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.

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.

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), 6min 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 54–99mmHg.

A systemic component of endothelial dysfunction might be involved in idiopathic, scleroderma-associated and chronic thromboembolic PAH that is correlated with disease severity.