OXYGEN-UPTAKE TRANSIENT KINETICS DURING CONSTANT-LOAD EXERCISE IN CHILDREN AFTER OPERATIONS OF VENTRICULAR SEPTAL-DEFECT, TETRALOGY OF FALLOT, TRANSPOSITION OF THE GREAT-ARTERIES, OR TRICUSPID-VALVE ATRESIA

Cardiovascular function accounts for endurance performance and, by a r apid increase in oxygen supply at the onset of exercise, contributes t o short-lasting intensive exertion prevailing in many kinds of sports activities. This study determined the time for oxygen uptake (VO2) to reach one half of its asymptotic level above rest, and the respective oxygen deficit following the onset of a constant load exercise corresp onding to 80% to 90% of the maximal oxygen uptake (VO(2)max) in 35 chi ldren after surgical closure of a ventricular septal defect, after cor rective surgery for tetralogy of Fallot, or after the Senning, Mustard , or Fontan procedures. In addition, VO(2)max and maximal blood lactat e were determined. The half-time of VO2 response and oxygen deficit wa s lowest in patients after closure of a ventricular septal defect, whe reas children had the most unfavorable VO2 transient kinetics after Fo ntan operation or with a transannular patch after correction of tetral ogy of Fallot. A negative correlation was evaluated between half-time of VO2 response and VO(2)max, whereas maximal blood lactate varied ind ependently of VO(2)max. It is concluded that many children with decrea sed VO(2)max after cardiac surgery also have unfavorable VO2 transient kinetics. In addition to being sass qualified for endurance performan ce, they are also less prepared for short-lasting intensive energy exp enditure. Therefore, the primary aim of training in these children is to improve the economy of motion of the respective tasks.