Syncope
Victoria E Judd
Disclosure Slide
• Nothing to disclose
Syncope Is
• the abrupt and transient loss of consciousness
• associated with absence of postural tone
• followed by complete and usually rapid
spontaneous recovery
Syncope
• alarming for the individual, witnesses, family, and
providers
• most often benign and self-limited
• a harbinger of a multitude of disease processes
• injuries resulting from syncopal attacks occur in
about one-third of patients
• recurrent episodes can be psychologically
devastating
• can be a premonitory sign of cardiac arrest,
especially in patients with organic heart disease
Syncope
• The most frequent age for first syncope is 15
years.
• The lifetime incidence of ≥ 1 fainting episodes
is ∼40%.
Vasovagal Syncope
• Mediated by emotional distress: fear, pain,
instrumentation, blood phobia
• Mediated by orthostatic stress
Situational Syncope
• Cough, sneeze
• Gastrointestinal stimulation (swallow, defecation,
visceral pain)
• Micturition (postmicturation)
• Post-exercise
• Postprandial
• Others (e.g., laughter, brass instrument playing,
weightlifting)
• Carotid sinus syncope
Syncope Due to Orthostatic
Hypotension
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Primary autonomic failure:
Pure autonomic failure, multiple system atrophy,
Parkinson's disease with autonomic failure, Lewy body
dementia
Secondary autonomic failure:
Diabetes, amyloidosis, uremia, spinal cord injuries
Drug-induced orthostatic hypotension:
Alcohol, vasodilators, diuretics, phenothiazine's,
antidepressants
Volume depletion:
Hemorrhage, diarrhea, vomiting, etc.
Cardiac Syncope
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Arrhythmia as primary cause:
Bradycardia:
Sinus node dysfunction (including
bradycardia/tachycardia syndrome)
Atrioventricular conduction system disease
Implanted device malfunction
Tachycardia:
Supraventricular
Ventricular (idiopathic, secondary to structural heart
disease or to channelopathies)
Drug-induced bradycardia and tachyarrhythmias
Cardiac Syncope
Structural disease:
• Cardiac: cardiac valvular disease, acute
myocardial infarction/ischemia, hypertrophic
cardiomyopathy, cardiac masses (atrial myxoma,
tumors, etc.), pericardial disease/tamponade,
congenital anomalies of coronary arteries,
prosthetic valves dysfunction
• Others: pulmonary embolus, acute aortic
dissection, pulmonary hypertension
Causes of Syncope
■Reflex (neurally-mediated; this includes
vasovagal, POTS) — 58 percent
■Cardiac disease, most often a bradyarrhythmia
or tachyarrhythmia — 23 percent
■Neurologic or psychiatric disease — 1 percent
■Unexplained syncope — 18 percent; a higher
value (41 percent) was noted in another large
series
The initial evaluation should answer
three key questions
■Is it a syncopal episode or other type of event?
■Has the etiology been determined?
■Is there evidence suggestive of a high risk of
cardiovascular events or death?
If Yes, Then Syncope
■Was loss of consciousness complete?
■Was loss of consciousness transient with rapid
onset and short duration?
■Did the patient recover spontaneously,
completely and without sequela?
■Did the patient lose postural tone?
Recurrent Syncope
• The number of syncopal episodes can predict
the risk of recurrence.
Clinical features that suggest a
diagnosis on initial evaluation
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Neurally mediated syncope:
Absence of heart disease
Long history of recurrent syncope
After sudden unexpected unpleasant sight, sound,
smell or pain
Prolonged standing or crowded, hot places
Nausea, vomiting associated with syncope
During a meal or post-prandial
With head rotation or pressure on carotid sinus (as in
tumors, shaving, tight collars)
After exertion
Clinical features that suggest a
diagnosis on initial evaluation
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Syncope due to Orthostatic Hypotension(OH):
After standing up
Temporal relationship with start or changes of
dosage of vasodepressive drugs leading to
hypotension
Prolonged standing especially in crowded, hot
places
Presence of autonomic neuropathy or
Parkinsonism
Standing after exertion
Clinical features that suggest a
diagnosis on initial evaluation
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•
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Cardiovascular syncope:
Presence of definite structural heart disease
Family history of unexplained sudden death or
channelopathy
During exertion, or supine
Abnormal ECG
Sudden onset palpitation immediately
followed by syncope
Cardiovascular syncope:
• ECG findings suggesting arrhythmic syncope:
• - Bifascicular block (defined as either LBBB or
RBBB combined with left anterior or left posterior
fascicular block)
• - Other intraventriclar conduction abnormalities
(QRS duration ≥0.12 s)
• - Mobitz I second degree AV block
• - Asymptomatic inappropriate sinus bradycardia
(<50 bpm), sinoatrial block or sinus pause ≥3 s in
the absence of negatively chronotropic
medications
Cardiovascular syncope:
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- Non-sustained VT
- Pre-excited QRS complexes
- Long or short QT intervals
- Early repolarization
- RBBB pattern with ST-elevation in leads V1-V3
(Brugada syndrome)
• - Negative T waves in right precordial leads,
epsilon waves and ventricular late potentials
suggestive of ARVC
• - Q waves suggesting myocardial infarction
Figure 2. Different patterns of QT prolongation in LQTS. Morphology of the QT segment and T
wave may be different in different genetic subsets of the LQTS, although there is significant
individual variation.
