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Background
Syncope means fainting. Fainting, if not due to a neurologic
event such as seizures, is nearly always due to an event start-
ing in the heart and/or blood vessels (cardiovascular syn-
cope). Whatever the exact cause of the cardiovascular event,the consequence is an interruption in blood flow or pressure
(perfusion) to the brain for more than a few seconds. This
momentary interruption in the delivery of oxygen and nutri-ents leads to dizziness or light-headedness, tunnel vision,
black-out vision (complete loss of vision), hearing percep-
tion changes, and the loss of consciousness (fainting). The
most common cause of cardiovascular syncope is vasovagalsyncope; perhaps called Garden-Variety Fainting. Syn-
cope due to disturbances of heart rhythm are less common
but very concerning when they are the cause. These need to
be ruled out as best as possible before the diagnosis of vas-
ovagal syncope can be made. Sometimes syncope is just one
part of a bigger set of disturbances of the body collectively
called POTS (Positional Orthostatic Tachycardia Syn-
drome.). More on this is described separately.
The term Vasovagal is a
combination of vaso, refer-
ring to the veins and arteries
of the body and vagal, re-ferring to the vagus nerve,
which is an important nerve
leading from the brain to the
heart and blood vessels. The
vagus nerve contributes in an important way to helping de-
termine the heart rate and blood vessel diameter. The com-
bination of heart rate and diameter of the veins and arteries
determines the blood pressure. When the rate is too low and/
or the blood vessels are too dilated for the situation, blood
pressure drops. The first place that looses perfusion is the
highest place in the body. Thats the head for a person sit-
ting or standing.
The Body as an Inflatable Jumper:
Indeed, the cardiovascular system
can be thought of a little like a kids
birthday party jumper castle.
The castle only stays plumply in-
flated if:
1) the sum of the parts that hold the
air inside (the tank) stays constant,
2) there is only a small leak from the tank that is relatively
constant and
3) there is a pump that is constantly pumping more air into
the tank at a sufficient rate to replace the loss.
Think of what happens when the circuit breaks and the pump
stops pumping. The jumper tank immediately begins to de-
flate. Likewise, if the jumper workmen come along and de-
cide the castle needed to be twice as big and opened a valve
suddenly to inflate a new part of the tank or if one of the kids
plays a prank and opens a valve such that air escapes more
rapidly than can be pumped in, then the castle begins to de-
flate. Indeed, the parts that crumple first are the castle turretswhich are at the top of the jumper.
The sum total of all the arteries in the body, large and small,
are like the tank of the jumper. These parts need to be
pumped plump-full in order for the part at the top, the
brain, to function. If the pump, the heart, is pumping
strongly and at the right rate, it keeps the exact amount of
blood pumped from the venous pools into the arteries to
keep the tank plump-full. But if the heart rate suddenly be-
comes too low, then the tank, which is always returning
blood back to the veins after the nutrients are used, loses it
plumpness and deflates particularly in the turrets (the
brain). Likewise, if parts of the tank are suddenly reposi-tioned higher above the pump, such a when a person stands
suddenly, the turrets are always the first to pay the price with
some deflation if only briefly. So perfusion of blood to thebrain is briefly interrupted in this way.
This is where the vagus nerve
comes into the story. It is respon-sible for fine-tuning the heart rate
and the diameter of the arteries
(vascular tone) which is another
way of saying the size of the tank.Activation of the vagus nerve
(increased vagal tone) slows the
heart rate and dilates vessels. Removal of vagal tone in-creases heart rate and constricts vessels. This fine tuning
keeps the blood pressure exactly where it needs to be in or-
der to perfuse the brain. When a person stands up quickly,
the vagus nerve must act instantaneously to cause the heartrate to increase and blood vessels to constrict in order to
keep the turret plumply pumped. If it doesnt do this just
right, perfusion of the brain is poor and the series of symp-
toms leading to syncope begins.
Vasovagal Syncope
Heart of the Valley Pediatric Cardiology5933 Coronado Lane Ste. 104
Pleasanton, CA 94588
(925) 416-0100
www.heartofthevalley.us
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Page 2Vasovagal Syncope
Autonomic Dysfunction
Something very strange starts happening with the vagus
nerve in many healthy people around the age of 9 and con-
tinues through late adolescence. About that time, the vagus
nerve stops controlling heartrate and blood vessel diame-
ter well. Perhaps this is be-
cause rapid gains in height
occur during this age and the
vagus nerve has trouble ad-
justing its input to accommo-
date the new height. In addi-
tion, the blood vessels of an
adolescent are extremely
healthy and able to dilate
very well. The combination
of these two factors results in
a person who faints easilyunder a variety of circum-
stances. Because the vagus
nerve belongs to the auto-
nomic nervous system (See
diagram), this phenomenon
is often called autonomic
dysfunction.
