This document provides an overview of syncope (fainting), including definitions, causes, diagnostic approaches, and management. The main points are: 1. Syncope is defined as a brief loss of consciousness due to reduced blood flow to the brain. It has many potential causes including cardiac arrhythmias, orthostatic hypotension, and vasovagal responses. 2. The diagnostic approach involves taking a medical history and conducting tests like an ECG, tilt table test, or Holter monitor depending on the situation. 3. Syncope has both cardiac and reflex causes. Cardiac causes are more serious and require prompt treatment, while reflex syncope often has identifiable triggers and presentations.

2. syncope
By
Prof/ Rasheed Abd El-Khalik
M.D.
Head of internal medicine department
And intensive care unit

4. Terminology
• Syncope (sɪŋkəpi/ SING-kə-pee), the medical term
for fainting, is precisely defined as a transient loss
of consciousness and postural tone characterized by
rapid onset, short duration, and spontaneous
recovery due to global cerebral hypoperfusion that
most often results from hypotension.

5. • Many forms of syncope are preceded by
a prodromal state that often includes dizziness and
loss of vision ("blackout") (temporary), loss of
hearing (temporary), loss of pain and feeling
(temporary), nausea and abdominal
discomfort, weakness, sweating, a feeling of
heat, palpitations and other phenomena, which, if
they do not progress to loss of consciousness and
postural tone are often denoted "presyncope".

6. • There are two broad categories of
syncope, cardiogenic or reflex, which underlie most
forms of syncope. Cardiogenic forms are more likely
to produce serious morbidity or mortality and
require prompt or even immediate treatment.
Although cardiogenic syncope is much more
common in older patients, an effort to rule out
arrhythmic, obstructive, ischemic, or
cardiomyopathic causes of syncope and circulatory
inadequacy is mandatory in each patient.

7. • Variants of reflex syncope often have
characteristic histories, including precipitants
and time course which are made evident by
skilled history taking. Thus, the clinical history
is the foremost tool used in the differential
diagnosis of syncope. Physical examination,
and electrocardiogram are part of the initial
evaluation of syncope and other more specific
tools such as loop recorders may be necessary
in clinically uncertain cases.

8. • Syncope does not occur with hypoxia which
can lead to death by suffocation and does not
fulfill the definition of syncope above.
Syncope needs to be distinguished
from coma or cerebrovascular accident which
can include persistent states of loss of
consciousness.

9. • Although syncope may cause physical injury such
as head trauma, it is specifically not directly caused
by head trauma (concussion) or by a seizure disorder
which may also produce short-lived unconsciousness
unless these are also associated with globally
reduced brain blood flow. Syncope is extraordinarily
common, occurring for the most part in two age
ranges: the teen age years, and during older age.

10. Contents
• 1 Differential diagnosis
– 1.1 Central nervous system ischaemia
– 1.2 Vasovagal
– 1.3 Cardiac
– 1.4 Blood pressure
– 1.5 Other causes
• 2 Diagnostic approach
– 2.1 Clinical tests
– 2.2 San Francisco syncope rule
• 3 Management
• 4 Society and culture
• 5 Different names of fainting

11. Differential diagnosis
• Central nervous system ischaemia
• The central ischaemic response is triggered by an
inadequate supply of oxygenated blood in the
brain.
• The respiratory system may contribute to oxygen
levels through hyperventilation, though a sudden
ischaemic episode may also proceed faster than
the respiratory system can respond. These
processes cause the typical symptoms of fainting:
pale skin, rapid breathing, nausea and weakness
of the limbs, particularly of the legs.

12. • If the ischaemia is intense or prolonged, limb
weakness progresses to collapse. An individual
with very little skin pigmentation may appear
to have all color drained from his or her face
at the onset of an episode. This effect
combined with the following collapse can
make a strong and dramatic impression on
bystanders.

