Systolic pressure, which is the higher number and first number in a blood pressure reading, measures the force of blood in the arteries as the heart contracts to push blood through the body. Doctors consider a systolic blood pressure greater than 120 mm Hg (millimeters of mercury) as unhealthy and it can lead to heart disease, stroke and vascular diseases of the legs. Diastolic pressure, the lower number, measures the pressure as the heart relaxes to fill with blood. A diastolic pressure greater than 80 mm Hg is also considered unhealthy. Pulse pressure is the difference between the diastolic and systolic readings. There is some controversy in the medical community over whether the monitoring of systolic, diastolic, or pulse pressure should be the focus in treating hypertension.
Researchers from Johns Hopkins studied the effects of high systolic and diastolic blood pressure simultaneously and found a direct and consistent correlation between increased systolic blood pressure and an increased risk of death from cardiovascular disease and for all other causes among all of the study participants. If you have high blood pressure, drugs may be necessary, but they will never "cure" the problem. Only lifestyle changes can do that. Additionally, many people with high blood pressure are overweight, so don't be fooled--make sure that you or your doctor uses an appropriate size cuff that is large enough for your arm.
Annals of Internal Medicine November 4, 2003