Blood pressure is the force of blood pushing against the walls of arteries (blood vessels). Each time the heart beats, it pumps blood through blood vessels, supplying the body's muscles, organs and tissues with the oxygen and nutrients that they need to function. Over the course of a day, an individual's blood pressure rises and falls transiently many times in response to various stimuli. Elevated blood pressure over a sustained period of time is a condition referred to as hypertension (HTN).
The American Heart Association estimates that nearly one in three American adults has high blood pressure. Approximately two-thirds of people over the age of 65 have high blood pressure. Of those people with high blood pressure, 71.8% are aware of their condition. Of all people with high blood pressure, 61.4% are under current treatment, 35.1% have it under control, and 64.9% do not have it controlled.
The cause of 90-95% of the cases of high blood pressure is not known; however, high blood pressure is easily detected and usually controllable.
From 1994 to 2004 the death rate from high blood pressure increased 15.5% and the actual number of deaths rose 41.8%.
Non-Hispanic blacks are more likely to suffer from high blood pressure than are non-Hispanic whites.
Within the African-American community, those with the highest rates of hypertension are more likely to be middle aged or older, less educated, overweight or obese, physically inactive, and diabetic.
In 2004, the death rates per 100,000 people from high blood pressure were 15.6 for white males, 49.9 for black males, 14.3 for white females and 40.6 for black females.
The World Health Organization (WHO) estimates that the prevalence of hypertension exceeds 10% in developed nations.
High blood pressure increases the risk of coronary heart disease (CHD) and stroke (lack of blood and oxygen to the brain), which are the leading causes of death among Americans.
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Hypertension (high blood pressure) can be mild, moderate, or severe. The National Heart, Lung, and Blood Institute classifies blood pressure as normal, pre-hypertension, hypertension stage 1, and hypertension stage 2. Normal blood pressure (BP) is a systolic pressure of less than 120 mmHg and a diastolic pressure less than 80 mmHg (120/80 mmHg).
Pre-hypertension is when the systolic and diastolic blood pressure is higher than normal (120/80 mm/Hg) but not high enough to be considered high blood pressure (140/90 mm/Hg). Pre-hypertension is a systolic (top number) between 120 and 139 or a diastolic (bottom number) between 80 and 89. For example, blood pressure readings of 138/82, 128/70, or 115/86 are all in the "pre-hypertension" range.
Stage 1 hypertension is a systolic pressure between 140 and 159mmHg, or a diastolic pressure between 90 and 99 mmHg or higher.
Stage 2 hypertension is a systolic pressure of 160mmHg or higher, or a diastolic pressure of 100 or higher.
Both increased systolic and diastolic blood pressures can increase the risk for congestive heart failure (CHF, or problems with the heart pumping blood to the body), heart attack, kidney disease, stroke (neurological damage to the brain due to a lack of oxygen), erectile dysfunction (inability of males to get an erection), amputation of the legs, and blindness.
As people become older, the diastolic pressure will begin to decrease and the systolic blood pressure will begin to increase, which may lead to high blood pressure. This disorder is called isolated systolic hypertension
Hypertensive emergency: Hypertensive emergency is a life-threatening form of high blood pressure, also known as malignant or accelerated hypertension, and is extremely rare. Uncontrolled blood pressures lead to progressive target organ dysfunction (TOD), or organ damage. Kidneys, brain, and heart can be damaged. Hypertensive emergency affects less than 1% of individuals with high blood pressure. Unlike the more common form of high blood pressure that usually develops over a number of years, this condition is marked by a rapid rise in blood pressure (called a hypertensive emergency), with the diastolic pressure shooting to 120mmHg or higher. Hypertensive emergencies must be treated immediately. Hypertensive emergencies can be caused by a history of kidney disorders, pheochromocytoma (tumor of the adrenal glands), and spinal cord disorders. Hypertensive urgency is a severe elevation of blood pressure, without evidence of organ damage.
Medications that may cause a hypertensive emergency include cocaine, monoamine oxidase inhibitors (MAOIs, used in depression), dopamine (an injectable blood pressure raising drug), and oral contraceptives. The abrupt withdrawal of beta-blockers (including propranolol, metoprolol, and amlodipine) and alpha-stimulants (including clonidine), or alcohol may also cause a hypertensive emergency. An intravenous (IV, into the veins) drug called sodium nitroprusside (Nipride®) is used in hypertensive emergencies.
Pre-eclampsia: Pre-eclampsia is a condition characterized by high blood pressure during pregnancy along with protein in the urine. It can cause serious complications for the mother and baby. Pre-eclampsia can decrease the supply of blood and oxygen available to the mother and developing child. This may result in conditions such as a lower birth weight and neurological (nervous system) damage. The mother is at risk for kidney problems, seizures, strokes, breathing problems, and even death, in rare instances. The cause of pre-eclampsia is not known. Pre-eclampsia usually occurs during the second half of the pregnancy, and affects about 5% of pregnant women.
Pulmonary hypertension: When pressure in the pulmonary circulation (blood flow to and from the lungs) becomes abnormally elevated, it is referred to as pulmonary hypertension. Pulmonary hypertension results from constriction, or tightening of the blood vessels that supply blood to the lungs. As a result, it becomes difficult for blood to pass through the lungs, making it harder for the heart to pump blood forward. This stress on the heart leads to enlargement of the heart and eventually fluid can build up in the liver or tissues, such as in the legs. Affected patients can sometimes notice increasing shortness of breath and dizziness. Pulmonary hypertension can be caused by diseases of the heart and the lungs, such as chronic obstructive pulmonary disease (COPD) or emphysema, sleep apnea (a sleeping disorder characterized by pauses in breathing), failure of the left heart ventricle, recurrent pulmonary embolism (blood clots traveling from the legs or pelvic veins obstructing the pulmonary arteries), or underlying diseases such as scleroderma (scar tissue in the organs).