Chronic thromboembolic pulmonary hypertension.

Chronic thromboembolic pulmonary hypertension (CTEPH) is a form of pulmonary hypertension (PH) characterized by the persistence of thromboembolic obstructing the pulmonary arteries as an organized tissue and the presence of a variable small vessel arteriopathy. The consequence is an increase in pulmonary vascular resistance resulting in progressive right heart failure. CTEPH is classified as group IV pulmonary hypertension according to the WHO classification of pulmonary hypertension. CTEPH is defined as precapillary pulmonary hypertension (mean pulmonary artery pressure ≥ 25 mmHg with a pulmonary capillary wedge pressure ≤ 15 mmHg) associated with mismatched perfusion defects on ventilation-perfusion lung scan and signs of chronic thromboembolic disease on computed tomography pulmonary angiogram and/or conventional pulmonary angiography, in a patient who received at least 3 months of therapeutic anticoagulation. CTEPH as a direct consequence of symptomatic pulmonary embolism (PE) is rare, and a significant number of CTEPH cases develop in the absence of history of PE. Thus, CTEPH should be considered in any patient with unexplained PH. Splenectomy, chronic inflammatory conditions such as inflammatory bowel disease, indwelling catheters and cardiac pacemakers have been identified as associated conditions increasing the risk of CTEPH. Ventilation-perfusion scan (V/Q) is the best test available for establishing the thromboembolic nature of PH. When CTEPH is suspected, patients should be referred to expert centres where pulmonary angiography, right heart catheterization and high-resolution CT scan will be performed to confirm the diagnosis and to assess the operability. Pulmonary endarterectomy (PEA) remains the gold standard treatment for CTEPH when organized thrombi involve the main, lobar or segmental arteries. This operation should only be performed by experienced surgeons in specialized centres. For inoperable patients, current ESC/ERS guidelines for the diagnosis and treatment of pulmonary hypertension recommend the use of riociguat and say that off-label use of drugs approved for PAH and pulmonary angioplasty may be considered in expert centres.