员鹏飞, 贾贺月, 王双静, 吴明炜, 熊江. 基于体外猪主动脉的多破口B型主动脉夹层模型研究[J]. 解放军医学院学报. DOI: 10.12435/j.issn.2095-5227.2024.079
引用本文: 员鹏飞, 贾贺月, 王双静, 吴明炜, 熊江. 基于体外猪主动脉的多破口B型主动脉夹层模型研究[J]. 解放军医学院学报. DOI: 10.12435/j.issn.2095-5227.2024.079
Yuan Pengfei, Jia Heyue, Wang Shuangjing, Wu Mingwei, Xiong Jiang. Study on Multi-entry Type B Aortic Dissection Model Based on Ex-vivo Porcine Aorta[J]. ACADEMIC JOURNAL OF CHINESE PLA MEDICAL SCHOOL. DOI: 10.12435/j.issn.2095-5227.2024.079
Citation: Yuan Pengfei, Jia Heyue, Wang Shuangjing, Wu Mingwei, Xiong Jiang. Study on Multi-entry Type B Aortic Dissection Model Based on Ex-vivo Porcine Aorta[J]. ACADEMIC JOURNAL OF CHINESE PLA MEDICAL SCHOOL. DOI: 10.12435/j.issn.2095-5227.2024.079

基于体外猪主动脉的多破口B型主动脉夹层模型研究

Study on Multi-entry Type B Aortic Dissection Model Based on Ex-vivo Porcine Aorta

  • 摘要:
    背景  目前缺乏从血流动力学角度分析主动脉内膜破口数量对B型主动脉夹层(type B aortic dissection,TBAD)影响的研究。
    目的  通过构建两破口和三破口的离体猪TBAD模型,分析不同数量破口对TBAD进展的影响。
    方法  获取成年猪主动脉,处理后使内膜外露,使用特殊刮板分离内膜和中膜形成夹层,控制夹层长度为20 cm,用手术刀在内膜制造不同破口,再次将动脉内外膜位置反转,以此分别构建两破口和三破口TBAD模型。其中两破口模型为A组:A1两破口直径相同,A2近端破口直径较小,A3远端破口直径较小;三破口模型为B组:B1三个破口直径相同,B2中间破口直径较小,B3支架封堵近端第一破口。模拟循环通路(mock circulation loop,MCL)是由控制系统、脉冲泵、单向阀、储液罐等组成来模仿人体循环通路。用40%甘油水溶液模拟血液,同时模拟心率为60 bpm,尼龙颗粒作为超声造影剂。将构建完成的模型与MCL相结合,就可以模拟真实TBAD患者的血流状态。通过多普勒超声测量各破口处的血流动力学参数,得到血流方向改变时间(reflux Time,RT)和时间流速积分(velocity-time integral,VTI),描述TBAD破口的血流变化。
    结果  A1组中,近端破口的血液先流入假腔后流出,以流入为主(19.4% vs 9.9%,P=0.013),对于远端破口血液先流出后流入,以流出为主(22.6% vs 7.6%,P=0.024)。A2组减小近端破口直径,发现其VTI rate减小(33.7% vs 51.0%, P=0.046),远端破口VTI rate无明显差异。A3组减小远端破口直径,发现其VTI rate减小(30.1% vs 15.3%, P=0.045),且血流变化时间RT变长(0.54s vs 0.71s)。B1组发现,在收缩期血液会通过中间破口从真腔流入假腔,在舒张期血液从假腔流入真腔,其中从假腔流入真腔的血流量占整个心动周期的64% ± 5.3%。近端破口流入假腔的血流量和从中间和远端破口流出假腔的血流量无差异(VTI:22.68 ± 6.76 vs 22.89 ± 7.69,P=0.800)。B2组减小中间破口直径,其VTI rate增加(36.4% vs 85.5%, P=0.000),RT反流时间会减少(0.27s vs 0.21s, P=0.341)。B3组中放置支架封堵近端第一破口后,中间破口VTI rate减小(36.4% vs 16.6%, P=0.004)。
    结论  破口数量、直径以及植入支架与否都会影响多破口TBAD不同破口的血流方向,血流量等参数,导致其对夹层进展的影响不同,临床上应针对不同破口的血流特点来制定治疗策略,以达到更好的预后。

