Heritable pulmonary arterial hypertension with elevated pulmonary wedge pressure.

A 50-year-old man, who is an active smoker without a previous medical history, was admitted for recent dyspnea (New York Heart Association functional class III) and an episode of exertional syncope. His familial history included the sudden death of his mother at the age of 50. His blood pressure was 123/90 mm Hg; heart rate, 80 beats/min; peripheral oxygen saturation, 95%; and clinical examination found a prominent pulmonary component of S2, jugular vein distension, and normal lung sounds. His ECG showed complete right bundle-branch block. Chest radiography showed central pulmonary artery, right atrium, and ventricle enlargements without major abnormalities of pulmonary parenchyma (Figure 1). Brain natriuretic peptide was 758 pg/mL (normal, 100 pg/mL) and troponin T was raised to 0.22 ng/mL (normal, 0.14 ng/mL). Transthoracic echocardiography showed severe dilatation of the right chambers, paradoxical wall motion septum, and pulmonary hypertension with a tricuspid regurgitant jet velocity of 4.5 m/s and an estimated systolic pulmonary arterial pressure of 96 mm Hg (Figure 2). Left ventricle, aortic and mitral valves, and left ventricle filling pressures were normal. High-resolution computed tomography of the chest showed neither acute nor chronic thromboembolic disease, nor severe parenchymal lung disease; in particular, radiological signs of pulmonary veno-occlusive disease were absent. The different causes of precapillary pulmonary hypertension were excluded by exhaustive investigations, including pulmonary function tests, ventilation/perfusion lung scan, antinuclear antibodies, HIV and hepatitis serologies, and abdominal ultrasound. Right heart catheterization was then performed to confirm the diagnosis of precapillary pulmonary hypertension; systolic and diastolic pulmonary arterial pressure were, respectively, 100 mm Hg and 48 mm Hg, with a mean pulmonary arterial pressure of 67 mm Hg. The assessment of pulmonary wedge pressure (PWP) was difficult technically because of the severity of pulmonary hypertension and was achievable only with the tip of the balloon catheter located in the right lower lobe (West zone 3), but not in the right upper lobe or in the left pulmonary arteries (Figure 3). A complete wedging of the balloon catheter was then obtained with evidence of distinct A and V waves, allowing correct measurements of PWP at the end of expiration. Surprisingly, we measured increased PWP at 37 mm Hg, suggesting postcapillary pulmonary hypertension. Because of this discrepancy between the value of PWP and the clinical and echocardiographic records, we decided to perform concomitantly a left ventricular catheterization to measure left ventricular end diastolic pressure, which was normal at 7 mm Hg (Figures 4 and 5), confirming precapillary pulmonary hypertension. Cardiac computed tomography was then performed and showed major dilatation of the right chambers, with an enlarged right atrium causing compression of the right inferior pulmonary vein (Figures 6 and 7). This extrinsic compression explained the falsely elevated PWP in this patient with authentic pulmonary arterial hypertension. Interestingly, genetic testing was done in this patient, who Figure 1. Chest radiograph shows bilateral hilar, right atrium, and ventricle enlargements resulting from pulmonary hypertension. Pulmonary parenchyma was normal.