Found this article today when I was surfing. A bit long, but I think well worth the read:

http://health.yahoo.com/topic/heart...H9D0touizfItMUF


Low blood pressure (hypotension)
Provided by: MayoClinic.com
Last Updated: 04/10/2006
Overview

Just a few decades ago, doctors thought a blood pressure reading of 160/95 millimeters of mercury (mm Hg) was an acceptable target rate for most Americans. Today, those numbers are regarded as dangerously high, and blood pressure lower than 120/80 is considered optimal for good health.

The ongoing downward revision of blood pressure standards had led some people to assume that just as you can't be too thin or too rich, your blood pressure can't be too low. But that's not always the case.

Many people who have low blood pressure (hypotension) are healthy and have no signs or symptoms related to lower than normal readings. But for others, low blood pressure can cause dizziness and fainting or indicate serious heart, endocrine or neurological disorders. Severely low blood pressure can deprive the brain and other vital organs of oxygen and nutrients, leading to shock, a life-threatening condition.
Signs and symptoms

Some people with low blood pressure are in peak physical condition with strong cardiovascular systems and a reduced risk of heart attack and stroke. For these people, low blood pressure, rather than being a cause for concern, is a cause for celebration.

But low blood pressure can also signal an underlying problem, especially when it drops suddenly or is accompanied by signs and symptoms such as:

* Dizziness or lightheadedness
* Fainting (syncope)
* Lack of concentration
* Blurred vision
* Nausea
* Cold, clammy, pale skin
* Rapid, shallow breathing
* Fatigue
* Depression
* Thirst

Causes

The heart is the prime mover of the circulatory system; with each beat it launches your blood on a journey through 60,000 miles of arteries, veins and capillaries, ultimately circulating about 2,000 gallons of blood each day.

To do this, it contracts an average of 70 times a minute with the same amount of force you'd use to squeeze a tennis ball. Blood pressure is a measurement of the pressure in your arteries during the active and resting phases of each heartbeat. Here's what the numbers mean:

* Systolic pressure. The first number in a blood pressure reading, this is the amount of pressure your heart generates when pumping blood through your arteries to the rest of your body.
* Diastolic pressure. The second number in a blood pressure reading, this refers to the amount of pressure in your arteries when your heart is at rest between beats.

Although you can get an accurate blood pressure reading at any given time, blood pressure isn't static. It can vary considerably in a short amount of time — sometimes from one heartbeat to the next, depending on your body position, breathing rhythm, stress level, physical condition, the medications you take, what you eat and drink, and even the time of day. Blood pressure is usually lowest at night and rises sharply on waking.

Blood pressure: How low can you go?
Current guidelines identify normal blood pressure as lower than 120/80 — many experts think 115/75 is optimal. Higher readings indicate increasingly serious risks of cardiovascular disease. Even blood pressures formerly considered healthy — 120 to 139 systolic and 80 to 89 diastolic — are now believed to increase the risks. Low blood pressure, on the other hand, is much harder to quantify.

Some experts define low blood pressure as readings lower than 90 systolic or 60 diastolic — you need have only one number in the low range for your blood pressure to be considered lower than normal. In other words, if your systolic pressure is a perfect 115, but your diastolic pressure is 50, you're considered to have lower than normal pressure.

Yet this can be misleading because what constitutes low blood pressure is highly relative, varying considerably from one person to another. For that reason, doctors often consider chronically low blood pressure too low only if it causes noticeable signs and symptoms.

On the other hand, a sudden fall in blood pressure can be dangerous. A change of just 20 mm Hg — a drop from 130 systolic to 110 systolic, for example — can cause dizziness and fainting when the brain fails to receive an adequate supply of blood. And precipitous plunges, especially those caused by uncontrolled bleeding, severe infections or allergic reactions can, be life-threatening.

How low blood pressure gets that way
Low blood pressure can be a boon when it results from a healthy lifestyle. Athletes and people who exercise regularly, for example, tend to have lower blood pressure than do people who aren't as fit. So, in general, do nonsmokers and people who eat well and maintain a normal weight.

