Blood pressure readings are given in two numbers. The top number is the maximum pressure your heart exerts while beating (systolic pressure), and the bottom number is the amount of pressure in your arteries between beats (diastolic pressure). The numeric difference between your systolic and diastolic blood pressure is called your pulse pressure. For example, if your resting blood pressure is 120/80 millimeters of mercury (mm Hg), your pulse pressure is 40 — which is considered a normal and healthy pulse pressure.
A high pulse pressure may be a strong predictor of heart problems, especially for older adults. Generally, a pulse pressure greater than 40 mm Hg is abnormal. A pulse pressure lower than 40 may mean you have poor heart function, while a higher pulse pressure may mean your heart's valves are leaky (valve regurgitation).
The most important cause of elevated pulse pressure is stiffness of the aorta, the largest artery in the body. The stiffness may be due to high blood pressure or fatty deposits on the walls of the arteries (atherosclerosis). The greater your pulse pressure, the stiffer and more damaged the vessels are thought to be. Other conditions — including severe iron deficiency (anemia) and overactive thyroid (hyperthyroidism) — can increase pulse pressure as well.
Treating high blood pressure usually reduces pulse pressure as well.