Actis Dato G M, Caimmi P, Di Rosa E, Deorsola L, Aidala E, Punta G, Poletti G, Di Summa M
Divisione di Cardiochirurgia, Università degli Studi, Torino.
Minerva Cardioangiol. 1998 Apr;46(4):97-101.
Stent deformation seems to be effective in the long term performances of bioprostheses.
The Inward Banding Angle (IBA) of three different models of bioprostheses explanted during the period 1991-1992 at our Division of Cardiac Surgery in 45 different patients (26 males; 9 females; mean age 59.71 +/- 10.74, range 26-75) has been measured. Explanted valves were as follow: Hancock, (H = 13); Carpentier-Edwards (C = 14) e Xenomedica (X = 18). Primary tissue failure was the most common cause of re-operation (n = 30; 66.7%) but also endocarditis (n = 6; 13.3%) and paraprothetic leak (n = 10; 22.2%). A semi-quantitative score (0-4) was used to assess calcifications (1.51 +/- 1.56); tears (0.41 +/- 0.98); vegetation's (0.51 +/- 0.99) and fibrosis (2.7 +/- 1.27). The mean follow-up was 7.77 +/- 3.79 years (range 1.5 +/- 16 years). The mean IBA evaluated after explantation was 3.34 +/- 2.29 degrees.
Statistical analysis showed a significance in term of IBA in the Hancock group vs Carpentier (P < 0.02); a less duration in the Xenomedica group vs H and C (p < 0.001) and an increased susceptibility to vegetation's and fibrosis in the Xvs C (p < 0.01) and H (p < 0.05) respectively. A suggestive correlation between IBA and time and between IBA and diameter was found but no statistical significance was observed.
In conclusions, it is suggested that all materials tends to deform during time and a possible explanation of stent deformation can be the different material used in the stent fabrication. Moreover, mechanical stress and compression around the ring can be another mechanism of creep.
支架变形似乎对生物假体的长期性能有效。
测量了1991年至1992年期间在我们心脏外科45例不同患者（26例男性；9例女性；平均年龄59.71±10.74岁，范围26 - 75岁）中取出的三种不同型号生物假体的向内束带角度（IBA）。取出的瓣膜如下：汉考克（H = 13）；卡彭蒂埃 - 爱德华兹（C = 14）和希诺梅迪卡（X = 18）。原发性组织衰竭是再次手术最常见的原因（n = 30；66.7%），但心内膜炎（n = 6；13.3%）和人工瓣膜旁漏（n = 10；22.2%）也较为常见。使用半定量评分（0 - 4）来评估钙化（1.51±1.56）；撕裂（0.41±0.98）；赘生物（0.51±0.99）和纤维化（2.7±1.27）。平均随访时间为7.77±3.79年（范围1.5±16年）。取出后评估的平均IBA为3.34±2.29度。
统计分析显示，汉考克组与卡彭蒂埃组在IBA方面有显著差异（P < 0.02）；希诺梅迪卡组与H组和C组相比持续时间更短（p < 0.001），并且X组与C组（p < 0.01）和H组（p < 0.05）相比，分别对赘生物和纤维化的易感性增加。发现IBA与时间以及IBA与直径之间存在提示性相关性，但未观察到统计学意义。
总之，建议所有材料随着时间推移都会发生变形，支架变形的一个可能解释可能是支架制造中使用的不同材料。此外，环周围的机械应力和压缩可能是另一种蠕变机制。
