Surgery for Chronic Thromboembolic Pulmonary Hypertension: Thromboendarterectomy of the Pulmonary Artery

<b>Introduction</b> Chronic thromboembolic pulmonary hypertension (CTEPH) is caused by proximal pulmonary artery thromboembolic occlusion or obstruction. Patients present with shortness of breath, early fatigue, and decreased exercise capacity. Once the obstruction sets in, it is accompanied by remodeling of the branches of the pulmonary artery. This causes pulmonary artery hypertension and subsequently leads to right ventricular (RV) dysfunction, which eventually leads to RV failure [1]. The American Heart Association makes a class 1 recommendation that indicates CTEPH should be promptly evaluated for pulmonary endarterectomy, even if symptoms are mild [1].Pulmonary thromboendarterectomy is a potentially curative surgery for CTEPH. The incidence is estimated to be between one and five percent among survivors of acute pulmonary embolism (PE) [2]. However, diagnostic data from echocardiography and computed tomography (CT) scans done when PE is first diagnosed suggest that many patients with CTEPH have undiagnosed pulmonary hypertension. This may indicate that the first clinical presentation of CTEPH may present as acute PE [3]. Apart from pulmonary embolism, hypercoagulable states may be the etiology of this disease.<br> Medical therapy is aimed at lowering the resistance of and pressure in pulmonary vessels. This includes vasodilators and drugs inducing remodeling of the vessels. It does improve symptoms such as exercise intolerance and oxygen desaturation. Medical therapy is not curative, and its effects are relatively modest [4]. Surgery is the only definitive therapy for CTEPH, and pulmonary thromboendarterectomy is the surgical procedure of choice.<br> <b>Patient History</b> The authors present a case of CTEPH. The patient was a 35-year-old man presenting as an outpatient with complaints of severe progressive dyspnea. He was diagnosed with pulmonary embolism in the past and has been on anticoagulation for more than three years. He has had CT scans and chest x-rays in between. Multiple transthoracic echocardiograms have been performed with evidence of slowly declining right ventricular function. This time, he presented to the cardiac surgery service with a severely dilated and dysfunctional right ventricle. He had been on diuretics and vasodilator treatment but had mild to no improvement. After a thorough review, the authors decided to perform a pulmonary thromboembolectomy. The CT scan images show a dilated RV and intravenous contrast reflux in the inferior vena cava (Figures 1-4). The thrombus can be seen starting in the main pulmonary artery and almost completely occluding it. The thrombus extends into the bilateral pulmonary arteries.<br>Learn more: https://www.ctsnet.org/article/surgery-chronic-thromboembolic-pulmonary-hypertension-thromboendarterectomy-pulmonary-artery

<b>引言</b> 慢性血栓栓塞性肺动脉高压（Chronic thromboembolic pulmonary hypertension, CTEPH）由近端肺动脉血栓栓塞性闭塞或梗阻引发。患者临床表现为呼吸困难、早期疲劳及运动能力下降。一旦出现梗阻，将伴随肺动脉分支重构，进而导致肺动脉高压，随后引发右心室（right ventricular, RV）功能障碍，最终进展为右心衰竭[1]。美国心脏协会（American Heart Association）给出1类推荐，建议无论患者症状轻重，均应及时评估是否可行肺动脉内膜剥脱术（pulmonary endarterectomy）[1]。

肺动脉血栓内膜剥脱术（pulmonary thromboendarterectomy）是治疗CTEPH的潜在根治性手术。急性肺栓塞（acute pulmonary embolism, PE）幸存者中，该病的发病率估计为1%至5%[2]。但在首次诊断肺栓塞时完成的超声心动图与计算机断层扫描（computed tomography, CT）检查的诊断数据显示，多数CTEPH患者并未被检出肺动脉高压，这提示CTEPH的首次临床表现可能表现为急性肺栓塞[3]。除肺栓塞外，高凝状态也可能为该病的病因。

药物治疗旨在降低肺血管阻力与压力，涵盖血管扩张剂及诱导血管重构的药物，可改善运动耐量下降、血氧饱和度降低等症状。但药物治疗无法根治疾病，且疗效相对有限[4]。手术是CTEPH唯一的确定性治疗手段，肺动脉血栓内膜剥脱术为首选术式。

<b>患者病史</b> 本文作者报告1例CTEPH病例。患者为35岁男性，以门诊身份就诊，主诉为进行性重度呼吸困难。患者既往曾确诊肺栓塞，并接受了3年以上的抗凝治疗，期间多次接受CT扫描与胸部X线检查。多次经胸超声心动图（transthoracic echocardiograms）检查显示右心室功能缓慢减退。此次患者因右心室重度扩张伴功能障碍就诊于心脏外科。患者此前已接受利尿剂与血管扩张剂治疗，但症状仅获轻度改善甚至无改善。经全面评估后，作者决定为其实施肺动脉血栓内膜剥脱术。CT扫描图像显示右心室扩张，下腔静脉可见造影剂反流（图1至图4）。血栓起源于主肺动脉，几乎完全阻塞管腔，并向双侧肺动脉延伸。

Learn more: https://www.ctsnet.org/article/surgery-chronic-thromboembolic-pulmonary-hypertension-thromboendarterectomy-pulmonary-artery