Fainting or “syncope” is a temporary loss of consciousness followed by spontaneous recovery. This is a common problem that contributes to 740,000 visits to emergency departments each year in the United States. Trying to identify the source of syncope is often difficult because its causes are varied (and occasionally obscure) and they range from benign to life-threatening. Add in the fact that many people will have multiple potential causes for fainting and a correct diagnosis of the underlying problem may take some time.
While syncope can occur at any age, the age distribution of syncope shows two distinct spikes: it occurs more often in teenagers (median age of onset: 18 years) and in people 70 years of age or older. The frequency of such faints varies widely; some people faint maybe once a year (or even less often); others experience their episodes in clusters and then are free of fainting for decades; others may experience syncope much more frequently. Recurrent fainting can dramatically disrupt one’s lifestyle, diminish quality of life, and even lead to serious injury or death resulting from sudden loss of consciousness at very inopportune times, such as while driving or climbing a ladder.
Syncope may occur without warning, or at least nothing that the person experiencing the event recalls afterward. That’s because amnesia may occur for a period before and shortly after a loss of consciousness, leading some people to rationalize their falls as nothing more than slips and trips because they really do not remember what happened. Consequently, doctors may want to ask questions of someone who witnessed a syncope event, because onlookers may have more details than the individual who fainted. For many people with syncope, there are warning signs: a person may feel faint, dizzy, or lightheaded (presyncope). People who experience syncope may become sweaty, their skin may look pale, and they may experience nausea or abdominal discomfort. After an episode of fainting, an individual may feel fatigue or weakness. In the elderly, warning signs may be nonexistent or they may occur but in an abbreviated manner compared to younger people.
CAUSES OF SYNCOPE
There is a long list of causes of syncope. Some are heart related, and some are not. The most common type of fainting is due to a stimulus that results in an exaggerated/inappropriate response in that part of the nervous system that regulates heart rate and blood flow. “Vasovagal” syncope, as it’s called, accounts for up to 66% of the syncope cases seen in hospital emergency rooms every year. It can be triggered by prolonged standing or sitting, hot environments, hunger, dehydration, systemic illness, emotional stress (including panic and fear), pain, and alcohol. It may occur in response to bodily functions such as swallowing, cough, urination, or defecation. It may be seen in response to really good news or really bad news. Even something as simple as having a health care professional take a sample of your blood can cause fainting.
Sometimes a broader term is used in medicine: neurocardiogenic, which suggests the combined neurologic and heart-related mechanisms leading to loss of consciousness. Momentary light-headedness upon standing from a seated or reclining position is a common neurocardiogenic response. The medical name for this is “orthostatic” or “postural” hypotension (low blood pressure); colloquially, it’s referred to as a “head rush” or “dizzy spell.” Sometimes it occurs within an hour after eating (“postprandial hypotension”) or after prolonged exposure to temperature extremes (e.g., getting out of a hot tub). As we age, our bodies don’t respond as quickly to large postural changes and the subsequent minor adjustments required of the nervous system to maintain adequate blood pressure are impaired. However, orthostatic hypotension is sometimes seen in teenagers, too, who have a similar problem when they experience a large amount of growth in a relatively short period of time.
Individuals with vasovagal syncope often start having fainting episodes in adolescence or early adulthood. Fortunately, when syncope occurs early in life the symptoms tend to run a benign course and diminish with maturity. On the other hand, syncope is less likely to be benign in older individuals, especially people with heart disease. If the underlying cause is left untreated, syncope in the elderly can greatly increase risk of death. There are other explanations for the increased risk of syncope in older individuals. There may be age-related changes that predispose the elderly to syncope; including reduced thirst (leading to dehydration or heat stress); multiple medications that increase the risk of drug interactions; plus, the elderly often have multiple health problems which can contribute to syncope. Whatever the cause, falls in the elderly result in significant loss of confidence, fear of falling, increased risk of injury, and an increased likelihood that they will no longer be able to live independently. All of this is to underscore the importance of getting a medical checkup whenever an older person experiences episodes of fainting.
Syncope may be due to prescription or over-the-counter medications. For example, orthostatic hypotension can be a side effect of certain anti-depressants. Sometimes syncope results from an interaction between two or more drugs, or it can be in response to starting a new medication (especially drugs for treating high blood pressure or arrhythmias), a change in dosage, or long-term chronic treatment with one drug.
There are many other causes of syncope. Irregular heartbeats, known as arrhythmias, are the second most common cause of fainting. Other cardiac-related causes include structural heart defects, ischemic disease, stroke or transient ischemic attack (so-called “mini-strokes”), and diseases of the heart muscle(cardiomyopathies). Unexplained syncope may also be the first manifestation of degenerative neurologic disorders such as Parkinson’s disease. In general, syncope is an uncommon manifestation of neurologic disease, but if syncope occurs while someone is lying down with the face up (the “supine” position), if it is preceded by a visual disturbance known as “an aura,” or if it is followed by confusion or amnesia, a neurologic cause is more likely. Finally, seizure disorders are sometimes mistaken for syncope.
Although the mechanism of syncope remains unexplained in about 40% of episodes, usually the cause of syncope can be determined with great accuracy from a careful history and physical examination. A history of heart attack, heart failure, or a repaired congenital defect in the heart raises the possibility of arrhythmias. Previous head trauma in a younger person with no heart disease suggests a neurologic cause, whereas syncope brought on by head rotation or pressure on the carotid artery (neck turning or tight collars, for example) suggests an overly sensitive carotid sinus (which is involved in regulation of blood pressure). If there is a family history of sudden cardiac death, recurrent syncope might suggest a hereditary problem, such as certain cardiomyopathies.
