Each time the heart beats (about 60 to 70 times a minute at rest) it pumps blood out into the blood vessels.
When the heart is pumping the blood, it is called systolic pressure.
When the heart is relaxing in between beats, your blood pressure falls; this is the diastolic pressure.
A normal blood pressure is less than 120 (systolic)/80 (diastolic). If the blood pressure is slightly above this, but not yet high enough to be called true hypertension, it is currently called “pre-hypertension.” This term implies that there is a risk of such mild elevation of blood pressure. Although this risk is not as great as with higher blood pressure, the lowering of the pressure is still important.
The higher the pressure over 120/80, the higher the risk of developing cardiovascular complications. Studies show that the association of risk of dying of a heart attack with different levels of blood pressure rises as blood pressure rises. The higher your blood pressure, the higher your risk.
Many people develop high blood pressure during their lifetime. Left untreated, high blood pressure can damage the eyes, kidneys, heart and brain. High blood pressure is a factor in 68 percent of all first heart attacks and 75 percent of all first strokes.
If high blood pressure is left untreated, it can cause:
Enlarged and thickened heart - If the heart has to work harder and longer, it tends to become larger and thicker. Eventually, the heart muscles stretch too much or get too thick. The blood supply to the heart itself, which travels through tiny pipes, called coronary arteries, has difficulty reaching the enlarged and thickened heart. As the heart’s own blood supply falls, the heart begins to suffer and fail.
Much like a body builder who has thick muscles and looks very “stiff” after exercising, the heart also becomes stiff as it thickens. Unfortunately for the heart, this thickening prevents it from relaxing, dilating, and filling with blood. This eventually can also lead to heart failure.
stroke - As the blood pressure in the brain increases, damage can occur in the lining of blood vessels, forming aneurysms (weakened areas in the blood vessel that may balloon or rupture). When an aneurysm ruptures, this causes a stroke. Possible paralysis, loss of bodily function and motor skills often result.
Uremia(failure of the kidneys to function properly) - Continued high blood pressure causes damage to blood vessels in the kidneys. This reduces the amount of fluid that the kidney can filter out and thus, a build up of waste products occurs.
atherosclerosis (hardening of the arteries) - The higher the blood pressure, the faster the plaque (collections of fatty material) accumulates in the artery walls.
heart attack - If one of the coronary arteries that supplies blood to the heart is closed off due to atherosclerosis, portions of the heart muscles are damaged and a heart attack can occur.
Vision loss - High blood pressure can cause blood clots or ruptures in the arterioles in the retina, leading to reduced vision or blindness.
In more than 90 percent of all high blood pressure cases, the exact cause is unknown. This is called primary or "essential" hypertension, and it can be associated with the following factors:
- Race - African-Americans develop high blood pressure more often than Anglo-Americans, and it tends to occur earlier and be more severe.
- Sex - men are more likely to develop high blood pressure than women.
- Age - high blood pressure occurs most often in people over the age of 35.
- obesity - people who weigh 30 percent or more above their ideal body weight are more likely to develop high blood pressure.
- Sodium sensitivity
- Alcohol consumption
- Oral contraceptives
- Physical inactivity
- Certain drugs such as diet pills or amphetamines
In the remaining 10 percent of all cases, high blood pressure is attributed to kidney disease, a hormonal imbalance, a narrowing of the artery to a kidney, a tumor of one of the adrenal glands, severe snoring while sleeping (called obstructive sleep apnea) or some other anatomic or physiologic abnormality. These cases are called "secondary hypertension," and the blood pressure usually normalizes when the primary problem is treated.