血流向量图评价功能性二尖瓣反流对扩张型心肌病患者左室流场的影响

Evaluation of functional mitral regurgitation on left ventricular flow field in patients with dilated cardiomyopathy by vector flow mapping

目的:应用血流向量图(vector flow mapping,VFM)观察合并二尖瓣反流时扩张型心肌病(dilated cardiomyopathy,DCM)患者左室流场特点和涡流的演变规律,探讨功能性二尖瓣反流(functional mitral regurgitation,FMR)对左室内流场影响的意义。方法:严格按标准选取在我院诊断为DCM的门诊及住院患者107例,按照美国超声心动图指南标准,未见或无法测得二尖瓣反流患者36例为无FMR组;其余71例为FMR组,其中轻-中度反流43例,重度反流28例。所有患者均行超声心动图检查,依次测量左室短轴舒张末内径(left ventricular end- diastolic diameter,LVEDD)及收缩末内径(left ventricular end-systolic dimension,LVESD),左室舒张末容积(left ventricular end-diastolic volume,LVEDV)及收缩末容积(left ventricular end-systolic volume,LVESV),二尖瓣反流容积(mitral reflux volume,MRV),并计算左室射血分数(left ventricle ejection fractions,LVEF)。利用VFM软件采集左室内血流向量图像,启用涡流模式图,测量时相选取二尖瓣关闭、主动脉瓣开放和收缩期涡流结束瞬间。结果:两组基本情况比较,FMR组重度反流患者NYHA心功能分级高于无FMR组、FMR组及轻-中度反流患者( P <0.05),其余指标无显著差异。超声指标显示左室大小容积及球形指数均随着反流程度的加重而变化,其中重度反流患者射血分数减低明显( P <0.05)。对于患者流场的观察发现全部患者均在二尖瓣关闭前形成左室整体涡流。87%的患者涡流持续整个收缩期,整体呈现涡流中心向心尖部左室前方移动的规律,涡流持续减小。通过相关分析寻找反流程度与主要流场参数间的关系,发现参数间存在一定相关性,其中PISA法测得的反流量与主动脉瓣开放瞬间涡流中心纵向位置间呈显著负相关,相关系数为0.74。结论: FMR对于DCM患者左室内收缩期流场有多方面的影响,造成血流结构多变,对血流动力学结果的影响效应也十分复杂。VFM技术能够无创、客观地反映不同程度FMR对DCM患者左室内收缩期流场演变规律的影响,开辟了FMR相关流场研究的新领域,有望在慢性心力衰竭的诊断、治疗和评估中发挥更大价值。

Objective: To observe the changes of left ventricular flow field and eddy current in patients with dilated cardiomyopathy(DCM) and mitral regurgitation by vector flow mapping(VFM),and to explore the effect of functional mitral regurgitation(FMR) on left ventricular flow field. Methods: A total of 107 outpatient and inpatient patients diagnosed as DCM in our hospital were selected strictly according to the criteria,36 patients with no functional mitral regurgitation (FMR) were selected as the non-FMR group,and the other 71 patients were selected as FMR group,43 patients with light-medium FMR,and 28 patients with severe FMR.The echocardiographic examination was performed,and the regular indices were measured including left ventricular end diastolic diameter(LVEDD),left ventricular end-systolic dimension (LVESD),left ventricular end-diastolic volume(LVEDV),left ventricular end-systolic volume(LVESV),mitral reflux volume(MRV) and left ventricle ejection fractions(LVEF).Left ventricular blood flow vector image were acquired by VFM software.Measured at mitral valve closing moment,aortic opening moment and the end of the systolic vortex. Results: The cardiac function grade of NYHA in the severe FMR patients was higher than that in non-FMR group and light-medium FMR patients( P <0.05),but there was no significant difference in the other indexes.Ultrasound showed that the volume of left ventricle and the spherical index changed with the severity of regurgitation.The ejection fraction of severe FMR patients was reduced significantly ( P <0.05).All patients developed left ventricular global eddy current before mitral valve regurgitation.The 87% of the patients sustained the whole systolic phase,and showed the rule that the center of eddy current moved forward to the apex of the heart.The eddy current size continues to decrease.The relationship between the degree of regurgitation and the parameters of the main flow field was found by correlation analysis .There was a significant negative correlation between the regurgitation measured by the PISA method and the longitudinal position of the vortex center at the moment of aortic valve opening .The correlation coefficient was 0.74. Conclusion: FMR effected the systolic flow field in the left ventricle of patients with DCM,which makes the structure of the blood flow varied and the effect on the hemodynamic results is very complex.This paper objectively reflects the influence of different degrees of FMR on the evolution of systolic flow field in left ventricle of DCM patients ,and opens up a new field of FMR related flow field research.It is expected to play a greater role in the diagnosis,treatment and evaluation of chronic heart failure.