A full set of PFTs (ie, spirometry plus assessment of lung volumes and diffusion capacity) is required to evaluate the abnormalities associated with chronic obstructive pulmonary disease (COPD), interstitial diseases, vascular abnormalities (particularly PH), as well as for certain preoperative assessments. The single breath diffusing capacity for carbon monoxide is a measure of the overall capillary alveolar surface area of the lung. It is decreased in emphysema and interstitial disease as well as pulmonary vascular disorders. It would be particularly useful in this case as the spirometry studies were normal.
In this case, the normal FVC renders a significant restrictive disorder unlikely and his normal forced expiratory volume (FEV1) and FEV1/FVC make a significant obstructive disorder unlikely. He did not show any bronchodilator response; however, this finding does not exclude the presence of underlying asthma or reactive airway disease as patients often will not show a bronchodilator response at time of testing if they are not experiencing active bronchospasm or constriction. Further provocative testing with a methacholine challenge could be used to assess for reactive airway disease.
►Dr. Clark: The patient continued to have dyspnea when he returned to his PCP. Given his family history of premature CAD, an ECG was obtained that showed normal sinus rhythm at a rate of 70 beats per minute. A cardiology consult was placed, and he was referred for cardiac stress testing.
Dr. Maron, there are many forms of cardiac stress tests. In this case, the patient is referred for a stress test due his dyspnea. Does that symptom help you decide which test to order? How often does dyspnea present as an anginal equivalent in the absence of other cardiovascular symptoms or known cardiovascular disease?
►Bradley Maron, MD, Codirector, Pulmonary Vascular Disease Center, VABHS: In this case, stress testing should include a functional (ie, exercise) assessment if possible. Exercise capacity is a critical determinant of prognosis across the spectrum of cardiovascular disease and in a young person can be particularly informative on global health status. Furthermore, the chief complaint from this patient is dyspnea on exertion, and therefore, exercise testing is likely to be needed to reproduce or provoke the main symptom in this case. Estimates for dyspnea as a presenting symptom for ischemic heart disease vary but may be as high as 25%.3 It should be noted that cardiopulmonary exercise testing is useful for evaluating patients with unexplained dyspnea, as exercise hypoxemia, blunted decrease in VD/VT (ventilatory dead space/tidal volume), and evidence of a pulmonary mechanical limit to physical activity can inform the differential diagnosis.
►Dr. Clark: The patient underwent exercise treadmill testing and was able reach the target heart rate (> 85% age-predicted maximal heart rate) and achieve 11 metabolic equivalents. He had no chest pain or diagnostic ECG changes. The report made no mention of whether he experienced dyspnea during the test and was read as negative for exercise-induced ischemia.
He was seen by a cardiologist who noted an increased intensity S2 heart sound on examination without any other cardiopulmonary findings. It was noted that his symptoms occurred when tamping the ground or starting to walk up a hill but resolved with rest. It was also noted that his symptoms did not occur with gradual increased activity such as that performed during an exercise tolerance test. A 2-view chest X-ray was obtained and read as normal. Given the data from this evaluation thus far, the patient was told that his symptoms were most likely a result of his asthma exacerbated by dirt and dust exposure. Continued use of albuterol inhaler therapy was recommended, and no further diagnostic assessment was pursued.
Approximately 11 months later, the patient presented again to his PCP and reported progressive dyspnea. He had delayed seeking further care as he started to “feel like my symptoms were possibly in my head” given his prior negative workup. His symptoms had escalated drastically to the point where he felt short of breath with minimal exertion in addition to feeling sweaty, dizzy, fatigued, and having near-syncope when standing.
He was referred for a transthoracic echocardiogram (TTE) that revealed a left ventricular ejection fraction (LVEF) of 55 to 60% with diastolic relaxation abnormality and a normal-sized left atrium. The TTE also showed (qualitatively) a moderately dilated right ventricle with reduced systolic function, moderately severe tricuspid regurgitation, and severe elevation (> 60 mm Hg) in estimated right ventricular systolic pressure.
Dr. Maron, can you comment on how these findings may explain the patient’s symptoms? What differential diagnoses would you now consider?