二尖瓣狭窄及人工瓣膜置换左室流场的超声向量血流图

Left Ventricular Flow in Patients with Mitral Valve Stenosis and Bileaflet Prosthesis Mitral Valve by Vector Flow Mapping Using Doppler Ehocardiography

目的应用超声向量血流图技术(VFM)对比风湿性心脏病二尖瓣狭窄、人工机械二尖瓣置换及人工生物二尖瓣置换后的左室流场变化规律,为临床评估手术指征、判断预后提供更客观、更丰富的参考依据.方法选取50例健康志愿者为对照组,43例临床诊断风湿性心脏病二尖瓣重度狭窄为病例组0,临床诊断风湿性心脏病二尖瓣重度狭窄人工机械瓣术后32例,人工生物瓣膜术后的患者26例,分别为病例组1、病例组2,记录3个心动周期,经过DSA-RSl脱机软件处理并进行漩涡描述参数测量.结果疾病组0、病例组1、病例组2观察结果均显示舒张期仅在舒张早期二尖瓣叶下方出现2个高速密集且对称旋转的小漩涡,这一现象与对照组相似,但是形态更加显著,漩涡中心位置更远离二尖瓣环连线水平,速度更快;二尖瓣人工机械瓣置换术后左心室内流场变化为舒张早期最大向量速度仍然大于对照组(P<0.05);二尖瓣人工生物瓣置换术后左心室内流场变化为舒张早期最大向量速度与对照组差异无统计学意义(P>0.05),但二尖瓣人工机械瓣置换及生物瓣置换术后左心室内血流主流方向均为室间隔转向至左室后壁、侧壁再汇入左室流出道,与正常对照组不同.结论 VFM图像能显示心室内血液流场的变化,能初步定量心腔内复杂流场结构,同时也可以为二尖瓣狭窄的评估、置换瓣膜选择及术后人工瓣膜功能评估提供更详尽的信息.

Objective To investigate the dynamic changes of left ventricle（LV） vortices in the patients with rheumatic heart disease mitral stenosis and after mitral valve replacement in mechanical valve or bioprosthetic valve prosthesis, in order to provide richer and more objective prognosis for the clinical evaluation of surgical indications,postoperative effectevaluation and follow- up judgments.Methods We selected 50 cases of healthy volunteers as a control group, 43 patients with rheumatic mitralv stenosis（case 0）, 32 patients with mechanical mitral valve prosthesis（case 1） and 26 patients with bioprosthetic valve prosthesis（case 2）, and assessed the parameters by Aloka Prosound α10.Images for flow visualization were acquired on VFM recorded of three heartbeat cycle,adjusting image width,depth,and spatial- temporal settings to obtain the highest possible frame rate while vector flow- mapping data, including parameters defining location, duration, rotation direction, intensity, and size of the detected vortices were measured after with DAS- RS1 software analyzed offline.Results The observation results of each case group showed that only in the early diastolic phase two high- intensitive and symmetrical rotation of the small vortex components appeared below the mitral valve near the apical side during the left ventricular diastolic.Compared with normal group, this phenomenon in case1 was more obvious, and vortex center position was further far away from the mitral annulus line level,had faster flow velocity vector in all the above cases.The changes of left ventricular diastolic flow field indicated the maximum speed was still higher in early diastolic phase than that of control group（P〈0.05）.Nevertheless, there was few significant difference between case 2 and control group（P〈0.05）.Different with control group, the mainstream direction of blood flow of left ventricle turned from ventricular septal to posterior wall and lateral wall,then to the left ventricular outflow tract in case1 and case2.Conclusion VFM images can reflect the changes of left ventricular flow field through quantifying LV vorticit parameters.VFM technology does help to evaluate hemodynamics of the normal and abnormal left ventricular flow field, thus provide more detailed information for assessment of preoperative valvular stenosis and postoperative prosthesis function and prosthesis selection.