A Veteran Presenting With Chronic Progressive Dyspnea on Exertion

►Dr. Maron: These echocardiography results exclude left ventricular systolic dysfunction or primary left-sided valvular disease at rest as a cause of the patient’s symptoms. In light of the patient’s prior normal stress test, high grade coronary disease in the absence of LV systolic dysfunction on echocardiography also seems unlikely. Estimated pulmonary artery systolic pressure > 60 mm Hg by echocardiography is highly suggestive of PH, but in and of itself does not diagnose PH nor inform pulmonary artery wedge pressure or pulmonary vascular resistance. Along with a direct measurement of pulmonary artery (PA) pressure, these data are needed to establish, classify, and prognosticate PH clinically.

►Dr. Clark: The patient was referred to a pulmonologist. His examination included bibasilar crackles and an enhanced P2 heart sound. A comprehensive pulmonary history was obtained, which noted his smoking history, possible asbestos exposure while serving in the Coast Guard, nighttime snoring without witnessed apnea events, and no personal or family history of thromboembolism or connective tissue disease.

Dr. Goldstein, is there anything in this patient’s history that could explain his symptoms and echocardiograph findings? Which tests would you order next?
 

►Dr. Goldstein: PH may be secondary to a wide variety of disorders including left heart disease (Group 2), advanced COPD, interstitial fibrosis, obstructive sleep apnea (OSA), or other lung diseases (Group 3), thromboembolic disorders (Group 4), and other systemic diseases such as sarcoidosis (Group 5). Group 1 is pulmonary arterial hypertension. (Table 2).

A right heart catheterization should be done to confirm the PA pressures estimated by echocardiogram. As to a cause, clinically he does not have heart failure. The limited smoking history and spirometry data do not support advanced COPD. He was noted to have crackles on physical examination suggesting an interstitial disorder. To assess the extent of interstitial disease, we would obtain a noncontrast computed tomography (CT) of the chest. The history of snoring suggesting the possibility of OSA indicating the need for overnight oximetry as significant nocturnal hypoxemia is a possible contributing cause to PH. A polysomnogram would be required to fully evaluate a sleep disturbance. The possible asbestos exposure is not likely a contributing factor as asbestosis requires significant exposure. We would obtain a ventilation/perfusion (V/Q) scan to rule out chronic thromboembolic disease. Targeted tests for causes of Group 5 disease should also be done.
 

►Dr. Clark: The impression from his pulmonologist was that the patient has severe PH, though the specific etiology was not yet known. Dr. Maron, can you review for us the pathophysiology behind PH and describe how the disease is classified?

►Dr. Maron: Elevated mean pulmonary artery pressure (> 20 mm Hg) diagnosed by supine right heart catheterization is the sine qua non of PH.⁴ However, this alone does not inform pathophysiology. As Dr. Goldstein noted, elevated PA pressure may be due to left heart disease, primary parenchymal lung disease/sleep-disordered breathing, in situ thrombotic remodeling of pulmonary arterioles following prior luminal pulmonary embolism, or in the setting of various specific predisposing conditions, such as sickle cell disease and sarcoidosis among others.⁵