The amount of blood ejected from the left ventricle during the contraction of the heart is called as stroke volume. During heart failure, there is not enough blood pumped to the cells, which causes organs to fail. The stroke volume is determined by three basic factors like preload, contractility and after load. The stroke volume index formula is used by the health cares to find any changes in the volume of blood. The stroke volume index is found by dividing the stroke volume and BSA.