High blood pressure, also known as hypertension, is a condition in which the force of the blood against the artery walls is consistently too high. Blood pressure is measured in millimeters of mercury (mm Hg) and is recorded with two numbers: systolic pressure (the higher number, indicating the pressure in the arteries when the heart beats) and diastolic pressure (the lower number, indicating the pressure in the arteries when the heart rests between beats). A reading of 140/90 mm Hg or higher is generally considered hypertension.
