Hypertension
Risks
Causes
Children and BP
Treatment
Benefits of Lower BP
Hypertension is a serious health problem in the U.S. that is present in over 50 million Americans 6 years of age and older and was considered the primary or contributing cause of 210,000 deaths in the U.S. in 2000 3. Hypertension is classified as a major risk factor for cardiovascular disease14. Hypertension is characterized by having a blood pressure of 140/90 mmHg or greater 3 and increases the risk of coronary artery disease, heart attack, stroke, and kidney disease. By having a high resting blood pressure, there is an increased shear stress on the blood vessels that causes damage and allows plaque to accumulate 2. People of ages 40-70 years double their risk of cardiovascular disease for every incremental increase of 20 mm Hg in SBP, or 10 mm Hg in DBP. There are many factors that increase blood pressure such as cholesterol level, insulin resistance, aging, and obesity. High blood pressure rarely has any symptoms. The only sure way to detect high blood pressure is though measurement 3. (American Heart Associations high blood pressure statistics, PDF )
Risks
Hypertension is a major risk factor for cardiovascular disease. Hypertension can lead to stroke, myocardial infarction, atherosclerosis, kidney disorders, and metabolic syndrome 14. In fact, high blood pressure is the #1 cause of stroke 3. The higher the blood pressure, the greater the risk of developing cardiovascular disease 14.
Caffeine intake is associated with an acute rise in blood pressure. However, habitual caffeine consumption does not appear to increase the risk of hypertension (in women). There is a significant association between the development of hypertension and the intake of cola drinks, both sugared and diet. 50 [Back to top]
Causes
In 90-95 percent of cases of hypertension, the cause of a high blood pressure is unknown, which is termed essential hypertension 3. In the other 5-10 percent, the causes of hypertension are known and is termed secondary hypertension 3. There are many factors that increase blood pressure such as cholesterol level, insulin resistance, aging, and obesity.
LDL cholesterol affects hypertension by building up on the inner lining of the blood vessels to cause more resistance, which increases blood pressure 20. HDLs retard the development of atherosclerosis by gathering the free cholesterol in the vessels and returning it to the liver to be eliminated or recycled 20. Low HDL levels are a risk factor for cardiovascular disease because it allows for a buildup of plaque to lead to atherosclerosis.
Insulin resistance is impairment in fasting glucose that results from the insulin not being able to take the glucose from the blood stream into the cells 20. Insulin resistance affects blood pressure by causing hyperglycemia which increases the amount of oxidative stress to the blood vessels 20.
Obesity (a body mass index of 30 or greater) is associated with hypertension. Increased sympathetic nervous system (S-ANS) activity is one cause of hypertension in obese individuals 4. Norepinephrine is a hormone secreted into the blood stream by the S-ANS that causes constriction of the blood vessels. Levels of norepinephrine in the blood increase with high caloric intake and decrease with diets that restrict caloric intake 4. Obesity is also related to having increased cholesterol levels which increases the resistance to blood flow and increase blood pressure.
As people age, blood pressure increases because there is an associated decrease in vascular distensibility 1. The arteries get stiffer due to age-associated changes in vascular connective tissue 1. These age-associated changes may be the result of increases in collagen, elastin, glycosaminoglycans, calcium, and lipids in the arterial walls of the elderly 1. Throughout life, systolic blood pressure increases, but diastolic blood pressure plateaus in the sixth decade and decreases thereafter.
The National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure give four classifications of hypertension, which are normal, prehypertension, and stage 1 & 2 hypertension (see table 1 for classification and management).
There are certain hormones that increase vasoconstriction of the blood vessels, where elevated resting levels would be a cause of hypertension. Sympathetic nerve activity increases the release of the hormone norepinephrine, which increases vasoconstriction and vascular resistance 43 . Endothelin is a hormone that causes potent and long-acting vasoconstrictive effect, increases the affect and activity of other vasoconstrictors and hormonal agents, and a mitogenic (inducing cell division) effect that may be involved in vascular wall remodeling 47,52.
Table 1
BP classification |
Systolic BP (mm Hg) |
Diastolic BP (mm Hg) |
Lifestyle Modification |
Intitial Drug Therapy |
Normal |
<120 |
<80 |
Encourage |
No |
Prehypertension |
120-139 |
80-89 |
Yes |
If compelling indications |
Stage 1 hypertension |
140-159 |
90-99 |
Yes |
Yes |
Stage 2 hypertension |
160 or greater |
100 or greater |
Yes |
Yes |
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Blood Pressure in Children
Normally, a child's blood pressure is much lower than an adult's. However, children are at risk for hypertension if they exceed the following levels:
- Ages three to five: 116/76 mm Hg
- Ages six to nine: 122/78 mm Hg
- Ages 10 to 12: 126/82 mm Hg
- Ages 13 to 15: 136/86 mm Hg
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Treatment
Treatment of hypertension includes the use of medications and/or lifestyle modifications. There are many classes of medications, which include beta blockers, alpha blockers, calcium channel blockers, nitrates, diuretics, angiotensin II receptor blockers and ACE inhibitors. (For more information on medications)
A healthy lifestyle is critical in the prevention and treatment of high blood pressure. Lifestyle modifications include weight reduction if overweight or obese, a diet rich with fiber, fruits and vegetables, and low in sodium or saturated fats, and moderation of alcohol consumption to no more than 2 drinks per day for most men and 1 drink for women 14. Increasing physical activity is also an important component to decrease blood pressure (Exercise Intervention).
Hypertension can be treated effectively by the right combinations of medication and lifestyle changes. Most people either are not on an effective therapy or are not on any therapy at all. The American Heart Association states that only 34% of people with high blood pressure are on adequate therapy even though high blood pressure is controllable. The goal of most blood pressure treatments are to get lower than 140/90 mm Hg, but for individuals with diabetes or the metabolic syndrome 130/85 mm Hg is the goal because of the greater cardiovascular risks they have 14. [Back to top]
Benefits of Lowering Blood Pressure
Lowering blood pressure can improve cardiovascular health. Antihypertensive therapy has been associated with 35-40% reductions in stroke incidents, 20-25% reductions in myocardial infarction, and over 50% reduction in heart failure incidents 14. Even minor decreases in blood pressure that may seem insignificant do have significant health benefits. A reduction of only 3 mm Hg in systolic blood pressure has been estimated to reduce coronary heart disease by 5-9%, stroke by 8-14%, and all-cause mortality by 4% 59 .
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