Influence of two-stage anatomic correction on size and distensibility of the anatomic pulmonary/functional aortic root in patients with simple transposition of the great arteries

Abstract

To evaluate the results of the two-stage anatomic correction of simple transposition of the great arteries the size, distensibility, and histologic characteristics of the anatomic pulmonary root, which arises from the anatomic left ventricle and which we termed the functional aortic root after anatomic correction, were determined in seven patients before and twice after anatomic correction (mean 43 and 671 days) and the results were compared with those in normal control subjects. The diameter of the systolic sinus of the anatomic pulmonary root increased after banding on the average to 140% of normal, whereas the diameter of the diastolic sinus of the functional aortic root increased after anatomic correction on the average of 150% of normal. Diameters of both the systolic and diastolic sinuses of the functional aortic root remained 30% to 55% larger than normal after anatomic correction. Growth potential of the functional aortic root after anatomic correction was normal, whereas its distensibility, as assessed by determination of the percent change in radius and pressure-strain elastic modulus (stiffness index), was decreased after anatomic correction. This pressure-strain elastic modulus was directly related to the corresponding body surface area and age at banding. In four of five specimens of the anatomic pulmonary aterial wall that were obtained at the time of anatomic correction, fragmentation and shortening of elastic fibers were observed. The histologic characteristics of the pulmonary root in the patient with the smallest body surface area of banding and normal distensibility of the anatomic pulmonary/functional aortic root before and after anatomic correction revealed normal aortic configuration of the elastic tissue. The results of this study support the policy of an earlier pressure loading of the anatomic pulmonary root in patients with transposition of the great arteries by banding and/or anatomic correction.