Cor pulmonale

The term "cor pulmonale" is still popular but there is presently no consensual definition and it seems more appropriate to define the condition by the presence of pulmonary hypertension (PH) resulting from diseases affecting the structure and/or the function of the lungs: PH results in right ventricular enlargement and may lead with time to right heart failure (RHF). Chronic obstructive pulmonary disease (COPD) is the first cause of cor pulmonale, far before idiopathic pulmonary fibrosis and obesity-hypoventilation syndrome. In chronic respiratory disease (CRD) PH is "pre-capillary," due to an increase of pulmonary vascular resistance (PVR). The first cause of increased PVR is chronic long-standing alveolar hypoxia which induces pulmonary vascular remodeling. The main characteristic of PH in CRD and particularly in COPD is its mild to moderate degree, resting pulmonary artery mean pressure (PAP) in a stable state of the disease usually ranging between 20 and 35 mmHg. However, PH may worsen during exercise, sleep, and exacerbations of the disease. These acute increases in afterload can favor the development of RHF. A minority (<5%) of COPD patients exhibit severe or "disproportionate" PH (PAP >40 mmHg), the mechanism of which is not well understood. At present long-term oxygen therapy (LTOT) is the logical treatment of PH since alveolar hypoxia is considered to be the major determinant of the elevation of PAP and PVR. LTOT stabilizes or at least attenuates and sometimes reverses the progression of PH, but PAP seldom returns to normal. Vasodilators (prostacyclin, endothelin receptor antagonists, sildenafil, nitric oxide) could be considered in patients with severe PH but controlled studies in this field are presently lacking.