Strickberger S et al. Circulation 2006;113:316-327
Copyright © American Heart Association, Inc. All rights reserved.
Figure 3. ECG changes in the Brugada syndrome.
Strickberger S et al. Circulation 2006;113:316-327
Copyright © American Heart Association, Inc. All rights reserved.
History
• "Auras" are associated with seizures. In
comparison, vasovagal (neurocardiogenic/reflex)
syncope is usually, but not always, associated
with a prodrome of nausea, warmth, pallor,
lightheadedness, and/or diaphoresis.
• Sudden onset of syncope without a prodrome is
more common among patients with cardiac
syncope (arrhythmic or mechanical cardiac
etiology).
History
• Neurocardiogenic syncope commonly occurs
when the patient is erect, not usually when
supine.
• Syncope resulting from orthostatic
hypotension is frequently associated with the
change from a supine to erect posture.
• In comparison, syncope that occurs when the
patient is supine suggests an arrhythmia.
History
• An evaluation to rule out potentially lifethreatening causes for syncope is required if
syncope occurs during exertion
History
• A prolonged loss of consciousness may
indicate a seizure. By comparison, arrhythmias
and neurocardiogenic syncope are often
associated with a brief period of syncope,
since the supine position reestablishes some
blood flow to the brain and can therefore
result in the restoration of consciousness.
Recovery of consciousness may occur even if
the arrhythmia is maintained.
History
• Persistence of nausea, pallor, and diaphoresis
in addition to a prolonged recovery from the
episode suggest a vagal event. These findings
are helpful in distinguishing neurocardiogenic
syncope from syncope due to an arrhythmia.
Significant neurologic changes or confusion
during the recovery period may be due to a
stroke or seizure.
History
• A witness to the syncopal event may verify the
loss of consciousness, any associated limb
movements, and the presence or absence of
pallor, diaphoresis, or a pulse.
• Neurocardiogenic syncope is more likely to
occur among young, otherwise healthy
patients.
History
• Important elements of the family history
include history of sudden death, pacemakers
in young people, syncope, seizures, single car
accidents, drowning, cardiomyopathy.
History
• Seizures are the probable cause of 5 to 15
percent of apparent syncopal episodes. They
can mimic syncope when the seizure is
atypical and not associated with tonic-clonic
movements, the seizure is not observed, or a
complete history cannot be obtained. In
addition, some patients with syncope present
with myoclonic or other involuntary
movements that are suggestive of a seizure
but are actually due to cerebral hypoxia.
History
• One distinguishing feature is that patients
with seizures rarely have a rapid and complete
recovery. Instead, the postictal state is
characterized by a slow and complete
recovery.
• Another feature is usually those with syncope
are pale and those with seizures are usually
flushed.
Physical Exam
• Blood pressure obtained in the supine, sitting,
and erect position may detect orthostatic
hypotension.
Orthostatic Measurement
• Orthostatic blood pressure measurement is
performed with the patient standing after at least
three minutes of lying supine. Blood pressure
should be measured each minute (or more often)
in the standing position for three minutes or
more (or as long as the patient tolerates) until the
blood pressure nadir is reached. A
sphygmomanometer (manual blood pressure
cuff) may allow greater flexibility than an
automatic arm-cuff device in measuring blood
pressure prior to and during active standing
Orthostatic syndromes
• ■Classic orthostatic hypotension (OH) is defined
as a decrease in systolic blood pressure (BP) of
≥20 mmHg and in diastolic BP ≥10 mmHg within
three minutes of standing. This syndrome is
diagnosed by active standing or tilt testing.
• ■Initial OH is defined by a BP decrease
immediately on standing of >40 mmHg with BP
spontaneously and rapidly returning to normal,
so the period of hypotension and symptoms is
<30 s. This is diagnosed by active standing.
Orthostatic syndromes
• ■Reflex syncope (vasovagal syncope) triggered by
standing is characterized by an initial normal
adaption reflex followed by rapid fall in venous
return and vasovagal reaction (reflex bradycardia
and vasodilatation). This is diagnosed by tilt table.
• ■Delayed (progressive) OH is defined by a slow
progressive decrease in systolic BP on standing
with no bradycardic reflex (in contrast to reflex
syncope). This is diagnosed by tilt table.
