Unexpected Growth of Small Right Ventricle After Failed Repair of Atrioventricular Septal Defect

Unbalanced atrioventricular septal defect with hypoplastic right ventricle in infants with trisomy 21 poses significant challenges as they are not ideal candidates for single-ventricle palliation. We describe a patient with the diagnoses who underwent a biventricular repair but subsequently required a Blalock-Thomas-Taussig shunt (BTTS) with enlargement of atrial communication because of severe right-sided heart failure and low cardiac output. Staged device embolization of the BTTS and atrial communication were achieved by 7 years of age. This demonstrated that employing the BTTS with a relatively large atrial defect allowed phenomenal right ventricular growth.