Syncope (medicine)

syncopefaintingfaintedfaintblackoutspassing outblackoutfaintnessfaintsloss of consciousness
Syncope, also known as fainting, is a loss of consciousness and muscle strength characterized by a fast onset, short duration, and spontaneous recovery.wikipedia
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Lightheadedness

presyncopelight-headednesslight-headed
There are sometimes symptoms before the loss of consciousness such as lightheadedness, sweating, pale skin, blurred vision, nausea, vomiting, or feeling warm.
Lightheadedness is a common and typically unpleasant sensation of dizziness or a feeling that one may faint.

Hypotension

low blood pressurehypotensivelow
It is caused by a decrease in blood flow to the brain, typically from low blood pressure.
If the blood pressure is sufficiently low, fainting may occur.

Orthostatic hypotension

postural hypotensionlow blood pressure with standingfeeling lightheaded with standing
There are three broad categories of causes: heart or blood vessel related; reflex, also known as neurally mediated; and orthostatic hypotension.
Severe drops in blood pressure can lead to fainting, with a possibility of injury.

Bradycardia

slow heart rateslowed heart ratebradyarrhythmia
Neurally mediated syncope occurs when blood vessels expand and heart rate decreases inappropriately.
When symptomatic, it may cause fatigue, weakness, dizziness, sweating, and at very low rates, fainting.

Pulmonary embolism

pulmonary embolipulmonary emboluspulmonary thrombosis
Heart related causes may include an abnormal heart rhythm, problems with the heart valves or heart muscle and blockages of blood vessels from a pulmonary embolism or aortic dissection among others.
Severe cases can lead to passing out, abnormally low blood pressure, and sudden death.

Brugada syndrome

BrugadaSantos Family
The ECG is useful to detect an abnormal heart rhythm, poor blood flow to the heart muscle and other electrical issues, such as long QT syndrome and Brugada syndrome.
Those affected may have episodes of passing out.

Electrocardiography

electrocardiogramECGEKG
A medical history, physical examination, and electrocardiogram (ECG) are the most effective ways to determine the underlying cause.

Aortic dissection

dissecting aortic aneurysmdissectionthoracic aortic dissection
Heart related causes may include an abnormal heart rhythm, problems with the heart valves or heart muscle and blockages of blood vessels from a pulmonary embolism or aortic dissection among others. Aortic dissection (a tear in the aorta) and cardiomyopathy can also result in syncope.
Less common symptoms that may be seen in the setting of AD include congestive heart failure (7%), fainting (9%), stroke (6%), ischemic peripheral neuropathy, paraplegia, and cardiac arrest.

Micturition syncope

There are many different syncope syndromes which all fall under the umbrella of vasovagal syncope related by the same central mechanism, such as urination ("micturition syncope"), defecation ("defecation syncope"), and others related to trauma and stress.
Micturition syncope or post-micturition syncope is the name given to the human phenomenon of fainting shortly after or during urination.

Wolff–Parkinson–White syndrome

Wolff-Parkinson-White syndromeBundle of KentWPW syndrome
SVT does not cause syncope except in Wolff-Parkinson-White syndrome.
Symptoms can include an abnormally fast heartbeat, palpitations, shortness of breath, lightheadedness, or syncope.

Heart block

blockheart-blockSinoatrial heart block
Bradycardia can be caused by heart blocks.
Despite the severe-sounding name, heart block may cause no symptoms at all in some cases, or occasional missed heartbeats in other cases (which can cause light-headedness, syncope (fainting), and palpitations), or may require the implantation of an artificial pacemaker, depending upon exactly where in the heart conduction is being impaired and how significantly it is affected.

Pulmonary hypertension

pulmonary arterial hypertensionPrimary pulmonary hypertensionpulmonary artery hypertension
Among other conditions prone to trigger syncope (by either hemodynamic compromise or by a neural reflex mechanism, or both), some of the most important are hypertrophic cardiomyopathy, acute aortic dissection, pericardial tamponade, pulmonary embolism, aortic stenosis, and pulmonary hypertension.
Symptoms include shortness of breath, syncope, tiredness, chest pain, swelling of the legs, and a fast heartbeat.