Orthostatic syndromes
• ■Delayed (progressive) OH plus reflex syncope
occurs when a vasovagal reaction (reflex
bradycardia and vasodilation) follows delayed
OH. This is diagnosed by tilt table.
Orthostatic syndromes
• ■Postural orthostatic tachycardia syndrome (POTS)
presents with severe orthostatic intolerance (not
syncope) with marked increase in heart rate (by >30
beats per minute or to >120 beats per minute)within
ten minutes of standing. This is diagnosed by tilt table
or passive standing. POTS can be diagnosed with
bedside measurements of heart rate and blood
pressure taken in the supine (laying down) and
standing up position at 2, 5 and 10 minute intervals.
• In children and adolescents, a revised standard of a 40
bpm or more increase has recently been adopted.
Physical Exam
• The heart rate may be rapid or slow due to a
number of possible rhythm disturbances, or
irregular due to atrial fibrillation.
• The pulse and blood pressure should be
obtained with the patient supine, seated, and
erect.
• Hyperventilation can be seen with pulmonary
embolism or psychiatric causes of syncope.
Physical Exam
• The cardiac examination may reveal the
murmur of aortic stenosis, pulmonic stenosis,
or atrial myxoma (mitral stenosis).
• Pulmonary hypertension may be suggested by
a loud, palpable P2.
• Increase in an outflow murmur with the
Valsalva maneuver may help diagnose
hypertrophic cardiomyopathy.
Physical Exam
• Unilateral abnormalities found upon
neurologic examination may reflect a cerebral
vascular accident.
ECG
• An electrocardiogram (ECG) should be obtained
in all patients with syncope. The ECG is suggestive
of an arrhythmic cause of syncope if any of the
following abnormalities is present:
■Bifascicular block (defined as left bundle branch
block or right bundle branch block combined with
left anterior or left posterior fascicular block)
■Other intraventricular conduction abnormalities
(QRS duration ≥0.12 sec)
■Mobitz II second degree atrioventricular block
ECG
• ■Asymptomatic sinus bradycardia (<50 beats/min),
sinoatrial block or sinus pause ≥3 seconds in the
absence of negatively chronotropic medications
• ■Preexcited QRS complexes, suggesting WolffParkinson-White syndrome
• ■Long or short QT intervals
• ■Right bundle branch block pattern with ST-elevation
in leads V1-V3 (Brugada syndrome)
• ■Negative T waves in right precordial leads, epsilon
waves and ventricular late potentials suggestive of
arrhythmogenic right ventricular cardiomyopathy
• ■Q waves suggesting myocardial infarction
Testing
Additional testing is based on the results of the
initial evaluation. A variety of tests, mostly
cardiologic, can be used in the evaluation of the
patient with syncope. Neurologic testing is generally
of low yield and overused, unless specifically
suggested by history or physical examination.
■Carotid sinus massage in patients >40 years old.
■Echocardiogram when there is previous known
heart disease or data suggestive of structural heart
disease or syncope secondary to cardiovascular
cause.
Testing
• Immediate ECG monitoring when there is a
suspicion of arrhythmic syncope.
• ■Orthostatic challenge (lying to standing
orthostatic test or head-up tilt testing) when
syncope is related to the standing position or
there is suspicion of a reflex mechanism
• ■Other less specific tests such as neurological
evaluation or blood tests are indicated only when
there is suspicion of non-syncopal transient loss
of consciousness.
Testing
• Echocardiography is recommended in patients
with syncope when structural cardiac disease
is suspected.
• Electrocardiographic (ECG) monitoring is
indicated if there is a high probability of
identifying an arrhythmia associated with
syncope.
• Electrophysiology study (EPS) is indicated in
selected patients with unexplained syncope.
Implantable Loop Recorders (ILR)
ILR
Automatically detects
bradycardia
tachycardia
asystole
Records rhythm at
time of trigger
Patient
Assist Device
ILRs
Example tracing from ILR
ILR in unexplained syncope
with normal conventional work-up
Tachycardia
Asystole /
bradycardia
11%
56%
33%
No arrhythmia
Diagnostic yield: 35%
(175/506 patients)
Brignole et al. Europace 2009;11,671-687
Testing
• Neurologic tests, including
electroencephalogram (EEG), brain CT scan,
brain magnetic resonance imaging, and
carotid Doppler ultrasound, are frequently
obtained in patients with syncope. In one
review of 649 patients, 53 percent had at least
one neurologic test. However, such testing
was rarely useful.
Postural Orthostatic Tachycardia
Syndrome (POTS)
• A form of orthostatic intolerance occurs in patients,
particularly younger adults and children, who
consistently or frequently experience symptoms of
orthostatic intolerance in response to postural
stressors.
