Title:
Surgical Shunts Causing Circular Shunt: An Approach to Management
Introduction:
Right-sided obstructive congenital heart diseases (CHD) sometimes require surgical shunts for reliable pulmonary blood flow, but the physiologic evolution of these shunts can be unpredictable. Circular shunt is a unique physiologic phenomenon described in Ebstein’s anomaly where patent ductus arteriosus, pulmonary and tricuspid regurgitation, and an atrial communication combine to create an intracardiac shunt with profound hypoxia. We describe a case of circular shunt resulting from the placement of multiple surgical shunts which was eliminated by transcatheter intervention.
Clinical Case:
The patient has a history of pulmonary atresia and Ebstein’s anomaly. Pulmonary blood flow was established with a valved right ventricular to pulmonary artery (RV-PA) conduit and a 3 mm central shunt at day of life 5. At 3 months of age, due to increased work of breathing and cyanosis, her central shunt was upsized to 3.5 mm. Postoperatively, her condition worsened with increasing oxygen and inotrope requirements; echocardiography showed freely regurgitant flow in her RV-PA conduit and severe regurgitation of the dysplastic tricuspid valve.
Cardiac catheterization confirmed a severe shock state with systemic blood flow 2.1 L/min/m2, descending aorta O2 saturation 75.2%, and SVC O2 saturation 15%. Angiography demonstrated significant blood flow from her central shunt to the main pulmonary artery, RV-PA conduit, right ventricle, and right atrium, resulting in circular shunt physiology and severe hypoxia.
We decided to occlude the RV-PA conduit with an Amplatzer Vascular Plug II (10 mm x 7 mm). The device was placed in good position with descending aorta O2 saturation improved to 92%. Her shock resolved over the next several days, allowing her to undergo a bidirectional Glenn, replacement of her RV-PA conduit, and tricuspid valve replacement 13 days later, followed by an uneventful recovery.
Discussion:
Establishing pulmonary blood flow with surgical shunts is one of the most common procedures in congenital cardiac surgery, and is often successful in stabilizing infants until definitive repair is more feasible. Our patient had a unique set of circumstances in which two surgical shunts combined with elevated pulmonary vascular resistance and regurgitation of multiple valves to create a circular shunt. While the surgical shunts were placed to improve oxygenation by increasing pulmonary blood flow, the existence of two shunts created more severe hypoxia through the circular shunt.
Transcatheter occlusion of collateral blood vessels is well described, but this has seldom been applied to surgical shunts, and no commercially available devices are designed for this purpose. Device placement was uncomplicated with stable device position achieved, and transcatheter intervention provided a better means of stabilization for this critically ill patient than surgical or medical options. Management of infants with complex CHD and surgical shunts may require counterintuitive solutions to obtain the most stable physiologic state.