But in some instances, low blood pressure can be a sign of serious, even life-threatening disorders. And although the reason for lower than normal blood pressure isn't always clear, doctors know that the following factors can cause or contribute to low and sometimes to dangerously low readings:

* Pregnancy. Because a woman's circulatory system expands rapidly during pregnancy, blood pressure is likely to drop. In fact, during the first 24 weeks of pregnancy, systolic pressure commonly drops by five to 10 points and diastolic pressure by as much as 10 to 15 points.
* Medications. A number of drugs can cause low blood pressure, including diuretics and other drugs that treat hypertension; heart medications such as beta blockers; drugs for Parkinson's disease; tricyclic antidepressants; Viagra, particularly in combination with nitroglycerine; narcotics, and alcohol. Other prescription and over-the-counter medications may cause low blood pressure when taken in combination with high blood pressure drugs.
* Heart problems. Among the heart conditions that can lead to low blood pressure are an extremely low heart rate (bradycardia), problems with heart valves, heart attack and heart failure. These are conditions in which your heart may not be able to circulate enough blood to meet your body's needs.
* Endocrine problems. These include an underactive or overactive thyroid (hypothyroidism and hyperthyroidism), adrenal insufficiency (Addison's disease) low blood sugar and in some cases, diabetes.
* Dehydration. Fever, vomiting, severe diarrhea, overuse of diuretics, and strenuous exercise can all lead to dehydration, a potentially serious condition in which your body loses more water than you take in. Even mild dehydration, a loss of as little as 1 percent to 2 percent of body weight, can cause weakness, dizziness and fatigue. Far more serious is hypovolemic shock, a life-threatening complication of dehydration. It occurs when low blood volume causes a sudden drop in blood pressure and a corresponding reduction in the amount of oxygen reaching your tissues. If untreated, severe hypovolemic shock can cause death within a few minutes or hours.
* Blood loss. A significant loss of blood from major trauma or severe internal bleeding reduces blood volume, leading to a severe drop in blood pressure.
* Severe infection (septic shock). Septic shock can occur when bacteria leave the original site of an infection — most often in the lungs, abdomen or urinary tract — and enter the bloodstream. The bacteria then produce toxins that affect your blood vessels, leading to a profound and life-threatening decline in blood pressure.
* Allergic reaction (anaphylaxis). Anaphylactic shock is a sometimes fatal allergic reaction that can occur in people who are highly sensitive to drugs such as penicillin, to certain foods such as peanuts, or to bee or wasp stings. This type of shock is characterized by breathing problems, hives, itching, a swollen throat and a sudden, dramatic fall in blood pressure.
* Postural (orthostatic) hypotension. This is a sudden decrease in systolic pressure, usually at least 20 mm Hg, when you stand up from a sitting or prone position. Ordinarily, blood pools in your legs whenever you stand, but your body compensates for this by increasing your heart rate and constricting blood vessels, thereby ensuring that enough blood returns to your brain. But in people with postural hypotension, this compensating mechanism fails and blood pressure falls, leading to dizziness, lightheadedness, blurred vision and even fainting. Postural hypotension can occur for a variety of reasons including dehydration, prolonged bed rest, diabetes, heart problems, burns, excessive heat, large varicose veins, adrenal insufficiency, and certain neurological disorders such as diabetic autonomic neuropathy and alcoholic polyneuropathy. A number of medications can also cause postural hypotension, particularly drugs used to treat high blood pressure — diuretics, beta blockers, calcium channel blockers and angiotensin-converting enzyme (ACE) inhibitors — as well as antipsychotics, tricyclic antidepressants and drugs for Parkinson's disease. Ironically, people with postural hypotension due to neurological disorders usually have high blood pressure when they're lying down, even during sleep, when blood pressure typically falls to its lowest levels.

