Massive systemic-to-pulmonary collateral arteries in the setting of a cavopulmonary shunt and pulmonary venous stenosis.

We report a patient in whom a cavopulmonary anastomosis had been constructed, along with repair of anomalous pulmonary venous drainage. Left-sided pulmonary venous obstruction led to redistribution of the flow to the right lung. The reversal of flow in the left pulmonary artery was accentuated by flow through collateral arteries feeding the left lung. Within 14 months, the collateral flow increased six-fold, resulting in a doubling of the cardiac output.