Nappi Francesco, Nenna Antonio, Larobina Domenico, Carotenuto Angelo Rosario, Jarraya Mohamed, Spadaccio Cristiano, Fraldi Massimiliano, Chello Massimo, Acar Christophe, Carrel Thierry
Department of Cardiac Surgery, Centre Cardiologique du Nord de Saint-Denis, Paris, France.
Department of Cardiovascular Surgery, University Campus Bio-Medico of Rome, Rome, Italy.
Interact Cardiovasc Thorac Surg. 2018 Aug 1;27(2):269-276. doi: 10.1093/icvts/ivy070.
Reinforcements for the pulmonary autograft (PA) in the Ross operation have been introduced to avoid the drawback of conduit expansion and failure. With the aid of an in silico simulation, the biomechanical boundaries applied to a healthy PA during the operation were studied to tailor the best implant technique to prevent reoperation.
Follow-up echocardiograms of 66 Ross procedures were reviewed. Changes in the dimensions and geometry of reinforced and non-reinforced PAs were evaluated. Miniroot and subcoronary implantation techniques were used in this series. Mechanical stress tests were performed on 36 human pulmonary and aortic roots explanted from donor hearts. Finite element analysis was applied to obtain high-fidelity simulation under static and dynamic conditions of the biomechanical properties and applied stresses on the PA root and leaflet and the similar components of the native aorta.
The non-reinforced group showed increases in the percentages of the mean diameter that were significantly higher than those in the reinforced group at the level of the Valsalva sinuses (3.9%) and the annulus (12.1%). The mechanical simulation confirmed geometrical and dimensional changes detected by clinical imaging and demonstrated the non-linear biomechanical behaviour of the PA anastomosed to the aorta, a stiffer behaviour of the aortic root in relation to the PA and similar qualitative and quantitative behaviours of leaflets of the 2 tissues. The annulus was the most significant constraint to dilation and affected the distribution of stress and strain within the entire complex, with particular strain on the sutured regions. The PA was able to evenly absorb mechanical stresses but was less adaptable to circumferential stresses, potentially explaining its known dilatation tendency over time.
The absence of reinforcement leads to a more marked increase in the diameter of the PA. Preservation of the native geometry of the PA root is crucial; the miniroot technique with external reinforcement is the most suitable strategy in this context.
在Ross手术中引入了对肺动脉自体移植物（PA）的强化措施，以避免管道扩张和失效的缺点。借助计算机模拟，研究了手术过程中应用于健康PA的生物力学边界，以定制最佳的植入技术以防止再次手术。
回顾了66例Ross手术的随访超声心动图。评估了强化和未强化PA的尺寸和几何形状变化。本系列采用了迷你根部和冠状动脉下植入技术。对从供体心脏取出的36个人类肺动脉和主动脉根部进行了机械应力测试。应用有限元分析在静态和动态条件下获得对PA根部、瓣叶以及天然主动脉类似组件的生物力学特性和施加应力的高保真模拟。
未强化组在主动脉窦水平（3.9%）和瓣环（12.1%）处平均直径增加的百分比显著高于强化组。机械模拟证实了临床成像检测到的几何和尺寸变化，并展示了与主动脉吻合的PA的非线性生物力学行为、主动脉根部相对于PA更硬的行为以及两种组织瓣叶类似的定性和定量行为。瓣环是扩张的最显著限制因素，并影响整个复合体内部的应力和应变分布，缝合区域有特别的应变。PA能够均匀吸收机械应力，但对周向应力的适应性较差，这可能解释了其随时间推移已知的扩张趋势。
缺乏强化导致PA直径更明显的增加。保留PA根部的天然几何形状至关重要；在这种情况下，带外部强化的迷你根部技术是最合适的策略。
