The cause of the hemodynamic disturbances in Ebstein's anomaly based on observations at operation.

Ten adult patients with Ebstein's anomaly had open-heart operation for interruption of a Kent bundle. The 4 patients in Group 1 had arrhythmias. One patient had a patent foramen ovale, which was closed. In 3 patients the Kent pathway was identified and interrupted, but in the other only the pathway's anterograde function was interrupted, leaving the patient subject to supraventricular tachycardia (SVT). The 3 patients in Group 2 had mild to moderate cyanosis and dyspnea during SVT as well as mild impairment during strenuous physical activity. Only interruption of their Kent bundles and closure of the patent foramen ovale were done. The 3 patients in Group 3 had dyspnea and cyanosis on exertion, and 1 had overt right heart failure. In each patient, obstruction between the atrialized right ventricle (RV) and functioning RV by the displaced tricuspid valve (TV) was relieved by valve excision and replacement. Interruption of the Kent bundle was successful in 2 of the 3 patients. Operation for Ebstein's anomaly is indicated when any of the following conditions are present: arrhythmias due to Kent bundles that are refractory to medical management; a defect in the atrial septum that must be closed because of a history of cyanosis or paradoxical emboli, or an arrhythmia that must be corrected by right atriotomy; and obstruction between the atrialized and functioning RV or a small functioning RV, both of which can be corrected by TV replacement.