What is fainting?
The medical term for fainting is syncope (pronounced sin-ko-pee). Syncope is defined as a sudden and temporary loss of consciousness that resolves without treatment. This is a very common problem, accounting for three percent of all emergency room visits in the United States. In fact, more than one in four people will experience a fainting spell at some point in their lives. Syncope is common in both young and old people and both healthy and ill people. I will use the terms "fainting" and "syncope" interchangeably throughout this article.
Did I have syncope?
The occurrence of syncope is determined by the medical history. I find it helpful to talk with my patients about how they were feeling in the days before the event, what they were doing at the time of the event, their description of the event, how they woke up, how they felt afterwards, and whether any injury occurred. It is extremely helpful to hear the account of others who may have witnessed the fainting episode. Bystanders can often provide an excellent account of the events prior to and during the fainting episode.
There are several reasons why a person could lose consciousness rapidly. Perhaps the most important distinction is whether you had syncope or a seizure because the causes and treatments are different for these two conditions. There are several details in the medical histories that are generally helpful. A seizure more typically is associated with auras (unusual sensations, such as smelling a particular odor or feeling tingling over a body part) before the loss of consciousness, vigorous involuntary movement of the limbs, passing of urine and/or feces, clenching teeth, and possibly tongue biting. In addition patients often feel disoriented upon awaking after a seizure. In contrast to the typical seizure, syncope may or may not be associated with symptoms before consciousness is lost. Sometimes, patients may feel lightheaded, sweaty, nauseated, or notice visual changes. Although syncope is associated with loss of posture, it is less common to see involuntary limb movements, tongue biting, or incontinence of urine or stool.
Despite the above clues, it can still be quite difficult to determine whether you had a fainting episode or a seizure. Sometimes I can find clues during a physical examination or basic laboratory testing. But even after extensive testing, it can be hard to categorize some cases as syncope or seizure.
What are the causes of fainting (syncope)?
Once we are sure that you fainted, the next question is "why?" This can be the most challenging question to answer. Often the fainting episode only happened once. Without having been there to witness the event, it can be a matter of educated guessing to figure out what happened. From my point of view, the most important goal of any syncope evaluation is to be reasonably sure that the cause of syncope is not life-threatening. While all episodes of syncope are caused by brief periods of decreased blood pressure to the brain, you will see that there are many diverse causes of fainting that are associated with very different outcomes and treatments.
The most common cause of fainting is due to abnormal or overly active cardiovascular reflexes that interfere with the ability to maintain blood pressure. This includes a wide variety of disorders, most of which are not particularly dangerous health problems. However, these causes of syncope can recur frequently in a small percentage of patients, leading to frequent fainting or injury at the time of the fainting episode. Vasovagal (pronounced vayzo-vay-gal) syncope is a fainting reflex that occurs upon prolonged standing. There are also a group of disorders referred to as situational syncope. This includes syncope that is repeatedly triggered by a certain situation, such as coughing, swallowing, pain, passing urine, or passing feces.
Syncope can also be caused by severe valvular heart diseases such as aortic stenosis or mitral stenosis (tight blockages in the heart's most important valves), slow heart rhythms (called bradycardias) and fast heart rhythms (called tachycardias). Very rarely migraine headaches, minor strokes (called TIAs for transient ischemic attack) or psychiatric problems can cause syncope.
Can tests help determine the cause of my fainting episode?
While a good medical history is the most useful step in determining the cause of a fainting episode, your physician may perform one or more tests to aid in diagnosis. I will provide a brief description of the most commonly used tests in this section.
Electrocardiogram (ECG or EKG): This is a tracing of the heart's electrical activity recorded from adhesive electrodes on the body surface. It provides important information about the heart's rhythm, the health of the heart's electrical conduction system, and the health of the heart muscle itself.
Echocardiogram (or echo): This is a movie of the heart beating that is acquired by scanning the chest with a special probe (similar to a microphone). It can detect whether there are any abnormalities in the heart's structure or pumping function. This includes thickening of the heart, weakness of the heart's contraction, valvular diseases, and scars from prior heart attacks. The echocardiogram is extremely useful in evaluating patients with syncope. I approach patients with normal echocardiograms quite differently than those with abnormal echocardiograms. Those with major abnormalities on echocardiogram are at much higher risk for dangerous heart rhythms as the cause of their fainting episode.
Tilt Table Testing: A tilt table test takes place on a motorized table. The patient lies flat on the table, held secure by safety straps. With your feet supported on a footboard, the table tilts upright, so that your head is up and your feet are down. You are monitored in this position for about 45 minutes or until low blood pressure or symptoms of fainting occur. In many cases, if a standard tilt table test is negative, your doctor may decide to give you a medication while upright to further "challenge" your cardiovascular system. The tilt test is useful to confirm whether your fainting was caused by abnormal blood pressure regulation during upright posture.
Holter Monitor: A Holter monitor is a small cassette recorder with ECG leads attached to it and is typically worn for 24 hours. The ECG leads record your heart's electrical activity, which is then stored on the cassette tape. The Holter monitor records every heartbeat for an entire day. This tape is returned to your doctor, who evaluates your heart's rhythm for abnormalities.
