Blood is carried from the heart to all the body's tissues and organs in vessels, called arteries. Blood pressure is the force of the blood pushing against the walls of those arteries.
Hypertension is defined as either:
- a systolic pressure consistently at 140 or higher or
- a diastolic pressure consistently at 90 or higher.
Each time the heart beats (about 60 to 70 times a minute at rest) it pumps blood out into the arteries.
When the heart is pumping the blood, it is called systolic pressure.
When the heart is resting or in between beats, your blood pressure falls; this is the diastolic pressure.
A normal blood pressure is less than 130 (systolic)/85 (diastolic). High normal blood pressure is a systolic from 131-139 and a diastolic from 85-89.
The higher the pressure over 120/80, the higher the risk of developing cardiovascular complications. Studies show that the association of risk of dying of a heart attack with different levels of blood pressure rises as blood pressure rises - the higher your blood pressure, the higher your risk
Most people develop high blood pressure during their lifetime. Left untreated, high blood pressure can damage the eyes, kidneys, heart and brain. High blood pressure is a factor in 68 percent of all first heart attacks and 75 percent of all first strokes.
If high blood pressure is left untreated, it can cause:
Enlarged heart - If the heart has to work harder and longer, it tends to become larger. Eventually, the heart muscles stretch too much or get too thick, and the blood supply from the coronary arteries becomes inadequate. The heart no longer functions, blood is not pumped into the back and the heart fails.
Stroke - As the blood pressure in the brain increases, damage can occur in the lining of blood vessels, forming aneurysms (weakened areas in the blood vessel that may balloon or rupture). When an aneurysm ruptures, this causes a stroke. Possible paralysis, loss of bodily function and motor skills are the result.
Uremia (failure of the kidneys to function properly) - Continued high blood pressure causes narrowing and thickening of the arteries. This reduces the amount of fluid that the kidney can filter out and thus, a build up of waste products occurs.
Atherosclerosis (hardening of the arteries) - The higher the blood pressure, the faster the plaque (collections of fatty material) accumulates in the artery walls.
In more than 90 percent of all high blood pressure cases, the exact cause is unknown. This is called primary or "essential" hypertension, and it can be associated with the following factors:
- Race - African-Americans develop high blood pressure more often than Anglo-Americans, and it tends to occur earlier and be more severe.
- Sex - men are more likely to develop high blood pressure than women.
- Age - high blood pressure occurs most often in people over the age of 35.
- Obesity - people who weigh 30 percent or more above their ideal body weight are more likely to develop high blood pressure.
- Sodium sensitivity
- Alcohol consumption
- Oral contraceptives
- Physical inactivity
- Certain drugs such as diet pills or amphetemines
In the remaining 10 percent of all cases, high blood pressure is attributed to kidney disease, a hormonal imbalance, a narrowing of the artery to a kidney, a tumor of one of the adrenal glands, or some other anatomic or physiologic abnormality. These cases are called "secondary hypertension," and usually disappear when the problem is controlled.
Since there are no symptoms, the diagnosis of high blood pressure is found when doing a physical examination for other medical reasons. The medical staff will use an instrument called a sphygmomanometer. It consists of a blood pressure cuff that is wrapped around the upper arm and inflated with air to stop the blood flow in the artery for a few seconds. A valve is opened and air is then released from the cuff. The sounds of the blood rushing through an artery is heard through a stethoscope. The first sound heard is the systolic pressure and the last sound is the diastolic pressure.
The cut-offs from normal levels to high blood pressure, with varying degrees of severity, are as follows:
- Optimal: systolic less than 120; diastolic less than 80
- Normal: systolic less than 130, diastolic less than 85
- High normal: systolic 130-139, diastolic 85-89
- High blood pressure:
- Stage 1 (mild) systolic 140-159, diastolic 90-99
- Stage 2 (moderate) systolic 160-179, diastolic 100- 109
- Stage 3 (severe) systolic 180-209, diastolic 110-119
Source: The Sixth Report of the Joint National Committee on the Prevention, Detection, Evaluation and Treatment of Hypertension, 1997 (updated 2000).
Most clinicians would consider some type of treatment for patients whose diastolic pressure (the bottom number) is above 95 and/or whose systolic pressure (the top number) is above 160. For patients with pressures immediately below these figures (140-160/90-95), the doctor will take into account age and other individual factors before recommending any medical treatment.
A variety of non-pharmacologic approaches to managing hypertension are useful. In some cases of mild hypertension, these approaches are enough to reach satisfactory levels of blood pressure:
- Quit smoking.
- Trim down if you are overweight. Obese people are 2-6 times more likely to develop high blood pressure (and even a small weight loss can improve blood pressure).
- Eat a healthy diet and avoid salty foods.
- Reduce alcohol consumption.
- Begin an program of regular physical activity.
- Get adequate dietary calcium.
- Control your stress.
If lifestyle changes do not lower your blood pressure enough, the doctor will begin drug therapy. Prescribing diuretics and beta-blockers is still the first line of treatment for hypertensives without any complicating problems, such as heart disease.
Diuretics or "water pills" (thiazide, hydroclorathyazide, chlorathalidone and indapamide) increase the elimination of salt and water through urination, thereby lessening blood volume and pressure.
Beta-blockers (such as propranolol, atenolol, nadolol, pindolol and labetolol) lower blood pressure by reducing the amount of blood pumped by the heart.
If this first line of treatment is ineffective or the patient has other medical conditions, other types of medications which may be used:
Angiotensin converting enzyme (ACE) inhibitors (captopril, enalapril and lisinopril) lower blood pressure by blocking the production of a hormone known as angiotensin, which increases blood pressure.
Calcium-channel blockers (nifedipine, nicardipine, verapamil and diltiazem) relax blood-vessel walls, thereby lowering pressure.
Vasodilators (hydralazine and minoxidil) relax the smooth muscle of the peripheral arteries, which causes them to dilate and so reduce the resistance to blood flow.
Centrally acting drugs (clonidine and guanabenz) block the transmission of nerve impulses with the autonomic nervous system, which controls the involuntary action of the heart and blood vessels among other organs.
What is a normal blood pressure?
What is considered dangerously high, and when should a physician be called?
What is the cause of the hypertension? Is it due to stress or could it be the result of renal disease or another identifiable cause?
What are the chances of having a stroke?
How is blood pressure taken?
How often should blood pressure be taken?
How can I best monitor my blood pressure at home?
Should a nutritionist or exercise specialist be consulted?
Does a change in diet need to be made?
What resources are there for learning how to cope with stress?
What limitations are there associated with high blood pressure and exercise?