BACKGROUND Pulmonary endarterectomy (PEA) is the gold standard treatment for patients with operable chronic thromboembolic pulmonary hypertension. However, persistent pulmonary hypertension (PH) after PEA remains a major determinant of poor prognosis. A concomitant small-vessel arteriopathy in addition to major pulmonary artery obstruction has been suggested to play an important role in the development of persistent PH and survival after PEA. One of the greatest unmet needs in the current preoperative evaluation is to assess the presence and severity of small-vessel arteriopathy. Using the pulmonary artery occlusion technique, we sought to assess the presence and degree of small-vessel disease in patients with chronic thromboembolic pulmonary hypertension undergoing PEA to predict postoperative outcome before surgery. METHODS Based on pulmonary artery occlusion waveforms yielding an estimate of the effective capillary pressure, we partitioned pulmonary vascular resistance in larger arterial (upstream resistance [Rup]) and small arterial plus venous components (downstream resistance) in 90 patients before PEA. For validation, lung wedge biopsies were taken from nonobstructed and obstructed lung territories during PEA in 49 cases. Biopsy sites were chosen according to the pulmonary angiogram still frames that were mounted in the operating room. All vessels per specimen were measured in each patient. Percent media (%MT; arteries) and intima thickness (%IT; arteries, veins, and indeterminate vessels) were calculated relative to external vessel diameter. RESULTS Decreased Rup was an independent predictor of persistent PH (odds ratio per 10%, 0.40 [95% CI, 0.23-0.69]; P=0.001) and survival (hazard ratio per 10%, 0.03 [95% CI, 0.00-0.33]; p=0.004). Arterial %MT and %IT of nonobstructed lung territories and venous %IT of obstructed lung territories were significantly increased in patients with persistent PH and nonsurvivors. Rup correlated inversely with %MT (r=-0.72, P<0.001) and %IT (r=-0.62, P<0.001) of arteries from nonobstructed lung territories and with %IT (r=-0.44, P=0.024) of veins from obstructed lung territories. Receiver operating characteristic analysis disclosed that Rup <66% predicted persistent PH after PEA, whereas Rup <60% identified patients with poor prognosis after PEA. CONCLUSIONS Pulmonary artery occlusion waveform analysis with estimation of Rup seems to be a valuable technique for assessing the degree of small-vessel disease and postoperative outcome after PEA in chronic thromboembolic pulmonary hypertension.

中文翻译：

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慢性血栓栓塞性肺动脉高压中的微血管疾病：血流动力学表型和组织形态计量学评估。

背景技术肺动脉内膜切除术（PEA）是可手术的慢性血栓栓塞性肺动脉高压患者的金标准治疗。然而，PEA后持续的肺动脉高压（PH）仍然是不良预后的主要决定因素。有人提出，除了严重的肺动脉阻塞外，还伴有小血管动脉病变，在PEA持续性PH的发展和生存中起着重要作用。当前术前评估中最大的未满足需求之一是评估小血管性动脉病的存在和严重程度。我们使用肺动脉闭塞技术，试图评估接受PEA的慢性血栓栓塞性肺动脉高压患者的小血管疾病的存在和程度，以预测手术前的术后结果。方法根据PEA前90例患者的肺动脉闭塞波形，估算有效毛细血管压力，我们将大动脉的肺血管阻力（上游阻力[Rup]）和小动脉加静脉成分（下游阻力）进行了划分。为验证有效性，在49例PEA期间，从非阻塞性肺和阻塞性肺区域进行了肺楔形活检。根据安装在手术室中的肺血管造影静止框架选择活检部位。在每个患者中测量每个标本的所有血管。相对于外部血管直径，计算了介质百分比（％MT；动脉）和内膜厚度（％IT；动脉，静脉和不确定的血管）。结果Rup的降低是持续性PH的独立预测因子（每10％的赔率，0.40 [95％CI，0.23-0。69]；P = 0.001）和生存率（每10％的危险比，0.03 [95％CI，0.00-0.33]； p = 0.004）。在患有持续性PH和非幸存者的患者中，非阻塞性​​肺区域的动脉％MT和％IT以及阻塞性肺区域的静脉％IT显着增加。Rup与来自非阻塞性肺区域的动脉的％MT（r = -0.72，P <0.001）和％IT（r = -0.62，P <0.001）呈负相关，与％IT（r = -0.44，P = 0.024）呈负相关肺部阻塞的静脉。接受者操作特征分析显示，Rup <66％预测PEA后持续PH，而Rup <60％则确定PEA后预后不良。