Hypertension is the medical name for high blood pressure. Blood pressure is the force of blood pushing against the walls of arteries as it flows through them. Arteries are the blood vessels that carry oxygenated blood from the heart to the body's tissues. Blood pressure varies throughout the day. However, when blood pressure remains higher than normal over time, the chronic medical condition known as hypertension (or high blood pressure) exists.
As blood flows through arteries it pushes against the inside of the artery walls. The more pressure the blood exerts on the artery walls, the higher the blood pressure will be. The size of small arteries also affects the blood pressure. When the muscular walls of arteries are relaxed, or dilated, the pressure of the blood flowing through them is lower than when the artery walls narrow, or constrict.
A normal blood pressure reading for adults is less than 120 over less than 80. The National Heart, Lung, and Blood Institute (NHLBI) has defined a blood pressure between 120/80 mmHg and 139/89 mmHg as prehypertension. An individual with prehypertension does not currently have high blood pressure but is likely to develop it in the future.
Hypertension is serious because people with the condition have a higher risk for heart disease and other medical problems than people with normal blood pressure. People can avoid serious complications from hypertension by getting regular blood pressure checks and treating hypertension as soon as it is diagnosed. A person has a better chance to be healthy when blood pressure is typically in the normal range.
If left untreated, hypertension can lead to the following medical conditions:
Arteries narrowed by arteriosclerosis may not deliver enough blood to organs and other tissues. Reduced or blocked blood flow to the heart can cause a heart attack. If an artery to the brain is blocked, a stroke can result.
Hypertension makes the heart work harder to pump blood through the body. The extra workload can make the heart muscle thicken and stretch. When the heart becomes so enlarged it cannot pump enough blood. If the hypertension is not treated, the heart may fail.
The kidneys remove the body's wastes from the blood. If hypertension thickens the arteries to the kidneys, less waste can be filtered from the blood. As the condition worsens, the kidneys fail, and waste builds up in the blood. Dialysis or kidney transplantation is needed when the kidneys fail. Hypertension is the cause of nearly 27% of cases of kidney failure.
Even though the cause of most hypertension is not known, some people have risk factors that increase their chance of developing hypertension. Many of these risk factors can be avoided to lower the chance of developing hypertension or as part of a treatment program to lower blood pressure.
Risk factors for hypertension include:
Some people inherit a tendency for hypertension. People with family members who have hypertension are more likely to develop it than those whose relatives are not hypertensive. People with these risk factors can avoid or eliminate other risk factors to lower their chance of developing hypertension. Hypertension has become more common in children and teens. Although blood pressure in children can be caused by some medical conditions, children who are obese have a risk for hypertension three times higher than children at normal weight percentiles.
The Centers for Disease Control and Prevention (CDC) stated that in 2014 high blood pressure was listed as a primary factor for approximately 30,000 deaths in the United Sates. The disease contributes to other deaths, such as from heart disease and stroke. In a 2013 report, the World Health Organization (WHO) stated that hypertension is the cause of more than 9 million deaths a year in the world and contributes to the heart and blood vessel disease that causes nearly 17 million deaths each year. In 2016, the CDC reported that slightly fewer than half of people with hypertension have their blood pressure under control. Nearly 70% of seniors (65 and older) have hypertension, but about 25% of them do not take their blood pressure medications as directed.
Hypertension is more common in men than in women. However, men are more likely to have high blood pressure when younger. Once women turn age 55, they are more likely than men to have hypertension.
Temporary increases in blood pressure are normal. Stressful situations or physical activity can make blood pressure go up, but when the stress goes away or the activity ends, blood pressure usually returns to normal. These temporary increases in blood pressure are not considered hypertension. A diagnosis of hypertension is made only when a person has multiple high blood pressure readings over a period of time.
Hypertension without a known cause is called primary or essential hypertension. The cause of hypertension is not known in 90%–95% of the people who have it.
When a person has hypertension caused by another medical condition, it is called secondary hypertension. Several illnesses can cause secondary hypertension. Many people with kidney disorders have secondary hypertension. The kidneys regulate the balance of salt and water in the body. If the kidneys cannot rid the body of excess salt and water, blood pressure goes up. Kidney infections, a narrowing of the arteries that carry blood to the kidneys (renal artery stenosis), and other kidney disorders can disturb the salt and water balance.