• Autonomic reflexes are relatively preserved in these
patients, and orthostatic hypotension and syncope
rarely occur.
• Some patients may have slightly elevated blood
pressure.
• The hallmark of this disorder is an exaggerated heart
rate increase in response to postural change.
Names of POTS
■Chronic orthostatic intolerance
■Mild orthostatic intolerance
■Orthostatic tachycardia
■Sympathotonic orthostatic hypotension
■Hyperdynamic beta adrenergic state
■Idiopathic hypovolemia
■Mitral valve prolapse syndrome
■Neurocirculatory asthenia
■Irritable heart
■Soldier's heart
■Effort syndrome
Facts POTS
• It is the most prevalent form of orthostatic
intolerance. It is estimated that 500,000
Americans suffer from this disorder.
• It is the most common syndrome of young
people seen in autonomic dysfunction clinics.
• Patients present at a relatively young age (14
to 45 years).
Facts POTS
• Women predominate among patients with
POTS with a female to male ratio of 4-5:1.
• The reason for this is not known, however,
observed gender differences in muscle
sympathetic nerve discharge characteristics in
healthy patients may explain why women are
more likely to develop POTS.
Etiology POTS
• The etiology of postural tachycardia syndrome
(POTS) is heterogeneous. Investigators have
reported a number of different abnormalities
in patients with POTS.
• It remains uncertain as to which of these
abnormalities are primary and causative and
which are secondary.
Etiology POTS
• Distal denervation — Several clinical and
empiric observations suggest the presence of
distal, predominantly lower extremity,
denervation with preserved cardiac
innervation in this disorder.
Etiology POTS
• Hypovolemia — Patients with POTS frequently
experience symptomatic improvement with saline
infusion.
• Additional evidence of a decrease and/or redistribution
of blood volume is observed in several studies of
patients with POTS, which have noted:
■Hypovolemia
■Trend toward hypovolemia
■Reduced erythrocyte volume
■Excessive venous pooling with redistributive
hypovolemia
Etiology POTS
• Changes in venous function — Abnormal
venous function with decreased venous return
on assumption of the upright posture could
stimulate a compensatory tachycardia in order
to maintain cardiac output.
• Baroreflex abnormalities — The increase in
heart rate without blood pressure change
upon standing in POTS suggests a primary
abnormality in baroreflex control.
Etiology POTS
• Increased sympathetic activity — Increased
sympathetic activity is the final common
pathway of most proposed mechanisms in
POTS.
• Genetic abnormalities — In one large series,
12.5 percent of 152 patients with POTS
reported a family history of orthostatic
intolerance
Clinical POTS
• Patients with postural tachycardia syndrome
(POTS) report dizziness, lightheadedness,
weakness, blurred vision, and fatigue upon
standing.
• Other predominantly orthostatic symptoms
include palpitations, tremulousness, and
anxiety.
Clinical POTS
• Gastrointestinal symptoms such as nausea,
abdominal cramps, early satiety, bloating,
constipation, and diarrhea may be particularly
problematic in some.
• There may also be evidence of venous
pooling, as manifested by acrocyanosis and
edema when upright.
• Syncope is relatively unusual, but does occur
in about 40 percent of patients.
Clinical POTS
• The onset often follows a flulike illness.
• Illness may occasionally represent a selflimited autoimmune disease.
• The role of immune and epigenetic factors
remains ill defined.
• Some patients have an insidious onset over
years, sometimes with a past history of VVS.
Clinical POTS
• ? Some patients have joint hypermobility
syndromes.
• Causality is unclear.
• While supine or seated, some patients appear
well, others pasty pale.
Clinical POTS
• Patients are unable to remain upright for long
periods of time.
• Symptoms are similar to the prodrome of VVS.
• BP is typically well maintained and may
increase when upright in hyperadrenergic
individuals.
• Prolonged laboratory tilt may provoke VVS.
Clinical POTS
• Cognitive deficits and exercise intolerance are
prominent complaints.
• Gastrointestinal symptoms include dysmotility
issues.
• Young women may be underweight, and POTS
must be differentiated from eating disorders,
which can produce POTS-like Orthostatic
Intolerance in early stages.
Clinical POTS
• Environmental heat reroutes blood to the skin
and makes patients worse.
• Air-conditioning may be required and standing
hot showers untenable.
• Schoolwork may be impaired. Home schooling
is common in adolescents.
• Colleges are often accommodating because of
adaptive scheduling and improved logistics.
Clinical POTS
• The symptoms may appear abruptly, often after a viral
illness; others experience a more insidious onset.
• The severity of symptoms is also quite variable.
• Some patients experience only mild symptoms and
often only in the setting of additional orthostatic stress
(e.g., menstrual cycle, relative dehydration).
• Others are profoundly incapacitated.
• The course of the disorder may be self limited or may
follow a relapsing remitting course over several years.
