The pulse wave in the ascending aorta is broad. The ascending portion of the pulse wave is the anachrotic limb and the descending portion is the catachrotic limb. The dichrotic notch on the descending portion results from closure of the aortic valve. The diastolic pressure is found immediately before the beginning of the ascending limb, while the systolic pressure is reached at the peak of the pulse wave. The difference between the two is the pulse pressure.
Systolic pressure is higher in the abdominal aorta than in the ascending aorta, and the diastolic pressure is lower in the former. The femoral artery has an even higher systolic pressure and lower diastolic pressure. Thus in these two peripheral arteries, the systolic pressure increases compared to that closer to the heart. When a small artery in the foot is reached, systolic pressure has fallen back to the value in the ascending aorta; nevertheless, diastolic pressure continues to fall. The pulse wave becomes steeper as it progresses through the arterial tree compared to that in the ascending aorta, with the systolic pressure increasing in the larger arteries for some distance (Figure 10). The diastolic pressure falls steadily. Thus the pulse pressure increases for some distance before beginning to decrease.
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