71: Double Outlet Right Ventricle

Epidemiology

• Relatively uncommon congenital anomaly seen in 0.09 in 1000 births

Pathophysiology

• Considerable variability in pathophysiology is seen with double outlet right ventricle (DORV) and is primarily dependent on the location of the ventricular septal defect (VSD), the relationship of the great arteries and the presence of great vessel stenosis

Clinical features

• Patients usually present by age 2 months (range 1 day–4 years). Presentation is variable and is dependent on the type of DORV and associated cardiac anomalies. Heart failure is seen in patients with unrestricted subaortic, doubly-committed or non-committed VSDs without right ventricular outflow tract obstruction (RVOTO). Cyanosis results from RVOTO leading to restriction of pulmonary blood flow or by preferential streaming of blood from the left ventricle (LV) to pulmonary artery (PA) as seen in the Taussig–Bing anomaly.

Diagnosis

• Echocardiography defines the relationship of the great arteries to the right ventricle (RV) and to each other, and delineates the size and position of the VSD. MRI may provide complementary information about intracardiac anatomy, size and status of the aortic arch and PAs, and 3-dimensional relationship of chambers and great arteries. Catheterization can be performed to determine hemodynamics, exclude pulmonary vascular disease and assess coronary anatomy.

Treatment

• Definitive management includes operation, preferably complete repair during infancy. The surgical repair is tailored to address the variable anatomical abnormalities. In patients with a subaortic or doubly-committed VSD without RVOTO, the repair is performed with an intraventricular tunnel from the VSD to the aorta. If RVOTO exists, right ventricular outflow tract (RVOT) augmentation or conduit placement is performed. The Taussig–Bing anomaly is treated with the arterial switch operation and tunneling of the VSD to the PA. Patients with a remote VSD, other complex valve abnormalities or unbalanced ventricles may require staged palliative single ventricle procedures.

Outcomes/prognosis

• Outcomes are determined by the anatomy and the repair performed. Late results may range from those of tetralogy of Fallot to those of complex intraventricular tunnels, with potential use of conduit, who are at subsequent risk for subaortic obstruction, conduit failure, and need for reoperation(s). Patients undergoing the arterial switch operation have excellent late survival but may have a greater incidence of neoaortic valve regurgitation requiring subsequent reoperation. Complex biventricular intracardiac repairs are associated with a higher operative risk and the potential need for reoperations. Fontan procedures for complex anatomy are associated with less operative mortality and lower reoperation rates. Functional benefits of complex biventricular repairs compared to single-ventricle palliation have not been defined.