Preparation of the left ventricle for anatomical correction in patients with simple transposition of the great arteries. Surgical guidelines

Pulmonary artery banding in combination with an aortopulmonary shunt was performed on 16 patients with simple transposition of the great arteries to prepare the left ventricle for anatomical correction. Three groups were identified after operation: Group I (four patients) had increased pulmonary blood flow and tight pulmonary artery banding; Group II (four patients) had increased pulmonary blood flow and moderate pulmonary artery banding; Group III (eight patients) had normal pulmonary blood flow and moderate pulmonary artery banding. Postoperative low cardiac output was present in all patients in Group I, whereas mild heart failure was present in two patients in Group II and in two in Group III. There was one hospital death (6%). The follow-up period was 125 patient-months. Left ventricular systolic pressure rose from 63 ± 11 torr before the operation to 101 ± 35 torr after the procedure in Group I (p < 0.05), from 59 ± 10 to 93 ± 33 torr in Group II (p < 0.05), and from 55 ± 10 to 84 ± 16 torr in Group III (p < 0.005). The increase in left ventricular muscle mass was from 44 ± 2 gm/m² preoperatively to 108 ± 12 gm/m² after operation in Group I (p < 0.01), from 43 ± 3 to 93 ± 8 gm/m² in Group II (p < 0.02), and from 46 ± 3 to 55 ± 14 gm/m² in Group III (p = no statistically significant difference). The postoperative change in left ventricular end-diastolic volume was from 100% ± 17% to 133% ± 23% of normal in Groups I and II (p < 0.05) and from 123% ± 29% to 107% ± 36% of normal in Group III (p = no statistically significant difference). In preparing the left ventricle for anatomical correction, avoidance of severe pulmonary artery banding decreases the incidence of postoperative myocardial dysfunction, a moderate degree of volume overload and pulmonary artery banding provides the most effective stimulus for ventricular growth, and a small to moderate atrial septal defect is advantageous because it ensures the volume preload necessary for the development of the left ventricle.