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Blood pressure is measured by the contraction of the heart muscle and the force exerted by the smooth muscle cells in the walls of your arteries. The pressure is greatest at the moment blood is pumped by the left ventricle. Blood pressure is measured in the arteries in units of millimeters (mm) of mercury (Hg) in two stages:

• When the heart is contracting (called the systolic reading).
• When the heart is relaxing (called the diastolic reading).
  
  High blood pressure or hypertension is a condition in which the blood pressure is consistently higher than normal. The condition may be mild, moderate or severe. If untreated, hypertension can lead to cardiovascular disease, heart attack, stroke or a kidney problem. A blood pressure of 120/80 or below is optimal, according to the National Institutes of Health. A systolic blood pressure range of 130 to 139 or a diastolic blood pressure of 85 to 89 is considered high normal. Hypertension is present when the blood pressure is consistently 140/90 or above. In severe hypertension, blood pressure exceeds 180/110.

  Risk Factors

  The specific cause of hypertension is unknown in 90% of patients; this condition is called essential or primary hypertension. A variety of factors can put a person at risk for high blood pressure. Some of these factors cannot be modified. For example:
• The risk of hypertension increases with age.
• Hypertension is more common in men than in women until age 55.
  
  The prevalence of hypertension differs among racial and ethnic groups compared to the general population of the United States. For example, the prevalence of hypertension among American Indians is the same or slightly higher than that of the general population, while among Hispanics the prevalence is the same or slightly lower. The prevalence of hypertension in African Americans is among the highest in the world.
  
  Some risk factors can be modified. These include:
• Excess Weight: Overweight individuals have a greater risk of developing high blood pressure. Losing as little as 10 pounds reduces blood pressure in a large proportion of overweight individuals.
• Physical Activity: When compared with their more active and fit peers, inactive individuals have a 20% to 50% increase in their risk of developing hypertension. Blood pressure can be lowered with moderately intense physical activity, which also can enhance weight loss.
• Dietary Sodium: Salt is linked to levels of blood pressure. Individuals with high blood pressure may be more sensitive to the effects of sodium on blood pressure; the same is true of older people and African Americans. Moderate reductions in sodium intake can reduce high blood pressure.
• Potassium: Inadequate potassium intake may increase blood pressure. A diet rich in fresh fruits and vegetables that contains potassium may protect against the development of hypertension.
• Calcium: Low dietary intake is associated with an increased prevalence of high blood pressure.
• Alcohol: Excessive drinking of alcoholic beverages is a risk factor for hypertension.
• Caffeine: While caffeine may raise blood pressure acutely, tolerance to this effect develops rapidly. Therefore, moderate caffeine intake has little long-term effect on blood pressure.
• Stress: Emotional stress can raise blood pressure acutely. The effect of chronic stress is less clear.
• Tobacco: A significant rise in blood pressure results from smoking each cigarette. Smoking has serious immediate and long-term adverse effects on cardiovascular health.
• Oral Contraceptives: In some women, use of oral contraceptives (“the pill”) has been associated with high blood pressure. The combination of cigarette smoking and oral contraceptive use significantly increases the risk for hypertension.
• Diabetes: Individuals with diabetes have a considerably greater chance of developing hypertension than those without diabetes. Almost half of the diabetic population will develop hypertension. Many die from kidney failure, which is aggravated by high blood pressure.

  Diagnosis

  A simple blood pressure check, using a device called a sphygmomanometer, quickly reveals whether a person’s blood pressure is high or low. However, a single check is inadequate for a conclusive diagnosis because blood pressure normally changes throughout the day. Vigorous activity, stress, anxiety, drinking caffeinated beverages, smoking, having a full bladder or eating immediately before having blood pressure checked may cause an inaccurate reading. Multiple checks should be made over a period of one or two months. The average blood pressure is needed for a conclusive diagnosis.

  Symptoms

  Most people with hypertension do not have any symptoms so they don’t know they have this serious health problem. Hypertension is often called “the silent killer” because often the first overt manifestation of undetected and untreated high blood pressure may be a heart attack, stroke or kidney problem.

  Complications

  Hypertension is a major risk factor for all forms of stroke. Hypertension causes the heart to work harder to pump blood. The heart, brain and kidneys are most susceptible to damage from hypertension. If hypertension is not treated, the heart must work harder and harder to pump enough blood and oxygen throughout the body. This extra work may cause the heart to become enlarged, making it more difficult to meet the body’s demands. Specific effects of hypertension include:
• Congestive Heart Failure: The heart is enlarged which compromises its ability to pump blood efficiently.
• Atherosclerosis: The arteries are scarred, less elastic and narrowed with plaque, making it difficult for them to carry blood throughout the body.
• Thrombus: Clots lodge in narrowed arteries, blocking the flow of blood and potentially causing a heart attack or stroke.

