超声心动图三维灰阶反转流体模型评估肥厚型梗阻性心肌病患者左心室流出道流场改变

Evaluation of fluid field of left ventricle outflow tract in hypertrophic obstructive cardiomyopathy with fluid models based on three-dimensional echocardiography with inverted grey values

目的使用三维超声灰阶反转和计算机流体动力进行肥厚型梗阻性心肌病(HOCM)左室流出道(LVOT)的流程构建,探索二尖瓣前移(SAM)对LVOT形态与功能的影响。方法选取2016年4月至2019年10月在武汉大学人民医院住院就诊的HOCM患者40例,将其分为SAM组(24例)和非SAM组(16例),采集患者二维及三维超声心动图数据。基于三维超声心动图数据后处理构建LVOT形态模型,基于时间-容积曲线获得左室流量数据并构建LVOT流场模型。在模型中测量LVOT峰值流速并评估与超声测量值的一致性;测量LVOT面积、平均流速、流量率和不同水平的涡流面积,并进行组间比较。结果心脏流体模型LVOT流速与超声测量值的相关性良好(r=0.943,P<0.01),Bland-Altman一致性区间为-75.0~111.3,92.5%的点分布在一致性界限之内。与非SAM组相比,SAM组LVOT峰值流速增高,LVOT面积减小,流量率减低,涡流面积增加(均P<0.01)。SAM组中16例患者模型中由SAM与室间隔接触将LVOT分割为双孔结构,1例患者SAM与室间隔接触构成单孔LVOT结构,7例患者SAM未与室间隔接触构成单孔流出道结构。与非SAM组相比,SAM组中双孔流出道亚组中LVOT峰值流速更高,LVOT面积更小且高水平涡流面积更大(均P<0.05)。结论基于三维超声灰阶反转技术可以构建准确的SAM患者LVOT的流体模型。在SAM患者中由于二尖瓣和室间隔的接触导致LVOT双孔结构的形成和涡流水平的增加。

Objective To explore the effect of systolic anterior motion(SAM)of mitral valves on the morphology and function of left ventricular outflow tract(LVOT)in patients with hypertrophic obstructive cardiomyopathy(HOCM)using computer fluid dynamics based on three-dimensional echocardiography with inverted grey values.Methods A total of 40 patients with hypertrophic cardiomyopathy were divided into SAM group(24 cases)and non SAM group(16 cases)in Renmin Hospital of Wuhan University from April 2016 to October 2019.Two dimensional and three-dimensional echocardiographic data of the patients were collected.The LVOT morphological model was constructed based on the post-processing of three-dimensional echocardiography data,and the LVOT flow field model was constructed based on the time-volume curve of left ventricle.LVOT peak velocity was obtained to assess the agreement with echocardiography measurements.Area of LVOT,average velocity,flow rate and iso-surface area of vortex of different levels were obtained and compared between the two groups.Results There was a good correlation between cardiac fluid model and echocardiographic measurement(r=0.943,P<0.01).The Bland-Altman consistency interval was-75.0-111.3,and 92.5%of the points were within the consistency limit.Compared with non-SAM group patients,the peak velocity of LVOT increased,the area of LVOT decreased,the flow rate decreased and the area of vortex increased in SAM patients(all P<0.01).In the SAM group,in 16 patients the double orifice LVOT was observed due to the contact between mitral valve and septum,in 1 patient the single orifice LVOT structure was observed with contact between mitral value and septum,and in 7 patients,single orifice LVOT without contact between mitral value and septum.In SAM patients,compared with single orifice LVOT,patients with double orifice LVOT were observed with higher LVOT velocity,smaller LVOT area and higher vortex area with high level(all P<0.05).Conclusions Accurate fluid models can be obtained using three-dimensional echocardiography with inverted grey values.In SAM patients,contact between mitral valve and septum leads to the formation of double orifice structure and the increase of vortex level in LVOT.