*8.3.3 Hypertension*

Hypertension or high blood pressure occurs when the blood exerts an excessive force against the walls of the blood vessels. In other terms, a persistently elevated blood pressure of more than 140 mmHg over 90 mmHg (i.e. a systolic pressure greater than 140 or diastolic pressure greater than 90) is considered to be hypertension. The most severe form of hypertension is chronic hypertension, which is an asymptomatic "silent" illness. It can lead to alterations in the retinal blood vessels, brain damage, kidney failure, and atypical thickening of the cardiac muscle.