13. • The weakness of the legs causes most sufferers
to sit or lie down if there is time to do so. This
may avert a complete collapse, but whether the
sufferer sits down or falls down, the result of an
ischaemic episode is a posture in which less
blood pressure is required to achieve adequate
blood flow. It is unclear whether this is a
mechanism evolved in response to the circulatory
difficulties of human bipedalism or merely a
serendipitous result of a pre-existing circulatory
response.

14. • Vertebro-basilar arterial disease
• Arterial disease in the upper spinal cord, or lower
brain, causes syncope if there is a reduction in blood
supply, which may occur with extending the neck or
after drugs to lower blood pressure.

15. • Deglutition (Swallowing) syncope
• Syncope may occur during deglutition.
• "Deglutition syncope is characterised by loss of
consciousness on swallowing; it has been associated
not only with ingestion of solid food, but also with
carbonated and ice-cold beverages, and even
belching."

16. • Vasovagal
• Vasovagal (situational) syncope, one of the most
common types, may occur in scary, embarrassing
or uneasy situations, or during blood drawing,
coughing, urination or defecation.
• Other types include postural syncope (caused by
a change in body posture), cardiac syncope (due
to heart-related conditions), and neurological
syncope (due to neurological conditions).

17. • There are many other causes of syncope, including
low blood-sugar levels and lung disease such as
emphysema and a pulmonary embolus. The cause of
the fainting can be determined by a doctor using a
complete history, physical, and various diagnostic
tests.

18. • The vasovagal type can be considered in two forms:
• 1- Isolated episodes of loss of consciousness,
unheralded by any warning symptoms for more than
a few moments. These tend to occur in the
adolescent age group, and may be associated with
fasting, exercise, abdominal straining, or
circumstances promoting vaso-dilation (e.g., heat,
alcohol). The subject is invariably upright. The tilt-
table test, if performed, is generally negative.

19. • 2- Recurrent syncope with complex associated
symptoms. This is so-called Neurally Mediated
Syncope (NMS). It is associated with any of the
following: preceding or succeeding sleepiness,
preceding visual disturbance ("spots before the
eyes"), sweating, light-headedness. The subject is
usually but not always upright. The tilt-table test, if
performed, is generally positive.

20. • A pattern of background factors contributes to the
attacks. There is typically an unsuspected relatively
low blood volume, for instance, from taking a low-
salt diet in the absence of any salt-retaining
tendency. Heat causes vaso-dilation and worsens the
effect of the relatively insufficient blood volume.
That sets the scene, but the next stage is the
adrenergic response.

21. • If there is underlying fear or anxiety (e.g., social
circumstances), or acute fear (e.g., acute
threat, needle phobia), the vaso-motor centre
demands an increased pumping action by the heart
(flight or fight response). This is set in motion via the
adrenergic (sympathetic) outflow from the brain, but
the heart is unable to meet requirement because of
the low blood volume, or decreased return.

22. • The high (ineffective) sympathetic activity is always
modulated by vagal outflow, in these cases leading
to excessive slowing of heart rate. The abnormality
lies in this excessive vagal response. The tilt-table
test typically evokes the attack.

23. • Much of this pathway was discovered in animal
experiments by Bezold (Vienna) in the 1860s. In animals,
it may represent a defence mechanism when confronted
by danger ("playing possum"). This reflex occurs in only
some people and may be similar to that described in
other animals.
• The mechanism described here suggests that a practical
way to prevent attacks might seem to be counter-
intuitive, specifically to block the adrenergic signal with
a beta-blocker. A simpler plan might be to explain the
mechanism, discuss causes of fear, and optimise salt as
well as water intake.

24. • Psychological factors also have been found to mediate
syncope. It is important for general practitioners and
the psychologist in their primary care team to work
closely together, and to help patients identify how
they might be avoiding activities of daily living due to
anticipatory anxiety in relation to a possible faint and
the feared physical damage it may cause. Fainting in
response to a blood stimulus, needle or a dead body
are common and patients can quickly develop safety
behaviours to avoid any recurrences of a fainting
response. See link for a good description of
psychological interventions and theories.

