What Is Hypertension?
Hypertension, or high blood pressure, is defined as a reading of 140/90 on three consecutive measurements at least six hours apart. The definition varies for pregnant women, where hypertension is defined as 140/90 on two consecutive measurements six hours apart. Consistently high blood pressure causes the heart to work harder than it should and can damage the coronary arteries, the brain, the kidneys, and the eyes. Hypertension is a major cause of stroke .A kidney (left) and a cross-section of a heart (right) that were affected by hypertension. The heart shows signs of advanced atherosclerosis, one possible complication arising from hypertension.

Types of Hypertension
Hypertension is classified as either primary (or essential ) hypertension or secondary hypertension. Primary hypertension has no specific origin but is strongly associated with lifestyle. It is responsible for 90 to 95 percent of diagnosed hypertension and is treated with stress management, changes in diet , increased physical activity, and medication (if needed). Secondary hypertension is responsible for 5 to 10 percent of diagnosed hypertension. It is caused by a preexisting medical condition such as congestive heart failure, kidney failure, liver failure, or damage to the endocrine ( hormone ) system.

Pregnancy-induced hypertension (PIH) may appear in otherwise healthy women after the twentieth week of pregnancy. It is more likely to occur in women who are overweight or obese . PIH may be mild or severe, and it is accompanied by water retention and protein in the urine. About 5 percent of PIH cases progress to preeclampsia. Preeclampsia is characterized by dizziness, headache, visual disturbance, abdominal pain, facial edema , poor appetite, nausea , and vomiting. Severe preeclampsia affects the mother's blood system, kidneys, brain, and other organs.

In rare cases, the woman can die. Preeclampsia is more likely to occur during first pregnancies, multiple fetuses, in women with existing hypertension, and in women younger than twenty-five years old or over thirty-five years old. If convulsions occur with PIH, it is called eclampsia. PIH disappears within a few weeks after birth.

Causes of Hypertension
Many prescription and over-the-counter drugs can cause or exacerbate hypertension . For example, corticosteroids and immunosuppressive drugs increase blood pressure in most solid-organ transplant recipients. Medication taken for pain and inflammation such as nonsteroidal anti-inflammatory drugs (NSAIDs) and cyclooxygenase-2 (COX-2) inhibitors may raise blood pressure since their antiprostaglandin properties affect the kidneys.

Tobacco products (cigarettes, cigars, smokeless tobacco) contain nicotine, which temporarily increases blood pressure (for about thirty minutes or less). The blood pressure of smokers should be rechecked after thirty minutes if initial readings are high. Nicotine patches that are used for smoking cessation do not appear to increase blood pressure.

There does not appear to be a direct relationship between caffeine and chronic hypertension, even though caffeine intake can cause an acute (rapid but brief) increase in blood pressure. This may be due to the fact that tolerance to caffeine develops rapidly.

Chronic overuse of alcohol is a potentially reversible cause of hypertension. Five percent of hypertension is due to alcohol consumption and 30 to 60 percent of alcoholics have hypertension. Alcohol-induced hypertension is more likely to occur in women than men.


Pharmacological Treatment of Hypertension
Hypertension is commonly treated with medication, and a combination of two or more drugs is common. Patients are usually given a diuretic to help them excrete excess fluids. However, most diuretics also cause excretion of potassium in the urine, and individuals on diuretics should monitor their potassium intakes. Drugs used to control hyertension include beta-blockers (e.g., atenolol [Tenorim]) which act to slow heart rate and cause some vasodilation (widening of the lumen, or interior, of blood vessels). Drugs that contain calcium channel blockers (e.g., amlopidine [Norvasc]) or angiotensinconverting enzyme (ACE) inhibitors also cause vasodilation.

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