Syncope Flashcards
What is syncope?
Syncope is the term used to describe the event of temporarily losing consciousness due to a disruption of blood flow to the brain, often leading to a fall. Syncopal episodes are also known as vasovagal episodes, or simply fainting.
What is a vasovagal episode?
A vasovagal episode (or attack) is caused by a problem with the autonomic nervous system regulating blood flow to the brain. When the vagus nerve receives a strong stimulus, such as an emotional event, painful sensation or change in temperature it can stimulate the parasympathetic nervous system. Parasympathetic activation counteracts the sympathetic nervous system, which keeps the smooth muscles in blood vessels constricted. As the blood vessels delivering blood to the brain relax, the blood pressure in the cerebral circulation drops, leading to hypoperfusion of brain tissue. This causes the patient to lose consciousness and “faint”.
Signs and symptoms of syncope?
Patients often remember the event and can recall how they felt prior to fainting. This is called the prodrome, and involves feeling:
Hot or clammy Sweaty Heavy Dizzy or lightheaded Vision going blurry or dark Headache
A collateral history from someone that witnessed the event is essential to get an accurate impression of what happened. During a vasovagal episode they may describe the person:
Suddenly losing consciousness and falling to the ground
Unconscious on the ground for a few seconds to a minute as blood returns to their brain
There may be some twitching, shaking or convulsion activity, which can be confused with a seizure
The patient may be a bit groggy following a faint, however this is different from the postictal period that follows a seizure. Postictal patients have a prolonged period of confusion, drowsiness, irritability and disorientation.
There may be incontinence with both seizures and syncopal episodes.
Causes of syncope?
When assessing someone presenting with a syncopal episode the key is to establish whether this was a simple faint and the child is otherwise healthy, or whether the syncope was due to a significant underlying health problem. Simple faints without underlying pathology are harmless and have no long term implications.
Primary syncope (simple fainting):
Dehydration
Missed meals
Extended standing in a warm environment, such as a school assembly
A vasovagal response to a stimuli, such as sudden surprise, pain or the sight of blood
Secondary causes:
Hypoglycaemia Dehydration Anaemia Infection Anaphylaxis Arrhythmias Valvular heart disease Hypertrophic obstructive cardiomyopathy
Important history with syncope?
Take a thorough history focusing on eliciting several key points, ideally with the help of a witness:
Features that distinguish a syncopal episode from a seizure
After exercise? Syncope after exercise is more likely to be secondary to an underlying condition.
Triggers?
Concurrent illness? Do they have a fever or signs of infection?
Injury secondary to the faint? Do they have a head injury?
Associated cardiac symptoms, such as palpitations or chest pain?
Associated neurological symptoms?
Seizure activity?
Family history, particularly cardiac problems or sudden death?
Features distinguishing syncope from seizure?
Examination of child following syncope?
Perform a thorough examination focusing on eliciting several key points:
Are there any physical injuries as a result of the faint, for example a head injury?
Is there a concurrent illness, for example an infection or gastroenteritis?
Neurological examination
Cardiac examination, specifically assessing pulses, heart rate, rhythm and murmurs
Lying and standing blood pressure
Investigations for child with syncope?
ECG, particularly assessing for arrhythmia and the QT interval for long QT syndrome
24 hour ECG if paroxysmal arrhythmias are suspected
Echocardiogram if structural heart disease is suspected
Bloods, including a full blood count (anaemia), electrolytes (arrhythmias and seizures) and blood glucose (diabetes)
Management of syncope?
Fainting is common in children, particularly in teenage girls. They usually resolve by the time they reach adulthood. The most important aspect of management is making a confident diagnosis and excluding other pathology.
Seizures or underlying pathology need to be managed by an appropriate specialist.
Once a simple vasovagal episode is diagnosed, reassurance and simple advice can be given to:
Avoid dehydration
Avoid missing meals
Avoid standing still for long periods
When experiencing prodromal symptoms such as sweating and dizziness, sit or lie down, have some water or something to eat and wait until feeling better
