Tissue Mechanics Laboratory, The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA.
Department of Computer Science, University of Miami, Coral Gables, FL, USA.
Interact Cardiovasc Thorac Surg. 2022 Jun 1;34(6):1124-1131. doi: 10.1093/icvts/ivac004.
The study objective was to evaluate the aortic wall stress and root dilatation before and after the novel V-shape surgery for the treatment of ascending aortic aneurysms and root ectasia.
Clinical cardiac computed tomography images were obtained for 14 patients [median age, 65 years (range, 33-78); 10 (71%) males] who underwent the V-shape surgery. For 10 of the 14 patients, the computed tomography images of the whole aorta pre- and post-surgery were available, and finite element simulations were performed to obtain the stress distributions of the aortic wall at pre- and post-surgery states. For 6 of the 14 patients, the computed tomography images of the aortic root were available at 2 follow-up time points post-surgery (Post 1, within 4 months after surgery and Post 2, about 20-52 months from Post 1). We analysed the root dilatation post-surgery using change of the effective diameter of the root at the two time points and investigated the relationship between root wall stress and root dilatation.
The mean and peak max-principal stresses of the aortic root exhibit a significant reduction, P=0.002 between pre- and post-surgery for both root mean stress (median among the 10 patients presurgery, 285.46 kPa; post-surgery, 199.46 kPa) and root peak stress (median presurgery, 466.66 kPa; post-surgery, 342.40 kPa). The mean and peak max-principal stresses of the ascending aorta also decrease significantly from pre- to post-surgery, with P=0.004 for the mean value (median presurgery, 296.48 kPa; post-surgery, 183.87 kPa), and P=0.002 for the peak value (median presurgery, 449.73 kPa; post-surgery, 282.89 kPa), respectively. The aortic root diameter after the surgery has an average dilatation of 5.01% in total and 2.15%/year. Larger root stress results in larger root dilatation.
This study marks the first biomechanical analysis of the novel V-shape surgery. The study has demonstrated significant reduction in wall stress of the aortic root repaired by the surgery. The root was able to dilate mildly post-surgery. Wall stress could be a critical factor for the dilatation since larger root stress results in larger root dilatation. The dilated aortic root within 4 years after surgery is still much smaller than that of presurgery.
本研究旨在评估新型 V 形手术治疗升主动脉瘤和根部扩张的主动脉壁应力和根部扩张情况。
纳入 14 名（中位年龄 65 岁[范围 33-78]；10 名男性，占 71%）接受 V 形手术的患者，获取其临床心脏计算机断层扫描图像。对于 14 名患者中的 10 名，术前和术后的全主动脉计算机断层扫描图像均可用，通过有限元模拟获得术前和术后状态下主动脉壁的应力分布。对于 14 名患者中的 6 名，在术后 2 个随访时间点（术后 1 次，术后 4 个月内；术后 2 次，术后 1 次后约 20-52 个月）获得主动脉根部的计算机断层扫描图像。我们分析了术后根部扩张，比较了这两个时间点根部有效直径的变化，并研究了根部壁应力与根部扩张之间的关系。
主动脉根部的平均和峰值最大主应力在术前和术后均显著降低，P=0.002（10 名患者中，术前平均根部应力中位数为 285.46kPa，术后为 199.46kPa；术前峰值根部应力中位数为 466.66kPa，术后为 342.40kPa）。升主动脉的平均和峰值最大主应力也从术前到术后显著降低，P=0.004（平均峰值术前为 296.48kPa，术后为 183.87kPa），P=0.002（峰值术前为 449.73kPa，术后为 282.89kPa）。术后主动脉根部直径平均扩张 5.01%，每年扩张 2.15%。较大的根部应力导致较大的根部扩张。
本研究是对新型 V 形手术的首次生物力学分析。研究表明，手术修复的主动脉根部壁应力显著降低。术后根部可轻度扩张。根部应力可能是扩张的关键因素，因为较大的根部应力会导致较大的根部扩张。术后 4 年内扩张的主动脉根部仍然明显小于术前。
