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。患者表现为呼吸困难、早期乏力及运动耐量下降。一旦发生梗阻，会伴随肺动脉分支重构，进而引发肺动脉高压，最终导致右心室（right ventricular, RV）功能障碍，甚至右心衰竭[1]。美国心脏协会给出Ⅰ类推荐：即便患者症状轻微，也应及时评估是否适合行肺动脉内膜剥脱术治疗CTEPH[1]。肺动脉血栓内膜剥脱术是治疗CTEPH的潜在根治性手术。据估算，急性肺栓塞（acute pulmonary embolism, PE）幸存者中CTEPH的发病率为1%~5%[2]。然而，初次确诊PE时所做的超声心动图与计算机断层扫描（computed tomography, CT）诊断数据显示，多数CTEPH患者存在未被诊断的肺动脉高压，这提示CTEPH的首次临床表现可能为急性PE[3]。除肺栓塞外，高凝状态也可能是该病的病因。

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该病，且疗效相对有限[4]。手术是CTEPH唯一的确定性治疗手段，其中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，以门诊患者身份就诊，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检查与胸部X线检查。多次经胸超声心动图检查显示其右心室功能呈进行性下降。本次就诊时，患者因右心室重度扩张且功能异常前往心脏外科就诊。此前患者已接受利尿剂与血管扩张剂治疗，但症状仅获得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扫描图像显示患者右心室扩张，且下腔静脉内可见对比剂反流（图1~图4）。血栓起源于主肺动脉，几乎完全闭塞管腔，并向双侧肺动脉延伸。

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