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首页> 外文期刊>Journal of Biomechanics >Turbulence downstream of subcoronary stentless and stented aortic valves.
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Turbulence downstream of subcoronary stentless and stented aortic valves.

机译：冠状动脉下无支架和带支架的主动脉瓣下游的湍流。

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Regions of turbulence downstream of bioprosthetic heart valves may cause damage to blood components, vessel wall as well as to aortic valve leaflets. Stentless aortic heart valves are known to posses several hemodynamic benefits such as larger effective orifice areas, lower aortic transvalvular pressure difference and faster left ventricular mass regression compared with their stented counterpart. Whether this is reflected by diminished turbulence formation, remains to be shown. We implanted either stented pericardial valve prostheses (Mitroflow), stentless valve prostheses (Solo or Toronto SPV) in pigs or they preserved their native valves. Following surgery, blood velocity was measured in the cross sectional area downstream of the valves using 10MHz ultrasonic probes connected to a dedicated pulsed Doppler equipment. As a measure of turbulence, Reynolds normal stress (RNS) was calculated at two different blood pressures (baseline and 50% increase). We found no difference in maximum RNS measurements between any of the investigated valve groups. The native valve had significantly lower mean RNS values than the Mitroflow (p=0.004), Toronto SPV (p=0.008) and Solo valve (p=0.02). There were no statistically significant differences between the artificial valve groups (p=0.3). The mean RNS was significantly larger when increasing blood pressure (p=0.0006). We, thus, found no advantages for the stentless aortic valves compared with stented prosthesis in terms of lower maximum or mean RNS values. Native valves have a significantly lower mean RNS value than all investigated bioprostheses.
机译：生物人工心脏瓣膜下游的湍流区域可能会损坏血液成分，血管壁以及主动脉瓣小叶。与支架式支架相比，无支架主动脉心脏瓣膜具有多种血液动力学优势，例如更大的有效孔面积，更低的主动脉经瓣压差和更快的左心室质量消退。是否通过减少湍流形成反映了这一点，尚待证实。我们将带支架的心包瓣膜假体（Mitroflow），无支架的瓣膜假体（Solo或Toronto SPV）植入猪中，或保留其天然瓣膜。手术后，使用连接到专用脉冲多普勒设备的10MHz超声探头在瓣膜下游的横截面积中测量血流速度。作为湍流的一种度量，在两个不同的血压（基线和增加50％）下计算了雷诺法向正常应力（RNS）。我们发现在任何调查的阀组之间，最大RNS测量值没有差异。天然瓣膜的平均RNS值明显低于Mitroflow（p = 0.004），Toronto SPV（p = 0.008）和Solo瓣膜（p = 0.02）。人工瓣膜组之间无统计学差异（p = 0.3）。当血压升高时，平均RNS明显更大（p = 0.0006）。因此，我们发现与无支架主动脉瓣相比，无支架主动脉瓣在降低最大或平均RNS值方面没有优势。天然瓣膜的平均RNS值明显低于所有研究的生物假体。

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