Spontaneous improvement of severe right ventricular dysfunction in the setting of hypoplasia of the left heart.

Right ventricular dysfunction is known to occur after the first stage of the Norwood sequence for treatment of patients with hypoplasia of the left heart. In a subset of patients, such ventricular dysfunction occurs without a specific anatomical cause. We describe two such cases with severe right ventricular dysfunction. In both cases, magnetic resonance imaging was used accurately to measure ventricular function and assess the arterial trunks. In both cases, cardiac transplantation was considered, but right ventricular function improved without invasive management. Transient right ventricular dysfunction in these cases may be due to the reduced ability of the right ventricle to adapt to the systemic vasculature. The improvement in ventricular function in these two cases may be due to delayed adaptation.