Symptom-limited cardiopulmonary exercise testing was performed on a 58- year-old man who had received a unilateral lung transplant 2.6 years previously. The patient exercised for 9 minutes using a standard Naughton treadmill protocol with a endpoint of subjective fatigue. The patient denied limiting dyspnea during the test. Heart rate, blood pressure, and the electrocardiogram results were normal. Arterial oxygen saturation was well maintained during exercise (97% rest, 93% exercise), and minute ventilation at peak exercise was only 36% of measured maximal voluntary ventilation, indicating that exercise tolerance was not ventilatory limited. Ventilatory equivalents for oxygen and carbon dioxide were higher than normal. Peak oxygen uptake was 866 mL/min (45% of the predicted value) and was believed to be consistent with marked deconditioning. During subsequent exercise training, however, symptoms of dyspnea during exertion worsened without deterioration in pulmonary function variables. Five months after beginning the exercise program, results of a repeat radionuclide angiogram demonstrated exercise-induced left ventricular dysfunction not appreciated on the pretransplant test. Coronary angiography results showed left anterior descending coronary artery disease that was successfully treated with angioplasty.
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