Fainting is the sudden loss of consciousness.
In general, fainting is caused by decreased blood flow to the brain.
This can occur due to:
- Vasovagal spells (most common cause) – simple fainting that can occur:
- During medical procedures
- During times of high stress, trauma, or fright
- After standing still for a long period of time
- Low blood pressure, especially when standing (called orthostatic hypotension)
- Anemia due to blood loss
- Side effect of a medication
- Stroke or transient ischemic attack
- Too rapid or too slow heart rhythm
- Organic heart problems such as:
- hypertrophic cardiomyopathy
- pulmonary stenosis
- constrictive pericarditis
A risk factor is something that increases your chance of getting a disease or condition.
- Heart disease, especially congestive heart failure or abnormal rhythms
- Blood loss
- Medications, including:
- Blood pressure medications
- Drugs that enlarge blood vessels
- Drugs that regulate the heart's rhythm
- Water pills (diuretics)
- Sudden loss of consciousness
- Inability to remain standing or sitting
- Consciousness regained without any need for intervention
- Dizziness or lightheadedness before losing consciousness
The doctor will ask about your symptoms and medical history, and perform a physical exam.
Tests may include (in order of importance):
Blood Tests – to look for anemia, hypoglycemia, low potassium, and low magnesium
Electrocardiogram (EKG) – a test that records the heart's activity by measuring electrical currents through the heart muscle
Holter Monitoring – a mobile EKG test that is performed over 24 hours, while you go about your usual daily activities
Head CT Scan – a type of x-ray that uses a computer to make pictures of the brain
MRI Scan of the Brain – a test that uses magnetic waves to make pictures of the brain
Echocardiogram – a test that uses high-frequency sound waves (ultrasound) to examine the size, shape, and motion of the heart
Cardiac Catheterization –a tube-like instrument inserted into the heart through a vein or artery (usually in the arm or leg) to detect problems with the heart and its blood supply
Electroencephalogram (EEG) – a test that records the brain's activity by measuring electrical currents through the brain
Treatment will depend on the underlying condition that has caused fainting. For example:
- Abnormal heart rhythms can be treated with medications or by implanting a pacemaker.
- If a medication is causing syncope, it may need to be changed or discontinued.
- Anemia or other blood abnormalities should be treated.
If you feel any warning signs, such as dizziness or lightheadedness, sit or lie down immediately so that you don't get hurt falling during a fainting spell.
If you are prone to fainting:
- Get up slowly and carefully from lying down. Start by sitting up. Don't ever jump to a standing position.
- Ask your doctor if you should be on a high-salt diet.
- Drink lots of fluids.