Abstract
To clarify the apparent hypoplasia of the descending aorta in infants with atrioventricular septal defect[AVSD] patients, we reviewed the catheterization data and angiograms of 34 consecutive patients with AVSD less than 1 year of age who underwent repair at our institution since 1985. We compared them to 10 patients with Atrial Septal Defect[ASD] and 10 patients with Ventricular Septal Defect[VSD] who were matched for age, size and Qp/Qs. The Descending Aorta Index [DAI] of the AVSD group was not different from the VSD or ASD groups, [147.9$\pm$ 34.8 mm2/m2 versus 158.6$\pm$ 31.5 mm2/m2 and 153.2$\pm$ 43.1 mm2/m2].However, the Pulmonary Artery Index [PAI] of the AVSD group was significantly larger than the other groups [684.3$\pm$ 170.7 mm2/m2 versus 454.1$\pm$ 109.1 mm2/m2 and 534.9$\pm$ 148.4 mm2/m2][p<0.05], as was the ratio of PAI/DAI in the AVSD group [4.99$\pm$ 1.77 versus 2.89$\pm$ 0.81 and 3.6$\pm$ 0.92][p<0.05]. Despite similar Qp/Qs ratios, both the mean PA pressure and the Rp/Rs in the AVSD group was higher than the VSD and ASD groups: 43.1$\pm$ 15.6 mmHg versus 29$\pm$ 11.6 mmHg and 24$\pm$ 18.1 mmHg [p<0.05], and 0.27$\pm$ 0.22 versus 0.14$\pm$ 0.03 and 0.11$\pm$ 0.05 [p<0.05] respectively. The apparent hypoplasia of the descending aorta in infants with AVSD is an illusion created by the abnormally large pulmonary arteries, which are significantly larger than in patients with ASDs or VSDs.