Pulse pressure is the difference between systolic pressure and diastolic pressure. Although it has been possible to determine pulse pressure ever since blood pressure has been measured, pulse pressure has been overshadowed by its more well-known counterparts—systolic blood pressure, diastolic blood pressure, and mean arterial pressure. As a result, guidelines for managing elevated blood pressure have focused mainly on increases in these three pressures and very little on changes in pulse pressure.
Changes in blood pressure vary considerably throughout the systemic circulation. As illustrated in figure below, pulse pressure is highest in the aorta and other large arteries, lower in the arterioles, and absent in the capillaries.
Figure: Variability of blood pressure in the circulatory system with each heartbeat. Pulse pressure is highest in the aorta and absent in the capillaries. From Guyton AC, Hall JE. Textbook of Medical Physiology, 10th ed. Philadelphia: WB Saunders, 2000, p. 145.
From a blood flow perspective, blood pressure is the force that blood exerts against the vessel wall, causing the wall of an artery to stretch outward. Systolic pressure determines how far an arterial wall needs to stretch; the diastolic pressure determines how much the wall recoils. The difference between these pressures is the pulse pressure, which is closely associated with the stretching and therefore stretching injury. The stretching injury to the arterial wall leads to arterial stiffness.
When the aorta and large arteries grow stiff from loss of compliance, diastolic pressure falls while systolic pressure increases. This leads directly to an increase in pulse pressure.