Maximal efficiency of cardiac filling requires that blood entering the LV decelerate and
mix evenly before energy is spent. This requires a rapid rollup of the flowing blood
into the vortical structures within the left ventricle. The strength and efficiency of
vortex rollup can be measured in terms of the maximum amount of the circulation
attained by the vortex during the formation process. Formation number, a descriptor of
vortex formation, in its non-dimensional form (f = ut/D, where u = mean velocity
over inflow period, t = inflow period, D = mitral annulus diameter) would be
expected to stay within a narrow range. We performed both in vitro and clinical studies
to quantify this parameter