Diagnosis POTS
• The characteristic autonomic abnormality in
patients with postural tachycardia syndrome
(POTS) is an exaggerated increase in heart rate on
tilt table testing or standing.
• Diagnostic criteria from several laboratories have
in common a sustained heart rate increase of
greater than 30 beats per minute or an increase
to 120 beats per minute or greater within the first
10 minutes of tilt.
• There is usually no orthostatic hypotension.
Diagnosis POTS
• Autonomic neuropathies, central dysautonomias,
bedrest deconditioning, side effects of
medications, and dehydration can produce
similar symptoms to POTS.
• Ruling out these conditions is essential to making
a diagnosis of POTS.
• In most cases, historical information and a
neurologic examination specifically looking for
other evidence of autonomic failure, neuropathy,
and extrapyramidal signs, will provide evidence of
the underlying disorder.
Diagnosis POTS
• Patients with POTS may be thought to have panic,
anxiety, somatization disorder, or chronic fatigue
syndrome in part because of the vague nature of the
symptoms.
• In fact, patients with POTS report subjective cognitive
dysfunction and have objectively increased scores on
inattention scales, but do not have an increased
prevalence of depression or anxiety.
• The prominent postural nature of the symptoms should
prompt the clinician to look for the diagnostic heart
rate response.
Diagnosis POTS
• The syndrome of inappropriate sinus
tachycardia is characterized by an elevated
heart rate that is not influenced by postural
changes.
Treatment POTS
• The optimal therapy of postural tachycardia
syndrome (POTS) is uncertain.
• No intervention has been systematically
studied.
• The placebo effect may be substantial in POTS,
highlighting the need for controlled studies.
• Exacerbating factors, medications,
dehydration, and inactivity should be avoided.
Treatment POTS
• Because many patients with POTS have a low
plasma volume, correction with oral volume
expansion, a high salt diet (3,000 mg to 10,000
mg per day), and fludrocortisone, a
mineralocorticoid agonist may improve
symptoms.
• This regimen is similar to that used in
orthostatic hypotension in general.
Treatment POTS
• Some patients report symptomatic benefit with acute
ingestion of 16 oz of water and from a saline infusion
of 500 to 2000 cc, corresponding to objective
improvement in tilt testing response.
• However, it is not clear that this translates to a
therapeutic response to chronic treatment.
• Fludrocortisone (0.1 to 0.4 mg per day) is most
effective when combined with increased salt and water
intake.
• Treatment may be complicated by supine
hypertension, fluid retention, and hypokalemia and
should be monitored closely.
Treatment POTS
• Adrenoreceptor agonists may be helpful in
some patients (e.g., midodrine 2.5 to 10 mg
three times daily).
• Both intravenous phenylephrine and oral
midodrine have been associated with
improved symptoms and heart rate response
in some patients during tilt testing.
• However, benefit from chronic therapy is not
established.
Treatment POTS
• Preliminary evidence suggests that the
acetylcholinesterase inhibitor pyridostigmine
(30 mg daily) may attenuate the tachycardia
and improve symptoms.
• Further confirmation from larger trials is
needed to establish the benefit of
acetylcholinesterase inhibition for POTS.
Treatment POTS
• Some patients, particularly those troubled by
prominent adrenergic symptoms, may benefit from
beta blocking agents.
• These should be started in low doses and increased
gradually (e.g., propranolol 10 to 20 mg three or four
times daily).
• In one placebo-controlled, randomized crossover study,
a single low-dose of oral propranolol (20 mg) was
associated with improved tachycardia and reduced
symptoms, while higher dose propranolol (80 mg) was
associated with unchanged or worsened symptoms.
POTS Treatment
• Water ingestion is a useful, short lived
palliation.
• Effects are through TRPV4 receptors in the
splanchnic vasculature.
• Sixteen ounces of water and waiting 20 to 30
minutes yields benefit for hours.
• Salt and water loading can help but often
require Spartan efforts.
POTS Treatment
• Even when the cause is known pharmacologic
treatment is rarely curative.
• Most young people improve over time. In
some, POTS persists.
Volume Expansion
Fludrocortisone 0.05-0.2 mg daily – Many
patients with POTS are hypovolemic 4, so
fludrocortisone (an aldosterone analogue) is
often used. Through enhanced renal sodium
retention, it should expand the plasma volume
(although the data are poor). Potassium wasting
can result in hypokalemia, so serum K+ should
be monitored periodically.
Sympatholysis
• Propranolol 10-20 mg PO QID – Many patients
report intolerance to beta blockers when first
seen at the Vanderbilt Autonomic Dysfunction
Center. The vast majority of POTS patients,
however, respond well hemodynamically and
symptomatically to low doses of propranolol. Of
note, more complete beta blockade with higher
doses of propranolol cause symptoms to worsen.
