Ius P, Thiene G, Minarini M, Valente M, Bortolotti U, Talenti E, Casarotto D
Department of Pathology, University of Padua Medical School, Italy.
J Heart Valve Dis. 1996 May;5(3):323-7.
The Liotta low profile porcine bioprosthesis (LBP) was designed in order to minimize complications due to excessive protrusion of the stent prongs in the left ventricle.
From April 1984 to November 1993, 25 LBP surgical explants were available for pathology study, which included gross and X-ray evaluations. Reoperation was performed after a mean period of 95 +/- 25 months (range 46 to 143 months), in five males and 20 females (mean age at implantation 51.1 +/- 11.4 years).
The cause of failure was stenosis due to cusp stiffness caused by dystrophic calcification in one and incompetence in 24 LBPs. In only one case was incompetence ascribable to endocarditis; in the remaining 23 the mechanism of regurgitation was due to commissural tearing (21 LBPs), commissural dehiscence (one LBP) and both tears and dehiscence (one LBP). Overall, 28 commissural tears were observed: 20 involved the right coronary cusp, eight the left coronary cusp, and none the non-coronary cusp. The anterior commissure was most frequently involved by tears (n = 17) followed by the right posterior (n = 9) and the left posterior (n = 2). Tears were calcium-related in all but two cases. Calcific deposits were observed in each explant, involving a total of 62 commissural attachments, 17 cusp bodies and five right muscular shelves.
In conclusion, valve regurgitation is the usual mode of LBP failure in the mitral position; commissural tearing of the right coronary cusp was the most common cause of valve regurgitation, and occurred even in the presence of pin-point calcification. These pathologic findings seem to confirm that low profile design, which implies bulging of the right coronary cusp, entails the risk of increased stress at the commissures, accelerated calcification and tearing.
设计Liotta低轮廓猪生物瓣膜（LBP）是为了将因支架尖过度突入左心室而导致的并发症降至最低。
1984年4月至1993年11月，有25个LBP手术切除标本可供病理研究，包括大体和X线评估。再次手术平均在95±25个月（范围46至143个月）后进行，患者中有5名男性和20名女性（植入时平均年龄51.1±11.4岁）。
失败原因中，1个LBP是由于营养不良性钙化导致瓣叶僵硬引起狭窄，24个LBP是功能不全。仅1例功能不全归因于心内膜炎；其余23例反流机制是由于瓣叶联合处撕裂（21个LBP）、瓣叶联合处裂开（1个LBP）以及撕裂和裂开同时存在（1个LBP）。总体而言，观察到28处瓣叶联合处撕裂：20处累及右冠状动脉瓣叶，8处累及左冠状动脉瓣叶，无一处累及无冠状动脉瓣叶。前联合处最常发生撕裂（n = 17），其次是右后联合处（n = 9）和左后联合处（n = 2）。除2例病例外，所有撕裂均与钙有关。在每个切除标本中均观察到钙化沉积，总共累及62个瓣叶联合附着处、17个瓣叶体和5个右肌性架。
总之，瓣膜反流是二尖瓣位LBP失败的常见方式；右冠状动脉瓣叶联合处撕裂是瓣膜反流最常见的原因，甚至在存在微小钙化时也会发生。这些病理结果似乎证实，低轮廓设计意味着右冠状动脉瓣叶膨出，会带来瓣叶联合处应力增加、钙化加速和撕裂的风险。