25. • An evolutionary psychology view is that some forms
of fainting are non-verbal signals that developed in
response to increased inter-group aggression during
the paleolithic. A non-combatant who has fainted
signals that she or he is not a threat. This would
explain the association between fainting and stimuli
such as bloodletting and injuries seen in blood-
injection-injury type phobias such
as trypanophobia as well as the gender differences.

26. • Cardiac
• Cardiac arrhythmias
• Most common cause of cardiac syncope. Two
major groups of arrhythmias
are bradycardia and tachycardia. Bradycardia can
be caused by heart blocks. Tachycardias include
SVT (supraventricular tachycardia) and VT
(ventricular tachycardia). SVT does not cause
syncope except in Wolff-Parkinson-White
syndrome.

27. • Ventricular tachycardia originate in the ventricles. VT
causes syncope and can result in sudden death.
Ventricular tachycardia, which describes a heart rate
of over 100 beats per minute with at least three
irregular heartbeats as a sequence of consecutive
premature beats, can degenerate into ventricular
fibrillation, which requires DC cardioversion.

28. • Typically, tachycardic generated syncope is caused
by a cessation of beats following a tachycardic
episode. This condition, called tachycardia-
bradycardia syndrome, is usually caused by sinoatrial
node dysfunction or block or atrioventricular block.

29. • Obstructive cardiac lesion
• Aortic stenosis and mitral stenosis are the most
common examples. Aortic stenosis presents with
repeated episodes of syncope. Pulmonary
embolism can cause obstructed blood vessels.
High blood pressure in the arteries supplying the
lungs (pulmonary artery hypertension) can occur
during pulmonary embolism. Rarely, cardiac
tumors such as atrial myxomas can also lead to
syncope.

30. • Structural cardiopulmonary disease
• These are relatively infrequent causes of faints. The
most common cause in this category is fainting
associated with an acute myocardial infarction or
ischemic event. The faint in this case is primarily
caused by an abnormal nervous system reaction
similar to the reflex faints. In general, faints caused
by structural disease of the heart or blood vessels
are particularly important to recognize, as they are
warning of potentially life-threatening conditions.

31. • 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.

32. • Other cardiac causes
• Sick sinus syndrome, a sinus node dysfunction,
causing alternating bradycardia and tachycardia.
Often there is a long pause asystole between
heartbeat.
• Adams-Stokes syndrome is a cardiac syncope which
may occur with seizures caused by complete or
incomplete heart block. Symptoms include deep and
fast respiration, weak and slow pulse and respiratory
pauses that may last for 60 seconds.

33. • Aortic dissection (a tear in the aorta)
and cardiomyopathy can also result in syncope.
• Various medications, such as β-blockers, may cause
bradycardia induced syncope.
• Other important cardio-vascular conditions that can
be manifested by syncope include subclavian steal
syndrome.

34. • Blood pressure
• Orthostatic (postural) hypotensive faints are as
common or perhaps even more common than
vasovagal syncope. Orthostatic faints are most often
associated with movement from lying or sitting to a
standing position.
• Apparently healthy individuals may experience minor
symptoms ("lightheadedness", "greying-out") as they
stand up if blood pressure is slow to respond to the
stress of upright posture.

35. • If the blood pressure is not adequately maintained
during standing, faints may develop. However, the
resulting "transient orthostatic hypotension" does
not necessarily signal any serious underlying disease.
• The most susceptible individuals are elderly frail
individuals, or persons who are dehydrated from hot
environments or inadequate fluid intake.

36. • More serious orthostatic hypotension is often the
result of certain commonly prescribed medications
such as diuretics, β-adrenergic blockers, other anti-
hypertensives (including vasodilators),
and nitroglycerin. In a small percentage of cases, the
cause of orthostatic hypotensive faints is structural
damage to the autonomic nervous system due to
systemic diseases (e.g., amyloidosis or diabetes) or in
neurological diseases (e.g., Parkinson's disease).

37. • Other causes
• Factors that influence fainting are fasting long
hours, taking in too little food and fluids,
low blood pressure, hypoglycemia, growth
spurts, high g-force, physical exercise in excess of
the energy reserve of the body, emotional
distress, and lack of sleep. Orthostatic
hypotension caused by standing up too quickly or
being in a very hot room can also cause fainting.