Cushing syndrome and tumors of the pituitary and adrenal glands often increase levels of the adrenal gland hormones cortisol, adrenalin, and aldosterone, which can cause hypertension. Other conditions that can cause hypertension are blood vessel diseases, thyroid gland disorders, some prescription drugs, alcoholism, and pregnancy.
One of the most dangerous features of hypertension is the fact that it does not usually cause symptoms. Individuals may not be aware that they have the condition, or they may mistakenly downplay its importance, simply because it is not causing any obvious problem. Without treatment, the damaging effects of hypertension become worse.
When blood pressure becomes extremely high, for example over 180/110 mmHg (termed malignant hypertension), symptoms such as headache, visual disturbances, anxiety, and shortness of breath may occur. If left untreated, the person can have a stroke or a hypertensive crisis, in which organs cannot receive enough blood supply and begin to fail.
The diagnosis of hypertension usually follows a series of blood pressure readings from at least three office visits to a family doctor, with each visit separated by at least one week. A complete medical history along with a physical examination of the patient helps to diagnosis the problem. If symptoms are present or if the blood pressure is exceptionally high at these visits, then the doctor may begin treatment immediately.
Because hypertension does not cause symptoms, it is important to have blood pressure checked regularly. Blood pressure is measured with an instrument called a sphygmomanometer. A cloth-covered rubber cuff is wrapped around the upper arm and inflated. When the cuff is inflated, an artery in the arm is squeezed to momentarily stop the flow of blood. Then, the air is let out of the cuff while a stethoscope placed over the artery is used to detect the sound of the blood spurting back through the artery. This first sound is the systolic pressure, the pressure when the heart beats. The last sound heard as the rest of the air is released is the diastolic pressure, the pressure between heartbeats. Both sounds are recorded on the mercury gauge on the sphygmomanometer.
Systolic hypertension of the elderly is common and is diagnosed when the diastolic pressure is normal or low, but the systolic pressure is elevated, e.g., 170/ 70 mmHg. This condition usually coexists with hardening of the arteries (atherosclerosis).
Blood pressure measurements are classified in stages, according to severity:
A typical physical examination to evaluate hypertension includes:
The medical and family history help the physician determine if the patient has any conditions or disorders that might contribute to or cause the hypertension. A family history of hypertension might suggest a genetic predisposition for hypertension.
The physical exam might include several blood pressure readings at different times and in different positions. The physician uses a stethoscope to listen to sounds made by the heart and blood flowing through the arteries. The pulse, reflexes, and height and weight are checked and recorded.
Because hypertension can cause damage to the blood vessels in the eyes; the eyes may be checked with an instrument called an ophthalmoscope. The physician looks for thickening, narrowing, or hemorrhages in the blood vessels.
A chest x-ray can detect an enlarged heart, other vascular (heart) abnormalities, or lung disease.
An ECG measures the electrical activity of the heart. It can detect whether the heart muscle is enlarged and if there is damage to the heart muscle from blocked arteries.
Urine and blood tests may be done to evaluate health and to detect the presence of disorders that might cause hypertension.
Most treatment for hypertension is to implement dietary changes, add or increase physical exercise, and initiate weight loss. The doctor might prescribe medication if the blood pressure is high enough.
There is no cure for primary hypertension, but blood pressure can almost always be lowered with the correct treatment. The goal of treatment is to lower blood pressure to levels that prevent heart disease and other complications of hypertension. In secondary hypertension, the disease that is responsible for the hypertension is treated in addition to the hypertension itself. Successful treatment of the underlying disorder may cure the secondary hypertension.
The physician should work with patients to agree on blood pressure goals and develop a treatment plan for the individual patient. Actual combinations of medications and lifestyle changes vary from one person to the next. Treatment to lower blood pressure can include making changes in diet, getting regular exercise, and taking antihypertensive medications. Patients falling into the prehypertension range who do not have damage to the heart or kidneys often are advised to make lifestyle changes only. Most adults with elevated blood pressures can lower them by making lifestyle changes and participating in the dietary approaches to stop hypertension (DASH) diet, which encourages eating more fruit and vegetables. Patients also can keep track of their blood pressure with home blood pressure machines.
Patients with stage 1 hypertension might be advised to take antihypertensive medication. Numerous drugs have been developed to treat hypertension. The choice of medication depends on the stage of hypertension, side effects, other medical conditions the patient may have, and other medicines the patient is taking.
