【摘要】 对国产GK2 7型机械二尖瓣进行了单次关闭方式的离体空化实验 ,采用数码相机拍摄了空泡照片。机械瓣阻塞体关闭后 ,云状空泡出现在挡座周围 ,呈放射状向外运动 ,空化原因是机械瓣关闭时阻塞体与挡座的撞击形成的局部挤压射流 ,挤压缝隙出口射流速度高达 9m/s ,局部低压造成空化 ,在机理上 ,这是附壁射流引起的旋涡空化。关闭速度是衡量机械瓣空化趋势的重要指标之一。空化历时随心室载荷率的增加而增加 ,在载荷率为2 75 0mmHg/s时 ,最大空化历时达 44 0 μs。机械瓣空化临界载荷率为 42 0mmHg/s,这比动物实验所得的正常生理条件 75 0mmHg/s低 ,因此在人体正常生理条件下 ,机械二尖瓣存在空化的可能更多还原

【Abstract】 Cavitation has been documented for GK mechanical heart valve in an in vitro flow system simulating the closing event in mitral position. From picture taken with digital camera, cavitation clouds moved outwards along the seat stop on the occlude surface after closure. Cavitation was investigated and explained by squeezing flow from the impact between occlude and seat stops at the closure of mechanical heart valve. Its mechanism is vortex cavitation from wall jet. Velocity of squeezing flow was estimated to be up to 9 m/s causing local low pressure contributing much to cavitation. Closing velocity of occlude was an important factor for cavitation potential of GK valve. Cavitation duration varied with the ventricular loading rate and was up to 440μs at loading rate of 2750mmHg/s. The loading rate threshold of cavitation was 420mmHg/s. This value was lower than that of normal physiological condition of 750mmHg/s in animal test. It was concluded that there was possibility of cavitation for GK mechanical heart valve.更多还原