BLOOD PRESSURE

What Is Blood Pressure?

Blood pressure is the force of blood against the walls of arteries. Blood pressure is recorded as two numbers—the systolic pressure (as the heart beats) over the diastolic pressure (as the heart relaxes between beats). The measurement is written one above or before the other, with the systolic number on top and the diastolic number on the bottom. For example, a blood pressure measurement of 120/80 mmHg (millimeters of mercury) is expressed verbally as "120 over 80."

Normal blood pressure is less than 120 mmHg systolic and less than 80 mmHg diastolic. 

High Blood Pressure

High blood pressure increases your chance (or risk) for getting heart disease and/or kidney disease, and for having a stroke. It is especially dangerous because it often has no warning signs or symptoms. Regardless of race, age, or gender, anyone can develop high blood pressure. It is estimated that one in every four American adults has high blood pressure. Once high blood pressure develops, it usually lasts a lifetime. You can prevent and control high blood pressure by taking action.

What Causes High Blood Pressure?

The causes of high blood pressure vary. Causes may include narrowing of the arteries, a greater than normal volume of blood, or the heart beating faster or more forcefully than it should. Any of these conditions will cause increased pressure against the artery walls. High blood pressure might also be caused by another medical problem. Most of the time, the cause is not known. Although high blood pressure usually cannot be cured, in most cases it can be prevented and controlled.

Effect of High Blood Pressure on Your Body

Its effects on the brain, eyes, arteries, kidneys, and heart to get a closer look at what high blood pressure does to these organs. 

Stroke

High blood pressure is the most important risk factor for stroke. Very high pressure can cause a break in a weakened blood vessel, which then bleeds in the brain. This can cause a stroke. If a blood clot blocks one of the narrowed arteries, it can also cause a stroke. 

Impaired Vision

High blood pressure can eventually cause blood vessels in the eye to burst or bleed. Vision may become blurred or otherwise impaired and can result in blindness.

Arteries

As people get older, arteries throughout the body "harden," especially those in the heart, brain, and kidneys. High blood pressure is associated with these "stiffer" arteries. This, in turn, causes the heart and kidneys to work harder.

Kidney Damage

The kidneys act as filters to rid the body of wastes. Over time, high blood pressure can narrow and thicken the blood vessels of the kidneys. The kidneys filter less fluid, and waste builds up in the blood. The kidneys may fail altogether. When this happens, medical treatment (dialysis) or a kidney transplant may be needed. 

Heart Attack

High blood pressure is a major risk factor for heart attack. The arteries bring oxygen-carrying blood to the heart muscle. If the heart cannot get enough oxygen, chest pain, also known as "angina," can occur. If the flow of blood is blocked, a heart attack results.

Congestive Heart Failure

High blood pressure is the number one risk factor for congestive heart failure (CHF). CHF is a serious condition in which the heart is unable to pump enough blood to supply the body's needs.

Prevention

You can take steps to prevent high blood pressure by adopting a healthy lifestyle. These steps include maintaining a healthy weight; being physically active; following a healthy eating plan, that emphasizes fruits, vegetables, and lowfat dairy foods; choosing and preparing foods with less salt and sodium; and, if you drink alcoholic beverages, drinking in moderation. In this section you will learn more about healthy lifestyle habits for preventing and controlling high blood pressure.

What is low blood pressure?

Many people worry about low blood pressure (hypotension), but probably don't need to.

Some people have a blood pressure level that is lower than normal. In general this may be good news - because the lower your blood pressure is, the lower your risk of stroke or heart disease. However, in a few cases, having low blood pressure can cause problems, so you might need to speak to your doctor or nurse.

What is a low blood pressure reading?

A low blood pressure reading is having a level that is 90/60mmHg, or lower.

Only one of the numbers has to be lower than it should be to count as low blood pressure. In other words:

    if the top number is 90 or less (regardless of the botton number) this may be low blood pressure

    if the bottom number is 60 or less (regardless of the top number) this may be low blood pressure.

What causes low blood pressure?

Some people have a blood pressure level that is naturally low. That is, there is no specific cause or reason why.

However, some health conditions or medicines can cause you to develop low blood pressure.

Is low blood pressure dangerous?

Usually, having low blood pressure is not a cause for concern. However, sometimes your blood pressure can drop to a point where you may feel faint or dizzy.

If you find that your blood pressure is suddenly much lower than usual, there may be a reason for this. Speak to your doctor or nurse.

How is low blood pressure treated?

Most people with low blood pressure will not need treatment.

If your doctor or nurse feels that you would benefit from treatment, they will often try to find a cause for your low blood pressure. If they can find the cause, they should be able to decide on the most appropriate treatment for you.