Antihypertensive medicines fall into several classes of drugs:
Diuretics help the kidneys eliminate excess salt and water from the body's tissues and the blood. This reduces the swelling caused by fluid buildup in the tissues. Reducing the fluid dilates the walls of arteries and lowers blood pressure. Diuretics are recommended as the first drug of choice for most patients with high blood pressure and as part of any multi-drug combination. A type of diuretic is hydrochlorothiazide (Microzide Oretic and generic).
Beta-blockers lower blood pressure by acting on the nervous system to slow the heart rate and reduce the force of the heart's contraction. They are used with caution in patients with heart failure, asthma, diabetes, or circulation problems in the hands and feet. Generics (and their branded counterparts) include atenolol (Tenormin), betaxolol, carvedilol (Coreg), and penbutolol (Levatol).
Calcium channel blockers block the entry of calcium into muscle cells in artery walls. Muscle cells need calcium to constrict, so reducing their calcium keeps them more relaxed and lowers blood pressure. Types of calcium channel blockers include bepridil (Vasocor), felodipine (Plendil), and nisoldipine (Sular).
ACE inhibitors block the production of substances that narrow blood vessels. They also help reduce the build-up of water and salt in the tissues. They often are given to patients who have heart failure, kidney disease, or diabetes. ACE inhibitors can be used together with diuretics. The ACE inhibitors include captopril (Capoten), enalapril (Vasotec), lisinopril (Prinivil, Zestril), and ramipril (Altace).
Angiotensin II receptor blockers block the chemical angiotensin, which can also narrow arteries. Some of these blockers are candesartan (Atacand), irbesartan (Avapro), and telmisartan (Micardis).
Alpha-blockers, also called alpha-adrenergic antagonists, act on the nervous system to relax arteries and reduce the force of the heart's contractions. Some examples of alpha-blockers are doxazosin (Cardura), prazosin (Minipress), and terazosin hydrocholoride (Hystrin).
Alpha-beta blockers combine the actions of alpha and beta blockers and usually are reserved only for patients having a hypertensive crisis or at risk of heart failure. Examples include carvedilol (Coreg) and labetalol hydrochloride (Normodyne, Trandate).
Alpha-2 receptor agonists lower activity of the involuntary nervous system and are the first choice for safely treating pregnant women. Methyldopa is a generic form of the drug.
Vasodilators act directly on arteries to relax their walls so blood can move more easily through them. They lower blood pressure rapidly and are injected into patients in hypertensive emergencies. Types of vasodilators used for high blood pressure include hydralazine hydrochloride (Apresoline). They are usually used with a beta-blocker and/or diuretic to treat high blood pressure or in other cases with ACE inhibitors or calcium channel blockers.
Peripheral adrenergic antagonists act on the nervous system to relax arteries and reduce the force of the heart's contractions. They usually are prescribed together with a diuretic. Peripheral acting adrenergic antagonists can cause troublesome side effects such as lack of energy or dizziness. These drugs include reserpine (Serpasil), guanethidine monosulfate (Ismelin), and guanadrel (Hylorel).
Central agonists act on the nervous system to relax arteries and slow the heart rate. They are usually used with other blood pressure medicines. Central acting agonists include clonidine (Catapres), guanabenz acetate (Wytensin), and alpha methyldopa (Aldomet).
Lifestyle changes that can reduce blood pressure by 5 to 10 mmHg include:
There is no cure for hypertension. However, it can be well controlled with proper treatment. Therapy that combines lifestyle changes and antihypertensive medicines can keep blood pressure at levels that will not cause damage to the heart or other organs. The key to avoiding serious complications of hypertension is to detect and treat it before damage occurs. Because antihypertensive medicines control blood pressure, but do not cure it, patients must continue taking the medications to maintain reduced blood pressure levels and avoid complications.
Hypertension is dangerous because it forces the heart to constantly work harder than normal. Consequently, it can lead to hardening of the arteries (atherosclerosis) and other serious medical problems such as blindness, kidney disease, and heart failure. To maintain a healthy lifestyle it is essential that people with hypertension lower their blood pressure. The best way to reduce high blood pressure is to live a healthy lifestyle, including a regular exercise and fitness routine and a heart-healthy diet.
Preventing hypertension depends on avoiding or eliminating known risk factors. Even those at risk because of age, race, sex, or inherited risk can lower their chance of developing hypertension by:
See also Blood pressure and exercise ; Hypertension .
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Teresa G. Odle
Revised by William A. Atkins, BB, BS, MBA