Abnormalities on Cardiopulmonary Exercise Test in a Dyspneic Patient

The cardiopulmonary exercise test (CPET) is frequently used for the quantitative evaluation of exercise tolerance and for the qualitative assessment of the origin of dyspnea. Although reasonably safe, CPET is contraindicated in acute clinical situations and relatively contraindicated in severe pulmonary hypertension. Pulmonary emboli are usually present during the acute onset of pulmonary hypertension; however, in situations where pulmonary vascular disease is more unsuspected, CPET may help with the diagnosis. We present a report of a 47-year-old Caucasian female with a 2-month history of exertional dyspnea. She had a normal pulmonary function test, arterial blood gas analysis and CT scan of the chest. On CPET she was found to have a higher than normal physiological dead space to tidal volume ratio, increased ventilatory equivalent for the elimination of CO₂ (V_E/VCO₂), persistently positive arterial-end-tidal PCO₂ difference at peak exercise, and a low anaerobic threshold suggestive of pulmonary vascular disease. She was subsequently diagnosed with pulmonary embolic disease by her ventilation/perfusion scan and pulmonary arteriogram. This report highlights the importance of recognizing the hallmarks of unsuspected pulmonary vascular disease on CPET.