Understanding this, its easy to see why
autonomic dysfunction
might be thought of as
an affliction of too much health
in that its the result of having
such healthy and easily distensible
arteries and a very active vagus
nerve. Having said that, its a
problem sometimes too of not
treating well the high perform-
ance machine that is a healthy
young body. This will be dis-
cussed later. On rare occasions,
the autonomic nervous system
becomes so dysfunctional that it
leads to many other symptomsincluding chronic fatigue, frequent
headaches, and chronic nausea
that is quite debilitating. This is what is often called POTS.
Orthostatic Hypotension: One very common circumstance
is with orthostatic changes (changing positions from lying to
sitting to standing). An adolescent may stand up quickly but
the withdrawal of vagal tone needed to allow the heart rate to
increase and blood vessels to constrict does not happen
quickly enough and a head-rush ensues. Sometimes this is
followed by black-out vision and even syncope after several
steps. This seems to be more exaggerated if the person was
lying for a long time, say, watching TV or sitting and doing
homework for hours.
Exaggerated Flushing: The
problem may not be confined
to orthostatic changes but to
other situations where exces-
sive vasodilatation oc-
curs. Common times that
vasovagal syncope occur
includes stepping out of a
long, hot shower, having
ones hair combed by an-other, standing for a long
time in a hot place, and hav-
ing a tight constrictive collar.These are times when the
body suddenly dilates the
small vessels that send blood
out to the skin. This effec-tively increases the tank size
rapidly and blood pressure is
lost centrally. Again, this affects the organs sitting highestin the tank the brain being the highest.
Vagal Hyper-reactivity: Other common times that vasova-
gal syncope occurs is when the vagus nerve becomes over-
active. Being that the vagus nerve is part of a bigger system
of nerves called the parasympathetic nervous system (See
diagram), when other parts of the parasympathetic nervous
system are activated, the vagus nerve sometimes gets
dragged into it. Urination and bowel movements requires
activation of the parasympathetic system and so sometimes
vagal tone increases and light-headedness occurs when one
stands up from the toilet. Nausea is a parasympathetic action
in the gut that also spills over to the vagus nerve so fainting
is a common outcome in circumstances involving nausea.
Additive Factors
Hypoglycemia: Vasovagal syncope occurs more readilywhen the blood sugar is rapidly dropping and even more so
when it is low (hypoglycemia). This may be because the
brain is receiving an independent insult in that not only is itlosing perfusion from vasovagal dysfunction, but was al-
ready starving for glucose. Its also possible that the vagus
nerve becomes all the more dysfunctional with rapid glucose
drops.
Dehydration: Understanding the details of vasovagal syn-
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cope thus far, its not surprising that having insufficient fluid
available to fill the tank would be a problem. Likewise,
dietary salt, which pulls fluid into the blood stream, is also
important in being able to fill the tank.
Sleep deprivation: Being chronically tired also seems toincrease the symptoms associated with vasovagal syncope.
This could also be an independent insult to the brain or the
effect may be through a change in vagal activity.
Exercise deprivation: When a healthy young person finds
themselves in a period of sedentary life, the symptoms of
autonomic dysfunction often appear or worsen. Just as their
muscles lose tone from inactivity its likely that so too do
their blood vessels leading to inappropriate vasodilation.
Diagnosis of Vasovagal Syncope
Vasovagal Syncope is really a diagnosis of exclusion to agreat extent. Before this diagnosis is made, the history
should very much be consistent with this one and all other
causes should be ruled out as best as possible.
History: The history should be typical; one with an inciting
trigger followed by a series of one or more prodromal symp-
toms, followed by near-loss or total loss of consciousness
that is very brief, followed by a short post-syncope period
and return to normal. Triggers include postural changes(standing up), excessive heat, a claustrophobic situation,
hypoglycemia, pain, or an objectionable sight such as
blood. The most common history is that of a person faint-
ing moments after getting up to a standing position. Oftenthis is first thing in the morning and often times right after
urination or getting up from the toilet. Its usually before
breakfast. Often times its after lying and watching TV for along time or after standing from sitting while doing home-
work a long time. Other common scenarios include after
coming out of a hot shower or while having ones hairbrushed, while standing for a long time in a line, or in band
practice while standing on a hot pavement, while standing in
the lunch line waiting for food, while standing in a crowded,
hot, church. Also, following an episode of extreme pain or
following the sight of blood or other sight objectionable to
the fainter.
