Vasovagal Syncope -- What You Need to Know

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Introduction

You have been diagnosed with a condition called vasovagal syncope. Other names for it include fainting, neurocardiogenic syncope and neurally mediated syncope. This is a very common condition that results in fainting or a blackout in as many as half of people at least once in their life. Three percent of people develop it repeatedly.




What is Vasovagal Syncope? 



Vasovagal syncope is not a serious or life threatening condition, but in effect an abnormal reflex. This results in a drop in blood pressure leading to decreased blood flow to the brain resulting in dizziness or fainting. The mechanism of vasovagal syncope is the subject of a great deal of research. It may best be described as the following:


• When we sit or stand, blood settles in the legs and abdomen

• As a result, less blood returns to the heart

• The blood vessels leaving the heart have detectors in them called baroreceptors that detect a decrease in blood pressure

• The baroreceptors send a message to the brain, which in turn sends a signal to the heart to increase the heart rate, and tighten up the blood vessels

• This process occurs constantly in all of us as we adapt to changes in posture

• In vasovagal syncope, an abnormal reflex occurs that results in withdrawal of the message that speeds up the heart and tightens up the vessels, often because of an overshoot in the reflex that compensates for the fall in blood pressure

• The resultant decrease in blood flow to the brain will result in dizziness or lightheadedness if mild, and progress to fainting or loss of consciousness if more severe

• There are several variants of vasovagal syncope that can trigger the same reflex, including situations such as the sight of blood, injury, blood testing (needles), going to the washroom and several others that are quite uncommon.




What are the symptoms?



The symptoms in vasovagal syncope are slightly different for each person, but often include many of the following characteristics:


• Most episodes occur while standing, occasionally sitting and almost never lying down

• Patients often describe feeling very warm and sweaty before blacking out

• Nausea and rarely vomiting can precede episodes

• Observers often describe the patients as pale (“white as a sheet”)

• Patients are usually unresponsive (“out”) for less than a minute

• Patients may have some twitching while unresponsive, but seldom shake violently, bite their tongue or lose control of bowel and bladder function. The latter are more suggestive of a primary seizure.

• After regaining consciousness, patients are usually immediately aware of their surroundings, who and where they are

• After an episode, patients often feel somewhat dizzy and report feeling tired for as much as 24 hours

• Patients that learn to recognize the warning signs can avert losing consciousness by sitting or lying down promptly.




What tests are done?



If you have reported your symptoms to your Doctor, he or she has already done the most important test to make the diagnosis of vasovagal syncope: hearing your description of the symptoms you experience (called a medical history). Tilt testing is sometimes performed to try to reproduce an episode. Tilt testing involves what doctors call a postural stress test. While the blood pressure and heart rate are monitored, the patient is tilted up to 80˚ (almost standing) to try to trigger an episode of loss of consciousness. The following is a description of a tilt test:


• Testing is usually done in the morning on an empty stomach

• Typically there are 2 nurses in the room, and a doctor in the room or nearby

• The patient lies on their back on a motorized table

• A blood pressure monitor is attached to the finger and the arm, and EKG electrodes are connected to monitor the heart rate

• An intravenous is inserted in the hand or arm

• The patient is monitored for 10 minutes at rest

• The table is raised to 80o and monitored for 30 minutes

• If an episode does not occur during this phase, a medication is usually added to trigger an event (Isoproterenol or nitroglycerin)

• If an episode occurs, the patients is quickly returned to the lying position, and the test is over



A tilt test is not a perfect test. 75% of patients that are felt to have vasovagal syncope will have a positive test. People that do not have fainting will have a positive test (i.e. faint) 15% of the time. The nurse or doctor will ask questions about the similarity of symptoms to episodes that have occurred spontaneously before the test.



Other heart and brain tests are often performed in patients with blackouts to look for other causes (link to a general section on syncope here). Vasovagal syncope is the most common cause of blackouts. Other common causes include an arrhythmia when the heart beats too fast or too slow, as well as seizures.




What are the treatments?



The treatment of vasovagal syncope ranges from simple lifestyle measures to medications, and very rarely pacemakers. Most patients are significantly improved with lifestyle measures, which are always tried first.



Lifestyle measures



These are primarily directed at raising the blood pressure and improving the blood pressure “reserve”.



• Trigger recognition: patients should do their best to recognize situations where episodes are likely to take place. This includes avoiding prolonged standing (church, assembly, lineups), looking away during blood testing etc. If symptoms occur, crossing the legs and squeezing while sitting, or laying down and elevating the legs will help shorten the episode and raise the blood pressure. Though awkward, this is less of a spectacle than blacking out and drawing attention to oneself. It is seldom necessary to attend the emergency room. 



• Salt and Water intake: The main components of blood are salt and water. Most patients with vasovagal syncope have periods of low blood pressure, or usually have low blood pressure. Increasing fluid intake to a minimum of 8 cups (2 liters) and preferably 12 cups (3 liters) per day often raises blood pressure. Ideally these fluids and the diet will include more salt to accompany the water. This can take the form of electrolyte solutions (Gatorade like fluids), fruit juices, salt in cooking or at the table, or salt tablets that can be requested from the pharmacist. Salt tablets may be hard to find. We have found them through IDA Pharmacies, Certified brand NaCL (sodium chloride) tablets, 600 mg each, usually taking 2-4 tablet per day. More salt and water are necessary if the weather is hot, or if vigorous exercise is performed, which increase body water loss.



• Tilt training is a simple way to train the blood vessels in the legs to improve their ability to pump blood back to the heart. Stand with your feet 15-20 cm (6-8”) from the wall and lean against the wall for 30 minutes at least 4 times a week. At first this may cause dizziness or even blackouts, but over time it will allow affected patient to tolerate standing without frequent dizziness. Regular weight bearing exercise (walking, jogging, stairmaster etc) will also improve muscle pumping of blood back to the heart.




Medications



Several medications are used in the small number of patients that do not respond to lifestyle measures. Clinical studies have suggested that each medication may have some effect, but there is not enough data to prove their effectiveness, and no information that compares one drug to another. The dose is usually built up gradually for all medications. Detailed information on each medication can be obtained from your local pharmacy. The following are frequently used medications:



• Beta blockers: metoprolol, atenolol, propranolol, bisoprolol. These medications block the adrenaline system, preventing the “overshoot” component of the abnormal reflex that precedes the blood pressure drop. They are usually taken once or twice a day.


• Fludrocortisone: Fluorief. This medication is the naturally occurring messenger that tells your kidneys to raise blood pressure by holding on to salt and water. It is usually taken once or twice a day.


• Midodrine: Amitine. This medication raises blood pressure by tightening blood vessels. Careful blood pressure monitoring is performed when starting the medicine. It is usually given 3 or 4 times a day.


• Paroxitine: Paxil. This medication and other similar medicines (SSRIs) are usually used to treat depression or anxiety. They also appear to prevent the brain reflex that leads to blood vessel relaxation and heart rate slowing. They often take 1-2 months to have an effect.



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ACKNOWLEDGEMENTS
Contributors to this information were:
Dr. R. Yee M.D., Arrhythmia Service, LHSC (UC)
Dr. A. Krahn MD, Arrhythmia Service, LHSC (UC)
and various staff members
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This page was last updated: Tue, Nov 18, 2003