远端残留裂口对主动脉夹层术后远期不良重塑的血液动力学机制研究

The initial therapy of aortic dissection patients is sealing the initial entry tear to induce the thrombosis of false lumen, whereas the distal tears tend to be left untreated. Many patients with distal intimal tears after proximal repair remained stable. However, some developed distal segmental aortic enlargement (DSAE) during follow-up, even aortic rupture and sudden death. There is no clear understanding in poor aortic remodeling after proximal repair. What's the risk of distal remainied tears for poor aortic remodeling? According to our research, the independent risk factors of DSAE are listed as follow: more tears in the thoracic descending aorta; fewer tears in the infra-renal abdominal aorta; closer distance of the first intimal tear to the left subclavian artery; larger average distance between tears; larger maximum distance between two tears, and larger area of remained tears. However, the underlying mechanisms are not clear. The present study focuses on computer simulation technique and animal experiments by exploring the hemodynamics features of remained distal tears to the aortic dissection. This study aims to reveal the hemodynamics of remained distal tears acting on poor aortic remodeling afer proximal repair for aortic dissection, which may have great clinical potential.

目前主动脉夹层治疗的主要方式是隔绝近端裂口，促使假腔血栓，而其远端裂口通常旷置。部分远端裂口存在的患者并没有发生远端扩张，但是，有不少患者随访期间出现术后主动脉远端扩张，甚至破裂、死亡。目前尚无研究明确夹层患者术后主动脉不良重塑的原因。那么远端残留裂口对于术后远期不良重塑有多大贡献？本研究前期在临床观察中，发现术后胸降主动脉的裂口数目越多、肾下腹主动脉的裂口数目越少、术后第一个裂口的位置越近、术后裂口的面积越大、术后裂口间距越大是夹层术后远端扩张的独立危险因素，其发生发展的生物力学机制亟需研究。因此，本研究拟从血液动力学原理入手，应用计算机模拟研究，结合动物实验，揭示残留远端裂口对主动脉夹层术后远期不良重塑的机制，明确其破坏远端旷置夹层稳态的原理，从而为不同的治疗方法提供参考数据，为提高主动脉夹层治疗水平提供理论依据。

目前主动脉夹层治疗的主要方式是隔绝近端裂口，促使假腔血栓，而其远端裂口通常旷置。部分远端裂口存在的患者并没有发生远端扩张，但是，有不少患者随访期间出现术后主动脉远端扩张，甚至破裂、死亡。目前尚无研究明确夹层患者术后主动脉不良重塑的原因。而远端残留裂口对于术后远期不良重塑有多大贡献呢？本研究发现夹层治疗成功的患者，术后远端主动脉扩张的发生率并不低（15.63%），通过COX和K-M曲线分析发现术后胸降主动脉的裂口数目越多、肾下腹主动脉的裂口数目越少、术后第一个裂口的位置越近、术后裂口的面积越大、术后裂口间距越大是夹层术后远端扩张的独立危险因素，进行分层分析其结果依然稳定。进一步构建猪主动脉夹层模型，建模成功16头，通过超声和CT评估实验动物，近端裂口处血流信号呈红色为主，提示血液自真腔流入假腔，平均流速127.50±6.74m/s，远端裂口处血流信号以蓝色为主，提示血液自假腔返回真腔，平均流速48.75±7.19m/s，并用患者CTA建立血液动力学模型，分析血流速度、TAWSS、OSI和RRT的分布情况。本研究揭示了残留远端裂口对主动脉夹层术后远期不良重塑的机制，明确其破坏远端旷置夹层稳态的原理，从而为不同的治疗方法提供参考数据，为提高主动脉夹层治疗水平提供新思路、新策略。