In vivo analysis of mechanical wall stress and abdominal aortic aneurysm rupture risk
In vivo analysis of mechanical wall stress and abdominal aortic aneurysm rupture risk
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DOI：
10.1067/mva.2002.125478
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发表时间：
2002-09-01
影响因子：
4.3
通讯作者：
Kennedy, FE
中科院分区：
文献类型：
--
作者：
Fillinger, MF;Raghavan, ML;Kennedy, FE
目的：本研究的目的是计算腹主动脉瘤（AAA）壁应力在体内破裂，症状，择期修复AAA与三维计算机建模技术，计算机断层扫描数据，血压和比较壁应力与当前的临床指标相关的破裂risk.Methods：CT扫描分析了48例AAA患者：18例AAA破裂（n = 10）或因症状紧急修复（n = 8），30例AAA足够大，需要在CT扫描后12周内进行择期修复。根据CT扫描数据重建AAA的三维计算机模型。AAA上的应力分布是由几何形状和血压引起的，通过有限元分析计算确定，该有限元分析采用超弹性非线性模型描述AAA壁的力学行为。（AAA表面上的最大应力）组间差异显著（破裂，47.7 +/- 6 N/cm（2）;紧急症状，47.5 +/- 4 N/cm（2）;择期修复，36.9 +/- 2 N/cm（2）; F = 0.03），血压（P = 0.2）或AAA直径（P = 0.1）无显著差异。由于直径有差异的趋势，因此仅与直径匹配的受试者进行比较。即使平均直径相同，破裂/症状性AAA的峰值壁应力也显著更高（46.8 +/- 4.5 N/cm（2）vs 38.1 +/- 1.3 N/cm（2）; P = 0.05）。最大壁应力预测破裂风险优于拉普拉斯方程（20.7 +/- 5.7 N/cm（2）vs 18.8 +/- 2.9 N/cm（2）; P = .2）或其他建议的破裂风险指数。最小的破裂AAA为4.8厘米，但这个动脉瘤的应力相当于平均electively修复6.3厘米的AAA。结论：峰值壁应力计算在体内的AAA附近的时间破裂显着高于峰值应力electively修复AAA，即使匹配的最大直径。与AAA直径或其他先前提出的临床指标相比，通过计算机模拟AAA三维几何结构计算壁应力似乎更准确地评估破裂风险。应力分析具有实用性和可行性，可能成为评估AAA破裂风险的重要临床工具。
Objective: The purpose of this study was to calculate abdominal aortic aneurysm (AAA) wall stresses in vivo for ruptured, symptomatic, and electively repaired AAAs with three-dimensional computer modeling techniques, computed tomographic scan data, and blood pressure and to compare wall stress with current clinical indices related to rupture risk.Methods: CT scans were analyzed for 48 patients with AAAs: 18 AAAs that ruptured (n = 10) or were urgently repaired for symptoms (n = 8) and 30 AAAs large enough to merit elective repair within 12 weeks of the CT scan. Three-dimensional computer models of AAAs were reconstructed from CT scan data. The stress distribution on the AAA as a result of geometry and blood pressure was computationally determined with finite element analysis with a hyperelastic nonlinear model that depicted the mechanical behavior of the AAA wall.Results: Peak wall stress (maximal stress on the AAA surface) was significantly different between groups (ruptured, 47.7 +/- 6 N/cm(2); emergent symptomatic, 47.5 +/- 4 N/cm(2); elective repair, 36.9 +/- 2 N/cm(2); F = .03), with no significant difference in blood pressure (P = .2) or AAA diameter (P = .1). Because of trends toward differences in diameter, comparison was made only with diameter-matched subjects. Even with identical mean diameters, ruptured/symptomatic AAAs had a significantly higher peak wall stress (46.8 +/- 4.5 N/cm(2) versus 38.1 +/- 1.3 N/cm(2); P = .05). Maximal wall stress predicted risk of rupture better than the Laplace equation (20.7 +/- 5.7 N/cm(2) versus 18.8 +/- 2.9 N/cm(2); P = .2) or other proposed indices of rupture risk. The smallest ruptured AAA was 4.8 cm, but this aneurysm had a stress equivalent to the average electively repaired 6.3-cm AAA.Conclusion: Peak wall stresses calculated in vivo for AAAs near the time of rupture were significantly higher than peak stresses for electively repaired AAAs, even when matched for maximal diameter. Calculation of wall stress with computer modeling of three-dimensional AAA geometry appears to assess rupture risk more accurately than AAA diameter or other previously proposed clinical indices. Stress analysis is practical and feasible and may become an important clinical tool for evaluation of AAA rupture risk.