Figures 2: a and b: Tendency curve of the mean hemodynamic parameters during the acute vasodilator test with sildenafil; mPAP: mean pulmonary artery pressure mmHg, TPG: transpulmonary gradient mmHg, PVR: pulmonary vascular resistances WU, PCWP: pulmonary capillary wedge pressure mmHg; CO: cardiac output l/min; SVR: systemic vascular resistances WU