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Vasovagal syncope: Difference between revisions
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* [[Blood phobia]] | * [[Blood phobia]] | ||
* [[Blood donation]] | * [[Blood donation]] | ||
=Triggers for Vasovagal Syncope= | |||
Vasovagal syncope can occur after exposure of a lot of different triggers. Recognised triggers for vasovagal syncope are prolonged orthostatic stress, blood drawing, medical instrumentation and psychological stressors. | |||
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==Psychological stressors== | |||
Psychological stressors include: | |||
*Stirring emotional news or witnessing a distressing accident <cite>Lewis</cite>,<cite>Engel44</cite> | |||
*Unexpected pain or threat <cite>Lewis</cite>,<cite>Greenfield</cite> | |||
*Unpleasant smells may trigger vasovagal syncope <cite>Engel47</cite>,<cite>Ganzeboom</cite> | |||
*During blood drawing, | |||
*Vaccination <cite>Braun</cite> | |||
*Instrumentation, pain of the procedure may contribute to vasovagal syncope | |||
*Sharp pain is reported to be an important factor during arterial blood sampling <cite>Rushmer</cite>. | |||
*Blood phobia: ''However, in a patient with blood phobia just thinking or talking about blood drawing may elicit a common faint <cite>Dijk01</cite>'' | |||
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==Post-exercise vasovagal syncope== | |||
Syncope after exercise is often neurally mediated, i.e. post-exercise vasovagal syncope. This condition is typically diagnosed in '''young fit, furthermore healthy young patients.''' | |||
Foremost, the diagnostic workup of all patients presenting with exercise-related syncope is aimed at '''excluding dangerous [[Cardiac syncope|cardiac conditions]]''' and includes echocardiography and exercise testing <cite>Krediet04b</cite>. Risk factors for a cardial problem are fainting while sitting or supine and suddenly fainting ''during'' exercise without presyncope. | |||
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Characteristically, syncope may occur while the individual is '''standing motionless''' during the first five to ten minutes after exercise <cite>Bjurstedt</cite>. Especially athletes in the (ultra) endurance sports are at risk for post exercise vasovagal syncope e.g. after marathon swimming <cite>Finlay</cite> or marathon running <cite>Tsutsumi</cite><cite>Holtzhausen95</cite><cite>Holtzhausen97</cite>. | |||
Vasovagal syncope after routine treadmill testing is rare (estimated 0,2% <cite>Schlesinger</cite>). However, when treadmill testing is immediately followed by passive head-up tilt testing, this percentage can increase up to 50-70% <cite>Bjurstedt</cite>. | |||
Vasovagal syncope after exercise is considered to be a benign occurrence <cite>Krediet04b</cite>. | |||
===Muscle pump=== | |||
During exercise, rhythmically contracting skeletal muscles in the lower part of the body reduce the degree of venous pooling by squeezing veins, thereby increasing the venous return of blood to the heart. This phenomenon is known as the ‘muscle pump. The sudden removal of the muscle pump after stopping exercise decreases cardiac preload which, together with a rapid return of vagal tone, may promote vasovagal syncope. | |||
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==Vasovagal syncope in airliners== | |||
Vasovagal episodes are the most common in-flight medical events, and may affect patients of all ages <cite>Gendreau</cite>. | |||
The following may all predispose vasovagal faints during air travel <cite>Sutton</cite>:<br> | |||
* Prolonged motionless sitting | |||
* The use of alcohol | |||
* Anxiety | |||
* Mild hypoxia during air travel | |||
Cabin pressure in commercial aircraft is usually adjusted to the equivalent of an altitude of 1500 to 2500 m above sea level. It appears that hypoxic syncope results from the super-imposed vasodilator effects of hypoxia on the cardiovascular system <cite>Halliwill</cite>. | |||
===Treatment=== | |||
Patients, who otherwise never experienced a (severe) vasovagal episode may suffer from convulsive syncope during air travel <cite>Wieling06</cite>. These patients should be advised to have: | |||
* A high salt intake in the days prior to travelling by plane | |||
* Reduce anti-hypertensive medication –if feasible- | |||
* And drink non-alcoholic beverages galore during the trip. | |||
