High Blood Pressure

Hypertension, the medical term for high blood pressure, is known as “the silent killer” because it is a serious condition that usually exhibits no symptoms. At least 72 million Americans (1 out of every 3) have high blood pressure, including 20 million who do not know that they have it. Uncontrolled high blood pressure can lead to extremely serious medical conditions: heart attack, heart failure, stroke, kidney failure, or blindness. In fact, most people will develop high blood pressure at some time in their lives because the lifetime risk for developing hypertension has been measured as high as 90 percent.

The heart pumps blood through a network of arteries, veins, and capillaries. The moving blood pushes against the artery walls, and the measurement of this force is the blood pressure. High blood pressure results when the smallest arteries (arterioles, which regulate the blood flow through the body), constrict and tighten. As the arterioles tighten, the heart must work harder to pump blood through the smaller space. This process increases pressure inside the blood vessels, causing hypertension.

What causes high blood pressure?
The cause of high blood pressure is unknown in up to 95% of the cases that are diagnosed as primary, or essential, hypertension, but a number of risk factors are associated with the condition, including:

• Having a family history of high blood pressure.
• Being African American.
• Being a male over the age of 18 or a female over the age of 55.
• Being older than 60 years of age.
• Experiencing high levels of stress.
• Being overweight or obese.
• Using tobacco products, especially smoking cigarettes.
• Using oral contraceptives, especially for women who also smoke cigarettes.
• Eating a diet high in saturated fat or salt.
• Drinking more than a moderate amount of alcohol.
• Being physically inactive.
• Having diabetes.

Additionally, researchers have found a gene that appears to be linked to high blood pressure. Carrying the gene does not absolutely dictate the development of the disease, but it does create a strong enough likelihood that carriers should have their blood pressure closely monitored.

The cause of high blood pressure is known in patients with secondary hypertension. Secondary hypertension occurs as a result of another condition or illness. Many cases of secondary hypertension are caused by kidney disease. Other conditions that may cause secondary hypertension include parathyroid gland problems, acromegaly, adrenal or pituitary gland tumors, reactions to certain medications, and pregnancy.


Most people with high blood pressure have no outward signs or symptoms. In some cases, a pounding feeling in the head or chest, lightheadedness, or dizziness has been reported. With no warning signs or routine checkups, patients can go years without knowing that they have high blood pressure.

Blood Pressure Readings

Blood pressure readings measure both parts of blood pressure: systolic (when the heart beats) and diastolic (when the heart rests).

Systolic pressure is listed first, and the pressure itself is measured in millimeters of mercury (mm Hg). For example, a blood pressure reading of 120/80 mm Hg indicates a systolic pressure of 120 mm Hg and diastolic pressure of 80 mm Hg.


Because hypertension is asymptomatic, adults should have their blood pressure checked yearly. A blood pressure cuff, called a sphygmomanometer, is used to measure blood pressure. Several different measurements are taken to confirm high readings. A stethoscope is used in conjunction with the blood pressure to cuff to listen to the heartbeat and the sound of blood flowing through the arteries. An ophthalmoscope is used to examine the blood vessels in the eyes. If these vessels have become thickened or narrowed or have burst, it may be a sign of high blood pressure. In some cases, a chest x-ray and electrocardiogram (ECG) are also ordered.

A final diagnosis of high blood pressure is usually not made until a patient registers at least two high blood pressure readings on three different days. Some patients are asked to wear a portable machine that measures blood pressure over the course of several days or to have their blood pressure checked daily in a reliable pharmacy or by a public health nurse. Blood pressure readings can also be tracked using the internet.

How High is High?

A blood pressure reading below 120/80 mm Hg is considered normal. Readings that range from 120/80 up to 139/89 are classified as pre-hypertension. Patients with pre-hypertension have twice the risk of developing high blood pressure. A blood pressure measurement of 140/90 or above indicates hypertension. The following table summarizes the blood pressure categories and measurements:

Category Systolic (mm Hg) Diastolic (mm Hg)
Normal Less than 120 Less than 80
Pre-hypertension 120—139 80—89
Stage 1 hypertension 140—159 90—99
Stage 2 hypertension 160 or higher 100 or higher

This classification chart is based on adults who are not taking high blood pressure medicine and who are not acutely ill. If systolic and diastolic measurements fall into different categories, the higher category is used to determine status.

Lifestyle changes are the first treatment option, especially for patients with pre-hypertension. These instructions include:
• Eating a low-fat, low-salt diet.
• Maintaining a healthy weight.
• Exercising daily.
• Managing stress.
• Not smoking.
• Drinking alcohol in moderation, if at all.

If these activities do not control the high blood pressure within 3 to 6 months, then medicines may be used in conjunction with the lifestyle changes. Examples of the types of medicines used include diuretics, ACE inhibitors, beta blockers, calcium channel blockers, and vasodilators.


Texas Heart Institute www.texasheartinstitute.com/HIC/Topics/Cond/hbp.cfm
National Heart, Lung, and Blood Institute www.nhlbi.nih.gov/hbp/hbp/intro.htm
Medline Plus www.nlm.nih.gov/medlineplus/highbloodpressure.html
Minneapolis Heart Foundation www.mplsheartfoundation.org/education/education_riskfactors_highbp.asp
American Heart Association www.americanheart.org/presenter.jhtml?identifier=2114