Does the Site of Insertion of a Systemic-Pulmonary Shunt Influence Growth of the Pulmonary Arteries?

Abstract

The modified Blalock-Taussig shunt is a common palliative procedure for children with cyanotic congenital heart disease. The distal shunt anastomosis can be done to a branch pulmonary artery or to the main pulmonary artery. The purpose of this study was to determine if the site of shunt connection influences pulmonary artery growth. The records of 101 patients with a modified Blalock-Taussig shunt undergoing a subsequent cardiac catheterization between January 2000 and April 2002 were retrospectively reviewed. From the cineangiograms, the diameters of the right and left pulmonary arteries at their first branching and the diameter of the descending aorta at the diaphragm were measured. If the distal shunt anastomosis was to the right pulmonary artery and there was no antegrade pulmonary flow then the left pulmonary artery was significantly smaller than if the distal connection was to the main pulmonary artery (p = 0.009). Absence of antegrade pulmonary blood flow resulted in significantly smaller right and left pulmonary artery size in general (p < 0.001). No significant differences in pulmonary artery growth were found with respect to gender, anatomic subtype, proximal shunt site, use of cardiopulmonary bypass or size of shunt. By multiple regression analysis absence of antegrade flow and the presence of right-sided shunts were statistically significant predictors of smaller left pulmonary artery and size discrepancy between right and left pulmonary artery. These data suggest that in the absence of antegrade pulmonary blood flow, a modified Blalock-Taussig shunt to the main pulmonary artery may promote more uniform branch pulmonary artery growth.