Vortex ring mixing in the left ventricle of the human heart

Background During rapid filling of the left ventricle, a vortex ring forms downstream from the mitral valve. Previous experiments in water tanks have shown that vortex ring formation is an optimized method for fluid transport. The rotation of the vortex ring leads to mixing of the inflowing blood and blood that was already in the ventricle (Figure 1). In water tanks, the amount of mixing decreases with increasing vortex formation ratio (VFR), a dimensionless parameter relating inflowing volume to the annulus diameter (Figure 2). However, the flow and anatomy of the left ventricle is more complex which may affect this established relationship. Therefore, we aimed to investigate if the relationship between VFR and mixing ratio demonstrated in water tank experiments holds in the human heart.