Poorly functioning right ventricle, pulmonary regurgitation, and atrial septal defect: an unfavorable combination for one-and-one-half ventricle circulation.

A newborn infant with pulmonary atresia, intact ventricular septum, and moderately hypoplastic right ventricle underwent radiofrequency perforation and balloon dilation of the pulmonary valve immediately after birth, followed by one-and-one-half ventricle (1.5 V) repair at 5 months of age. At 7 years of age, the patient developed worsening cyanosis and exercise intolerance with increasing right-to-left shunting through the atrial septal defect (ASD). Due to the combination of tricuspid regurgitation and such ASD shunting, the pulmonary regurgitation fraction reached 110%. Consequently, the advantages of utilizing the right ventricle as an additional antegrade source of pulmonary blood flow in the 1.5 V circuit were not achieved. This case report highlights the importance of phase-by-phase assessment of blood flows using phase-contrast magnetic resonance imaging for understanding the complex hemodynamics.