     

    Abstract:
    Background  The number of entry tears impacts the development and prognosis of Type B Aortic Dissection (TBAD). This study aims to analyze the influence of different entry tear on the occurrence and progression of TBAD by constructing and comparing flow parameters at each entry in two-entry and three-entry porcine TBAD models, thereby illustrating changes in blood flow direction and volume.
    Methods  Adult porcine aortas were acquired and processed to expose the intima. A special scraper was used to separate the intima and media to create a dissection, with the length of the dissection controlled at 20cm. Subsequently, surgical knives were used to create different tears in the intima. The artery was then flipped again to construct models of TBAD with either two or three entry tears. Among them, the two-entry models are categorized as Group A: A1 with two entry tears of the same diameter, A2 with a smaller proximal entry tear, A3 with a smaller distal entry tear; the three-entry models are categorized as Group B: B1 with three entry tears of the same size, B2 with a smaller middle entry tear, B3 with the first proximal entry tear sealed by a stent graft. The mock circulation loop (MCL) consists of a control system, pulsatile pump, one-way valves, and a reservoir tank to mimic the human circulatory system. A 40% glycerol water solution was used to simulate blood, with a simulated heart rate of 60 bpm, and nylon particles served as ultrasound contrast agents. By integrating the completed model with the MCL, it is possible to simulate the blood flow condition of real TBAD patients. Doppler ultrasound measurements were conducted to assess blood flow variations at each entry and obtain hemodynamic parameters such as blood flow velocity.
    Results  In three-entry TBAD, there were no changes in blood flow direction at the proximal and distal entry tears, but characteristic alterations were observed in the intimal flap and blood flow at the middle entry tear. During the systolic phase, blood flowed from the true lumen into the false lumen (36% ± 5.3%), while during diastole, blood moved fro0.m false lumen into true lumen, with a flow reversal time of 0.27 ± 0.058 seconds. The majority of blood, approximately 64% ± 5.3%, flowed from false lumen into true lumen, and there was a statistically significant difference in flow volumes between inflow and outflow from false lumen (7.1 vs 13.2, P < 0.05). The blood flow volume entering false lumen from the proximal tear and exiting false lumen through the middle and distal tears showed no difference (VTI: 22.68 ± 6.76 vs 22.89 ± 7.69, P=0.800). In two-entry TBAD, at the proximal entry tear, blood initially entered false lumen before exiting, with inflow dominating (19.4 vs 9.9, P < 0.05). For the distal entry tear, blood initially exited before entering, with outflow dominating (22.6 vs 7.6, P < 0.05). There is no difference in the blood flow volume entering false lumen from the proximal tear and exiting false lumen from the distal tear (VTI: 9.50 ± 3.44 vs 14.93 ± 11.43, P=0.254). Additionally, changes in blood flow direction occurred earlier at the proximal entry tear (0.52 s vs 0.62 s, P < 0.05).
    Conclusion  In cases of two-entry tear TBAD, reducing the diameter of the proximal entry tear, which serves as the inflow pathway, will decrease the blood flow into the false lumen. Conversely, reducing the diameter of the distal entry tear, which serves as the outflow pathway, will increase blood flow into the false lumen, potentially increasing the risk of disease progression. In three-entry tear TBAD, lowering systolic pressure may have the potential to reduce the blood flow through the mid-entry tear into the false lumen, subsequently reducing the pressure within the false lumen. This could slow down the progression of acute TBAD and the rate of arterial dilation. However, this theory requires further experimental and clinical validation.

     

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