  Treatment

  Hypertension cannot be cured, but it can usually be controlled by weight loss, diet, exercise, changes in lifestyle and, when necessary, medications and diuretics. Because hypertension does not begin to cause serious damage for about 10 to 20 years, early detection and treatment can often prevent problems from ever developing. Controlling hypertension is one of the most effective ways to prevent heart disease and stroke.
  
  Blood pressure should be checked regularly to ensure that treatment is effective. A home monitoring device may be recommended to determine a person’s average blood pressure with measurements taken at different times of the day and in a variety of circumstances.
  
  Weight Loss. Extra body weight forces the heart to work harder. Diet and regular exercise should be part of an approved weight loss and maintenance program. Obese people who lose weight often find their blood pressure returns to normal.
  
  Diet. Sodium is an essential dietary nutrient that has an important role in fluid regulation. Excessive dietary sodium may raise blood pressure. Americans typically consume 6,000 to 12,000 milligrams of sodium each day. The American Heart Association recommends sodium intake be limited to 3,000 milligrams per day.
  
  The most common source of dietary sodium is table salt, which is 40% sodium and 60% chloride. One teaspoon of salt contains 2,300 milligrams of sodium. Because sodium naturally occurs in a wide variety of foods, salt added at the table or during cooking should be limited to one-half teaspoon per day if a low sodium diet is recommended. Processed foods and restaurant meals generally have a high sodium content. Preservatives, flavorings, other food additives, medicines and softened water may also contribute significantly to one’s daily sodium intake.
  
  In addition to restricting sodium intake, a person with hypertension should follow a heart-healthy diet consisting of 30% or less of total daily calories from fat, less than 300 milligrams of cholesterol per day, and 20 to 30 grams of fiber. Caffeine intake should be limited or restricted.
  
  Exercise. A regular exercise program has many benefits, including weight and blood pressure control. Aerobic exercises, which use the large muscle groups in a continuous, rhythmic motion (as in walking, swimming and running), often help decrease blood pressure levels. A 30- to 45-minute aerobic exercise session three to four times a week is recommended. A “cool-down” session for five to 15 minutes at the end of the exercise period will allow blood pressure to return to resting levels. Many medications can affect exercise tolerance. A physician should help plan both the exercise program and the medication schedule.
  
  Smoking Cessation. Cigarettes contain nicotine, a highly addictive drug that increases the blood pressure and heart rate and causes arteries in the arms and legs to narrow. This makes the cardiovascular system work harder and less efficiently. Blood pressure increases when a cigarette is smoked. Smoking is the most easily preventable risk factor for cardiovascular disease and should be ceased.
  
  Stress Management. Learn to do things that are relaxing or restful. Try to relax 15 to 20 minutes twice a day. Practice muscle relaxation, deep breathing and pleasant imagery.
  
  Medication. If changes in diet and exercise do not reduce blood pressure to safe levels, medications may be prescribed. They must be taken on a regular schedule as instructed by the doctor. Taking them too close together or too far apart may cause the blood pressure to be over- or under-controlled for a part of the day, resulting in wide swings in blood pressure that can be dangerous.
  
  Medications only control blood pressure while they are being taken as prescribed. Because hypertension cannot be cured, medications may need to be taken for life if diet and exercise cannot keep it under control. Your physician may prescribe one or more of the following types of medications:
• Diuretics eliminate excess fluid and sodium from the body. Excess fluids in the body force the heart to work harder and can irritate sensitive blood vessels.
• Beta blockers cause the heart rate to drop and the blood vessels to relax.
• Vasodilators reduce pressure on the blood vessels by making them relax and expand.
• Calcium channel blockers cause the blood vessels to relax and increase the supply of blood and oxygen to the heart.
• Enzyme (ACE) inhibitors prevent the formation of a hormone that constricts blood vessels. Since everyone reacts differently to medication, a “trial period” will probably be necessary to identify the best prescription for an individual. Side effects should be reported to the doctor so that another medication can be substituted. Patients should not stop taking a prescribed medication or alter the timing and dose without a doctor’s approval, even when blood pressure is normal.