Postural hypotension is especially common in older adults who are more likely to use antihypertensive drugs and to have problems with blood pressure regulation than younger people are. But it can also affect young, otherwise healthy people who stand up suddenly after sitting with their legs crossed for long periods or after working for a time in a squatting position.
* Multiple system atrophy with orthostatic hypotension. Also called Shy-Drager syndrome, this rare disorder causes progressive damage to the autonomic nervous system, which controls involuntary functions such as blood pressure, heart rate, breathing and digestion. Although multiple system atrophy can involve muscle tremors, slowed movement, problems with coordination and speech, and incontinence, its main characteristic is severe orthostatic hypotension in combination with very high blood pressure when lying down. Multiple system atrophy can't be cured and usually proves fatal within seven to 10 years of diagnosis.
* Postprandial hypotension. A problem that almost exclusively affects older adults, postprandial hypotension is a sudden drop in blood pressure after a meal. Just as gravity pulls blood to your feet when you stand, a large amount of blood flows to your digestive tract after you eat. Ordinarily, your body counteracts this by increasing your heart rate and constricting certain blood vessels to help maintain normal blood pressure. But in some people these mechanisms fail, leading to dizziness, faintness, and falls. Postprandial hypotension is more likely to affect people with high blood pressure or autonomic nervous system disorders such as Parkinson's disease. Lowering the dose of antihypertensive drugs and eating small, low-carbohydrate meals may help reduce symptoms.
* Neurally mediated hypotension. Unlike orthostatic hypotension, this disorder causes blood pressure to drop after standing for long periods, leading to symptoms such as dizziness, nausea and fainting. Although the end result is similar, neurally mediated hypotension differs from orthostatic hypotension in other important respects: It primarily affects young people, for instance, and rather than resulting from failed blood pressure regulation, it seems to occur because of a miscommunication between the heart and the brain. When you stand for extended periods, your blood pressure falls as blood pools in your legs. Normally, your body then makes adjustments to normalize your blood pressure. But in people with neurally mediated hypotension, nerves in the heart's left ventricle actually signal the brain that blood pressure is too high, rather than too low, and so the brain lessens the heart rate, decreasing blood pressure even further. This causes more blood to pool in the legs and less blood to reach the brain, leading to lightheadedness and fainting.
* Nutritional deficiencies. A lack of the essential vitamins B-12 and folic acid can cause anemia, which in turn can lead to low blood pressure.

More On This Topic

* Dehydration
* Type 1 diabetes
* Hypoglycemia
* Shy-Drager syndrome
* Heart arrhythmias
* Heart failure

When to seek medical advice

In many instances, low blood pressure isn't serious. If you have consistently low readings but feel fine, your doctor is likely to monitor you during routine exams. Even occasional dizziness or lightheadedness may be relatively minor — the result of mild dehydration, low blood sugar or too much time in the sun or a hot tub, for example. In these situations, it's not a matter so much of how far, but of how quickly, your blood pressure drops. Still, it's important to see your doctor if you experience any signs or symptoms of hypotension because they sometimes can point to more serious problems. It can be helpful to keep a record of your symptoms, when they occur and what you were doing at the time.
Screening and diagnosis

The goal in evaluating low blood pressure is to find the underlying cause. This helps determine the correct treatment and identify any heart, endocrine or neurological problems that may be responsible for lower than normal readings. To help reach a diagnosis, your doctor may recommend one or more of the following:

* Blood tests. These can provide a certain amount of information about your overall health as well as whether you have hypoglycemia or anemia, both of which can cause lower than normal blood pressure.
* Electrocardiogram (ECG, EKG). This noninvasive test, which can be performed in your doctor's office, detects irregularities in your heart rhythm, structural abnormalities in your heart, and problems with the supply of blood and oxygen to your heart muscle. It can also tell if you're having a heart attack or if you've had a heart attack in the past. Sometimes you may be asked to wear a 24-hour Holter monitor to record your heart's electrical activity as you go about your daily routine.
* Echocardiogram. Using the same technology that allows you to view a fetus in the womb, an echocardiogram produces images of your heart that may show abnormalities in your heart muscle or valves.
* Valsalva maneuver. This noninvasive test checks the functioning of your autonomic nervous system by analyzing your heart rate and blood pressure after several cycles of a type of deep breathing: You take a deep breath and then force the air out through a closed mouth, as if you were trying to blow up a stiff balloon.
* Tilt-table test. If you have postural or neurally mediated hypotension, your doctor may suggest a tilt-table test, which evaluates how your body reacts to changes in position. During the test, you lie on a table that's tilted to raise the upper part of your body, which simulates the movement from a prone to a standing position.

More On This Topic

* Electrocardiogram: Tracing the electrical path through the heart
* Echocardiogram: Sound imaging of the heart

Complications

Even moderate postural, postprandial or neurally mediated hypotension can seriously affect quality of life, leading not only to dizziness and weakness but also to fainting and a risk of injury from falls. And severely low blood pressure from any cause can deprive your body of enough oxygen to carry out its normal functions, leading to damage to your heart and brain.

