Chronic Thromboembolic Pulmonary Hypertension

Abstract

C hronic thromboembolic pulmonary hypertension (CTEPH) has emerged as one of the leading causes of severe pulmonary hypertension. The disease is notoriously underdiagnosed, and the true prevalence is still unclear. CTEPH is characterized by intraluminal thrombus organization and fibrous stenosis or complete obliteration of pulmonary arteries. 1 The consequence is an increased pulmonary vascular resistance resulting in pulmonary hypertension and progressive right heart failure. Vascular disobliteration by pulmonary endarterectomy (PEA) is the preferred treatment for patients with CTEPH, 2 but not all patients are eligible for surgery. Recent research has provided evidence suggesting that the mechanistic view of CTEPH as a disease caused solely by obliteration of central pulmonary arteries due to organized thrombi may have been too simplistic. Pulmonary embolism, either as a single episode or as recurrent episodes, is thought to be the initiating event followed by progressive pulmonary vascular remodeling. This concept explains the clinical observation that CTEPH patients may have severe pulmonary hypertension out of proportion to the pulmonary vascular obliteration seen on a pulmonary angiogram. Thus, treatment of CTEPH often requires a multidisciplinary approach and may involve surgery, medical treatment, or both. However, many aspects of the pathogenesis of CTEPH are poorly understood, the diagnostic approach to these patients has not been standardized, and neither randomized controlled trials nor guidelines have been published in this field.In July 2005, a group of international experts met in Zurich, Switzerland, for a comprehensive discussion of CTEPH. The members of this group are listed in the Appendix (in the online-only Data Supplement). This report will review the issues surrounding CTEPH that were discussed during that meeting: its etiology and pathogenesis, epidemiology, diagnosis, treatment options, and associated prognosis. Current issues, including challenges in assessing surgical candidacy and predicting postoperative outcome, will be introduced. Finally, potential ways of resolving uncertain and controversial issues, such as the role of medical therapy and the requirement for randomized controlled trials, will be discussed. Algorithms for the diagnosis and management of CTEPH will be proposed. EpidemiologyThe true incidence and prevalence of CTEPH are unknown. Originally, it was believed that 0.1% to 0.5% of patients who survive an episode of acute pulmonary embolism develop CTEPH. [3][4][5] However, in a prospective follow-up study of 78 survivors of acute pulmonary embolism, echocardiographic findings suggestive of persistent pulmonary hypertension and/or right ventricular dysfunction were present in 44% of the patients after 1 year. 6 Four patients (5.1%) developed definite CTEPH, and 3 of these subsequently underwent successful PEA. The only identifiable risk factors for persistent pulmonary hypertension were an age Ͼ70 years and a systolic pulmonary artery pressure Ͼ50 mm Hg at the initial p...

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“…1,2 Although the incidence of CTEPH is usually estimated to be <1% among patients with acute PE, [2][3][4] several studies have proposed that this low incidence was an underestimation and showed approximately 4%, a relatively high incidence of CTEPH after PE. [5][6][7] In addition, it has not been shown why some PE patients develop CTEPH and others do not.…”

“…The observation that the majority of acute PE patients do not go on to develop CTEPH suggests that there are actually other factors that are important in the development CTEPH. 2 Therefore, it is important to determine the possible risk factors and/or predictors for the CTEPH in patients with PE in order to decrease the morbidity and mortality of CTEPH.…”

Sequential Hybrid Therapy With Pulmonary Endarterectomy and Additional Balloon Pulmonary Angioplasty for Chronic Thromboembolic Pulmonary Hypertension

“…Chronic thromboembolic pulmonary hypertension (CTEPH) is characterized by stenoses and obstruction of the pulmonary arteries caused by organized thrombus 1, 2, 3, 4, 5. Without being treated, the prognosis is so poor that a 5‐year survival rate in patients with a mean pulmonary artery pressure (mPAP) >50 mm Hg is 10% 6.…”

Contrast‐enhanced multidetector‐row computed tomography vs. Time‐resolved magnetic resonance angiography vs. contrast‐enhanced perfusion MRI: Assessment of treatment response by patients with inoperable chronic thromboembolic pulmonary hypertension

“…CTEPH is related to an increase in the resistance to flow through the pulmonary arteries, which results initially from obstruction of pulmonary arterial vessels from main to subsegmental levels by analyzed thromboembolic materials, and subsequently from vascular remodeling in small unobstructed vessels. Previous studies (43)(44)(45)(46)(47)(48)(49) have reported that improvement in conventional parameters such as CI, 6-MWD, mPAP, and/or PVR showed significant differences between the responder and nonresponder groups, and suggested their usefulness for disease severity assessment and/or treatment response evaluation for CTEPH patients in routine clinical practice. Our results for conventional parameters were comparable with those reported in the past literature for CTEPH patients undergoing drug therapy (43)(44)(45)(46)(47)(48)(49).…”

“…However, our results demonstrated that improvements in CTEPH MRA and PBF showed better correlation with conventional parameters than did improvements in RV/LV diameter ratio, CTEPH CTA , PBV, and MTT. According to several pharmacological reports (43)(44)(45)(46)(47)(48)(49), improvement due to drug therapy is theoretically observed at small vessels in the lung parenchyma and as improved lung peripheral perfusion. Although CTEPH CTA and CTEPH MRA can both qualitatively assess lung parenchyma perfusion, CTEPH MRA is more affected by lung parenchyma perfusion changes than CTEPH CTA because it shows a reduction in perfusion as well as clots in the pulmonary artery.…”