Takaya Hiroki, Masuda Shinya, Naganuma Masaaki, Yoshioka Ichiro, Takahashi Goro, Akiyama Masatoshi, Adachi Osamu, Kumagai Kiichiro, Sugita Shukei, Saiki Yoshikatsu
Division of Cardiovascular Surgery, Tohoku University Graduate School of Medicine, 1-1 Seiryocho, Aoba-ku, Sendai, Miyagi, 980-8575, Japan.
Research Division of Sciences for Aortic Disease, Tohoku University Graduate School of Medicine, Sendai, Japan.
Gen Thorac Cardiovasc Surg. 2018 Sep;66(9):523-528. doi: 10.1007/s11748-018-0959-1. Epub 2018 Jun 28.
Stentless bioprosthetic valves provide hemodynamic advantages over stented valves as well as excellent durability. However, some primary tissue failures in bioprostheses have been reported. This study was conducted to evaluate the morphometrical and biomechanical properties of the stentless Medtronic Freestyle™ aortic root bioprosthesis, to identify any arising problem areas, and to speculate on a potential solution.
The three-dimensional heterogeneity of the stentless bioprosthesis wall was investigated using computed tomography. The ascending aorta and the right, left, and non-coronary sinuses of Valsalva were resected and examined by an indentation test to evaluate their biomechanical properties.
The non-coronary sinus of Valsalva was significantly thinner than the right sinus of Valsalva (p < 0.01). Young's modulus, calculated as an indicator of elasticity, was significantly greater at the non-coronary sinus of Valsalva (430.7 ± 374.2 kPa) than at either the left (190.6 ± 70.6 kPa, p < 0.01) or right sinuses of Valsalva (240.0 ± 56.5 kPa, p < 0.05).
Based on the morphometrical and biomechanical analyses of the stentless bioprosthesis, we demonstrated that there are differences in wall thickness and elasticity between each sinus of Valsalva. These differences suggest that the non-coronary sinus of Valsalva is the most vulnerable and at greater risk of tissue failure. The exclusion of the non-coronary sinus of Valsalva may be beneficial to mitigate the long-term risks of tissue failure in the stentless bioprosthesis.
无支架生物瓣膜相比有支架瓣膜具有血流动力学优势以及出色的耐用性。然而，已有报道称生物瓣膜存在一些原发性组织故障。本研究旨在评估无支架美敦力Freestyle™主动脉根部生物瓣膜的形态测量和生物力学特性，识别任何出现问题的区域，并推测一种潜在的解决方案。
使用计算机断层扫描研究无支架生物瓣膜壁的三维异质性。切除升主动脉以及主动脉瓣的右、左和无冠状动脉窦，并通过压痕试验进行检查以评估其生物力学特性。
主动脉瓣无冠状动脉窦明显比主动脉瓣右窦薄（p < 0.01）。作为弹性指标计算的杨氏模量在主动脉瓣无冠状动脉窦处（430.7±374.2 kPa）明显高于主动脉瓣左窦（190.6±70.6 kPa，p < 0.01）或右窦（240.0±56.5 kPa，p < 0.05）。
基于对无支架生物瓣膜的形态测量和生物力学分析，我们证明主动脉瓣各窦之间的壁厚和弹性存在差异。这些差异表明主动脉瓣无冠状动脉窦最脆弱，组织故障风险更高。排除主动脉瓣无冠状动脉窦可能有利于降低无支架生物瓣膜组织故障的长期风险。