The history should include prodromal symptoms (symptoms
that precede the loss of consciousness. Light-headedness,
spots before eyes, tunnel vision, black-out of vision, hearing
changes where those talking around sound distant or other
change, nausea are all common feelings just before faint-
ing. Its rare for a person who had a vasovagal event to
suddenly loss consciousness without any symptoms before-
hand.
The history should not include the feeling of palpitations or
a racing heart as the first sensation before lightheadedness
and fainting. Syncope should not occur while in the midst of
heavy exertion but it may occur during the recovery from
exertion. Whats difficult to discern is the athlete who stag-gers across the finish line then faints immediately after. The
history should also not include any seizure-like activity be-
fore or in the early part of loss of consciousness. However,
seizure-like activity is very often seen when one is recover-
ing from a vasovagal event. Unconsciousness should be
very brief with vasovagal syncope; on the order of 30 to 60
seconds. This is prolonged if the person faints in a sitting
position as restoration of cerebral blood flow is delayed in
that position.
Family history should also be carefully evaluated. This is
mainly to increase suspicion of other more serious causes of
syncope. Having said that, those who have vasovagal syn-cope often have a parent who also had similar episodes
when they were the same age.
Examination: Typically, there are no unusual physical
exam findings in a person who fainted from a vasovagal
cause. Orthostatic blood pressure measures in the lying,
sitting and standing position almost always reveals a nearlyconstant blood pressure but may reveal a heart rate rise that
is greater than 20 faster than the lying position (orthostatic
changes). However, very often the evaluation is taking
place on a day different from the most recent event and so
those additive factors glycemic state, hydration status and
amount of sleep) are often not the same and no abnormality
is found.
Studies: ECGs should always be done and echocardiograms
should often be done to
rule-out more serious
causes of syncope. If there
is any suggestion of sei-
zure as a cause, a neurol-
ogy referral should be
sought and an EEG may be
in order. If there is any
suggestion that an arrhyth-mia is the cause, event re-
corders, and a Holter moni-
tor may be ordered. Tilt-
table test is not performed
any more as this shows
little information over the
orthostatic pressure meas-
ures that should be done
with vital signs.
Page 3Vasovagal Syncope
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Treatment of Vasovagal Syncope
Now that the pathophysiology of vasovagal syncope is under-
stood, its easy to understand the ways to minimize the ef-
fects of vasovagal hyperactivity during the years it may affect
an individual. Basically, it begins by realizing that the youngbody is a high-performance machine and needs to be treated
as such. Just as you would not put cheap gasoline and oil in
a Ferrari and not maintain all its fluids correctly, you should
not put cheap food and drink in your body and not maintain
its fluids correctly. The management for vasovagal syncope
is most often entirely lifestyle changes. In the rare event that
these dont work, however, pharmacologic management of-
ten does the trick.
Think of the young body as a high-performance
sports car; just as you would not put cheap gaso-
line and oil in a Ferrari and not maintain all its
fluids correctly, you should not put cheap food
and drink in your body and not maintain its fluids
correctly.
Lifestyle Modifications
1) Eat a healthy diet with frequent meals of a low-glycemic-
index diet. Eat 5 meals a day; breakfast, lunch and din-
ner and two snacks in between. Make sure there is pro-
tein and fat in every
meal. Make sure the carbohy-
drate chosen is complex and
slowly digestible. The idea is to
eat in such a way that blood
glucose is maintained evenly
throughout the day and minimal
insulin is released from the pan-crease. Swings in blood glucose
increase vasovagal symp-
toms. A very good example of
a diet that helps manage vasova-
gal syncope well is The South
Beach Diet.
http://www.southbeachdiet.com/sbd/publicsite/how-it-works/
faqs.aspx
Page 4Vasovagal Syncope
2) Hydrate Well. This is with water or flavored waters that
have no sugars added. The amount required to hydrate varies
with metabolism, activity level and environment. A typical
adolescent would be required to drink three 750 ml bottles of
water each day in addition to what they normally drink atmeal times. If they work-out, they need to drink
more. One can judge if they are well hydrated if they need
to go to the bathroom several times a day and their urine is
diluted (clear, not concentrated).
