[Pulmonary hypertension: definition, classification and treatments]

Abstract

Pulmonary hypertension (PH) is a cardio-pulmonary disorder that may involve multiple clinical conditions and can complicate the majority of cardiovascular and respiratory diseases. Its definition is an increase in mean pulmonary artery pressure (mPAP) \hbox{$\geqslant $} ⩾ 25 mmHg at rest, leading to right heart failure and ultimately death. The clinical classification of pulmonary hypertension (PH) categorizes PH into groups which share similar pathophysiological and hemodynamic characteristics and treatments. Five groups of disorders that cause PH are identified: pulmonary arterial hypertension (Group 1) which is a pre-capillary PH, defined by a normal pulmonary artery wedge pressure (PAWP) \hbox{$\leqslant $} ⩽ 15 mmH, due to remodelling of the small pulmonary arteries (<500 μm); pulmonary hypertension due to left heart disease (Group 2) which is a post-capillary PH, defined by an increased pulmonary artery wedge pressure (PAWP) >15 mmHg; pulmonary hypertension due to chronic lung disease and/or hypoxia (Group 3); chronic thrombo-embolic pulmonary hypertension (Group 4); and pulmonary hypertension due to unclear and/or multifactorial mechanisms (Group 5). PAH (PH group 1) can be treated with agents targeting three dysfunctional endothelial pathways of PAH: nitric oxide (NO) pathway, endothelin-1 pathway and prostacyclin pathway. Patients at low or intermediate risk can be treated with either initial monotherapy or initial oral combination therapy. In patients at high risk initial combination therapy including intravenous prostacyclin analogues should be considered. Patients with inadequate clinical response to maximum treatment (triple therapy with an intravenous prostacyclin) should be assessed for lung transplantation. Despite progresses, PAH remains a fatal disease with a 3-year survival rate of 58%. Treatment of group 2, group 3 and group 5 PH is the treatment of the causal disease and PAH therapeutics are not recommended. Treatment of group 4 PH is pulmonary endarteriectomy if patients are eligible, otherwise balloon pulmonary angioplasty and/or medical therapy can be considered.