|
|||||||
|
|
||||||||||||||||||||||||||||||||||||||||
The medical term for fainting is syncope (pronounced SIN-co-pee, from the Greek meaning "to cut off"). You lose consciousness, become unresponsive, and your muscles go slack. After a few minutes, you recover spontaneously on your own. Syncope is not considered a disease in itself, but rather a symptom of one or more possibly serious conditions. Syncope accounts for about 3% of emergency department visits and 2%—6% of hospital admissions each year. Syncope is seen twice as often in adults 70 years and older, and 3—4 times as often in adults 80 and older than in younger adults.
How Does It Happen? Syncope happens most commonly while a person is standing. When we stand up, between one and two pints of blood temporarily "pool" in our legs. In younger people, this decrease in circulating blood volume alerts the nervous system to correct the problem. The nervous system signals the blood vessels in the legs to contract and the heart to beat faster, which protects us from large drops in blood pressure. With aging, the heart progressively loses its ability to beat faster, so it can’t always respond promptly or adequately. This leaves us vulnerable to a drop in blood pressure and possible syncope. A drop in blood pressure when changing position from lying (or sitting) to standing is called orthostatic hypotension. Causes of Syncope Syncope has many possible causes, ranging from those that are essentially harmless to those that are life threatening. Causes include the following:
Syncope is generally caused by a sudden decrease in blood flow to the brain, which is most commonly associated with a drop in blood pressure. This may be due to normal aging of the heart and circulation, or to underlying diseases or medications that can interfere with normal control of blood pressure. In older adults, syncope may have multiple causes, making it difficult to diagnose. Orthostatic hypotension Orthostatic hypotension is a common cause of syncope. It is associated with symptoms such as lightheadedness, dizziness, or unsteadiness. Although we all feel this effect from time to time (eg, lightheadedness from standing up suddenly), orthostatic hypotension that happens frequently or results in fainting suggests an underlying inability to maintain adequate blood pressure. This means a person is more likely to experience further drops in blood pressure related to dehydration, blood loss, or medications. Adverse effects from medications are the most common cause of orthostatic hypotension in older adults. Drugs used to treat high blood pressure are commonly to blame, although many other medications can occasionally be involved. Sometimes, blood pressure drops immediately after eating, which can be made even worse by taking blood pressure medications just before a meal. Prolonged bed rest can also result in a drop in blood pressure when a person gets up to a standing position. This is probably caused by loss of conditioning within the heart and blood vessels. Orthostatic hypotension can also result from diseases of the nervous system. The symptoms suggesting such diseases may include dizziness, visual problems, urinary incontinence (ie, wetting oneself), inability to sweat, difficulty tolerating the heat, constipation, chronic fatigue, and impotence. Parkinson’s disease, multiple strokes, and vascular problems are common brain disorders that are associated with orthostatic hypotension and problems maintaining blood pressure. Heart disease Syncope may be associated with heart problems. This is usually serious, and up to one third of people die from the underlying heart problem within a year. Narrowing of the aortic heart valve can cause fainting during physical activity when the narrowing becomes severe. Warning signs of aortic valve narrowing are chest pain and shortness of breath. Irregular heart rhythms or congestive heart failure can also result in loss of consciousness because of reduced blood flow to the brain. Loss of consciousness can also be a sign of heart attack and is sometimes the only symptom of heart attack in older adults. Other causes Low blood volume can cause a drop in blood pressure and syncope. As we age, our kidneys don’t function as well as they used to, and we don’t always drink enough liquids (see Nutrition). This can lead to dehydration and a drop in blood pressure. An additional factor is that an aging heart does not always increase rate like it should, adding to the problems caused by low blood volume. If our blood volume is reduced or if medications cause our blood vessels to expand (or dilate), we become increasingly vulnerable to a drop in blood pressure. Even mild disturbances can lead to syncope if blood flow to the brain is already reduced from one of the conditions listed above. Situations such as rapid breathing, coughing, urinating, or having a bowel movement can result in a loss of consciousness in these individuals (see also Dizziness). Thus, syncope is a result of the combined effects of less blood flow to the heart, slow or impaired nervous system reflexes, and an aging heart and blood vessels. Syncope after a meal occurs because blood has "pooled" in the abdomen to help digest food, and