38. • More serious causes of fainting include
cardiac (heart-related) conditions such as an
abnormal heart rhythm (an arrhythmia),
wherein the heart beats too slowly, too
rapidly, or too irregularly to pump enough
blood to the brain. Some arrhythmias can be
life-threatening.

39. Diagnostic approach
• Clinical tests
• If one is suffering from syncope, there are many
underlying causes that may be contributing to the
episodes. It is important to understand that there is
no master list of tests that are currently being used
to diagnose the underlying cause(s). However, there
are some common diagnostic tests for fainting.
• A hemoglobin count may indicate anemia or blood
loss. However, this has been shown to be useful in
only about 5% of patients being evaluated for
fainting.

40. • An electrocardiogram (ECG) records the electrical
activity of the heart. It is estimated that from 20%-
50% of patients will have an abnormal ECG.
However, while an ECG may identify conditions such
as atrial fibrillation, heart block, or a new or old
heart attack, it typically does not provide a definite
diagnosis for the underlying cause for fainting.
• The Tilt table test is performed to elicit orthostatic
syncope secondary to autonomic dysfunction
(neurogenic).

41. • Sometimes, a Holter monitor may be used.
This is a portable ECG device that can record
the wearer's heart rhythms during daily
activities over an extended period of time.
Since fainting usually does not occur upon
command, a Holter monitor can provide a
better understanding of the heart's activity
during fainting episodes.

42. • For patients with more than two episodes of syncope
and no diagnosis on “routine testing”, an insertable
cardiac monitor might be used. It lasts 28-36 months.
Smaller than a pack of gum, it is inserted just
beneath the skin in the upper chest area. The
procedure typically takes 15 to 20 minutes. Once
inserted, the device continuously monitors the rate
and rhythm of the heart. Upon waking from a
“fainting” spell, the patient places a hand held pager
size device called an Activator over the implanted
device and simply presses a button. This information
is stored and retrieved by their physician and some
devices can be monitored remotely.

43. • San Francisco syncope rule
• The San Francisco syncope rule was developed to
isolate patients who have higher risk for a serious
cause of syncope. Anyone with high risk criteria
needs to be further investigated. They are summed
up by the CHESS mnemonic: congestive heart failure,
hematocrit <30%, electrocardiogram abnormality,
shortness of breath, or systolic blood pressure <90
mm Hg

44. Management
• Recommended treatment involves returning blood
to the brain by positioning the person on the ground,
with legs slightly elevated or leaning forward and the
head between the knees for at least 10-15 minutes,
preferably in a cool and quiet place. As the dizziness
and the momentary blindness passes, the person
may experience a brief period of visual
disturbances in the form of phosphenes, sudden sore
throat, nausea, and general shakiness. For individuals
who have problems with chronic fainting spells,
therapy should focus on recognizing the triggers and
learning techniques to keep from fainting.

45. • At the appearance of warning signs such as
lightheadedness, nausea, or cold and clammy skin,
counter-pressure maneuvers that involve gripping
fingers into a fist, tensing the arms, and crossing the
legs or squeezing the thighs together can be used to
ward off a fainting spell. After the symptoms have
passed, sleep is recommended. If fainting spells
occur often without a triggering event, syncope may
be a sign of an underlying heart disease.

46. Society and culture
• Fainting in women was a commonplace trope or
stereotype in Victorian England and in contemporary
and modern depictions of the period. This may have
been partly due to genuine ill-health (the respiratory
effects of corsets are frequently cited), but it was
fashionable for women to affect an aristocratic frailty
and create a scene by fainting at a dramatic moment.

47. Different names of fainting
• Some individuals occasionally or frequently play the
"fainting game" (also referred to in the US as the
"choking game"), which involves the deliberate
induction of syncope via voluntary restriction of
blood flow to the brain, an action that can result in
acute or cumulative brain damage and even death.

49. Thank you