Background: Pulmonary vascular resistance (PVR) and compliance are comparable in proximal and distal chronic thromboembolic pulmonary hypertension (CTEPH). However, proximal CTEPH is associated with inferior right ventricular (RV) adaptation. Early wave reflection in proximal CTEPH may be responsible for altered RV function. The aims of the study are 1) investigate whether reflected pressure returns sooner in proximal than in distal CTEPH, and 2) elucidate whether timing of reflected pressure is related to RV dimensions, ejection fraction (RVEF), hypertrophy and wall stress. Methods: Right heart catheterization and cardiac MRI were performed in 17 patients with proximal and 17 patients with distal CTEPH. In addition to determination of PVR, compliance and characteristic impedance, wave separation analysis was performed to determine the magnitude and timing of the peak reflected pressure (as % of systole). Findings were related to RV dimensions and time-resolved RV wall stress. Results: Proximal CTEPH was characterized by higher RV volumes, mass and wall stress, and lower RVEF. While PVR, compliance and characteristic impedance were similar, proximal CTEPH was related to an earlier return of reflected pressure than distal CTEPH (proximal 53±8% vs. distal 63±15%, P<0.05). The magnitude of the reflected pressure waves did not differ. RV volumes, RVEF, RV mass and wall stress were all related to the timing of peak reflected pressure. Conclusions: Poor RV function in patients with proximal CTEPH is related to an early return of reflected pressure wave. PVR, compliance and characteristic impedance do not explain differences in RV function between proximal and distal CTEPH.

中文翻译：

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在慢性血栓栓塞性肺动脉高压中，反射波的早期返回会增加右心室壁应力

背景：在近端和远端慢性血栓栓塞性肺动脉高压（CTEPH）中，肺血管阻力（PVR）和顺应性相当。但是，近端CTEPH与右下室（RV）适应有关。近端CTEPH中的早期波反射可能是RV功能改变的原因。该研究的目的是：1）研究反射压力是否比近端CTEPH更早返回，以及2）阐明反射压力的时间是否与RV尺寸，射血分数（RVEF），肥大和壁应力有关。方法：对17例近端CTEPH和17例远端CTEPH患者进行了右心导管检查和心脏MRI检查。除了确定PVR，一致性和特征阻抗外，进行波分离分析以确定峰值反射压力的大小和时间（以收缩压的百分比表示）。研究结果与RV尺寸和时间分辨的RV壁应力有关。结果：近端CTEPH的特征是RV体积更大，质量和壁应力更大，RVEF更低。尽管PVR，顺应性和特征阻抗相似，但近端CTEPH与远端CTEPH较早的反射压力恢复有关（近端53±8％与远端63±15％，P <0.05）。反射压力波的大小没有变化。RV容积，RVEF，RV质量和壁应力均与峰值反射压力的时间有关。结论：CTEPH近端患者右室功能不佳与反射压力波的早期恢复有关。PVR，