The clinical features and diagnosis of a discordant atrioventricular connexion.

Seventy-three patients were studied with a discordant atrioventricular connexion (ages 3 months to 46 years). In 58 the diagnosis was proved by angiography and in the other 15 at necropsy. Forty-eight had usual atrial arrangement and 25 mirror-image atria. Fifty-two patients had ventriculo-arterial discordance, 13 double outlet right ventricle, 4 ventriculoarterial concordance, 3 single outlet of the heart and 1 double outlet left ventricle. Nine with ventriculoarterial discordance had no other associated defects. The spatial relationship of the ventricles was variable, but in usual atrial arrangement the morphologically left ventricle tended to be on the right, and in mirror-image arrangement to the left of the morphologically right ventricle. The spatial relationship between the arterial valves was also variable, but in ventriculoarterial discordance and double outlet right ventricle the aortic valve was anterior and either to the right or left of the pulmonary valve in all but 3 cases. There is no typical clinical picture for these malformations. Symptoms depend upon the associated anomalies or the presence of atrioventricular dissociation. The diagnosis of a discordant atrioventricular connexion is best achieved by the echocardiographic and haemodynamic studies, but the electrocardiogram, chest radiograph and nuclear medicine studies may suggest its presence. Most patients are asymptomatic and progress normally to adult life. Only the symptomatic patients require surgical correction. Postoperative follow-up in the survivors is excellent, only 2 of 14 patients dying after surgery.