Systemic ventricular function in patients with tetralogy of fallot, ventricular septal defect and transposition of the great arteries repaired during infancy.

Abstract

Work-function curves relating systemic ventricular end-diastolic pressure (EDP) to minute work index (MWI) were used to assess ventricular performance in 8 patients with tetralogy of Fallot (TOF), 5 patients with ventricular septal defect (VSD) and 9 patients with d-transposition of the great arteries (TGA). All patients underwent repair when they were younger than 18 mo. of age and, when studied 13 mo. after surgery, had satisfactory anatomic results by catheterization. Results were compared with 7 control subjects. All patients had normal systemic ventricular hemodynamics at rest. A work-function curve for each patient was generated using a methoxamine infusion to increase afterload and measuring EDP, mean ventricular systolic pressure and cardiac index. Heart rate was maintained within a narrow range for each patient. The systemic ventricle in the TGA patients responded to the afterload stress with a smaller increase in MWI than was noted for either the TOF (P < 0.05), VSD (P < 0.01) or control (P < 0.01) groups. This difference in MWI for the TGA patients occurred despite a comparable increase in systemic ventricular EDP for all groups. The net result was a highly significant difference in mean slope of the work-function curves for the TGA patients compared with the TOF (P < 0.02), VSD (P < 0.01) or control (P < 0.01) patients. There was no significant difference in mean slope for the TOF, VSD and control groups. An afterload stress at early postoperative follow-up identified preclinical systemic ventricular dysfunction in TGA patients not evident in age-matched TOF and VDS patients. This finding takes on added significance with the recent development of alternative surgical approaches to repair of TGA that use the left ventricle as the systemic pumping chamber.