Long acting propranolol was not found to be
helpful.
Sympatholysis
• Methyldopa 125mg QHS-BID – Methyldopa is a
false neurotransmitter that can lower central
sympathetic tone. It is particularly useful in
hyperadrenergic patients.
• Clonidine 0.05-0.2 mg PO BID (or a long acting
patch) - Alpha 2 adrenergic agonist that acts
centrally to decrease sympathetic nervous system
tone. It can stabilize HR and BP, but it can also
cause drowsiness, fatigue and worsen the mental
clouding of some patients.
Vasoconstrictor Therapy
• Midodrine 5-10mg PO q4H x3/day - Since a
failure of vascular resistance may be an
integral part of neuropathic POTS,
vasoconstrictors such as midodrine (alpha-1
agonist) can be employed.
Increasing Vagal Tone
• Pyridostigmine 30-60 mg PO TID – Pyridostigmine
is a peripheral acetylcholinesterase inhibitor. By
increasing synaptic acetylcholine at both the
autonomic ganglia and the peripheral muscarinic
parasympathetic receptors, pyridostigmine
significantly restrains the heart rate in response
to standing in patients with POTS. Pyridostigmine
is most effective in combination with low dose
propranolol. Since pyridostigmine enhances
bowel motility, it is often not well tolerated in
patients with diarrhea-predominant irritable
bowel syndrome symptoms.
? Treatment of POTS
• Cardiovasc Ther. 2014 Feb 4. doi: 10.1111/17555922.12067. [Epub ahead of print]
• Melatonin reduces tachycardia in Postural
Tachycardia Syndrome (POTS): A Randomized,
Crossover Trial.
• Green EA1, Black BK, Biaggioni I, Paranjape SY,
Bagai K, Shibao C, Okoye MC, Dupont WD,
Robertson D, Raj SR.
• Autonomic Dysfunction Center, Division of Clinical
Pharmacology, Departments of Medicine,
Vanderbilt University, Nashville, Tennessee, USA.
Figure. Treatment strategies for POTS.
Grubb B P , and Karabin B Circulation. 2008;118:e61-e62
Copyright © American Heart Association, Inc. All rights reserved.
POTS Treatment
• One confounding and alarming issue is the tendency for
POTS patients to bed rest.
• Prolonged bed rest emulates microgravity and has
deleterious effects including Orthostatic Instability (OI)
profound reductions in blood volume and cardiac size,
redistribution of blood, osteoporosis, skeletal muscle pump
atrophy, and more.
• Vasoconstriction is impaired.
• Bed rest causes a self-perpetuating state of OI, which can
emulate or intensify POTS.
POTS Treatment
• It is paramount for POTS patient to leave bed and
recondition.
• Well-structured exercise protocols are essential and must
accommodate patients who start off bed rested.
• Reconditioning invariably improves patient well-being.
Recent work supports the idea that POTS patients are also
exercise deconditioned compared with matched volunteers.
• Although exercise deconditioning may or may not be causal
in POTS, it is clear that exercise reconditioning is beneficial
and should be advocated for all POTS patients.
Diagnostic Criteria for Postural Tachycardia Syndrome
• HR increase ≥30 bpm from lying to standing
• Absence of significant drop in BP with standing
• Positional symptoms
• ○ Many symptoms are worse with upright posture and improve on lying down
• ○ Some symptoms can be non-positional (e.g. fatigue, headache)
• Chronic symptoms
• ○ Duration ≥6 months
• Absence of other overt cause for tachycardia
• ○ E.g., acute blood loss, prolonged bedrest, hyperthyroidism, tachycardia
promoting medications
Reflex (Neurally Mediated) Syncope
• Reflex (neurally mediated) syncope is a transient
loss of consciousness due to a reflex response
that encompasses vasodilatation and/or
bradycardia (rarely tachycardia), leading to
systemic hypotension and cerebral
hypoperfusion.
• Types of reflex syncope include vasovagal
syncope, situational syncope, carotid sinus
syncope, and atypical forms (without apparent
triggers and/or atypical presentation).
Reflex Syncope
Vasovagal:
• Mediated by emotional distress: fear, pain,
instrumentation, blood phobia
• Mediated by orthostatic stress
Reflex Syncope
•
•
•
•
•
•
•
•
Situational:
Cough, sneeze
Gastrointestinal stimulation (swallow, defecation,
visceral pain)
Micturition (postmicturition)
Post-exercise
Postprandial
Others (e.g., laughter, brass instrument playing,
weightlifting)
Hair grooming
Stretching
Reflex Syncope
• Carotid sinus syncope
• Atypical forms (without apparent triggers
and/or atypical presentation)
Reflex Syncope
• Vasovagal syncope (also known as
neurocardiogenic syncope) is the most common
cause of syncope.
