High Blood Pressure Numbers
Blood pressure is expressed in millimeters of mercury, or mm Hg. High blood pressure is defined as a systolic blood pressure reading greater than 140 mm Hg or a diastolic blood pressure reading greater than 90 mm Hg. The systolic blood pressure is the top number of a blood pressure reading. This shows the maximum pressure in the blood vessels. Pressure is highest as the heart contracts and circulates blood throughout the body.