Arrhythmias - Fainting (General)

 

SYNCOPE
© Alan B. Schwartz, M.D. January 1999/version 1.0

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 transient loss of consciousness. 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 consciousness means that you black out and loose postural tone. If you were standing, you would fall to the ground. If you were sitting you might slump over. This may happen with or without warning symptoms. The period of unconsciousness usually lasts from several seconds to minutes.

PATHOPHYSIOLOGY

There are a lot of causes of syncope. Because of this, it is sometimes difficult to determine the exact cause. While the precise basis is not able to be determined in 38 to 47% of cases, doctors generally can tell you whether or not you have a serious or benign case.

Despite what you might think, most syncope has nothing to due with the brain. Most syncope is due to a cardiac cause. 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 scans of the brain and MRI scans of the brain and angiography. The small numbers of patients who have a neurological cause of syncope usually have obvious manifestations of seizures

The root of loss of consciousness is due to lack of oxygen to brain cells. Brain cells need oxygen to function and maintain consciousness. The lack of oxygen may be due to a decrease in oxygen carrying capacity due to lower blood flow or due to a decrease in the elements that carry oxygen such as red blood cells.

The most likely causes of syncope are listed below. Most are benign but some could be the early warning of a life-threatening problem.

Causes of Syncope

• Cardiac Causes
• Mechanical obstruction to blood flow which decrease cardiac output
• Aortic valve malfunction
• Mitral valve malfunction
• Pulmonary Hypertension
• Electrical causes which decrease cardiac output
• Slow heart rates
• Heart block
• Pacemaker malfunction
• Drugs
• Fast heart rates (which decrease cardiac filling and subsequently cardiac output)
• Supraventricular tachycardia
• Ventricular tachycardia
• Neuro-cardiac:
• Neuro-cardiogenic
• Drops in blood pressure when standing
• Brain
• Rare

PROGNOSIS

The prognosis of syncope is related to the severity underlying cardiovascular disease. If there is none, the prognosis is excellent and there is a high chance of spontaneous remission. Furthermore, there is a very small risk of any life threatening consequence.

On the other had if there is underlying serious cardiac disease, the 1 year death rate could be as high as 30%. Underlying serious cardiac disease includes heart attacks, heart valve disease and poor heart function. In these patients, the symptom of syncope must be taken very seriously.

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 a preliminary 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 to 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 (so that if he or she passes out she will not be able to fall) and the table is tilted 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 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 worn on the belt with thin wires attached to electrodes on the body which had a 5 minute memory loop. 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 associated rhythm associated with the loss of consciousness.

For patients with underlying organic heart disease, the most likely cause of syncope is still a benign cause but more serious life-threatening possibilities should be excluded first. The best way to do this is with an Electrophysiology test. This is a heart catheterization done as outpatient procedure at the hospital under heavy sedation. During this test multiple small "spaghetti like" tubes called catheters are inserted into various chambers of the heart to test whether any life-threatening rhythms may be occurring. When abnormal findings are discovered the kinds of treatments may involve a traditional pacemaker, an internal cardioverter defibrillator (ICD), catheter ablation procedure and/or medications.

TREATMENT

The treatment possibilities involve medications, pacemaker devices or ICD’s, or catheter ablation. Your doctor will discuss these possibilities with you in depth.

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

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