Slide 150 Syncope is the medical term for fainting. Syncope has a variety of causes, most of which are benign (not life threatening). Occasionally syncope is caused by a neurologic problem, such as a seizure or unusual migraine headache; however, you have probably been sent to the cardiologist because your doctor was worried about a heart cause of syncope.
There are two causes of syncope that can be due to the heart and blood vessels. The first is due to a rhythm abnormality, such as the heart rate being two slow or too fast. The other cause, is due to irregularities in the involuntary (autonomic) nervous system causing low blood pressure, low flow to the brain, and fainting. Syncope, or loss of consciousness, is the body’s normal response to low blood pressure, causing you to fall to the ground and allowing the blood which may be pooled in your legs or abdominal organs to return to the heart, raising the blood pressure and returning you to consciousness. Because of this, lying down is an effective means of both preventing syncope and treating it when it occurs.
To help determine whether you have a rhythm abnormality, your doctor will have done an electrocardiogram (ECG). You may have also had, or have ordered, a 24 hour ECG called a Holter monitor. Some patients will also have had an electroencephalogram (EEG). Generally the ECG, in combination with the details that you tell us are enough to decide whether you have a neurologic cause of syncope, a rhythm related one, or the benign autonomic form of syncope. Occasionally, we also perform a “Tilt” test where you will be tilted to a near standing position with your legs held still in an effort to provoke the benign form of syncope.
The common, benign form of syncope has the medical name of neurally mediated syncope; however, your doctor may have used one of many other names including neurocardiogenic, vasovagal, vasodepressor, or a simple faint. All of these names refer to the same problem.
The typical mechanism for neurally mediated syncope is an inappropriate relaxation of the blood vessels and lowering of the heart rate, leading to low blood pressure at a time when the body actually needs constriction of the blood vessels and a slightly higher heart rate. These inappropriate changes in the heart and blood vessels are due to an irregularity in the control of the autonomic (involuntary) nerves which carry signals from the heart and blood vessels to the brain and back to the heart and blood vessels.
In some way we do not understand completely, the brain’s control of these involuntary signals gets confused and withholds the activity of the sympathetic autonomic nerves which release adrenaline, when it should be activating them. The result is the process which leads to low blood pressure described above.
There are three basic types: hydration, recognition, and antigravity maneuvers.
Staying well hydrated (having plenty of fluid) is the most effective way of preventing both dizziness and fainting spells. First of all, you should eliminate all drinks containing caffeine which can exacerbate fainting problems. If you drink a large amount of caffeinated beverages (coffee, tea, coca-cola), you should eliminate them slowly over a period of one to two weeks to avoid excess tiredness or depression. The second step is to monitor your hydration by examining your urine color and frequency. Your kidneys act as sort of an overflow valve, so that if you are well hydrated your urine color will be clear and you will have to urinate more frequently; if you are poorly hydrated, your urine will be dark yellow and you will urinate infrequently.
If your urine color is not generally clear and your urination frequency is low, you can improve your hydration by drinking beverages that contain salt and/or sugar. Examples are Gatorade, decaffeinated beverages such as gingerale or sprite, most juices, and other sports drinks. Water is an acceptable (but less desirable) substitute if none of these beverages are available. It is generally a good idea to drink approximately one third to a half liter of one of the above beverages just prior to any sustained period of exercise.
Finally, although I do not recommend adding large amounts of salt to your diet, it is important to not be on a low salt diet. Generally, foods such as meats or rice can have salt added at the time of cooking, or if there is a family member who should avoid salt, add it to your food at the table.
The most important step in avoiding syncope is to recognize the symptoms which occur prior to syncope (pre-syncope). These include dizziness or lightheadedness, sweating, nausea, buzzing in the ears, spinning, and pale or gray color when observed by others. You may have all of the above symptoms, or only a few, but are very unlikely to have no symptoms prior to fainting. Thus, you should be able to recognize these symptoms, allowing you to follow the antigravity maneuvers below, and avoid fainting.
The purpose of these maneuvers is to reduce the effect of gravity on the blood in your body. Gravity tends to pull the blood down into the veins of your legs and the organs in your abdomen. As soon as you recognize the very earliest signs of pre-syncope (see above), you should begin these maneuvers. The strongest of them is to lie down on your back with your knees bent. Because lying down is often difficult or embarrassing, a maneuver which is almost as effective is a low squat. Squatting brings your heart closer to your legs, returns much of the pooled blood to the heart, and kinks off the arteries to the legs, raising the blood pressure to the rest of the body. A more subtle, but somewhat less effective maneuver is to cross your legswhile standing in place, and tense your abdominal muscles. This maneuver tends to work very well during the earliest of the symptoms and may be particularly useful when standing still in a setting such as church, choir, or a performance. In addition, this maneuver can be used on a routine basis while standing around talking to people in the hall or at a party, and may be very effective at preventing only dizziness.
If you can maintain the habit of good hydration, learn to recognize the earliest symptoms of fainting, and employ the antigravity maneuvers above, you will almost certainly avoid all fainting spells and most dizzy spells. In addition, because migraine headaches represent a related but different abnormality of the involuntary nerves, you may also be able to improve headache symptoms as well.
If the non-pharmacological maneuvers fail to work for you, there are a number of medications which may be useful for neurally mediated syncope. However, these do not cure the problem and are generally only tried when all of the above measures are not helping.