Especially during long flights (> 2 hours) they should perform in-chair [[Physical counterpressure manoeuvers|muscle tensing and relaxing exercise]] and have a regular walk through the isle. In recurrent cases '''midodrine''' prior to flying or '''supportive stockings''' can be considered. | |||
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==Sleep vasovagal syncope== | |||
Sleep vasovagal syncope is defined as loss of consciousness in a non-intoxicated adult occurring during the night (e. g. 10:00 pm to 7:00 am), in which the patient wakes up with pre-syncopal and abdominal symptoms (i.e. an urge to defecate) and losses consciousness in bed or immediately upon standing. | |||
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There is no tongue biting or post-ictal confusion. There is usually a history of daytime vasovagal syncope and there seems to be a more pronounced fear of blood and medical procedures than in other syncope patients <cite>Jardine06b</cite>. Physical examination, ECG and EEG are within normal limits. The vasovagal reaction is thought to start while asleep <cite>Krediet04a</cite><cite>Jardine06a</cite>, and continuing after waking up, hence the name. During syncope there may be a profound sinus-bradycardia <cite>Krediet04a</cite>. Vasovagal sleep syncope occurs at all ages. | |||
===Differential Diagnosis=== | |||
Sleep vasovagal syncope is diagnosed by excluding beyond reasonable doubt the hereafter mentioned disorders <cite>Jardine06a</cite>. | |||
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Epilepsy is the foremost alternative diagnosis to consider, but can often easily be ruled out on clinical grounds. Complex partial, generalized tonic-clonic and myoclonic epilepsy may occur during sleep and can imitate syncope when causing cause sinus-bradycardia <cite>Tinuper</cite>. | |||
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There are a number of related conditions, including “'''abdominal epilepsy'''” and '''Panayiotopoulos syndrome''' (typically with vomiting) <cite>Covanis</cite>, in which the associated clinical features are abdominal pain and confusion. | |||
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Sleep paralysis and hypnogogic hallucinations occur in '''narcolepsy''' but also as isolated phenomena, mostly with other characteristic features in the history (e. g., daytime somnolence, in contrast to syncope there’s no amnesia.) and abnormal polysomnography, which can also be used to diagnose sleep apnoea and night terrors. | |||
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Occasionally cardiac disorders may cause cardiac arrhythmias during sleep. Most of these are unlikely if the 12-lead ECG is normal, and in some patients long-term ambulatory ECG monitoring is required <cite>Brierley</cite>. | |||
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Some patients with a diagnosis of defaecation syncope (see below) described abdominal and pre-syncopal symptoms that started simultaneously during sleep <cite>Pathy</cite><cite>Fisher</cite> there may be some overlap between this condition and sleep syncope <cite>Jardine06a</cite>. | |||
==References== | |||
<biblio> | |||
#Lewis pmid=20776843 | |||
#Engel44 Engel GL, Romano J, & McLin TR (1944). Vasodepressor and carotid sinus syncope - clinical, eletroencephalographic and electrocardiographic observations. Arch Intern Med 74, 100-119. | |||
#Greenfield GREENFIELD AD (1951). An emotional faint. Lancet 1, 1302-1303. | |||
#Engel47 Engel GL & Romano J (1947). Studies of Syncope: IV. Biologic interpretation of vasodepressor syncope. Psychosom Med 9, 288-294. | |||
#Ganzeboom pmid=12686351 | |||
#Braun pmid=9080932 | |||
#Rushmer Rushmer, R.F. Circulatory collapse following mechanical stimulation of arteries. Am. J. Physiol. 1944;141:722. | |||
#Dijk01 pmid=11227958 | |||
#Krediet04b pmid=15480927 | |||
#Bjurstedt pmid=6650203 | |||
#Finlay pmid=8531620 | |||
#Tsutsumi pmid=52682 | |||
#Holtzhausen95 pmid=8614313 | |||
#Holtzhausen97 pmid=9397327 | |||
#Schlesinger pmid=4800477 | |||
#Gendreau pmid=11932475 | |||
#Sutton pmid=11543489 | |||
#Halliwill pmid=15531565 | |||
#Wieling06 pmid=16836688 | |||
#Jardine06b Jardine DL, Krediet CT, Cortelli P, & Wieling W (2006b). Sleep syncope: clinical features and autonomic profiles. Clin Auton Res 16, 321-322. | |||
#Krediet04a pmid=15084573 | |||
#Tinuper pmid=11701591 | |||
#Covanis pmid=16950946 | |||
#Brierley pmid=11445105 | |||
#Pathy pmid=83099 | |||
#Fisher pmid=264159 | |||
</biblio> | |||