Concomitant Intracardiac Shunt and Venous Collaterals After Fontan Procedure: A Case Report of Percutaneous Management.

A 40-year-old man with complex congenital heart disease (double-inlet left ventricle with transposition of the great arteries), previously treated with a Blalock-Taussig shunt in infancy and a modified Fontan procedure (including superior vena cava-to-pulmonary artery anastomosis, atriopulmonary connection, and tricuspid valve closure with a Dacron patch), presented to the emergency department with worsening dyspnea and hypoxemia (SpO2 < 80%). Echocardiography suggested a shunt through the tricuspid patch, possibly related to prior atrial flutter ablation. Cardiac catheterization confirmed an approximately 10 mm fenestration in the calcified patch causing a significant bidirectional shunt, along with two fistulae between the innominate vein and the left atrium. The fenestration was successfully closed using a septal occluder via right femoral venous access under transesophageal echocardiographic guidance. The venous collaterals were occluded with vascular plugs via right femoral and left brachial approaches. Technical success of the closure of the intracardiac and the venous shunts was confirmed angiographically at the end of the procedure. Oxygen saturation improved immediately from 72% to 91% and remained stable at the 2-year follow-up. Similarly, NYHA functional class improved from IV to II and episodes of tachycardia became less frequent and better tolerated, with sustained benefit throughout follow-up.