second.