≥5cm 与 <5cm 升主动脉瘤患者的壁面应力分析。
Wall stress analyses in patients with ≥5 cm versus <5 cm ascending thoracic aortic aneurysm.
机构信息
Department of Surgery, University of California San Francisco and San Francisco Veterans Affairs Medical Centers, San Francisco, Calif.
Department of Radiology, University of California San Francisco and San Francisco Veterans Affairs Medical Centers, San Francisco, Calif.
出版信息
J Thorac Cardiovasc Surg. 2021 Nov;162(5):1452-1459. doi: 10.1016/j.jtcvs.2020.02.046. Epub 2020 Feb 19.
OBJECTIVE
Current guidelines for elective surgery of ascending thoracic aortic aneurysms (aTAAs) use aneurysm size as primary determinant for risk stratification of adverse events. Biomechanically, dissection may occur when wall stress exceeds wall strength. Determining patient-specific aTAA wall stresses by finite element analysis can potentially predict patient-specific risk of dissection. This study compared peak wall stresses in patients with ≥5.0 cm versus <5.0 cm aTAAs to determine correlation between diameter and wall stress.
METHODS
Patients with aTAA ≥5.0 cm (n = 47) and <5.0 cm (n = 53) were studied. Patient-specific aneurysm geometries obtained from echocardiogram-gated computed tomography were meshed and prestress geometries determined. Peak wall stresses and stress distributions were determined using LS-DYNA finite element analysis software (LSTC Inc, Livermore, Calif), with user-defined fiber-embedded material models under systolic pressure.
RESULTS
Peak circumferential stresses at systolic pressure were 530 ± 83 kPa for aTAA ≥5.0 cm versus 486 ± 87 kPa for aTAA <5.0 cm (P = .07), whereas peak longitudinal stresses were 331 ± 57 kPa versus 310 ± 54 kPa (P = .08), respectively. For aTAA ≥5.0 cm, correlation between peak circumferential stresses and size was 0.41, whereas correlation between peak longitudinal wall stresses and size was 0.33. However, for aTAA <5.0 cm, correlation between peak circumferential stresses and size was 0.23, whereas correlation between peak longitudinal stresses and size was 0.14.
CONCLUSIONS
Peak patient-specific aTAA wall stresses overall were larger for ≥5.0 cm than aTAA <5.0 cm. Although some correlation between size and peak wall stresses was found in aTAA ≥5.0 cm, poor correlation existed between size and peak wall stresses in aTAA <5.0 cm. Patient-specific wall stresses are particularly important in determining patient-specific risk of dissection for aTAA <5.0 cm.
目的
目前，择期升主动脉瘤（aTAA）手术的指南将瘤体大小作为预测不良事件风险的主要决定因素。从生物力学的角度来看，当壁应力超过壁强度时，可能会发生夹层。通过有限元分析确定患者特定的 aTAA 壁应力，有可能预测患者特定的夹层风险。本研究比较了直径≥5.0cm 和<5.0cm 的 aTAA 患者的峰值壁应力，以确定直径与壁应力之间的相关性。
方法
研究了直径≥5.0cm（n=47）和<5.0cm（n=53）的 aTAA 患者。从超声心动图门控计算机断层扫描获得的患者特定的动脉瘤几何形状被网格化，并确定了预应力度量。使用 LS-DYNA 有限元分析软件（LSTC Inc，加利福尼亚州利弗莫尔），根据用户定义的纤维嵌入材料模型，在收缩压下确定峰值壁应力和应力分布。
结果
收缩压时，aTAA≥5.0cm 的峰值周向应力为 530±83kPa，aTAA<5.0cm 的峰值周向应力为 486±87kPa（P=0.07），而 aTAA≥5.0cm 的峰值纵向应力为 331±57kPa，aTAA<5.0cm 的峰值纵向应力为 310±54kPa（P=0.08）。对于 aTAA≥5.0cm，峰值周向应力与尺寸之间的相关性为 0.41，而峰值纵向壁应力与尺寸之间的相关性为 0.33。然而，对于 aTAA<5.0cm，峰值周向应力与尺寸之间的相关性为 0.23，而峰值纵向应力与尺寸之间的相关性为 0.14。
结论
总体而言，直径≥5.0cm 的患者特定的 aTAA 壁峰值应力大于直径<5.0cm 的 aTAA。虽然在 aTAA≥5.0cm 中发现了尺寸与峰值壁应力之间的一些相关性，但在 aTAA<5.0cm 中，尺寸与峰值壁应力之间的相关性较差。患者特定的壁应力对于确定 aTAA<5.0cm 的患者特定的夹层风险特别重要。
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