Mechanism of Early-Diastolic Mitral Regurgitation

A hemodynamically stable 64-year-old man with ischemic cardiomyopathy was referred for echocardiographic evaluation before catheter ablation of ventricular arrhythmias. Echocardiography showed a severely enlarged left ventricle with extended akinetic regions at the apical level and mild functional mitral regurgitation (MR). Pulmonary arterial diastolic pressure estimated from the pulmonary regurgitation velocity was 10 mmHg. Surprisingly, the MR occurred not only in systole but also in early diastole (Figure A, Supplementary Figure; Supplementary Movie). Vector flow mapping (VFM) images revealed that a clockwise vortex under the anterior mitral leaflet existed during the cardiac cycle (Figure B, white arrows) and a counterclockwise vortex occurred just under the aortic valve in the isovolumic relaxation period (IVR) (Figure B4, red arrow), generating blood flow towards the anterior mitral leaflet from the boundary of these vortices, which caused the occurrence of early-diastolic MR (Figure B5, circle). The pressure difference from the left ventricular (LV) outflow tract to the apex at IVR was severely reduced and the early-diastolic pressure was slightly higher in the apex compared with the base (Figure C,D), suggesting loss of LV suction. These findings suggested that boundary friction from sustained clockwise vortex, together with loss of driving pressure from the left atrium to the LV apex due to low left atrial pressure and loss of LV suction, caused the counterclockwise vortex in the LV outflow tract and subsequent early-diastolic MR.

Figure.

Color M-mode Doppler image showing early-diastolic mitral regurgitation (MR) (A). Serial vector flow mapping images from late to early diastole (B). A clockwise vortex generated at late diastole existed through the cardiac cycle, moving to the apical side (white arrows). Thereafter, a counterclockwise vortex occurred (B4, red arrow) and subsequent blood flow towards the anterior mitral leaflet was observed (B5, circle). Intra-left ventricular (LV) pressure relative to mid LV along the LV outflow (C) and LV inflow (D).

Although the presence and physiological significance of late-diastolic MR has previously been recognized, that of early-diastolic MR has not been reported. VFM provided novel information on the mechanism of early-diastolic MR generation.

Conflict of Interest / Funding / Grants

None.

Supplementary Files

Supplementary Movie. Color Doppler image of apical long-axis view demonstrating functional mitral regurgitation, which was observed in systole to early diastole.

Please find supplementary file(s);

http://dx.doi.org/10.1253/circj.CJ-20-0678