Abstract
Cardiopulmonary exercise testing（CPET） is a kind of clinical testing that allows for the analysis of gas exchange during exercise. Maximal oxygen uptake（VO2max）, an index of cardiac, respiratory, and skeletal muscle functions, is one of the most 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（VE/VCO2 slope）is an established prognostic marker in cardiac failure. The oxygen uptake efficiency slope（OUES）, a submaximal index of cardiorespiratory functional reserve, correlates strongly with VO2max and is utilized as a prognostic tool for various heart diseases including congenital heart defects.