• The diagnosis may be suggested or diagnosed by
a specific history with well-known triggers, but a
classic history is not required.
• The diagnosis can also be made by exclusion of
other causes of syncope and by a characteristic
response to upright tilt table testing during which
the patient may pass out from bradycardia
and/or hypotension.
Reflex Mechanism - Bezold Jarisch
Trigger
Venous return
BP
Vagal
efferent
Small ventricle
Reflex
Sympathetic
tone
Syncope
C-fibers
Wall stretch
Inotropy
Contractility
Arterial
tone
HR
Vagal
afferent
Vasodilation
BP
Sympathetic
withdrawal
BP
Chang-Sing P. Cardiol Clinics. 1991;9(4):641-651
Reflex Syncope
• Upright posture causes pooling of blood in
lower extremities
• Decrease in venous return causes transient
hyperdynamic ventricle
• Cardiac C fibers (mechanoreceptors) activate
causing parasympathetic response resulting in
bradycardia, peripheral vasodilation and
hypotension
• Abrupt decrease in BP and HR ± asystole
Reflex Syncope
• Alterations in autonomic activation are
responsible for reflex syncope. Three types of
responses are seen: a cardioinhibitory
response, a vasodepressor response, and a
mixed response with features of both.
Reflex Syncope
• An individual patient may have separate syncopal
events characterized by a primary vasodepressor,
cardioinhibitory or mixed responses, but the episodes
can vary in their presentation for any individual such
that asystole may occur at one time and hypotension at
another.
• Furthermore, the response observed during tilt table
testing is not necessarily the same as that recorded
during clinical episodes. Asystolic pauses are more
common during spontaneous episodes, but
hypotension is more common during tilt table testing.
Reflex Syncope
• Vasovagal (neurocardiogenic) syncope (also known as the
“common faint”) refers to a variety of clinical scenarios in
which a neural reflex results in usually self-limited systemic
hypotension characterized by bradycardia and/or
peripheral vasodilation.
• It is the most common cause of syncope (approximately 20
to 35 percent of cases), particularly in patients without
apparent cardiac or neurologic disease.
• However, reflex syncope is the most common cause of
syncope even among patients with heart disease and
should be considered as a potential cause in such patients.
Reflex Syncope
• Vasovagal syncope is a common cause of syncope
in athletes.
• However, other potential causes of syncope
should be considered and evaluated before
identifying the etiology of syncope, particularly if
the syncope occurs during exertion.
• Athletes with syncope during physical activity
should be evaluated for potential risk of sudden
death.
History Reflex Syncope
• Clinical presentation — Patients with vasovagal syncope are
most commonly young and otherwise healthy.
• Typical triggers and premonitory symptoms are strongly
suggestive of vasovagal syncope, although these may be
absent or difficult to correlate to the syncopal episode.
• Women and patients younger than 40 are more likely to
have typical symptoms.
• However, older patients are also frequently diagnosed with
vasovagal syncope.
• Older individuals have specific triggers that may be absent
in younger individuals (i.e., micturition, cough, defecation,
deglutition).
History Reflex Syncope
• Vasovagal syncope (“classical”) refers to
syncope triggered by emotional or orthostatic
stress such as venipuncture (experienced or
witnessed), painful or noxious stimuli, fear of
bodily injury, prolonged standing, heat
exposure, or exertion (post exertion).
History Reflex Syncope
• Vasovagal syncope is often associated with a
prodrome and persistence of nausea, pallor,
and diaphoresis, consistent with increased
vagal tone.
• Syncope is typically of short duration and
occurs in the sitting or standing position.
• The supine position restores adequate blood
flow to the brain.
History Reflex Syncope
• However, full recovery may be delayed as the
patient may feel depressed or fatigued.
• This course may help distinguish vasovagal
syncope from syncope associated with
arrhythmia, which is typically of abrupt onset and
of short duration.
• Loss of consciousness may be prolonged with
some other causes of syncope, such as seizures
and aortic stenosis, but rarely with vasovagal
syncope
Tilt Table Testing
• The tilt table test has limited specificity,
sensitivity, and reproducibility.
Treatment Reflex Syncope
• No therapy has been proven effective for
recurrent vasovagal syncope.
• Some intuitively appealing therapies have not
proven effective.
• Therapy is particularly important in patients who
have recurrent syncope in high-risk settings (e.g.,
commercial vehicle driver, pilot) and who wish to
continue these activities.
• Patients with recurrent episodes may require
restriction of activities until therapy is shown to
be effective.
Treatment Reflex Syncope
• Explanation — Patients with vasovagal syncope should be
provided with reassurance and education regarding the
nature, risks, and prognosis of the condition.
• The patient should be advised to assume the supine
position with legs raised at the onset of symptoms.
• The patient should be advised to avoid trigger events when
feasible, and medications that may induce hypotension
should be modified or discontinued.
