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What is syncope ?

Syncope is the medical term for what is commonly known as fainting or blackouts. They are associated with a sudden but temporary loss of consciousness that recover quickly, completely and on their own.

Syncope is a symptom of another underlying problem and not a disease itself, although the end result is unconsciousness due to the brain receiving insufficient blood supply and oxygen. There can be many different causes of syncope. The symptoms may take the form of or be associated with:

  • Fainting
  • Near fainting (near or pre-syncope)
  • Dizziness
  • Palpitations

Syncope can affect people of all ages, usually as an isolated event without further problems. Sometimes however there can be serious consequences, including:

  • Injury due to falls or road traffic accidents during the blackout
  • Inability to do their job
  • Inability to perform normal daily activities for fear of further episodes.

While the majority of patients experience syncope as an isolated event, some may have further episodes. Often the cause can be difficult to identify. As syncope may come on without warning, it can lead to falls, car crashes and other safety risks. This can lead to patients being unable to drive or perform their jobs and is compounded by not knowing why they faint.

What causes syncope ?

Fainting or syncope is caused when the brain does not receive enough oxygenated blood. This results in a temporary loss of consciousness. The blood supply to the brain being restored when the patient falls to the ground.

There are many and widely differing causes of syncope, ranging from:

  • Simple faints or vasovagal syncope. This is an exaggerated form of the common faint. It is due to excessive pooling of blood in the legs and usually occurs following prolonged sitting or standing. This pooling of blood induces a fall in blood pressure, which in turn stimulates a further fall in blood pressure and heart rate causing dizziness and then syncope.
  • Standing up too quickly.
  • Neurological disorders.
  • Stress.
  • Side-effects from certain medications.
  • Abnormalities of the heart including disturbances of the heart rhythm (also called ‘arrhythmias), problems with the heart muscle, valves or coronary arteries.

In a small minority of patients, cardiac causes of syncope can prove serious and potentially life-threatening. In these cases the heart may beat too slowly, too rapidly or too irregularly to pump enough blood to the key parts of the body, including the brain.

How are the causes of syncope diagnosed?

The cause of syncope is sometimes hard to find because often the patient’s symptoms are very infrequent, with no detectable abnormality between episodes. For patients experiencing syncope, the tests they will undergo will be determined by what the doctor thinks is the most likely underlying cause. Such tests may include any of the following:

  • Blood tests.
  • A chest X-ray
  • An electrocardiogram (ECG).
  • Neurological evaluation with an electroencephalogram (EEG a test that looks at the electrical activity of the brain) or a head CT scan.
  • Psychological or psychiatric evaluation.

If the doctor suspects that the fainting episode may be related to the heart then more detailed heart investigations will be necessary to exclude potentially dangerous conditions. Further tests may include:

  • An ultrasound scan of the heart, called an echocardiogram. This is a painless test that provides important information about the way the heart is working. It provides pictures of the heart in motion and allows the doctor to assess the pumping action of the heart and how the heart valves are working.
  • More prolonged periods of heart rhythm monitoring, for example using Holter monitoring over a 24-hour period or longer.
  • Tilt table testing. A procedure that attempts to simulate conditions that may cause fainting.
  • Electrophysiological testing also known as EPS. This is a minimally invasive study assessing the electrical activity of the heart in more detail.

These tests are particularly useful and likely to be helpful in patients who have symptoms on a frequent basis and thus more likely to occur during testing. For patients with very infrequent symptoms, a tiny heart monitor (called an implantable loop recorder) can be placed under the skin on the chest to record the heartbeat for about a year.

How is syncope treated

Treatment of syncope is aimed at dealing with the underlying cause. As there are potentially many different causes for syncope, treatment options may differ significantly from one patient to another.

Simple faints

Simple faints can be avoided in the majority of patients by:

  • Sitting down as soon as you feel your symptoms starting, if possible lie down putting your legs up in the air, for example against a wall. Remember to get up slowly once your symptoms have eased and be prepared to sit or lie down promptly if they recur.
  • Avoid prolonged sitting or standing especially in warm environments.
  • Drink plenty of fluids (avoiding coffee unless advised otherwise) soon after getting up in the morning. Drink about 2 litres of fluid early on, then enough to keep your urine ‘clear’ for the rest of the day, avoiding excessive amounts of alcohol as this may make symptoms worse.
  • After discussion with your doctor consider increasing your salt intake. This should be avoided if you have high blood pressure.
  • Consider wearing support tights during the day, but remember to remove them before going to bed.

Neurological disorders, once investigated and a diagnosis established, may require further treatment. The treatments available will depend upon the cause found.