Peripheral endothelial dysfunction in patients with pulmonary arterial hypertension.

BACKGROUND Pulmonary endothelium plays an important role in the mechanism of pulmonary arterial hypertension (PAH). However, there is only a few data regarding the systemic endothelium in this syndrome. This study focused on the systemic endothelial involvement in PAH. METHODS Endothelial function was evaluated in 54 patients with idiopathic (n=28), scleroderma-associated (n=10), chronic thromboembolic (n=7), or Eisenmenger (n=9) PAH and 21 controls (13 healthy; eight scleroderma and normal pulmonary pressure). All underwent clinical evaluation, pulmonary assessment, echocardiography, and pulmonary cardiac stress test. Endothelial function was evaluated by measuring the forearm blood flow dilatation response to brachial arterial occlusion by a non-invasive plethysmograph, yielding a peripheral arterial tone (PAT) ratio. RESULTS The PAT ratio was significantly lower (p<0.05) than healthy controls in all patients except the Eisenmenger group (control: 2.20+/-0.25; idiopathic 1.84+/-0.51; scleroderma 1.66+/-0.66; thromboembolic 1.89+/-0.32; Eisenmenger 2.17+/-0.62). The impaired hyperemic response significantly correlated with disease severity, as measured by NYHA classification (r=-0.210, p=0.035), pulmonary pressure (r=-0.228, p=0.035), 6 min walking distance (r=0.215, p=0.047), and oxygen desaturation on effort (r=0.207, p=0.038). Mean systolic pulmonary pressure among patients was 54-99 mmHg. CONCLUSION A systemic component of endothelial dysfunction might be involved in idiopathic, scleroderma-associated and chronic thromboembolic PAH that is correlated with disease severity.