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...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。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的通路。用40%甘油水溶液模拟血液,同时模拟心率为60/min,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(VTI:19.39±5.88 vs 9.89±3.41,P=0.013),对于远端破口血液先流出后流入,以流出为主(VTI:22.61±11.81 vs 7.67±3.26,P=0.024)。A2组减小近端破口直径,发现其VTI比值(破口血流方向发生改变后的VTI与整个周期VTI的比值)减小(33.70%±4.22%vs 51.00%±4.80%,P=0.046),远端破口VTI比值无统计学差异。A3组减小远端破口直径,发现其VTI比值减小(30.10%±7.75%vs 15.30%±3.19%,P=0.045),且血流变化时间RT变长[(0.54±0.08) s vs (0.71±0.01) s,P=0.023]。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64.19%±5.30%。近端破口流入假腔的血流量与从中间和远端破口流出假腔的血流量无统计学差异(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比值增加(36.39%±5.84%vs 87.00%±5.66%,P<0.001),RT反流时间减少[(0.27±0.06) s vs (0.21±0.04) s,P=0.341]。B3组中放置支架封堵近端第一破口后,中间破口VTI比值减小(36.39%±5.84%vs 16.61%±0.86%,P=0.004)。结论 破口数量、直径以及置入支架与否均会影响多破口TBAD不同破口的血流方向和血流量等参数,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。展开更多
主动脉夹层(AD)是一种死亡率很高的致命性心血管疾病。目前,计算机断层扫描(CT)成像是诊断和评估主动脉疾病的主要方式,提供血管结构的详细可视化。然而,CT成像在评估主动脉内血流动力学变化方面存在局限性。最近,计算流体动力学(CFD)...主动脉夹层(AD)是一种死亡率很高的致命性心血管疾病。目前,计算机断层扫描(CT)成像是诊断和评估主动脉疾病的主要方式,提供血管结构的详细可视化。然而,CT成像在评估主动脉内血流动力学变化方面存在局限性。最近,计算流体动力学(CFD)作为一种先进的无创技术出现,可以实现血管内血流动力学状况的可视化。这项技术为临床医生提供了对主动脉疾病更全面的了解,有助于改进诊断、治疗计划和预后评估。本研究中,先模拟了一例直管的血流,将出口压力与解析解比较,结果吻合良好,验证了数值模拟的准确性。然后,模拟了一例AD的血流,并定量和定性分析收缩期和舒张期AD的压力和壁剪切应力(WSS)。结果表明,AD真腔和假腔的压差可促进主动脉壁内膜破裂,形成夹层,过低的壁面剪切力可增强血流对主动脉壁的撕裂作用,促进夹层的形成,这为今后AD的研究和临床实践提供参考。Aortic dissection (AD) is a fatal cardiovascular disease with a high mortality rate. Currently, computed tomography (CT) imaging is the primary modality for diagnosing and evaluating aortic diseases, providing detailed visualization of vascular structures. However, CT imaging has limitations in assessing the hemodynamic changes within the aorta. Recently, computational fluid dynamics (CFD) has emerged as an advanced noninvasive technique that enables the visualization of hemodynamic conditions within blood vessels. This technology provides clinicians with a more comprehensive understanding of aortic disease, facilitating improved diagnosis, treatment planning, and prognosis assessment. In this study, the blood flow of a straight tube was simulated first, and the outlet pressure was compared with the analytical solution. The results were in well agreement, which verified the accuracy of the numerical simulation. Then, we simulated the blood flow of an AD and analyzed the pressure and wall shear stress (WSS) during systolic and diastolic. The results suggest that the pressure difference between the true and false cavities may trigger intimal rupture and dissection formation, and low WSS may increase aortic wall tearing and promote dissection, which provides valuable insights for future research and clinical practice of AD.展开更多
文摘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。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的通路。用40%甘油水溶液模拟血液,同时模拟心率为60/min,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(VTI:19.39±5.88 vs 9.89±3.41,P=0.013),对于远端破口血液先流出后流入,以流出为主(VTI:22.61±11.81 vs 7.67±3.26,P=0.024)。A2组减小近端破口直径,发现其VTI比值(破口血流方向发生改变后的VTI与整个周期VTI的比值)减小(33.70%±4.22%vs 51.00%±4.80%,P=0.046),远端破口VTI比值无统计学差异。A3组减小远端破口直径,发现其VTI比值减小(30.10%±7.75%vs 15.30%±3.19%,P=0.045),且血流变化时间RT变长[(0.54±0.08) s vs (0.71±0.01) s,P=0.023]。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64.19%±5.30%。近端破口流入假腔的血流量与从中间和远端破口流出假腔的血流量无统计学差异(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比值增加(36.39%±5.84%vs 87.00%±5.66%,P<0.001),RT反流时间减少[(0.27±0.06) s vs (0.21±0.04) s,P=0.341]。B3组中放置支架封堵近端第一破口后,中间破口VTI比值减小(36.39%±5.84%vs 16.61%±0.86%,P=0.004)。结论 破口数量、直径以及置入支架与否均会影响多破口TBAD不同破口的血流方向和血流量等参数,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。
文摘主动脉夹层(AD)是一种死亡率很高的致命性心血管疾病。目前,计算机断层扫描(CT)成像是诊断和评估主动脉疾病的主要方式,提供血管结构的详细可视化。然而,CT成像在评估主动脉内血流动力学变化方面存在局限性。最近,计算流体动力学(CFD)作为一种先进的无创技术出现,可以实现血管内血流动力学状况的可视化。这项技术为临床医生提供了对主动脉疾病更全面的了解,有助于改进诊断、治疗计划和预后评估。本研究中,先模拟了一例直管的血流,将出口压力与解析解比较,结果吻合良好,验证了数值模拟的准确性。然后,模拟了一例AD的血流,并定量和定性分析收缩期和舒张期AD的压力和壁剪切应力(WSS)。结果表明,AD真腔和假腔的压差可促进主动脉壁内膜破裂,形成夹层,过低的壁面剪切力可增强血流对主动脉壁的撕裂作用,促进夹层的形成,这为今后AD的研究和临床实践提供参考。Aortic dissection (AD) is a fatal cardiovascular disease with a high mortality rate. Currently, computed tomography (CT) imaging is the primary modality for diagnosing and evaluating aortic diseases, providing detailed visualization of vascular structures. However, CT imaging has limitations in assessing the hemodynamic changes within the aorta. Recently, computational fluid dynamics (CFD) has emerged as an advanced noninvasive technique that enables the visualization of hemodynamic conditions within blood vessels. This technology provides clinicians with a more comprehensive understanding of aortic disease, facilitating improved diagnosis, treatment planning, and prognosis assessment. In this study, the blood flow of a straight tube was simulated first, and the outlet pressure was compared with the analytical solution. The results were in well agreement, which verified the accuracy of the numerical simulation. Then, we simulated the blood flow of an AD and analyzed the pressure and wall shear stress (WSS) during systolic and diastolic. The results suggest that the pressure difference between the true and false cavities may trigger intimal rupture and dissection formation, and low WSS may increase aortic wall tearing and promote dissection, which provides valuable insights for future research and clinical practice of AD.