• A study of self-reported symptom burden in 418 patients
diagnosed with vasovagal syncope indicated that 35
percent were symptom free at median five-year follow-up,
regardless of presenting symptom or treatment received.
Treatment Reflex Syncope
• Physical counterpressure — Studies have found that
isometric activity, such as crossing the legs and the arms,
may be helpful to offset a syncopal response, but release of
this position may be associated with precipitous decline in
heart rate and blood pressure.
• Counter-pressure maneuvers, such as tensing the arms
with clenched fists, leg pumping, and leg-crossing may
abort a syncopal episode or at least delay it long enough
that patients can assume the supine position.
• Physical counterpressure maneuvers are intended to
reduce lower-extremity venous pooling and therefore
improve cardiac output and prevent vasovagal syncope.
Treatment Reflex Syncope
Maneuvers include:
■Leg-crossing with simultaneous tensing of leg,
abdominal, and buttock muscles.
■Handgrip, which consists of maximum grip on
a rubber ball or similar object.
■Arm tensing, which involves gripping one hand
with the other while simultaneously abducting
both arms
Treatment Reflex Syncope
• Evidence from clinical trials suggests a limited
role for pacemaker therapy in patients with
vasovagal syncope.
Treatment Reflex Syncope
• Some have recommended support stockings
(in some cases, Jobst stockings), volume
expansion by liberalizing salt intake, and
occasionally administration of the
mineralocorticoid fludrocortisone (similar to
the regimen used in the treatment of
orthostatic hypotension).
• Data are lacking to support this approach in
treating reflex syncope.
Treatment of Reflex Syncope
Beta blockers
• Although beta blockers have been the most commonly
used drug therapy for vasovagal syncope, available
evidence does not support their efficacy.
• They have been postulated to act upon the ill-defined
afferent limb of the reflex arc involved in the BezoldJarisch reflex and to potentially also inhibit the
discharge frequency of the C fibers originating from the
cardiac mechanoreceptors and chemoreceptors.
Treatment Reflex Syncope
• ■Midodrine, an alpha-1-adrenergic agonist, had a
beneficial effect in a small randomized trial and a
number of observational studies.
• The benefits have ranged from prevention of syncopal
episodes in 95 percent of previously untreated patients
to efficacy for up to 22 months in as many as 78
percent of patients who failed to respond to a beta
blocker or other conventional therapy.
• However, the efficacy of midodrine is uncertain, and
another alpha agonist, etilefrine, was ineffective in a
placebo-controlled study of 126 patients
Treatment Reflex Syncope
• Some patients with vasovagal syncope
respond poorly to general measures.
Orthostatic or tilt training may be an effective
approach, although study results have been
mixed.
Treatment Reflex Syncope
• The efficacy of orthostatic training started in hospital
and continued at home was suggested by a controlled
but non-randomized study. Forty-seven patients with
recurrent syncope and a positive upright tilt table test
who were refractory to traditional therapies were
assigned to a tilt-training program or to continued
medical therapy, depending upon their consent. The
training program included five daily in-hospital upright
tilt table studies increasing in duration from 10 to 50
minutes. The training program was continued at home
with the patient instructed to stand against a wall for
up to 40 minutes twice a day, under supervision of a
family member.
Treatment Reflex Syncope
• Wall stands with progressive increase in time
over 6 to 8 weeks can improve symptoms,
possibly by retraining baroreceptor reflexes.
While the individual is standing, the upper
back is positioned against a wall without arm
and leg movement, beginning with 5-minute
intervals twice daily and increasing gradually
to 30-minute to 40-minute intervals over 6 to
8 weeks.
Treatment Reflex Syncope
• Moderate exercise training — Limited
uncontrolled data suggest that moderate
exercise training may increase orthostatic
tolerance in patients with syncope.
Driving Restrictions
• The 2009 ESC guidelines recommend no restriction
with a single mild episode of vasovagal syncope in a
private driver.
• If there are recurrent and severe episodes, private
drivers are allowed to return to driving after symptoms
are controlled.
• For a professional driver, no restriction is
recommended for a single mild episode, unless it
occurs during high-risk activity.
• For recurrent and severe episodes, permanent
restriction is recommended unless effective treatment
has been established.
References
• Vanderbilt Autonomic Dysfunction site
(www.mc.vanderbilt.edu/gcec/adc)
• http://www.dysautonomiainternational.org
• DOI: 10.1542/peds.2012-2610 Pediatrics
2013;131;968; originally published online April 8,
2013; Julian M. Stewart Common Syndromes of
Orthostatic Intolerance
• Postural Tachycardia Syndrome: A Heterogeneous
and Multifactorial Disorder Eduardo E. Benarroch,
MD, DScMayo Clin Proc. 2012;87(12):1214-1225