Journal of Pediatric Cardiology and Cardiac Surgery

Cardiopulmonary exercise testing (CPET) is a clinical testing that allows for the analysis of gas exchange during exercise. Maximal oxygen uptake (V̇O₂max), a comprehensive index of cardiac, respiratory, and skeletal muscular functions, is one of the important measurements obtained in CPET. Anaerobic threshold, the exercise intensity at which lactate starts to accumulate in the blood, is widely used, as it represents an exercise level that is not too strenuous, but not too mild. The minute ventilation/carbon dioxide output relationship (V̇E/V̇CO₂ slope) is often used as a prognostic marker of cardiac failure. The oxygen uptake efficiency slope (OUES) is a submaximal index of cardiorespiratory functional reserve, and correlates strongly with V̇O₂max. This marker is utilized as a prognostic tool for various heart diseases including congenital heart defects.