Arrhythmias - Fainting (Neurocardiogenic Syncope)

 

NEURO-CARDIOGENIC SYNCOPE
© Alan B. Schwartz, M.D. January1999/version 1.2

INTRODUCTION

Loss of consciousness is a scary symptom. The threat of sudden and random loss of control over your body leaves you vulnerable, open to injury and dependent on others.

Certain freedoms which are essential in daily life, which you may have taken for granted, like driving, become dangerous.

As unsettling as this symptom is, it is also a common symptom accounting for 3% of all emergency department admissions and 1 to 6% of all hospital admissions. It has been estimated that up to 30% of the population has had at least one episode sometime during his or her life.

Fortunately, most causes of this disorder are benign with a good prognosis and can be treated with simple measures. In most cases, this symptom does not reflect any serious underlying heart disease.

Hopefully, this information sheet will provide you with the understanding of the diverse causes of these symptoms, methods of evaluation and treatment options.

DEFINITION

Syncope is the medical name for temporary loss of consciousness associated with loss of postural tone and with spontaneous recovery. This is to be distinguished from other medical terms such as dizziness or vertigo in which there is no loss of consciousness and coma which is not transient. Although these other terms seem related, the implications and the evaluation of them is quite different.

Loss of postural tone means that if you were standing, you would fall to the ground and that if you were sitting you might slump over without any recollection of what had happened. Syncope may happen with or without warning symptoms. The period of unconsciousness usually lasts from several seconds to minutes.

CAUSE

There are a lot of medical conditions which can lead to syncope. Because of this, it is sometimes difficult to determine the exact cause. While the precise basis is not able to be determined in 20-40% of cases, doctors generally can tell you whether or not you have a serious or benign kind.

Despite what you might think, most syncope has nothing to due with the brain. Most syncope is due to the heart. This finding comes from many studies of such patients who have had brain wave tests (EEG’s), carotid artery test (Non invasive carotid Doppler ultrasound), CT or CAT scans of the brain and MRI scans of the brain and MRI angiography. The small numbers of patients who actually do have a neurological cause of syncope usually have telltale manifestations or a history of neurological disease or seizures.

While there are many causes of syncope, you doctor believes you have neuro-cardiogenic syncope which is a benign cause.

This form of syncope occurs when blood pressure drops precipitously. In a standing individual, adequate blood pressure is need to propel the oxygen carrying red blood cells from the heart against gravity up to the brain. However, in the horizontal position even a low blood pressure is sufficient to get oxygen to the brain since it does not need to work against gravity. This is why persons with this disorder who pass out usually wake up soon after lying down.

PROGNOSIS

The prognosis of syncope is related to the severity underlying cardiovascular disease. If there is none, the prognosis is excellent. With neuro-cardiogenic syncope there is also a high chance of spontaneous remission. There is a very small risk of any life threatening consequence.

SYMPTOMS

The symptoms associated with this kind of syncope are characteristic. There is usually a warning phase during which time the person feels "different". These early feelings may be dizziness, warmth, sweating, anxiety, blurred vision, nausea, palpitations, and/or yawning. The circumstances that trigger these symptoms are typically associated with pain, prolonged standing, heat, dehydration, fear, a blood test etc. The symptoms progress over several seconds to minutes and will lead to loss of consciousness if nothing is done. The vision may narrow and appear as though in a tunnel. The patient then loses consciousness and falls to the ground at which time he awakens with in seconds to minutes. Afterward, the feeling of needing to go to the bathroom is not uncommon as well as fatigue which may last for hours. Usually when the individual awakens he is not confused and regains his full mental faculties almost immediately.

WORK UP

The most important part of the evaluation is the history taken by the doctor. In the majority of the cases this leads to the working diagnosis. In some cases the diagnosis is in question and then further tests are necessary.

If there is no evidence for underlying heart disease based on the history, physical examination and EKG, the usual cause is neuro-cardiogenic and a head-up Tilt table test may be performed to confirm the diagnosis. The Tilt test is done at the hospital but is very "low tech". It is basically a "standing test".

The patient is placed on a table which can tilt from a horizontal to an upright position. An intravenous line is started so that fluids and medicines can be given if necessary. The person is strapped to the table (to prevent falling) and the table is tilted, head upright. The patient is watched in this position for 45 minutes. If the test is negative to that point it is repeated with intravenous infusion of an adrenaline like substance. Most, but not all, persons with neuro-cardiogenic syncope will have a positive test, thus confirming the diagnosis. Sometimes this test is used to assess therapy by repeating it on medications to see whether the medication can prevent syncope. If it does then the medication is assumed to be likely to work.

The other test frequently employed in persons with normal cardiac evaluation is the event monitor. This is a very light weight tape recorder which has a 5-minute memory loop and is worn on the belt with thin wires attached to electrodes on the body. The person who passes out pushes a button on the device after regaining consciousness. As long as no more than 5 minutes has elapsed, the recorder will show the rhythm associated with the loss of consciousness.

TREATMENT

Non medical therapy is very effective. Since the episodes involve a sudden drop in blood pressure, those persons with already low blood pressures are at the greatest risk of loss of consciousness.

1. The treatment in these cases is to follow a moderate to high salt diet to raise the blood pressure. Avoid fasting or dehydration for prolonged periods of time.
2. When the symptoms occur, lay down if possible for 20 to 30 minutes by which time the symptoms usually have passed. Also avoid the stress that causes the symptoms if they occur under predictable circumstances.
3. You should not drive your car until your doctor has "cleared" you to do so.

When these simple measures are insufficient, oral medicines and medicine "skin patches" can be prescribed to prevent future episodes. These medications and patches are prescribed on an individual fashion in order to tailor the medicine to individual to find the optimum therapy with the least side effects.

Recent information now indicates that pacemakers can decrease episodes of syncope in some. This kind of therapy is currently used when none of the above measures has been effective.

If you have any questions, please call or write Alan Schwartz, M.D. by telephone, e-mail or fax.

Click here for more information on signs and symptoms
Click here for more information on tilt table test