Hypertension: Also known as high blood pressure is, by definition, a repeatedly elevated blood pressure exceeding 140 over 90 mmHg -- a systolic pressure above 140 or a diastolic pressure above 90. Chronic hypertension is a "silent" condition that does not have symptoms. It can cause blood vessel changes in the back of the eye (retina), abnormal thickening of the heart muscle,?kidney failure, and brain damage.