in the natural aging process, aortic stenosis often increases afterload because the left ventricle must overcome the pressure gradient caused by the calcified and stenotic aortic valve, in addition to the blood pressure required to eject blood into the aorta. for instance, if the blood pressure is 120/80, and the aortic valve stenosis creates a trans-valvular gradient of 30 mmhg, the left ventricle has to generate a pressure of 110 mmhg to open the aortic valve and eject blood into the aorta.