P52714D-flow cardiac magnetic resonance analysis of left ventricular blood flow dynamics in mid-ventricular obstructive hypertrophic cardiomyopathy

Abstract

Abstract Background Mid-ventricular obstructive hypertrophic cardiomyopathy (MVO-HCM) has different blood flow dynamics from other phenotypes, but there are few detailed data on blood flow dynamics in the left ventricle. Methods 4D-Flow MRI were performed at 1.5 T or 3 T with 9 MVO-HCM patients and 22 control patients (LVEF>50%, no wall motion abnormality). Myocardial infarction, severe valvular disease, HCM cases other than MVO were excluded. We calculated the cardiac function parameters and observed blood flow dynamics in the left ventricle using 4D-Flow MRI. Results LV mass was significantly higher in MVO-HCM group than in Control group (Control group; 73.3g vs MVO-HCM group; 109.5g, P=0.019). LVEF was higher in MVO-HCM group (Control group; 61.6% vs MVO-HCM group; 70.6%, P=0.026), but Stroke volume did not differ between the two groups (Control group; 68.8ml vs MVO-HCM group; 64.4ml, P=0.43).One or two vortices were observed in the left ventricle after opening the mitral valve. Two vortices were observed in 16 cases (72.7%) in the control group and 9 cases (100%) in the MVO-HCM group. Two vortices were formed on the anterior side and the posterior side. Blood flow pattern in which the vortex on the posterior side was formed to be the same size or larger than the vortex on the anterior side was observed only in the MVO-HCM group (Control group; 0% vs MVO-HCM group; 66.7%, P<0.001). Streamline of MVO-HCM & Control Conclusion Characteristic blood flow patterns in the left ventricle of the MVO-HCM were revealed by using 4D-MRI. We thought that blood flow collides with the left ventricle wall due to the marked hypertrophy in the mid-ventricle, and normal vortex ring can not be formed in the MVO-HCM cases.