Hypertension - High Blood Pressure

Blood pressure is expressed in millimeters of mercury, or mm Hg. High blood pressure is defined as a systolic blood pressure reading greater than 140 mm Hg or a diastolic blood pressure reading greater than 90 mm Hg. The systolic blood pressure is the top number of a blood pressure reading. This shows the maximum pressure in the blood vessels. Pressure is highest as the heart contracts and circulates blood throughout the body. The diastolic blood pressure is the bottom number of a blood pressure reading. It shows the lowest pressure in the blood vessels. Pressure is lowest between heartbeats, when the heart is at rest.

The National Institutes of Health has further defined high blood pressure. These categories are for people 18 years and older who do not take medication for high blood pressure and do not have a short-term serious illness. These categories are as follows.

What is going on in the body?

The heart, blood vessels, brain, and kidneys control blood pressure. Blood pressure is also controlled by the amount of fluid and salt in the body. Certain hormones in the body can affect both blood vessels and body fluids. The force of the contraction of the heart can also affect blood pressure.

In most people who have high blood pressure, the cause is unknown. In this case, high blood pressure is called primary, or essential, hypertension.

What are the causes and risks of the condition?

Ninety to 95% of the time, high blood pressure is labeled as essential hypertension. This means that the cause is unknown. The American Heart Association has identified both controllable and noncontrollable risk factors for high blood pressure.

Uncontrollable risk factors for high blood pressure include age, heredity, and race. In men, high blood pressure occurs most often between 35 and 50 years of age. In women, it generally starts after menopause. An individual is more likely to develop high blood pressure if his or her parents or close relatives have it. Certain races have a higher incidence of high blood pressure. For example, African Americans develop high blood pressure earlier and more often than Caucasians.

Controllable risk factors for high blood pressure include the following:

Secondary high blood pressure is caused by one of the following conditions:

What are the signs and symptoms of the condition?

Often, a person will have high blood pressure without any symptoms. Over time, however, a person may develop any or all of the following symptoms:

The main sign of high blood pressure is an elevated systolic or diastolic blood pressure. Blood pressure tends to rise with stress or exercise. It should return to normal when the person is at rest.

How is the condition diagnosed?

The diagnosis of high blood pressure is made on the basis of many blood pressure readings. It is diagnosed if several readings show a systolic blood pressure greater than 140 or a diastolic blood pressure greater than 90. Other tests may be ordered to look for conditions causing the high blood pressure.

What can be done to prevent the condition?

The American Heart Association guidelines to reduce high blood pressure include:

What are the long-term effects of the condition?

Uncontrolled high blood pressure can lead to many serious long-term effects. Damage can occur in the brain, kidneys, and heart. There can also be blood vessel damage to the eye. High blood pressure can lead to serious health issues, including the following:

What are the risks to others?

High blood pressure is not contagious and poses no risk to others.

What are the treatments for the condition?

Secondary high blood pressure can sometimes be controlled by treating the underlying condition. Effective treatment of Cushing's syndrome may lower blood pressure. Open heart surgery to correct coarctation of the aorta can correct high blood pressure.

There are many types of medications used to treat high blood pressure. The medications are classified as follows:

Calcium channel blockers have been used for more than 20 years to treat high blood pressure. However, the findings of two recent studies have shown that people who take a calcium channel blocker have a much higher incidence of complications than people taking other medications for high blood pressure. One study, for example, found that the risk of heart attack was 27% greater. The risk of congestive heart failure was 26% higher. The American Heart Association recommends discussing the risks and benefits of the medication with the healthcare provider.

The choice of medication varies depending on a person's medical history. Beta-blockers usually are avoided in someone with breathing problems such as asthma. ACE inhibitors and diuretics are especially useful for people with kidney disease or diabetes. A person who has high blood pressure may be on multiple medications.

The goal of treatment is to keep the top number below 140 and the bottom number below 90. In a person with diabetes, the goal is to keep the top number below 130 and the bottom number below 85. For an individual with heart disease or kidney disease, the goal is to get the blood pressure as low as can be tolerated.

What are the side effects of the treatments?

The side effects of treatment of high blood pressure vary according to the medications used. Beta-blockers can worsen asthma. Diuretics can cause dehydration and salt imbalance. Calcium channel blockers can cause swelling of the legs, as well as a higher risk of heart attack and congestive heart failure. ACE inhibitors may lead to chronic dry cough.

What happens after treatment for the condition?

A person who has high blood pressure needs to continue to take the prescribed medications daily. Blood pressure may return to normal as a result of lifestyle changes. These changes include weight loss, increased physical activity, reduction of alcohol intake, and a diet low in sodium. In most cases, a person will need to continue to take blood pressure medications for life.

How is the condition monitored?

High blood pressure is monitored through frequent visits to a healthcare professional. A person who has high blood pressure often records blood pressure readings between office visits. Any new or worsening symptoms should be reported to the healthcare provider.

Author:Bill Harrison, MD
Date Written:
Editor:Ballenberg, Sally, BS
Edit Date:04/30/01
Reviewer:Eileen McLaughlin, RN, BSN
Date Reviewed:08/09/01