Gregoric Igor D, Eya Kazuhiro, Tamez Daniel, Cervera Roberto, Byler Denise, Conger Jeff, Tuzun Egemen, Chee Hyun Keun, Clubb Fred J, Kadipasaoglu Kamuran, Frazier O H
Cardiovascular Surgical Research Laboratory, Texas Heart Institute, Houston, Texas 77030, USA.
J Heart Valve Dis. 2004 Mar;13(2):254-9.
The hemodynamic characteristics of a new trileaflet mechanical heart valve (TTV) (TriFlo Inc., Costa Mesa, CA, USA) in the aortic position were evaluated in a bovine model. The TTV was designed to combine the durability of mechanical heart valves with the central flow characteristics of a bioprosthesis.
Using nine calves, the native aortic valve was replaced with a 21-mm TTV (n = 6) or a St. Jude Medical (SJM) valve (n = 3). Hemodynamic values were assessed with echocardiography at implantation and with catheterization at explantation. All calves underwent a necropsy, followed by gross pathology and light microscopy studies.
The mean implant duration was 159 +/- 55 days for the TTV and 102 +/- 67 days for the SJM valve. Immediately before euthanasia, the peak and mean pressure gradients were respectively 35 +/- 14 and 24 +/- 9 mmHg for the TTV, and 100 +/- 72 and 59 +/- 38 mmHg for the SJM valve (p = 0.03). Two of the SJM-valve animals were electively sacrificed after showing symptoms of aortic stenosis. At necropsy, all nine valves were free from thrombi, pannus, occlusive tissue, or mechanical impairment of leaflet motion. The prematurely sacrificed SJM-valve animals had concentric myocardial hypertrophy consistent with severe functional aortic stenosis.
The significantly higher gradients and left ventricular hypertrophy in the SJM-valve animals were related to a smaller effective orifice area, which precluded adaptation to increasing transvalvular volumes in the growing animal. This problem was not seen with the TTV, which performed hemodynamically as well as the SJM valve. The high transvalvular gradients seen with the SJM valve at study end may suggest that the hemodynamic characteristics of the TTV may be superior, though additional studies are needed to confirm this.
在牛模型中评估一种新型三叶机械心脏瓣膜（TTV）（TriFlo公司，美国加利福尼亚州科斯塔梅萨）置于主动脉位置时的血流动力学特性。该TTV旨在将机械心脏瓣膜的耐用性与生物假体的中心血流特性相结合。
使用9头小牛，将天然主动脉瓣替换为21毫米的TTV（n = 6）或圣犹达医疗（SJM）瓣膜（n = 3）。植入时通过超声心动图评估血流动力学值，取出时通过心导管检查评估。所有小牛均进行尸检，随后进行大体病理学和光学显微镜研究。
TTV的平均植入持续时间为159±55天，SJM瓣膜为102±67天。在安乐死前不久，TTV的峰值和平均压力梯度分别为35±14和24±9 mmHg，SJM瓣膜为100±72和59±38 mmHg（p = 0.03）。2只植入SJM瓣膜的动物在出现主动脉狭窄症状后被选择性处死。尸检时，所有9个瓣膜均无血栓、血管翳、闭塞组织或瓣叶运动的机械性损伤。过早处死的植入SJM瓣膜的动物有与严重功能性主动脉狭窄一致的同心性心肌肥厚。
SJM瓣膜组动物中显著更高的梯度和左心室肥厚与较小的有效瓣口面积有关，这使得生长中的动物无法适应增加的跨瓣容积。TTV未出现此问题，其血流动力学表现与SJM瓣膜相当。研究结束时SJM瓣膜出现的高跨瓣梯度可能表明TTV的血流动力学特性可能更优，不过还需要更多研究来证实这一点。