In addition, chronic low blood pressure may increase the risk of Alzheimer's-type dementia in some older adults. A diastolic pressure lower than 70 over a long period of time is most closely associated with dementia, and for every 10-point drop in pressure, the likelihood of dementia may increase by as much as 20 percent.

For years, researchers debated whether the low blood pressure often seen in people with Alzheimer's was a consequence or a cause of the disease. Current research seems to indicate that it's both, although in younger people, lower blood pressure is usually associated with a reduced risk of dementia.

Scientists speculate that age-related changes in cardiovascular function may explain the difference. Because older adults are more likely to have blocked arteries than younger people are, their blood pressure may need to be higher to maintain adequate blood flow to the brain.
Treatment

Low blood pressure that doesn't cause signs or symptoms rarely requires treatment. In symptomatic cases, the appropriate therapy depends on the underlying cause, and doctors usually try to address the primary health problem — dehydration, heart failure, diabetes or hypothyroidism, for example — rather than low blood pressure itself. When hypotension is drug-induced, treatment usually involves changing the dose of the medication or stopping it entirely.

If it's not clear what's causing hypotension or no effective treatment exists, the goal is to raise your blood pressure and reduce signs and symptoms. Depending on your age, health status and the type of hypotension you have, this may be accomplished in several ways:

* Increased salt intake. Experts usually recommend limiting the amount of salt in your diet because sodium can raise blood pressure, sometimes dramatically. But for people with low blood pressure, that can be a good thing. Still, it's not quite as simple as dousing your salads with one of the new designer salts such as fleur de sel. Because excess sodium can lead to heart failure, especially in older adults, it's important to check with your doctor before upping your salt intake.
* Increased water. Although nearly everyone can benefit from drinking more water, this is especially true of people with low blood pressure. Fluids increase blood volume and help prevent dehydration, both of which are important in treating hypotension.
* Compression stockings. The same elastic stockings and leotards commonly used to relieve the pain, swelling, and blood stagnation of varicose veins may help reduce the pooling of blood in your legs.
* Medications. Doctors traditionally have used the drug midodrine to raise standing blood pressure levels in people with orthostatic hypotension. But many of those people have high blood pressure when sitting or lying down and at night, when blood pressure typically declines. In addition to increasing standing blood pressure, midodrine also raises already-high supine pressure, leading to the possibility of strokes. Now it appears that another drug, pyridostigmine (Mestinon), increases standing blood pressure without affecting supine pressure.

Self-care

Depending on the reason for your low blood pressure, you may be able to take certain steps to help reduce or even prevent symptoms. For instance, drinking more water may help prevent low blood pressure caused by dehydration. Other suggestions include:

* Drink more water, less alcohol. Alcohol is dehydrating and can lower blood pressure, even if you drink in moderation. Water, on the other hand, combats dehydration and increases blood volume.
* Follow a healthy diet. Get all the nutrients you need for good health by focusing on a variety of foods, including grains, fruits, vegetables, and lean chicken and fish. If your doctor suggests increasing your sodium intake but you don't like too much salt on your food, try using natural soy sauce — a whopping 1,200 milligrams of sodium per tablespoon — or adding dry soup mixes, also loaded with sodium, to dips and dressings.
* Go slow. You may be able to reduce the dizziness and lightheadedness that occur with orthostatic hypotension by taking it easy when you move from a prone to a standing position. Instead of jumping out of bed in the morning, breathe deeply for a few minutes and then slowly sit up before standing. Sleeping with the head of your bed slightly elevated also can help fight the effects of gravity. If you begin to get symptoms while standing, cross your thighs in a scissors fashion and squeeze or put one foot on a ledge or chair and lean as far forward as possible. These maneuvers encourage blood to flow from your legs to your heart.
* Eat small, low-carb meals. To help prevent blood pressure from dropping sharply after meals, eat small portions several times a day and limit high-carbohydrate foods such as potatoes, rice, pasta and bread. Drinking caffeinated coffee or tea with meals may temporarily raise blood pressure, in some cases by as much as 3 to 14 millimeters of mercury (mm Hg). But because caffeine can cause other problems, check with your doctor before investing in a fancy espresso maker.