Chronic thromboembolic pulmonary hypertension (CTEPH) is a form of pulmonary hypertension caused by non-resolving thromboembolisms of the pulmonary arteries. In Japan, in contrast to Western countries, CTEPH is more prevalent in women. A Japanese multicenter study reported that a form of CTEPH unrelated to deep vein thrombosis is associated with HLA-B⁎5201, suggesting that this form of CTEPH may be associated with vasculopathy. CTEPH can be cured by pulmonary endarterectomy, provided that the thrombi are surgically accessible; thus, early diagnosis is important, and all patients with exertional dyspnea should be evaluated for pulmonary hypertension. Ventilation/perfusion scans provide an excellent non-invasive means to distinguish CTEPH from pulmonary arterial hypertension. Similarly, computed tomographic pulmonary angiograms allow for the detection of thrombi and evaluation of pulmonary hemodynamics in a minimally invasive manner. Importantly, the absence of subpleural perfusion on pulmonary angiograms can suggest the presence of small vessel disease. Small vessel disease might be involved in the pathogenesis of CTEPH, and its detection is essential in preventing operative death. Although no modern therapies for pulmonary arterial hypertension have been approved for treatment of CTEPH, a recent randomized control trial of riociguat in patients with CTEPH demonstrated that riociguat significantly improved 6-min walking distance. Further investigations into treatments that target endothelial dysfunction and hyperproliferative CTEPH cells are needed. Recently, balloon pulmonary angioplasty has emerged as a promising treatment modality in Japan. A specialized medical team, including at least one expert surgeon, should make decisions regarding patients' candidacy for pulmonary endarterectomy and/or balloon pulmonary angioplasty.
Keywords: 6-min walk distance; BPA; Balloon pulmonary angioplasty; CT; CT pulmonary angiography; CTEPH; CTPA; Chronic thromboembolic pulmonary hypertension; DVT; MD; MHLW; MR; Ministry of Health, Labor and Welfare; PAH; PE; PEA; PH; PVR; Ppa; Pulmonary endarterectomy; RCT; SPECT; V/Q; balloon pulmonary angioplasty; chronic thromboembolic pulmonary hypertension; computed tomographic; computed tomographic pulmonary angiography; deep vein thrombosis; magnetic resonance; pulmonary arterial hypertension; pulmonary arterial pressure; pulmonary embolism; pulmonary endarterectomy; pulmonary hypertension; pulmonary vascular resistance; randomized controlled trial; single-photon emission computed tomography; ventilation/perfusion.
© 2013 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.