Nagy Z L, Fisher J, Walker P G, Watterson K G
Yorkshire Heart Centre, Leeds General Infirmary, UK.
Eur J Cardiothorac Surg. 1999 Mar;15(3):294-301. doi: 10.1016/s1010-7940(99)00016-0.
We established an in vitro model to investigate the effect of size mismatch between the aortic and pulmonary root on the hydrodynamic performance and leaflet motion of the pulmonary autograft.
Ten fresh porcine pulmonary roots (annulus diameter: 19-25 mm) were tested in a pulsatile flow simulator. The autografts then were implanted in fresh porcine aortic roots (annulus diameter: 19-30 mm) and retested in the flow simulator. Three roots were oversized by 21-39%, three were undersized by 32-45% and there were four size for size implantations. The external diameter of the roots and autografts was measured at the sinotubular junction at hydrostatic pressures of 0 - 120 mmHg. The transvalvular gradient and regurgitation were also measured and the effective orifice area was calculated. The leaflet motion was recorded on video.
The fresh pulmonary roots were more compliant than the fresh aortic roots (46 +/- 8.4% vs. 35 +/- 7.8% dilatation from 0 to 120 mmHg). The group of matching size autografts dilated by 43 +/- 4.9% in the same pressure range. The external diameter of the undersized autografts was 10 +/- 2.1% bigger than before implantation at 0 pressure and then the dilatation was 40 +/- 5.3% at 120 mmHg. The oversized implantation made the autografts 11 +/- 9.4% smaller in their relaxed state, but then they dilated by 65 +/- 11% as the pressure increased to 120 mmHg, resulting in a net dilatation of 54% over the original undilated state. The under or oversizing had little effect on the pressure gradient measured across the valves (5.6 +/- 2.57 mmHg before, 6.3 +/- 3.27 mmHg after implantation). Only the oversized valves showed significantly higher gradients than the native pulmonary valves. The effective orifice area of the undersized autografts was slightly bigger and the oversized autografts was slightly smaller after implantation, although the differences were not significant. The size mismatch did not cause regurgitation on the valves. The video images showed very low-open leaflet-bending deformation, both on the fresh pulmonary and the autograft valves.
Under or oversizing the pulmonary autograft up to 40% of the annulus diameter did not affect the hydrodynamic parameters significantly. The compliance of the autograft root was able to compensate for the size mismatch without adversely influencing the valve performance.
我们建立了一个体外模型，以研究主动脉根部与肺动脉根部尺寸不匹配对肺动脉自体移植物流体动力学性能和瓣叶运动的影响。
在脉动流模拟器中对10个新鲜猪肺动脉根部（瓣环直径：19 - 25毫米）进行测试。然后将自体移植物植入新鲜猪主动脉根部（瓣环直径：19 - 30毫米），并在流模拟器中重新测试。3个根部尺寸过大21 - 39%，3个根部尺寸过小32 - 45%，4个为尺寸匹配植入。在0 - 120毫米汞柱静水压下，在窦管交界处测量根部和自体移植物的外径。还测量了跨瓣压差和反流情况，并计算有效瓣口面积。用视频记录瓣叶运动。
新鲜肺动脉根部比新鲜主动脉根部更具顺应性（从0到120毫米汞柱扩张率分别为46±8.4%和35±7.8%）。尺寸匹配的自体移植物组在相同压力范围内扩张率为43±4.9%。尺寸过小的自体移植物在0压力下外径比植入前大10±2.1%，在120毫米汞柱时扩张率为40±5.3%。尺寸过大的植入使自体移植物在松弛状态下小11±9.4%，但随着压力升至120毫米汞柱，它们扩张了65±11%，相对于原始未扩张状态净扩张54%。尺寸过小或过大对跨瓣压差影响不大（植入前为5.6±2.57毫米汞柱，植入后为6.3±3.27毫米汞柱）。只有尺寸过大的瓣膜显示出比天然肺动脉瓣明显更高的压差。尺寸过小的自体移植物植入后有效瓣口面积略大，尺寸过大的自体移植物略小，尽管差异不显著。尺寸不匹配未导致瓣膜反流。视频图像显示，新鲜肺动脉瓣和自体移植瓣膜上的瓣叶开放弯曲变形都非常小。
肺动脉自体移植物尺寸过小或过大至瓣环直径的40%，对流体动力学参数无显著影响。自体移植物根部的顺应性能够补偿尺寸不匹配，而不会对瓣膜性能产生不利影响。
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