What Is Low Blood Pressure (Hypotension )? (by webmd.com)

Hypotension is the medical term for low blood pressure (less than 90/60) with no symptoms.

A blood pressure reading appears as two numbers. The first and higher of the two is a measure of systolic pressure, or the pressure in the arteries when the heart beats and fills them with blood.

The second number measures diastolic pressure, or the pressure in the arteries when the heart rests between beats.

Normal blood pressure is usually in the range of 120/80 (systolic/diastolic). In healthy people, especially athletes, low blood pressure is a sign of good cardiovascular (heart and blood vessel) health.

But low blood pressure can be a sign of an underlying problem -- especially in the elderly -- where it may cause inadequate blood flow to the heart, brain, and other vital organs.

Chronic low blood pressure with no symptoms is almost never serious. But health problems occur when blood pressure drops suddenly, and the brain is deprived of an adequate blood supply.

This can lead to dizziness or lightheadedness. Sudden drops in blood pressure most commonly occur in someone who's rising from a prone or sitting position to standing.

This kind of low blood pressure is known as postural hypotension, orthostatic hypotension, or neurally mediated orthostatic hypotension.

For more information, please visit http://www.webmd.com/heart/understanding-low-blood-pressure-basics