In general, unless there is underlying heart disease, syncope is not associated with excess mortality. When there is no heart disease that could be causing or compounding the problem, the main risk is related to physical harm that may occur if the patient faints. In these cases, the intensity of the workup to establish a diagnosis is determined by the “malignancy” of the episode. A malignant episode of syncope is one that occurs with little or no warning and results in significant injury or property damage.
The following summary points are derived from the AHA/ACCF Scientific Statement on the Evaluation of Syncope published in 2006. It is important to remember that not all guidelines are applicable to all patients under all circumstances. It is always wise to discuss your particular situation with your personal physician.
EVALUATION OF SYNCOPE
Because most syncope is neurocardiogenic in origin or due to an arrhythmia, an extensive neurologic evaluation (other than a physical exam) in patients with syncope is unwarranted on a routine basis and should be limited to patients with symptoms or signs suggestive of a neurologic disorder, e.g., an aura.
There are different ways to monitor heart rhythm in patients in whom syncope is suspected to be caused by an arrhythmia. Holter monitors can record the heart rhythm for 24 hours. Event monitors can be used for 30 days. However, when syncope is sporadic and unexplained, an implantable loop recorder may be the best option. An implantable loop recorder looks a bit like a pacemaker and is implanted directly under the skin through a small incision. It can be used to monitor the heart rhythm for a year or more.
Although tilt table testing is commonly used to evaluate patients with recurrent syncope, this test is not perfect and may miss some people with true neurocardiogenic syncope. Even when the test is negative, the most likely cause of syncope is still neurocardiogenic syncope.
Invasive testing (an electrophysiology (EP) study) is most helpful in patients with known coronary artery disease (heart artery blockages) and syncope of uncertain cause. EP testing is less useful in other settings.
LIFESTYLE MODIFICATIONS
Education is very important for reducing the most common types of syncope; sometimes simple behavioral maneuvers can abort an attack and might be as good as many of the medications available for treating syncope.
1. One cornerstone of treatment is avoidance of triggers known to cause syncope. Individuals with recurrent syncope should make sure they drink plenty of fluids, avoid temperature extremes, avoid long periods of standing, and never stand up quickly or “jump up” quickly from a reclining position.
2. Be vigilant for the onset of warning signs of vasovagal syncope and initiate counter maneuvers immediately. Traditionally, that means lying down with feet elevated. Fist clenching, arm tensing, and leg crossing all decrease pooling of blood in the extremities. Another simple technique is contraction of the major leg muscles before standing or during periods of standing.
3. While athletes may experience fainting due to a number of benign problems such as dehydration, heat, exertion, and electrolyte imbalance, athletes with syncope should be carefully evaluated to uncover any underlying cardiovascular disease or rhythm disorder. Hypertrophic cardiomyopathy, congenital heart disease, and coronary artery anomalies should be ruled out in young patients with syncope, particularly when the syncope occurs with activity. When such conditions go undetected, there is a strong risk of sudden death in even young athletes.
4. A few small studies of young adults suggest that salt supplementation may be effective at reducing syncope. Salt and fluids increase blood volume, but this cannot be recommended for older people due to the high prevalence of high blood pressure in this patient cohort.
5. Compression hosiery is sometimes recommended, especially for elderly individuals with recurrent syncope, although studies have shown limited success with these elastic stocking.
DRUG AND DEVICE THERAPIES
Most patients experience infrequent faints and seldom require more than counseling and reassurance. Patients with frequent and/or unpredictable syncope, however, can be severely disabled and require therapy. Treatment of syncope is directed at its cause. If the underlying cause is an arrhythmia, for example, then the treatment will include antiarrhythmic therapy.
1. Individuals with syncope related to arrhythmias, advanced structural heart disease, cardiomyopathy, and/or a family history of unexplained sudden cardiac death may be considered for implantation of a device that detects arrhythmias and uses electrical shocks to restore normal heart rhythm (implantable cardiac defibrillator or ICD). There are many considerations that go into this decision and these are specific to each patient.
2. If medication is thought to be the cause of syncope, your physician needs to be consulted before there is any change to your prescription medicines. Simply halting drug therapy without your doctor’s knowledge and advice is not recommended.
Guideline-Based Standards of Care: What You Should Know
The American College of Cardiology (ACC) and the American Heart Association (AHA) work together on an ongoing basis to publish Guidelines addressing standards of care for the diagnosis, management and prevention of cardiovascular disease. The ACC/AHA Guidelines represent a consensus of expert medical opinion, with the goal of establishing a standard on which to base cardiovascular care decisions, serving the patient’s best interests.
The guidelines are intended to help health care providers and patients make informed, best-possible decisions regarding care for specific clinical circumstances. The ACC strongly believes that adoption of these standards leads to higher quality cardiovascular care, cost-effectiveness, and most importantly, better outcomes for patients.
Please note that the ACC/AHA Guidelines attempt to define practices that meet the needs of most patients in most circumstances. However, everyone is unique, and the extent to which the guidelines apply specifically to you should be a key point of discussion between you and your cardiologist or health care provider. The ultimate judgment regarding your care must be made by you and your healthcare provider together, in light of circumstances specific to you as a patient.
Although all ACC/AHA Guideline documents are freely available, and can be downloaded from the ACC’s Cardiosource web site, these documents are often extremely long, and written primarily for the healthcare provider. Here at CardioSmart you will find a summary of the key points from the Guidelines, written specifically with the patient in mind. We urge you to review these key points, print them out if you like, and engage your healthcare provider in a discussion of how the guidelines relate to you and your condition.
That is, after all, what being CardioSmart is all about – being empowered to work with your physician in managing your care to assure the best possible outcome!
If you’d like to read the full guidelines from which this summary is derived, please click on either of the links below. Please note that these documents are large, so please have patience while they load.
AHA/ACCF Scientific Statement on the Evaluation of Syncope