3 bottles on an inactive day, more if working out or
sweating a lot
3) Salt Addition. If one is eating a typical Western Diet
which includes frequent fast foods
and processed food, one is noteating the type of diet described
above and is already taking in ex-
cessive amounts of salt. However,
when one eats consistently health-
ily with fresh fruits, vegetables,
meats, fish, and dairy, and whole
grains, salt in the diet is much less
and addition of salt may improve
symptoms. This is a recommendation for young, healthy
people with normal blood pressure and its because they have
such pliable blood vessels that they are able to tolerate salt
well and indeed need it added to their diet. When a person
becomes older, and their blood vessels become stiff, they
need to avoid salt as it causes hypertension. The sources of
salt in the diet should be carefully chosen. It should not
come from unhealthy snack foods like French fries or potato
chips but rather from nuts and sunflower seeds. The exact
amount of salt to add and its affect at re-lieving symptoms is different for each
person. Experts in autonomic dysfunction
believe that 2 to 4 grams of salt per day is
needed to manage this issue but varies
with salt metabolism, activity level and
environment basically, how quickly one
loses salt through sweat. One should aim
closer to 4 grams per day if one sweats a
lot with activities and work-out often.
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Often times, this amount of
salt cannot be obtained from
snacks and by salting ones
food and that is when salt tab-
lets become handy.
Theramtabs are a recom-mended buffered salt tablet.
These can be purchased at
Amazon.com or Drug-
store.com.
4) Good Sleep Habits. A full nights restful sleep helps re-
duce symptoms of vasovagal hyper-reactivity.
5) Consistent Aerobic Exercise. Exercise such as running,
biking, swimming, or even brisk walking, if its done a regu-
lar basis, likely tones the blood vessels and makes them less
likely to dilate inappropriately.
6) Recognition of Early Symptoms. Progression of vasova-gal symptoms to syncope can be aborted if the early symp-
toms are recognized and acted on. Whenever light-
headedness advances to a change in vision or hearing, lie
down flat immediately to get the head and heart at the samelevel. Gravity is then out of the equation and blood flow to
the brain is restored. Its even
better to raise the legs against a
wall or placed on a chair to help
further drain blood toward thehead. While this might seem
embarrassing to suddenly lie
down in front of friends and
school mates, it is much safer
and less embarrassing than faint-
ing. Also, it saves calls to 911
and trips by ambulance to the
emergency room as well as
costly head MRIs.
Page 5Vasovagal Syncope
Pharmacologic and Other Intervention: Lifestyle changes
are usually sufficient to minimize symptoms and avoid fur-
ther syncope. When a clear trial of these measures fail to
work, then medications can sometimes help. One common
medication is fludrocortisone. See details of this medicationseparately. This is given at a starting dose of 0.1mg per day
and can be doubled to achieve effect. This is usually contin-
ued for a full year before trying a person off the medication
again to see if the symptoms return.
Loss of Consciousness and Driving: Syncopal events that
are deemed to be vasovagal in origin usually do not require
reporting to the DMV and restrictions from driving. How-
ever, any loss of con-
sciousness that occurs
without warning or is oth-
erwise worrisome for the
wellbeing of the patient orothers, requires a report to
the DMV and a restriction
to driving. In California,
the restriction is usually
for 6 months and release
from restriction requires a
doctors signature. (Form
DS 326) More informa-
tion can be found at
http://www.dmv.ca.gov/dl/driversafety/lapes.htm
Autonomic Dysfunction and POTS
At times the problem is bigger than just syncope and in-
cludes chronic dizziness, fatigue, episodes of racing heart,
nausea and other gastrointestinal symptoms. These symp-
toms are all due to the same autonomic dysfunction de-
scribed and their severity and how much they interfere with
ones life falls on a continuum from mild and occasional to
debilitating and continual. When a combination of these
symptoms are present to the point of interference with nor-
mal daily activity, POTS should be considered and addi-
tional treatments may be necessary (see discussion on
POTS). Rarely, chronically repetitive syncopal events with
unusual histories sometimes arise. Work-up of these revealsno underlying cause and yet the history is still not consistent
with a vasovagal mechanism. Sometimes these are due to
narcolepsy or malingering. Treatment with lifestyle changes
and fludrocortisones may prove ineffective in these cases.
There may be a role for cognitive therapy in these situa-
tions.