Pathophysiology of the right ventricle and of the pulmonary circulation in pulmonary hypertension: an update.

The function of the right ventricle determines the fate of patients with pulmonary hypertension. Since right heart failure is the consequence of increased afterload, a full physiological description of the cardiopulmonary unit consisting of both the right ventricle and pulmonary vascular system is required to interpret clinical data correctly. Here, we provide such a description of the unit and its components, including the functional interactions between the right ventricle and its load. This physiological description is used to provide a framework for the interpretation of right heart catheterisation data as well as imaging data of the right ventricle obtained by echocardiography or magnetic resonance imaging. Finally, an update is provided on the latest insights in the pathobiology of right ventricular failure, including key pathways of molecular adaptation of the pressure overloaded right ventricle. Based on these outcomes, future directions for research are proposed.

Long-term therapy with oral treprostinil in pulmonary arterial hypertension failed to lead to improvement in important physiologic measures: results from a single center.

Sustained-release oral treprostinil, an oral prostacyclin, led to significant improvement in 6-minute walk distance (6MWD) versus placebo in treatment-naive patients with pulmonary arterial hypertension (PAH) but failed to lead to significant improvement in two 16-week trials in patients receiving background PAH therapies (FREEDOM studies). Long-term studies are lacking. Our objective was to evaluate 6MWD, functional class, hemodynamics, and other long-term outcomes during oral treprostinil administration in PAH. Patients receiving oral treprostinil through the FREEDOM studies at our institution were included and were followed for up to 7 years. The primary end point was change in pulmonary vascular resistance (PVR) at first follow-up catheterization. Other end points included 6MWD, functional class, and other hemodynamic results. Thirty-seven patients received oral treprostinil for a median of 948 days, with 81%, 61%, and 47% continuing therapy at 1, 2, and 3 years, respectively. Mean treprostinil dose at 3, 12, and 24 months was 4.3 ± 2.3, 8.6 ± 3.2, and 11.7 ± 5.8 mg/24 h, respectively. Compared with pretreatment values, there was no significant change in 6MWD at 3 or 12 months, no improvement in functional class at 12 months, and no significant change in hemodynamics at the first follow-up catheterization (N = 34). Oral treprostinil dose was inversely associated with change in PVR (r = -0.42, P < 0.05), and change in PVR was numerically better among patients in the highest dosing quartile. No significant improvement in 6MWD, functional class, or hemodynamics versus pretreatment values was seen with long-term oral treprostinil therapy, potentially because of inability to achieve a clinically effective dose.