Quantification of Biomechanical Interaction of Transcatheter Aortic Valve Stent Deployed in Porcine and Ovine Hearts
Quantification of Biomechanical Interaction of Transcatheter Aortic Valve Stent Deployed in Porcine and Ovine Hearts
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DOI：
10.1007/s10439-012-0694-1
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发表时间：
2013-03-01
影响因子：
3.8
通讯作者：
Sun, Wei
中科院分区：
文献类型：
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作者：
Mummert, Joseph;Sirois, Eric;Sun, Wei
经导管主动脉瓣置换术的部署和功能的成功与否在很大程度上取决于组织-支架的相互作用。本研究量化了自膨式经导管主动脉瓣支架置入猪和猪主动脉根部时重要的组织-支架接触变量，如支架的径向扩张力、支架拔出力、环变形响应和组织-支架接触界面上的摩擦系数。研制了编织镍钛合金支架，通过支架卷曲实验测试支架卷曲直径与支架径向力的关系，并在体外部署支架，通过主动脉根部-支架相互作用实验量化支架拔出、主动脉环变形以及支架与主动脉组织之间的摩擦系数。结果表明，在体温从26 mm卷曲到19 mm时，21和23 mm支架的径向力比在室温下卷曲时的径向力高30-40%。随着支架钢丝直径的增加和环径从23 mm减小到19 mm，摩擦系数稳定在约0.10+/-A0.01。不管主动脉环的大小和测试的种类，似乎至少需要2.5毫米的环状扩张，这是由支架扩张引起的约60N的径向力造成的，以锚定支架以抵挡向左心室的拔出。对动物主动脉组织接触生物力学的研究有助于我们更好地了解组织-支架相互作用的特点，并量化非钙化的主动脉组织的基线反应。
Success of the deployment and function in transcatheter aortic valve replacement is heavily reliant on the tissue-stent interaction. The present study quantified important tissue-stent contact variables of self-expanding transcatheter aortic valve stents when deployed into ovine and porcine aortic roots, such as the stent radial expansion force, stent pullout force, the annulus deformation response and the coefficient of friction on the tissue-stent contact interface. Braided Nitinol stents were developed, tested to determine stent crimped diameter vs. stent radial force from a stent crimp experiment, and deployed in vitro to quantify stent pullout, aortic annulus deformation, and the coefficient of friction between the stent and the aortic tissue from an aortic root-stent interaction experiment. The results indicated that when crimped at body temperature from 26 mm to 19, 21 and 23 mm stent radial forces were approximately 30-40% higher than those crimped at room temperature. Coefficients of friction leveled to approximately 0.10 +/- A 0.01 as stent wire diameter increased and annulus size decreased from 23 to 19 mm. Regardless of aortic annulus size and species tested, it appeared that a minimum of about 2.5 mm in annular dilatation, caused by about 60 N of radial force from stent expansion, was needed to anchor the stent against a pullout into the left ventricle. The study of the contact biomechanics in animal aortic tissues may help us better understand characteristics of tissue-stent interactions and quantify the baseline responses of non-calcified aortic tissues.