Studies have found that intraventricular pressure continues to fall during rapid filling and negative intraventricular pressures have been reported, suggesting that the ventricle "sucks" blood from the atria, veins, etc. Because the heart is doing work on the blood after contraction ceases, this has caused some physiologists to espouse alternate views of the cardiac cycle, where systole is re-defined as the heart doing work, in whatever form. In this view, systole also includes isovolumic relaxation and rapid filling. See Misconception number 1.