How Local Annular Force and Collagen Density Govern Mitral Annuloplasty Ring Dehiscence Risk.
How Local Annular Force and Collagen Density Govern Mitral Annuloplasty Ring Dehiscence Risk.
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DOI：
10.1016/j.athoracsur.2016.01.107
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发表时间：
2016-08
期刊：
影响因子：
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通讯作者：
Yoganathan AP
中科院分区：
文献类型：
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作者：
Pierce EL;Siefert AW;Paul DM;Wells SK;Bloodworth CH 4th;Takebayashi S;Aoki C;Jensen MO;Gillespie MJ;Gorman RC;Gorman JH 3rd;Yoganathan AP
环成形术环破裂是二尖瓣修复失败的一个很好的机制。明确裂缝的机制可能有助于预防裂缝。使用绵羊模型检查控制缝线断裂的因素。在活体动物（N=5）进行小尺寸环成形术后，使用定制传感器测量心脏收缩期间作用于缝合线的循环力（FC）。在10个缝合位置测量FC，在整个心脏周期中，峰值左室压（LVPmax）分别为100、125和150mmHg。对外植的二尖瓣环腔（N=12）进行缝线拔出试验，测定缝线在各位置的保持强度。最后，通过双光子激发透视评估环周围缝合部位的相对胶原密度差异。每次LVPmax时，前FC均超过后FC（如LVPmax=125mmHg时，2.8±1.3 n比1.8±1.2N, p<0.01）。前支力大于后支力（6.4±3.6 n vs. 3.9±1.6N, p<0.0001）。基于LVPmax=150mmHg时的FC，三角区（不包括三角区）与其他部位相比，拔线前的安全裕度要高得多（4.8±0.9 n vs 1.9±0.5N, p<0.001）。安全边际与胶原密度有较强的相关性（R2=0.947）。尽管后缝合线的循环载荷较低，但较弱的二尖瓣后环组织会产生较高的开裂风险，这显然是由于胶原含量减少所致。由于该区域胶原蛋白减少和整体硬度升高，缝合在三角区上方的安全性不如预期。这些发现强调了三角间组织作为优越的锚点，并对下一代二尖瓣假体的设计和植入技术具有指导意义。
Annuloplasty ring dehiscence is a well described mechanism of mitral valve repair failure. Defining the mechanisms underlying dehiscence may facilitate its prevention. Factors governing suture dehiscence were examined using an ovine model. Following undersized ring annuloplasty in live animals (N=5), Cyclic Force (FC) acting on sutures during cardiac contraction were measured using custom transducers. FC was measured at 10 suture positions, throughout cardiac cycles with peak left ventricular pressure (LVPmax) of 100, 125, and 150mmHg. Suture pullout testing was conducted on explanted mitral annuli (N=12) to determine suture holding strength at each position. Finally, relative collagen density differences at suture sites around the annulus were assessed by two-photon excitation fluoroscopy. Anterior FC exceeded posterior at each LVPmax (e.g. 2.8±1.3 vs. 1.8±1.2N at LVPmax=125mmHg, p<0.01). Anterior holding strength exceeded posterior (6.4±3.6 vs. 3.9±1.6N, p<0.0001). Based on FC at LVPmax=150mmHg, margin of safety before suture pullout was vastly higher between the trigones (exclusive) versus elsewhere (4.8±0.9 versus 1.9±0.5N, p<0.001). Margin of safety exhibited strong correlation to collagen density (R2=0.947). Despite lower cyclic loading on posterior sutures, the weaker posterior mitral annular tissue creates higher risk of dehiscence, apparently due to reduced collagen content. Sutures placed atop the trigones are less secure than predicted, due to a combination of reduced collagen and higher overall rigidity in this region. These findings highlight the inter-trigonal tissue as the superior anchor, and have implications on the design and implantation techniques for next-generation mitral prostheses.