<P> Early diastole is a suction mechanism between the atrial and ventricular chambers . Then , in late ventricular diastole , the two atrial chambers contract ( atrial systole ) , causing blood pressure in both atria to increase and forcing additional blood flow into the ventricles . This beginning of the atrial systole is known as the atrial kick -- see Wiggers diagram . The atrial kick does not supply the larger amount of flow ( during the cardiac cycle ) as about 80 per cent of the collected blood volume flows into the ventricles during the active suction period . </P>
about 80 of blood is passed from the atria to ventricles by
the active suction period