Tetralogy of Fallot. Development of hypoplastic pulmonary arteries after palliation.

Thirty-one patients with tetralogy of Fallot were studied angiographically before and after palliation with Blalock-Taussig operation (n = 9), Brock operation (n = 12), or enlargement of the right ventricular outflow tract with extracorporeal circulation (ECC) (n = 10). The relative diameter of the pulmonary vascular ring (PVR), pulmonary trunk (PT), and right and left pulmonary arteries (RPA, LPA) were measured before and 24.8 +/- 20.9 months after palliation. Using correlation analysis, the magnitude of growth of the pulmonary artery system was inversely related to its initial size. Mean pressure in the pulmonary artery after palliation as well as the period between date of surgery and recatheterization did not correlate significantly with growth. After Blalock-Taussig operation, the ipsilateral pulmonary artery predominantly increased in size without significant growth of PVR and PT. Brock operation and enlargement of the right ventricular outflow tract with ECC, improving the flow in the pulmonary vascular system centrally, induced a significant, symmetrical growth of the pulmonary vascular system and, therefore, are our methods of choice for palliation in patients with tetralogy of Fallow combined with hypoplastic pulmonary arteries.