Syncope (fainting) is a temporary loss of consciousness usually related to insufficient blood flow to the brain. It’s also called fainting or “passing out.” It most often occurs when blood pressure is too low (hypotension) and the heart doesn’t pump enough oxygen to the brain. The patient is motionless and limp and usually has cool extremities, a weak pulse, and shallow breathing. Sometimes brief involuntary muscle jerks occur, resembling a seizure. It can be benign or a symptom of an underlying medical condition.
Syncope is a common condition. It affects 3% of men and 3.5% of women at some point in life. Syncope is more common as you get older and affects up to 6% of people over age 75. The condition can occur at any age and happens in people with and without other medical problems.
Most syncope results from insufficient cerebral blood flow. Some cases involve adequate flow but with insufficient cerebral substrate (oxygen, glucose, or both). Most deficiencies in cerebral blood flow result from decreased cardiac output (CO).
Decreased CO can be caused by
• Cardiac disorders that obstruct outflow
• Cardiac disorders of systolic dysfunction
• Cardiac disorders of diastolic dysfunction
• Arrhythmias (too fast or too slow)
• Conditions that decrease venous return
Outflow obstruction can be exacerbated by exercise, vasodilation, and hypovolemia (particularly in aortic stenosis and hypertrophic cardiomyopathy), which may precipitate syncope.
The most common symptoms of syncope (fainting) include –
• Blacking out
• Feeling lightheaded
• Falling for no reason
• Feeling dizzy
• Feeling drowsy or groggy
• Fainting, especially after eating or exercising
• Feeling unsteady or weak when standing
• Changes in vision, such as seeing spots or having tunnel vision
Many times, patients feel an episode of syncope coming on. They have what are called “premonitory symptoms,” such as feeling lightheaded, nauseous, and heart palpitations (irregular heartbeats that feel like “fluttering” in the chest). If you have syncope, you will likely be able to keep from fainting if you sit or lie down and put your legs up if you feel these symptoms.
There are several types of syncope, each with a different cause.
• Reflex syncope
Reflex syncope, also known as neurally mediated syncope, is the most common type of fainting. It happens when certain reflexes are not properly regulated. This can cause your heart to slow down and a drop in blood pressure. In turn, this can decrease the flow of blood to your brain.
There are three kinds of reflex syncope:
This happens when your body overreacts to a trigger. There are many types of triggers, which can include things like intense pain, distress, or standing too long. Vasovagal syncope accounts for 50 percent of all cases of fainting.
This type of fainting happens when you perform certain actions, such as laughing, coughing, or swallowing.
* Carotid sinus
This type of fainting happens when pressure is placed on your carotid artery, located in your neck. Fainting can occur due to certain neck motions, wearing shirts with a tight collar, or shaving.
• Cardiac syncope
Cardiac syncope is fainting caused by a problem with your heart. When your heart isn’t working quite as it should, your brain receives less blood. It’s estimated that cardiac syncope causes about 15 percentof fainting episodes.
• Orthostatic syncope
Orthostatic syncope happens due to a drop in blood pressure when you stand up. The drop in blood pressure occurs due to the effects of gravity.
Normally, your brain works to stabilize this. But in orthostatic syncope this doesn’t happen. As a result, it can lead to fainting.
Symptoms are usually consistent with the warning signs that are commonly experienced before a fainting episode. However, orthostatic syncope may also happen suddenly, without warning.
• Cerebrovascular syncope
This type of syncope happens due to a problem with the blood vessels in and around the brain that can prevent the brain from getting enough blood.
Syncope(Fainting) may have a variety of causes. A simple episode, also called a vasovagal attack or neurally-mediated syncope, is the most common type of fainting spell. It is most common in children and young adults.
A vasovagal attack happens because blood pressure drops, reducing circulation to the brain and causing loss of consciousness. Typically an attack occurs while standing and is frequently preceded by a sensation of warmth, nausea, lightheadedness and visual “grayout.” If the syncope is prolonged, it can trigger a seizure.
You may suffer from a simple fainting spell due to –
• intense emotional stress
• use of alcohol or drugs.
Most people who suffer from simple fainting have no underlying heart or neurological (nerve or brain) problem.
