Dwight C. McGoon

Surgical repair of univentricular heart (double inlet left ventricle) with obstructed anterior subaortic outlet chamber

The results of operation in all patients with univentricular heart and an obstructed anterior subaortic outlet chamber who were operated on utilizing extracorporeal circulation at the Mayo Clinic from 1973 through 1983 were reviewed. Ten of the 18 patients died during the immediate postoperative period and there was one late death. Factors significantly related to operative and immediate postoperative mortality were age at operation, cardiothoracic ratio on X-ray examination, degree of ST depression on electrocardiogram and pressure gradient across the outlet foramen at catheterization. Autopsy in eight cases revealed significant hypertrophy of ventricular myocardium and a small outlet foramen that was considered stenotic relative to either body surface area or aortic root area. The ventricular myocardium showed histologic changes of chronic ischemia that predated the surgical procedure.

Surgical heart block

Abstract Heart block is a serious complication when it develops in the course of surgical procedures for congenital heart defects. Nearly half of the patients will convert to a sinus rhythm within the first three or four weeks after operation; none, however, have converted permanently to sinus rhythm thereafter. Permanent surgical heart block is nearly always the result of direct trauma to the central conduction bundle. The incidence of this occurrence, with the use of proper technics, has been reduced to less than 1 per cent for ventricular septal defect. When permanent heart block does develop as the result of operation, a temporary myocardial electrode should be sutured in place and an external pacemaker should control the heart rate either until sinus rhythm becomes permanently established or, if this does not occur, until a permanent implantable pacemaker is inserted. This radical plan of therapy is warranted by the extremely grave prognosis associated with persistent surgical heart block.

Truncus arteriosus with single pulmonary artery: Influence of pulmonary vascular obstructive disease on early and late operative results

Nineteen patients with truncus arteriosus and single pulmonary artery had corrective operations at the Mayo Clinic from 1969 to 1983. At operation, their ages ranged from 4 months to 20 years (mean 8.1 years). The preoperative pulmonary resistance divided by 2 was used to predict the degree of pulmonary vascular obstructive disease at operation. The influence of elevated pulmonary resistance and the intraoperative postrepair ratio of pulmonary artery to left ventricular pressure on operative and late mortality were examined. The outcome of patients with single pulmonary artery was compared with the outcome of 148 patients with truncus arteriosus and two pulmonary arteries operated on during the same period. Patients with a single pulmonary artery had an operative mortality similar to that of patients with two pulmonary arteries (32 versus 28%, p greater than 0.05). Late mortality was, however, significantly greater (p less than 0.001) for patients with a single pulmonary artery. Elevated ratios of intraoperative postrepair pulmonary artery to left ventricular pressure were associated with significantly higher (p less than 0.02) operative and late mortality, but elevated preoperative pulmonary resistance was not (p greater than 0.10). Truncus arteriosus with single pulmonary artery is associated with poor postoperative survival, and although elevated pulmonary resistances preoperatively did not predict outcome, elevated intraoperative postrepair pulmonary artery to left ventricular pressure ratios were associated with increased operative and late survival, suggesting a deleterious role of pulmonary hypertension.