Pulse pressure is the systolic blood pressure minus the diastolic blood pressure. The systemic pulse pressure is approximately proportional to stroke volume, or the amount of blood ejected from the left ventricle during systole and inversely proportional to the compliance of the aorta. The aorta has the highest compliance in the arterial system due in part to a relatively greater proportion of elastin fibers versus smooth muscle and collagen. This serves the important function of damping the pulsatile output of the left ventricle, thereby reducing the initial systolic pulse pressure but slightly raising the subsequent diastolic phase. If the aorta becomes rigid because of disorders such as arteriosclerosis or atherosclerosis, the pulse pressure would be very high because the aorta becomes less compliant due to the formation of rigid lesions to the aorta wall.
A pulse pressure is considered abnormally low if it is less than 25% of the systolic value. The most common cause of a low pulse pressure is a drop in left ventricular stroke volume. In trauma, a low or narrow pulse pressure suggests significant blood loss. If the pulse pressure is extremely low, i.e. 25 mmHg or less, the cause may be low stroke volume, as in Congestive Heart Failure and/or cardiogenic shock. A narrow pulse pressure is also caused by aortic valve stenosis and cardiac tamponade.
High (Wide) Pulse Pressure
High values during or shortly after exercise
Usually, the resting pulse pressure in healthy adults, sitting position, is about 30–40 mmHg. The pulse pressure increases with exercise due to increased stroke volume, healthy values being up to pulse pressures of about 100 mmHg, simultaneously as systemic vascular resistance drops during exercise. In healthy individuals the pulse pressure will typically return to normal within about 11 minutes. For most individuals, during aerobic exercise, the systolic pressure progressively increases while the diastolic remains about the same. In some very aerobically athletic individuals, for example distance runners, the diastolic will progressively fall as the systolic increases. This behavior facilitates a much greater increase in stroke volume and cardiac output at a lower mean arterial pressure and enables much greater aerobic capacity and physical performance. The diastolic drop reflects a much greater fall in systemic vascular resistance of the muscle arterioles in response to the exercise. Individuals with larger BMIs due to increased muscle mass have also been shown to have lower diastolic pressures and larger pulse pressures.
Recent work suggests that a high pulse pressure is an important risk factor for heart disease. A meta-analysis in 2000, which combined the results of several studies of 8,000 elderly patients in all, found that a 10 mm Hg increase in pulse pressure increased the risk of major cardiovascular complications and mortality by nearly 20%. Heightened pulse pressure is also a risk factor for the development of atrial fibrillation. The authors of the meta-analysis suggest that this helps to explain the apparent increase in risk sometimes associated with low diastolic pressure, and warn that some medications for high blood pressure may actually increase the pulse pressure and the risk of heart disease.
Self measurement
Pulse pressure readings can be taken on a home blood pressure monitoring device. These devices display systolic and diastolic blood pressure and pulse rate readings. Monitoring at home can be helpful to a medical provider in interpreting in-office results and progression of disease processes.
Treatment
If the patient suffers from elevated pulse pressure, treatment may include medications that address this factor, such as an angiotensin-converting enzyme inhibitor.
A 2005 study found that 5 mg of folate daily over a three-week period reduced pulse pressure by 4.7 mm of Hg compared with a placebo, and concluded that folic acid is an effective supplement that targets large artery stiffness and may prevent isolated systolic hypertension. A longer-term study in 158 clinically healthy siblings of patients with premature atherothrombotic disease also found an effect of folic acid plus pyridoxine on pulse pressure, but the effect was not independent of mean arterial blood pressure, and there was no effect on common carotid artery stiffness.
