Hypertension is high blood pressure.
When blood flows freely through healthy, elastic blood vessels, blood pressure measures within the normal range. The harder it is for blood to flow through blood vessels, the higher the blood pressure measurement will be. The top number, or systolic reading, indicates the amount of pressure in the arteries when the heart beats. The lower number, or diastolic reading, shows the amount of pressure in the arteries when the heart rests between beats. Uncontrolled hypertension can lead to coronary heart disease, and can damage the body in a number of ways.