Aortic stenosis

aortic valve stenosisaorticstenosis
Aortic stenosis and mitral stenosis are the most common examples.
If heart failure, loss of consciousness, or heart related chest pain occur due to AS the outcomes are worse.

Adams–Stokes syndrome

Adams-Stokes syndromeStokes-Adams attackStokes-Adams disease
Adams-Stokes syndrome is a cardiac syncope that occurs with seizures caused by complete or incomplete heart block.
Stokes–Adams syndrome is a periodic fainting spell in which there is a intermittent heart block due to an arrhythmia that may last for seconds, hours, days, or even weeks before the conduction returns.

Implantable loop recorder

implanted cardiac monitorimplanted loop recorderInsertable Cardiac Monitor
More specific tests such as implantable loop recorders, tilt table testing or carotid sinus massage may be useful in uncertain cases.
The ILR is a useful diagnostic tool when patients experience symptoms such as syncope (fainting), seizures, recurrent palpitations, lightheadedness, or dizziness regularly but not often enough to be captured by a 24-hour or 30-day external monitor.

Cardiomyopathy

cardiomyopathiesmyocardial degenerationcardiomyopathic
Aortic dissection (a tear in the aorta) and cardiomyopathy can also result in syncope.
An irregular heart beat and fainting may occur.

G-LOC

blackoutblacked outlosing consciousness
Factors that influence fainting are fasting long hours, taking in too little food and fluids, low blood pressure, low blood sugar, high g-force, emotional distress, and lack of sleep.
G-force induced loss of consciousness (abbreviated as G-LOC, pronounced "JEE-lock") is a term generally used in aerospace physiology to describe a loss of consciousness occurring from excessive and sustained g-forces draining blood away from the brain causing cerebral hypoxia.

Atrial fibrillation

atrial fibrilationparoxysmal atrial fibrillationAtrial fibrillation with rapid ventricular response
A number of factors make a heart related cause more likely including age over 35, prior atrial fibrillation, and turning blue during the event.
Occasionally there may be heart palpitations, fainting, lightheadedness, shortness of breath, or chest pain.

Subclavian steal syndrome

Subclavian steal syndrome arises from retrograde (reversed) flow of blood in the vertebral artery or the internal thoracic artery, due to a proximal stenosis (narrowing) and/or occlusion of the subclavian artery.

Long QT syndrome

QT prolongationProlonged QT intervalLong QT syndrome type 3
The ECG is useful to detect an abnormal heart rhythm, poor blood flow to the heart muscle and other electrical issues, such as long QT syndrome and Brugada syndrome.
It results in an increased risk of an irregular heartbeat which can result in fainting, drowning, or sudden death.

Heart arrhythmia

cardiac arrhythmiaarrhythmiaarrhythmias
Heart related causes may include an abnormal heart rhythm, problems with the heart valves or heart muscle and blockages of blood vessels from a pulmonary embolism or aortic dissection among others.
In more serious cases, there may be lightheadedness, passing out, shortness of breath or chest pain.

Supraventricular tachycardia

tachycardia, supraventricularAV re-entrant arrhythmiacatecholamine surge
Tachycardias include SVT (supraventricular tachycardia) and VT (ventricular tachycardia).

Tilt table test

tilt tableTilt table testingtilt-table test
More specific tests such as implantable loop recorders, tilt table testing or carotid sinus massage may be useful in uncertain cases.
A tilt table test (TTT), occasionally called upright tilt testing (UTT), is a medical procedure often used to diagnose dysautonomia or syncope.

Hypertrophic cardiomyopathy

hypertrophic obstructive cardiomyopathyAsymmetric septal hypertrophyFeline hypertrophic cardiomyopathy
Among other conditions prone to trigger syncope (by either hemodynamic compromise or by a neural reflex mechanism, or both), some of the most important are hypertrophic cardiomyopathy, acute aortic dissection, pericardial tamponade, pulmonary embolism, aortic stenosis, and pulmonary hypertension.
It may also result in chest pain or fainting.

Dehydration

dehydrateddehydratedehydrating
This is often due to medications that a person is taking but may also be related to dehydration, significant bleeding or infection.
For severe cases of dehydration where fainting, unconsciousness, or other severely inhibiting symptom is present (the patient is incapable of standing or thinking clearly), emergency attention is required.