Chronic thromboembolic pulmonary hypertension (CTEPH) is caused by recurrent or unresolved pulmonary thromboemboli, leading to perfusion defects and increased arterial wave reflections. CTEPH treatment aims to reduce pulmonary arterial pressure and reestablish adequate lung perfusion, yet patients with distal lesions are inoperable by standard surgical intervention. Instead, these patients undergo balloon pulmonary angioplasty (BPA), a multi-session, minimally invasive surgery that disrupts the thromboembolic material within the vessel lumen using a catheter balloon. However, there still lacks an integrative, holistic tool for identifying optimal target lesions for treatment. To address this insufficiency, we simulate CTEPH hemodynamics and BPA therapy using a multiscale fluid dynamics model. The large pulmonary arterial geometry is derived from a computed tomography (CT) image, whereas a fractal tree represents the small vessels. We model ring- and web-like lesions, common in CTEPH, and simulate normotensive conditions and four CTEPH disease scenarios; the latter includes both large artery lesions and vascular remodeling. BPA therapy is simulated by simultaneously reducing lesion severity in three locations. Our predictions mimic severe CTEPH, manifested by an increase in mean proximal pulmonary arterial pressure above 20 mmHg and prominent wave reflections. Both flow and pressure decrease in vessels distal to the lesions and increase in unobstructed vascular regions. We use the main pulmonary artery (MPA) pressure, a wave reflection index, and a measure of flow heterogeneity to select optimal target lesions for BPA. In summary, this study provides a multiscale, image-to-hemodynamics pipeline for BPA therapy planning for inoperable CTEPH patients.

中文翻译：

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慢性血栓栓塞性肺动脉高压血管功能的多尺度模型

慢性血栓栓塞性肺动脉高压 (CTEPH) 是由复发性或未解决的肺血栓栓塞引起的，导致灌注缺陷和动脉波反射增加。CTEPH 治疗旨在降低肺动脉压并重建足够的肺灌注，但远端病变患者无法通过标准手术干预进行手术。相反，这些患者接受球囊肺血管成形术 (BPA)，这是一种多阶段的微创手术，使用导管球囊破坏血管腔内的血栓栓塞材料。然而，仍然缺乏一种综合的、整体的工具来确定治疗的最佳目标病变。为了解决这一不足，我们使用多尺度流体动力学模型模拟 CTEPH 血流动力学和 BPA 治疗。大肺动脉几何形状来自计算机断层扫描 (CT) 图像，而分形树代表小血管。我们对 CTEPH 中常见的环状和网状病变进行建模，并模拟正常血压条件和四种 CTEPH 疾病情景；后者包括大动脉病变和血管重塑。BPA 治疗是通过同时降低三个位置的病变严重程度来模拟的。我们的预测模拟了严重的 CTEPH，表现为平均近端肺动脉压升高至 20 mmHg 以上和明显的波反射。病变远端血管的流量和压力均降低，而畅通的血管区域则增加。我们使用主肺动脉 (MPA) 压力、波反射指数和流量异质性测量来选择 BPA 的最佳目标病变。总之，