Fainting, or syncope (sin' ko-pe), is the sudden loss of consciousness and the ability to stand, also called passing out. This common problem is the cause of many falls and injuries. One-third of people faint at least once during their life. Syncope may occur without warning or is signaled by feelings of:
Causes
Fainting
is due to a sudden decrease in blood flow and oxygen to the brain.
There are many causes of syncope, but most fall into three major types.
Abnormal Nerve Reflex
Nerves that control heart rate,
blood pressure and other body functions may respond in an abnormal way
and cause syncope. This can be triggered by:
Fainting due to an abnormal nerve reflex is more likely to occur in certain conditions such as dehydration or viral infection, or after prolonged bed rest, lack of sleep or irregular food intake. Types of syncope that involve an abnormal nerve reflex include:
Vasovagal (neurocardiac) syncope is the most common type and can occur at any age. It often occurs when blood pools in the leg veins. This triggers a reflex and the heart rate, blood pressure or both may suddenly fall. It is generally not a dangerous condition and can be prevented by avoiding situations that can trigger syncope.
Carotid sinus hypersensitivity is more common in the elderly. In some people, pressure on the neck, such as a tight collar, heavy necklace, or a tumor, affects nerves that run close to the carotid artery. This triggers a slow heart rate and/or lowers blood pressure. Treatment may include a pacemaker. Orthostatic hypotension is a drop in blood pressure when a person stands up from a lying position. It is often seen in patients who are dehydrated or taking certain medicines.
Postural Orthostatic Tachycardia Syndrome (POTS) is another type of syncope and dizziness common after viral illness or prolonged bed rest. In POTS patients, the heart rate is normal when a person is lying down but becomes fast when standing, as the body tries to maintain a normal blood pressure. The heart rate becomes even faster with a small amount of physical exertion. POTS may cause chronic fatigue, poor sleep, headaches, dizziness or exercise problems.
Heart Conditions
Defects or damage to the heart may also lead to fainting. Most often, syncope is related to an heart rhythm. If the heartbeat is too slow or too fast, there may be a lack of blood flow to the brain. Sometimes a thick heart muscle or valve disorder may decrease blood flow. Palpitations, chest tightness, shortness of breath, excess perspiration or a feeling of anxiety may occur.Other Causes
Diseases, such as diabetes, migraines, seizure disorders, or nervous system problems, may cause syncope. Since syncope may be the first sign of a more serious problem, it is important to see your doctor to find out the cause and needed treatment.
Diagnosis
Because there
are many causes of fainting, making a diagnosis may take time. The
process begins with a history and physical exam. Tell your doctor or
nurse about your medical history and bring a list of all your
medicines. Describe how you felt or what you were doing just before and
right after you fainted. Tests may include an electrocardiogram, tilt
table testing, echocardiogram (ultrasound of the heart), heartbeat monitoring at home, or an exercise test. Further testing may be needed.
Treatment
Depending
on the cause, treatment may vary. If fainting is rare, treatment may
include avoiding certain activities. Being aware of warning signs and
taking steps, such as crossing the legs and tightening the leg muscles
while lying down, can often avoid fainting. Increased intake of fluids
and salt is often helpful. If fainting persists, medicine or a
pacemaker may be needed. Other treatments may be used for arrhythmias
and heart disorders.
Contact
Electrophysiology Department
(312) 926-4753
Review Date: 11/04
