'You didn't see them, but now you do!': use of balloon occlusion angiography in the identification of systemic venous anomalies before and after cavopulmonary procedures

We describe the importance of angiographic identification of collateral ven ous channels by balloon occlusion venography after bidirectional cavopulmon ary connections. Use of the balloon occlusion technique is essential for id entification of these vessels, as they can easily be missed by standard ven ous angiography, with possible clinical consequences for postoperative mana gement.