Cardio-pulmonary exercise testing in the evaluation of mitral and aortic valve incompetence.

Cardio-pulmonary exercise (CPX) testing can be used to discern the functional integrity of the right and left heart and pulmonary circulation in patients with chronic mitral or aortic valvular incompetence. The noninvasive determination of VO2 max and anaerobic threshold in these patients serves to assess the severity of chronic circulatory failure and to predict the maximum exercise cardiac output (or cardiac reserve). Invasive monitoring of right heart pressures and left ventricular filling (wedge) pressure identifies abnormalities in ventricular function and the pulmonary circulation that may not be otherwise apparent. Noninvasive and invasive CPX testing is therefore a valuable tool which can also be applied to the serial evaluation of these patients. CPX offers several advantages over traditional indices of ventricular function (e.g., resting cardiac output, filling pressure and ejection fraction) in that it objectively identifies the patients functional status, the heart's pumping reserve, and the integrity of the cardio-pulmonary unit. The utility of CPX, however, in assessing an early and subtle decline in left ventricular function and its ability to predict the appropriate timing for valve replacement in chronic mitral or aortic valvular incompetence remains to be elucidated.