this causes a drop in blood pressure. Sometimes, syncope is related to pressure sensors in the carotid arteries in the neck being overly sensitive, which can be further aggravated by wearing tight collars, turning the head and neck, and taking certain medications. It is rare for syncope to result from a primary problem in the brain, such as a stroke or epilepsy. However, when it does, there are usually other severe neurologic changes. Seizures may accompany any case of syncope caused by loss of blood flow to the brain. Diagnosis and Evaluation Your physician will rely heavily on your clinical history and physical examination to diagnose syncope. In many cases, a diagnosis can be made based on the clinical history you–and others who have seen your fainting spells–describe. You should describe your fainting spells and the situations under which they happen as carefully as possible. Your physician will first try to distinguish syncope from dizziness or lightheadedness, and will ask questions similar to those asked after a dizzy spell (see Dizziness). He or she will also ask several additional key questions, including:
Your physician will also want to check into other health conditions, especially heart problems. Be sure to tell your physician about any chest pains, shortness of breath, and palpitations or other symptoms associated with heart problems (see Heart Disease). As in many other conditions, a complete medication history (including over-the-counter medicines) is essential. The physical examination will include many of the same procedures and tests used to diagnose dizziness (see Dizziness). These include multiple blood pressure measurements and evaluations for heart disease. You will probably have an electrocardiogram (ECG), and you may be asked to wear a heart monitor at home for a time. This device monitors your heartbeat while you go about your normal activities, including the activity you were doing just before a fainting spell. Another test is a "tilt-table" test. In this test, you are strapped to a table that moves from horizontal to vertical. Changes in symptoms, blood pressure, or heart rhythm in different positions can help pin down the cause of syncope. It is important to remember that syncope can be caused by a wide range of possible conditions. Many sophisticated tests may be needed, and a complete diagnostic evaluation may be complex, time consuming, and expensive. Even after extensive testing, the cause of syncope is not always clear. In fact, a clear cause is not found in up to one half of cases. However, it is a great comfort to know that if no cause is found after careful evaluations, the condition is not life threatening. Treatment The treatment of syncope should focus on the underlying cause. This is particularly important when heart problems are involved. Heart attacks may require aggressive medical therapy. Problems with heart valves are typically treated by surgery. Treatment for heart rhythm problems, such as atrial flutter or fibrillation, may involve antiarrhythmic drugs or pacemakers. Orthostatic hypotension is common among older adults and can often be managed by changes in medications or other measures (see below). In particular, avoiding drugs that expand (dilate) blood vessels often helps. If necessary, diuretics can be discontinued, or at least reduced, and salt intake can be increased to maintain blood volume. Other measures that may help include waist-high compression stockings, squatting exercises, and sleeping in a head-up position. Avoiding extremely warm environments and activities associated with straining may be beneficial in some cases. Management of Orthostatic Hypotension Low blood pressure associated with eating may be improved by avoiding alcohol and large carbohydrate meals. Caffeine consumption and lying down after meals may also help. When fainting is associated with something in particular, such as certain smells, tight collars, or rapid neck movements, these "triggers" should be avoided. When syncope has several causes, a broader approach is needed for management. An important decision is whether to discontinue or change the dosages of medication(s) potentially causing low blood pressure. Sometimes, changing the dosing schedule might be enough, eg, a medication for high blood pressure could possibly be taken at a time other than with meals to avoid adding to the low blood pressure that often develops in older adults after eating. Whatever the situation, you should always be sure to check with your health care provider before making any changes in medication. Protecting yourself If no cause can be determined, but syncope continues, you should protect yourself (and others) from harm. Syncope causes falls, so you may want to avoid stairs, ladders, tile floors, and other surfaces that increase the chance of injury in case of a fall. You may also need to consider giving up driving. Guidelines from the American Heart Association recommend that driving be restricted for several months, and only resumed if you don’t have any fainting spells during that time. Many states have laws that prohibit someone who has fainting spells from driving. |
|
|||||||||||||||||||||||||||||||||||||||
Published: 2/28/2005