Vasovagal Syncope 3.0

7/31/2019 Vasovagal Syncope 3.0

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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.



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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


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.


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.

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Vasovagal Syncope 3.0