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

OBJECTIVE: To investigate cardiopulmonary performance in patients after a Fontan procedure, comparing it to patients following a Senning operation. METHODS: We studied 21 children, with a mean age of 11.1 years, after a total cavopulmonary anastomosis, comparing them to 13 with complete transposition after a Senning procedure, having a mean age of 11.8 years, and 21 control subjects with a mean age of 11.2 years. All were tested on a bicycle ergospirometer. RESULTS: Peak consumption of oxygen, maximal work rate, peak oxygen 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 highest in the control group (p < or = 0.0278). Production of carbon dioxide, and minute ventilation at a work rate of 1.5 Watt/kg, was highest in the patients after Fontan procedure, and lowest in the healthy subjects (p < or = 0.0163). Production of carbon dioxide per single 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 significant differences between the three groups. CONCLUSIONS: The reaction to exercise was identical qualitatively in both groups of patients, and comparable to the behaviour of patients with chronic heart failure. Quantitatively, the results of the patients following a Senning procedure lay between those of control subjects and those who had undergone a Fontan operation. The only exception was dead space ventilation, where the patients after a Fontan procedure differed from the two other groups because of their increased ventilation-perfusion mismatch.