Similarities and differences in the exercise performance of patients aftera modified Fontan procedure compared to patients with complete transposition following a Senning operation

Objective: To investigate cardiopulmonary performance in patients after a F ontan procedure, comparing it to patients following a Senning operation. Me thods. We studied 21 children, with a mean age of 11.1 years, after a total cavopulmonary anastomosis, comparing them to 13 with complete transpositio n after a Senning procedure, having a mean age of 11.8 years, and 21 contro l subjects with a mean age of 11.2 years. All were tested on a bicycle ergo spirometer. Results. Peak consumption of oxygen, maximal work rate, peak ox ygen pulse and endexpiratory pressure of carbon dioxide at a work rate of 1 .5 Watt/kg were lowest in patients with a modified Fontan procedure, and hi ghest in the control group (p less than or equal to 0.0278). Production of carbon dioxide, and minute ventilation at a work rate of 1.5 Watt/kg, was h ighest in the patients after Fontan procedure, and lowest in the healthy su bjects (P less than or equal to 0.0163). Production of carbon dioxide per s ingle breath was lower in those having a Fontan procedure (28.9 ml) than in the two other groups (35.1 ml, p = 0.0243). The tidal volume showed no sig nificant differences between the three groups. Conclusions: The reaction to exercise was identical qualitatively in both groups of patients, and compa rable to the behaviour of patients with chronic heart failure. Quantitative ly, the results of the patients following a Senning procedure lay between t hose of control subjects and those who had undergone a Fontan operation. Th e only exception was dead space ventilation, where the patients after a Fon tan procedure differed from the two other groups because of their increased ventilation-perfusion mismatch.