Impaired cardiorespiratory response to brief sudden strenuous exercise in the postoperative tetralogy of Fallot patients: A ten-second pedaling test

No studies of cardiorespiratory response to brief, sudden, strenuous exercise in patients after tetralogy of Fallot (TOF) repair have been reported. We investigated the exercise capacity of TOF patients using a ten-second pedaling test designed to study cardiorespiratory responsiveness to brief, sudden, strenuous exercise. We assessed exercise capacity using a ten-second pedaling test (ten seconds maximal of voluntary cranking as fast as possible against an ergometer's inertial resistance), coupled with a conventional ramp-type progressive exercise test at a constant rate to the limit of tolerance, in eight male postoperative TOF patients and eight male control subjects. In the ten-second pedaling test, there were no significant differences in the integrated areas of heart rate (HR) and oxygen uptake (VO₂) responses between the TOF patients and controls, but there were significantly longer decreasing phase time constants of HR and VO₂ responses in the TOF patients than in the controls. In the conventional exercise test, the endurance time, peak-HR, and peak-VO₂ did not differ between the groups. The TOF group, with a normal exercise capacity assessed by a conventional exercise test, had an impaired cardiorespiratory response to brief, sudden, strenuous exercise assessed by a ten-second pedaling test.