Some people have a problem with the way their body regulates their blood pressure, particularly when they move too quickly from a lying or sitting position to a standing position. It may be severe enough to cause fainting. This type of fainting is more common in the elderly, people who recently had a lengthy illness that kept them in bed and people who have poor muscle tone.
Some more causes of syncope (fainting) are –
• Diseases of the autonomic nervous system.
Autonomic nervous system problems include acute or subacute dysautonomia, chronic post-ganglionic autonomic insufficiency, and chronic pre-ganglionic autonomic insufficiency. Autonomic nervous system is the part of the nervous system that controls involuntary vital functions, such as the beating of your heart, the degree to which your blood vessels are constricted, and breathing.
• Conditions that interfere with the parts of the nervous systemthat regulate blood pressure and heart rate.
These conditions include diabetes, alcoholism, malnutrition, and amyloidosis (in which waxy protein builds up in the tissues and organs). If you take certain high blood pressure drugs, which act on your blood vessels, you may be more likely to suffer from fainting. If you are dehydrated, which may affect the amount of blood in your body and, thus, your blood pressure, you may be more likely to faint.
• Heart or blood vessel problems that interfere with blood flow to the brain.
These may include heart block (a problem with the electrical impulses that control your heart muscle), problems with the sinus node (a specialized area of your heart that helps it beat), heart arrhythmia (irregular heart rhythm), a blood clot in the lungs, an abnormally narrowed aortic heart valve, or certain other problems with the structure of your heart.
• Conditions that may cause unusual patterns of stimulation to particular nerves.
These include micturition syncope (fainting during or after urination), glossopharyngeal neuralgia (fainting due to inflammation and pain in a particular nerve to the mouth); cough syncope (fainting after intense coughing), and stretch syncope (fainting that occurs when stretching the neck and arms).
If you become intensely anxious or panicked and breathe too quickly, you may feel faint from hyperventilation (taking in too much oxygen and getting rid of too much carbon dioxide too quickly).
It is important to identify the cause of syncope, if possible, to rule out a dangerous heart condition. Depending on your symptoms and circumstances, the following tests may be used to find the cause –
▪︎ On-site Diagnostic Tests
• Electrocardiogram(ECG or EKG): wires taped to various parts of your body to create a graph of your heart’s electrical rhythm
• Exercise stress test: ECG recorded while strenuously exercising
• Echocardiogramor transesophageal echocardiogram: ultrasound of the heart
• Physical examination, including orthostatic vital signs and carotid sinus massage
• Tilt table test: measurement of heart rate and blood pressure in response to upright tilt, which simulates prolonged standing
• Electrophysiology study(EP): test that examines the heart’s electrical activity from the inside; used to diagnose many heart rhythm disorders
▪︎ In-home Diagnostic Monitors
• Holter monitor: a portable ECG you wear continuously for one to seven days to record your heart rhythms over time
• Event monitor: a portable ECG you wear for one or two months, which records only when triggered by an abnormal heart rhythm or when you manually activate it
What should you do if you felt like to faint?
• If you’re feeling faint, lie down.
Position yourself so your head is low and your legs are raised. This can help increase the blood flow to your brain. Lying down also lowers your risk of injury if you were to faint.
• If you can’t lie down, sit down.
Depending on the situation, you may not be able to lie down. In this case, sit down and put your head between your knees to increase the blood flow to your brain.
• Stay lying down or seated until the feelings of faintness pass.
Don’t get up too quickly, as this may make you feel faint again.
Your treatment options will depend on what is causing your syncope and the results of your evaluation and testing.
Treatment options include –
• Taking medications or making changes to medications you already take.
• Wearing support garments or compression stockings to improve blood circulation.
• Making changes to your diet. Your doctor may suggest that you eat small, frequent meals; eat more salt (sodium); drink more fluids, increase the amount of potassium in your diet; and avoid caffeine and alcohol.
• Being extra cautious when you stand up.
• Elevating the head of your bed while sleeping. You can do this by using extra pillows or by placing risers under the legs of the head of the bed.
• Avoiding or changing the situations or “triggers” that cause a syncope episode.
• Treatment for structural heart disease.
• Implanting a pacemaker to keep your heart rate regular (only needed for patients with certain medical conditions).
• An implantable cardiac defibrillator (ICD). This device constantly monitors your heart rate and rhythm and corrects a fast, abnormal rhythm (only needed for patients with certain medical conditions).
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