One very important feature of a Holter monitor is its ability to correlate symptoms with your heart's rhythm. This is accomplished through the use of an event button and a diary. If you experience a symptom, it is important to press the event button, a tiny button on the top of the cassette recorder. This marks a place on the tape recording that will be evaluated carefully by the physician who reviews your Holter monitor. Each time you press the event button, you should make a note in your diary. This note should include the time (preferably the time indicated on the clock of the Holter monitor) and the reason why the event button was pressed. For example, if you experienced palpitations and lightheadedness, you should record the time the button was pressed and the words "palpitations and lightheadedness" in your diary.
Loop Recorder: While Holter monitors are the most commonly used heart monitoring devices for non-hospitalized patients, loop recorders are also very helpful in the evaluation of arrhythmias that occur infrequently. A loop recorder is smaller in size than a Holter monitor and can be used for several weeks or even several months. Loop recorders are capable of recording the heart's rhythm for several minutes, including a few minutes before and after the event button is pressed. After an event is recorded, the information is transmitted through your telephone to a laboratory, which then sends a tracing of the heart rhythm to your doctor. Like in the case of the Holter monitor, recording a careful diary of symptoms is important in getting the most information about your symptoms.
Implantable Loop Recorders: Occasionally even loop recorders are unsuccessful in revealing the type of arrhythmia causing your symptoms. In certain cases, your doctor may discuss implantation of a permanent loop recorder. This is a simple and brief procedure in which a small metal box (smaller than a pack of gum) is placed beneath the surface of the skin. This allows long-term monitoring of your heart rhythm, and can be quite useful when other testing is unrevealing.
Electrophysiologic Study (EP Study): An EP study is a test in which catheters are advanced from a vein in the leg into the heart and used to stimulate the heart (in the same way that a pacemaker stimulates the heart to beat). In this controlled and carefully monitored setting, a cardiologist will attempt to provoke abnormal heart rhythms. The ability to induce abnormal heart rhythms may provide important information about the cause of your fainting episode.
Exercise Test (Stress Test): Exercise stress testing can provide important information in the evaluation of fainting. First, when fainting or dizziness occurs during exercise, this test can be used to try to provoke the symptom in a controlled setting for diagnostic purposes. In addition, stress testing is commonly used to evaluate patients for coronary artery disease. The presence of coronary artery disease makes it more likely that the fainting episode was caused by a dangerous heart rhythm. Furthermore, active coronary artery disease may play a role in triggering arrhythmias, which may become controlled following treatment of the coronary artery disease.
What treatments are available for people with fainting disorders?
There are several treatments available to patients with fainting disorders that vary according to the cause of the fainting disorder. These treatments include behavioral therapy, dietary modifications, medications, implanted devices and catheter ablation therapy. You should consult your doctor to find out which treatments are appropriate for you.
Behavioral therapy can include simple measures such as recognizing the warning signs of a fainting episode. This can often give you time to seek a safe area and/or lie down to prevent injury from fainting or even prevent the fainting episode altogether. Wearing supportive stockings can also be helpful for some patients. Supportive stockings prevent pooling of blood in the legs and encourages blood flow to return to the heart, which can help in maintaining overall blood pressure.
Dietary modifications can be important and typically involve modifying dietary salt intake. Many people with fainting disorders do not eat enough salt in their diets. While eating excess salt should not be encouraged in patients with certain heart diseases, kidney diseases, or hypertension, many people can safely increase the amount of salt that they consume. Because salt increases the amount of fluid in your circulatory system, this simple measure can prevent the fainting in many cases.
Medications can be helpful in preventing fainting. Salt tablets and other medications that increase the body's salt levels are very helpful. Other commonly used medications include various antidepressants and blood pressure modifying drugs.
If your fainting spell is caused by a slow heartbeat of uncorrectable or unknown cause, then you likely will need a pacemaker implanted. When fainting is caused by a fast heartbeat, it is sometimes treatable with medications. In other cases, your doctor may discuss the option of an implantable cardioverter defibrillator (ICD). This is a small machine that monitors your heart for life-threatening heart rhythms. When such rhythms are detected it terminates them by either acting a very fast pacemaker or delivering a shock to the heart. Some arrhythmias that lead to fainting can be treated with a catheter ablation procedure. Finally, if a fainting disorder is due to an abnormal heart valve, surgical repair of the valve can correct the fainting disorder.
Conclusion
Fainting is a common medical problem with many different causes. Fainting tends to be a much more serious concern for patients who have significant diseases of the heart. If you have fainted, it is important to see a physician who is familiar with the evaluation and treatment of fainting disorders. When there is uncertainty about the cause of fainting or a more serious cause of fainting is suspected, there are many tests that we use to determine why you may have fainted. If you fainted and have known heart disease such as congestive heart failure, previous myocardial infarction (heart attack), significant coronary artery disease or serious valvular heart disease, it is helpful to seek the advice of a cardiovascular specialist. Many treatments are available for the treatment of fainting disorders, including dietary modifications, patient education, medications, pacemakers and implantable cardioverter-defibrillators (ICDs). Choosing the right approach is dependent on a good understanding of the cause of fainting and is then individually tailored on a case-to-case basis.
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