Cardiopulmonary Exercise Testing in Congenital Heart Disease

Abstract

Exercise intolerance is one of the major symptoms of chronic heart failure. Cardiopulmonary exercise testing (CPX) allows for the simultaneous study of responses to cardiovascular and ventilator systems to a known exercise stress through the measurement of gas exchange at the airway. During exercise, oxygen consumption and carbon dioxide production at the contracting muscle are coupled with the external respiration at the lung through the cardiovascular system. Therefore, by studying external respiration in response to exercise, it is possible to address the functional competence of the cardiovascular system to meet the increased cellular respiratory demands during exercise. Objective assessment of exercise intolerance by means of CPX is especially important in patients with congenital heart disease (CHD), as they have made lifelong adaptations to their cardiovascular disease and its slow progression. Thus, they are not aware of the true extent of their exercise intolerance. Moreover, recent studies have demonstrated the ability of several CPX parameters to predict the long-term survival of patients with CHD. Because CHD patients often require high-risk surgical or catheter interventions and risk stratification based on individual risks is essential in this population, CPX plays a major role in the management of CHD. On the other hand, there are several pitfalls in interpreting the results of CPX in CHD. This review provides an overview of the interpretation and application of CPX in CHD.