Growth of the pulmonary anulus and pulmonary arteries after the Waterston anastomosis

Twenty-six patients with tetralogy of Fallot underwent angiocardiography before a Waterston shunt and again several years later, prior to complete repair (mean interval 40 +/- 15.6 [SD] months). The ratio between the diameter of the pulmonary valve anulus (PVA) and that of the descending thoracic aorta (Ao) increased by 0.32 +/- 0.233, significantly more than is reported to occur after a Blalock-Taussig anastomosis (p = 0.0001). This increase had some relation to the interval between the two angiographic studies (r = 0.34, p = 0.08) and to the mean pressure in the main pulmonary artery (MPA) at the time of the second study (r = 0.35, p = 0.08). The ratio of diameter of the right (RPA) and left pulmonary arteries (LPA) and that of the Ao also increased by 0.24 +/- 0.226 and 0.20 +/- 0.201, respectively. These data suggest that an initial large aortopulmonary shunt may result in less need for transannular patching at complete repair.