模拟心室驱动曲线对机械瓣流体动力学性能的影响(英文)

Effect of mimic cardiac ventricle driving curve on the hydrodynamics of mechanical valvular prostheses

背景:脉动流模拟循环装置是评价人工心脏瓣膜流体动力学性能的最佳手段,而脉动流模拟循环装置本身的性能,尤其是模拟心室驱动曲线对机械瓣流体动力学性能的影响研究较少。目的:观察在生理条件下模拟心室驱动曲线对机械瓣流体动力学性能的影响。设计、时间及地点:对比观察实验,于1999-04/2000-02在四川大学建筑学院生物医学工程中心流体力学实验室完成。材料:采用脉动流模拟循环装置,设定模拟心输出量为4L/min,模拟心率为75次/min。方法:脉动流模拟循环装置系统的主动脉瓣位置入25mm CarboMedics双叶瓣,二尖瓣位置入27mmBjrk-Shiley侧倾碟瓣。调用系统中的标准心室驱动曲线,调节测试系统各参数,维持主动脉压在16.0/10.7kPa(120/80mmHg),实验流体为生理盐水-甘油混合液,黏度为3.5mPa·s(3.5Cp),密度1.06g/cm3。维持模拟循环系统整个状态不变,即舒张末期心室容积、主动脉顺应性、外周阻力和外周顺应性等不变。设定模拟心输出量为4L/min,模拟心率为75次/min,收缩时间0.37s,通过对标准心室驱动曲线上若干点的坐标进行修改,确定4个控制曲线;最后对以上曲线进行自动插值、拟合、波形光滑、滤波处理,得到最终4个控制曲线,并逐一测试每一控制曲线下的流体动力学性能。主要观察指标:观察5种心室驱动曲线情况下机械瓣平均跨瓣压差、有效瓣口面积、关闭量和泄漏量的变化。结果:生理范围内,心室驱动曲线形态上的改变,对测试瓣膜的平均跨瓣压差可产生2.9%的变异,有效瓣口面积的变异在1.5%,关闭量在6.6%,泄漏量为3.6%。结论:机械瓣的流体动力学性能受心室驱动曲线的影响,从而对瓣膜流体动力学性能评价的客观性和可比性产生不利作用。

BACKGROUND： Mimic pulsatile flow system is the optimal device to assess the hydrodynamic performance of mechanical valvular prostheses, but few studies concern about the performance of mimic pulsatile flow system and the effect of mimic cardiac ventricle driving curve on hydrodynamic performance of mechanical valvular prostheses. OBJECTIVE： To research the effect of cardiac ventricle driving curve on the hydrodynamic performance of mechanical valvular prostheses under physiological condition DESIGN, TIME AND SETTING： This study, a control observation, was carried out in the Hydrodynamics Laboratory, Biomedical Engineering Center, College of Architecture and Environment, Sichuan University （Chengdu, Sichuan, China） from April 1999 to February 2000. MATERIALS： Mimic pulsatile flow system was adopted, with the mimic cardiac output at 4 L per minute and heart rate at 75 beats per minute. METHODS： The mimic pulsatile flow system was implanted with 25 mm CarboMedics bileaflet prosthesis into the aortic valve position, with 27 mm Bjork-Shiley tilting disc prosthesis into the mitral valve position. Standard cardiac ventricle driving curve was employed to test the system parameters and maintain the aortic pressure at 16.0/10.7 kPa （120/80 mm Hg）. Experimental liquid was a mixture of saline and glycerine, at a viscosity of 3.5 mPa · s （3.5 Cp） and a density of 1.06 g/cm^3. The mimic flow system kept at an unchanged level of ventricular end diastolic volume, aorta arterial compliance, peripheral resistance and peripheral compliance. The coordinate on several points of standard cardiac ventricle driving curve was modified to define 4 control curves, followed by a series of procedures, such as automatic interpolation, fitting, waveform smoothing and filtering. The hydrodynamic performance of each controlled curve was also tested. MAIN OUTCOME MEASURES： The mean transvalvular pressure gradient, effective orifice area, closing volume and leakage volume of mechanical valvular prostheses were evaluated in five cardiac ventricle driving curves. RESULTS： The cardiac ventricle driving curves developed morphological changes within physiological conditions, subsequently induced a 2.9% variance of mean transvalvular pressure gradient, 1.5% variance of effective orifice area, 6.6% variance of closing volume and 3.6% variance of leakage volume. CONCLUSION： The cardiac ventricle driving curve has a certain effect on the hydrodynamic performance of mechanical valvular prosthesis, thereby leads to an adverse effect on the objectivity and comparability of the hydrodynamic evaluation.