What are the possible causes of neonatal nephrocalcinosis?

The development of pulmonary arteriovenous fistulas after bidirectional cavopulmonary operations, such as the bidirectional Glenn shunt and Kawashima's procedure, has raised concern. Development of these fistulas, which are more frequent than initially thought, can represent a limiting factor in the late outcome of these patients and may even limit the indication for these types of surgery. Whether the fistulas can be reversed by transforming the surgical procedures has yet to be established. In the hope of avoiding this kind of complication, thought to be caused by the lack of passage of a hypothetical hepatic factor through the pulmonary circulation, we have developed an inverted type of bidirectional cavopulmonary connection in which the blood coming from the liver perfuses immediately both lungs. This is made possible by shunting via an intra-atrial tunnel the blood from the superior caval vein directly to the left atrium, and the blood from the inferior caval vein to the right branch of the pulmonary trunk (keeping its bifurcation intact). We describe findings in two patients undergoing successful surgery with this technique. Serial follow-up with contrast echocardiography did not show evidence of arteriovenous pulmonary fistulas. Despite our numbers being small, and the time of follow-up being limited, we believe that it is important to document these and similar cases.