Left ventricular function after repair of tetralogy of fallot and its relationship to age at surgery

Left ventricular (LV) work-function curves were used to assess LV performance in eight postoperative tetralogy of Fallot (TOF) patients who underwent repair before 2 years of age (group 1) and 12 patients who underwent repair after 2 years of age (group 2). All patients were without significant residual shunts or pulmonary stenosis. Results were compared with those in seven control patients. Left- and right-heart hemodynamics were measured at various levels of afterload induced by methoxamine while heart rate was maintained constant. Cardiac output was serially measured. The slope (m) for each patient's LV end-diastolic pressure (EDP) vs LV minute-work index (MWI) relationship was determined. There were no significant differences in resting cardiac index, LV systolic pressure, LVEDP, aortic oxygen saturation or MWI among the groups. However, with afterload stress, group 2 patients had abnormal work-function curves with depressed slopes (m = 0.21 +/- 0.04) compared with the values for group 1 patients (m = 0.89 +/- 0.13, p less than 0.001) or the control group (m = 1.13 +/- 0.12, p less than 0.001). Thus, LV dysfunction unmasked by an afterload stress was present in the older TOF patients but not in the patients repaired during infancy. These findings raise the possibility that early, definitive repair of TOF may help preserve postoperative LV function.