Hypertension artérielle pulmonaire et retentissement cardiaque droit des affections respiratoires chroniques

Pulmonary hypertension (PH) is generally defined by the presence of a resting pulmonary artery mean pressure (PAP) over 20 or 25 mmHg, whereas the pulmonary capillary wedge pressure is normal, which defines the precapillary feature of this PH. PH complicating respiratory disease, and particularly chronic obstructive pulmonary disease (COPD), is the most common of all forms of precapillary PH. It is not a severe PH bearing a poor prognosis and, in this regard, it markedly differs from idiopathic PH, but it may cause the occurrence of right heart failure. In most of the patients PAP, measured in a stable state of the disease, is mildly to moderately elevated (20-35 mmHg) but PH may worsen markedly during acute exacerbations, during exercise and during sleep. These sudden increases in right ventricular afterload can bring about the development of right heart failure. Alveolar hypoxia is by far the major cause of PH in COPD and, accordingly, the best treatment of hypoxic PH is long-term oxygen therapy during > 16-18 h/day. Long-term oxygen therapy improves or, at least, stabilizes pulmonary hypertension.