Vortices Formed on the Mitral Valve Tips Aid Normal Left Ventricular Filling

Abstract

For the left ventricle (LV) to function as an effective pump it must be able to fill from a low left atrial pressure. However, this ability is lost in patients with heart failure. We investigated LV filling by imaging the cardiac blood flow using 2D phase contrast magnetic resonance imaging and quantified the intraventricular pressure gradients and the strength and location of vortices. In normal subjects, blood flows towards the apex prior to the mitral valve opening, and the mitral annulus moves rapidly away after the valve opens, with both effects enhancing the vortex ring at the mitral valve tips. Instead of being a passive by-product of the process as was previously believed, this ring facilitates filling by reducing convective losses and enhancing the function of the LV as a suction pump. The virtual channel thus created by the vortices may help insure efficient mass transfer for the left atrium to the LV apex. Impairment of this mechanism contributes to diastolic dysfunction, with LV filling becoming dependent on left atrial pressure, which can lead to eventual heart failure. Better understanding of the mechanics of this progression may lead to more accurate diagnosis and treatment of this disease.

Doppler vortography - Detection and quantification of the vortices in the left ventricle

“…Our quantitative analysis of the anterior and apical vortices by estimating their vorticity could help to improve the assessment of the heart function in the echocardiographic laboratory. The recent research studies have also revealed an emerging clinical interest for characterization of intra-ventricular flow velocities and supported our findings in this research study [1,2,45,46,62,63,85,86,94,132,133]. Rodevand et al…”

Left Ventricular Fluid Mechanics: The Long Way from Theoretical Models to Clinical Applications

“…31 Using twodimensional CMR it was also demonstrated that the vortex formation facilitates the LV filling process with relatively low pressure gradients. 11 On these premises, a method able to depict vortex dynamics and quantify IVPGs could be of great value in understanding the effects that the complex heterogeneity in timing of regional loading (or unloading) conditions could exert in triggering and maintaining the spiral of events leading to LV remodeling and heart failure. Moreover, it was shown by Echo-PIV that the LV vortex formation process is immediately modified, within few heartbeats, by de-activation of pacing therapy, despite changes in the tissue dynamics could not be evidenced.…”

Quantification of 4D Left Ventricular Blood Flow in Health and Disease

“…in the heart can be measured. Intracardiac pressure cannot be measured non-invasively; however, relative pressure can be calculated from measured velocity data (15,31,89,102).…”