脉动流下机械心脏瓣膜瓣阀开启状态的评价

背景：体外机械型人工心脏瓣膜(机械瓣)性能的评价涉及心输出量、反流量、有效瓣口面积、跨瓣压差，以及应力场、流场和成穴现象等。目的：对3种机械瓣的瓣阀开启状态进行可视性观察和评价。方法：用脉动流模拟循环装置系统，维持系统整个状态不变，在模拟心搏出量4 L/min、模拟心率75次/min和收缩时间占其循环周期46.2%的条件下，分别将久灵双叶瓣、Carbomedics双叶瓣和C-L侧倾碟瓣置于主动脉瓣位，将高速摄像机置于模拟循环装置动脉腔的正上方，观察10个连续模拟心动周期中瓣阀开启状态。利用自编图像处理软件包，捕获瓣阀开启角度最大的1幅图像，作为计算该只瓣膜在1个心动周期中最大开放面积和开启角度的基准。结果与结论：脉动流下，25 mm CarboMedics瓣、25 mm和23 mm久灵双叶瓣在开放到最大位时，可见瓣阀抖动现象，27 mm C-L侧倾碟瓣未见瓣阀抖动。用不同的计算方法测量上述瓣膜的瓣口面积显示，由厂家提供的瓣口实际面积最大，用Green公式计算的瓣膜开放面积次之，用Gorin公式计算的有效瓣口面积最小。根据三角形定理计算的瓣阀开放角度，久灵双叶瓣和CarboMedics瓣的两个瓣阀的开放角度不一致，并均小于瓣膜固有的开放角度；C-L侧倾碟瓣的开放角度也未达其固有的开放角度。提示机械型人工心脏瓣膜双叶瓣的瓣阀开放不同步，瓣阀有抖动现象；瓣阀在脉动周期中呈不完全性开启。

Evaluation on opening status of the mechanical heart valve in vitro under pulsatile flow

BACKGROUND:During the estimation of mechanical heart valve prosthesis, many studies related to cardiac output, regurgitant volume, effective orifice area, pressure differences and shear stresses and flow fields, and cavitation phenomenon.OBJECTIVE:To carry out visual observation and evaluation on the opening status of the leaflets to three kinds of mechanical artificial heart valve prostheses.METHODS:The pulsatile flow testing experiments were conducted by installing the testing heart valve prosthesis (US-made CarboMedics bileaflet valve, China-made Jiuling bileaflet valve and C-L tilting disc valve) in the aortic position of the physiological mock flow loop. The testing condition was set at pulse frequency of 75 beats/min and a constant cardiac output of 4 L/min and contraction of the cycle time of under 46.2%, respectively. The opening status of the disc valves in 10 continuous pulse cycles was observed by a high-speed camera installed light above the simulated cycle device of arterial lumen upper part. With self designed image processing software package, a picture of the biggest opening angle of the disc valve was shot and it was used as a datum to calculating its biggest opening area and angle for each valve.RESULTS AND CONCLUSION:The disc valves fluttering were observed when 25 mm CarboMedics bileaflet valve, 25 mm and 23 mm Jiuling double leaflet disc opened to the maximum angle, but 27 mm C-L disc valve was not. The measurement of disc mouth by different calculating methods showed that actual area mouth provided by manufacturers was the biggest, and that the opening area of disc calculated by Green formula was the second, and that the effective opening area calculated by Gorin formula was the smallest. The opening angle of disc valves that calculated by Triangle Law demonstrated that the opening angle of two disc leaflet was inconsistent and less than the inherent opening angle for Jiuling valves and CarboMedics valves. And the opening angle of C-L valve did not reach its inherent opening angle either. The disc leaflets of the mechanical artificial heart valve did not open synchronously and was fluttering in view, the disc leaflets opened incompleted.