Risk factors were similar between the mild PH group and moderate to severe PH groups.

Rats with severe PH had evidence of RV failure by decreased cardiac output and systemic hypotension.

This study assessed the effect of sildenafil on pulmonary hemodynamics and gas exchange in severe PH associated with COPD.

Conclusions: Echocardiography assessment of PR in the pulmonary circulation and severe PH may identify patients with adverse outcome following mitral surgery.

Methods and results: We found that apelin-null mice developed more severe PH compared with wild-type mice when exposed to chronic hypoxia.

Limited data are currently available on the hemodynamic and clinical effect of phosphodiesterase 5 inhibitors in patients with severe PH associated with COPD.