Effect of Endothelin-1 Receptor Blockade on Circulating Endothelial Microparticles Levels in Patients With Pulmonary Hypertension

pulmonary hypertension, to determine if there is a trans-pulmonary gradient in the levels of emps in patients with ph, to determine if the emps measured at the pulmonary capillary wedge position correlates even more strongly with the severity of ph than the circulating levels, to determine if ph therapy with et-1 receptor blocker will modify emps levels, observational