心室流腔角度对主动脉瓣影响的脉动流实验研究

目的探究左心室流腔与主动脉轴线所呈角度对主动脉瓣力学性能的影响。方法依据从华中科技大学同济医学院附属协和医院获得的患者CT图像上的心室流腔角度大小,通过3D打印技术制作心室流腔角度分别为0°、16.5°和30°的3组主动脉根部模型。然后将人工生物瓣安装在主动脉根部模型上,在Vivitro心脏-血管模拟实验系统中进行不同心输出量条件下的脉动流实验。心率设定为70次/min,脉动流流动速率分别为2、3、4、5、6、7 L/min的条件下,测试瓣膜的跨膜压差、反流比和有效开口面积。在每个脉动流流动速率条件下测试10次,取平均值。结果不同心室流腔角度模型之间,生物瓣的跨膜压差存在差异但均符合国家标准GB 12279—2008/ISO 5840:1996,即小于10 mmHg(1 mmHg=0.133 k Pa)。对于心输出量较低的情况,较小的心室流腔角度有助于反流比的下降,较大的心室流腔角度有助于增大瓣膜的有效开口面积;而对于心输出量较高的情况,较小的心室流腔角度有利于瓣膜有效开口面积的增大。结论手术时,医生可根据患者的各项参数大小选择合适的心室流腔角度。

Experimental study of the influence of the angle of ventricular flow chamber on the pulsatile flow of aortic valve

Objective To investigate the influence of different angles between the ventricular flow chamber and the aortic lumen on the mechanical performance of aortic valve. Methods Based on the angles of ventricular flow in CT images obtained from Wuhan Union Hospital, three models of aortic root with different angles(0°, 16.5°, 30°)of ventricular flow chamber were manufactured by using 3D printing technique. Artificial bioprosthetic valve was assembled in the aortic models, and experiments of pulsatile flow in a simulation system of pulsatile circulation were performed under different cardiac output conditions. The heart rate was 70 times/min,and the flow rates of pulsatile flow were 2,3,4,5,6,7 L/min respectively. In this condition, the transvalvular pressure gradients, the regurgitation fraction and effective orifice area were measured. The tests were carried out for ten times under each pulsatile flow condition, and the mean values of the ten tests were obtained for the final result. Results The transvalvular pressure gradients for the heart valve prosthesis models with different angles of ventricular flow chamber were different, yet all of them satisfied the standard and less than 10 mmHg. For the case of low cardiac output,smaller angle of ventricular flow chamber facilitated the decrease of the regurgitation fraction,while larger angle of ventricular flow chamber facilitated the increase of the effective valve orifice area;for the case of high cardiac output,smaller angle of ventricular flow chamber facilitated the increase of the effective valve orifice area. Conclusions Surgeons can select applicable angle of ventricular flow chamber according to the patient parameters.