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Syncope is a sudden and brief loss of consciousness associated with loss of ... The pathophysiology of all forms of syncope consists ... Posterior fossa tumors ... – PowerPoint PPT presentation

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  • General Medicine lecture
  • John Liuzzo, M.D.

  • Define syncope
  • Distinguish syncope from other symptoms
  • Differential diagnosis
  • Diagnose the cause of syncope
  • Diagnostic tests
  • Determine need for hospitalization
  • Drug therapy

  • Syncope is a sudden and brief loss of
    consciousness associated with loss of postural
    tone, from which recovery is spontaneous.
  • The pathophysiology of all forms of syncope
    consists of a sudden decrease in or brief
    cessation of cerebral blood flow.
  • Associated symptoms lightheadness, visual
    blurring proceding to blindness, visual spots,
    diaphoresis, heaviness in LE, postural sway,
    nausea, vomiting, pallor or ashen gray face,
    sense of feeling bad

  • Syncope is common and it is disabling
  • Approximately 5-20 of adults will have one or
    more episodes of syncope by age 75
  • Accounts for about 1 of hospital admissions and
    about 3 of emergency room visits
  • Annual incidence in institutionalized elderly
    (gt75 y/o) is 6 previous lifetime episodes is
  • (JAMA 1992 2682553-60)

Is it syncope?
  • Distinguishing syncope from other symptoms
  • Dizziness, presyncope, and vertigo do not result
    in loss of consciousness or postural tone
  • Vertigo is associated with a sense of motion
  • Drop attack which is falling without warning,
    often due to compression of the vertebral
    arteries or a hyperirritable carotid sinus,
    occurs without loss of consciousness
  • The use of cardioversion to regain consciousness
    is by definition cardiac arrest, not syncope

Distinguishing syncope from seizure
  • Loss of consciousness precipitated by pain,
    exercise, micturition, defecation, or stressful
    events is usually syncope
  • Sweating or nausea before or during the episode
    are associated with syncope an aura is typical
    of seizures
  • Rhythmic movements, e.g. clonic or myoclonic
    jerks, suggests seizure, (but syncope can cause
  • Disorientation after the event, headaches, slow
    to return to consciousness, and unconsciousness
    lasting more than five minutes suggest a seizure

Differential Diagnosis
(NEJM 2000 3431856-62)
Neurally-mediated syncope(neurocardiogenic or
vasovagal syncope)
  • Most common
  • Result of reflex-mediated changes in vascular
    tone and heart rate
  • Examples
  • emotional fainting
  • situational syncope (e.g. in response to
  • cough, or
  • carotid sinus syncope
  • Glossopharyngeal neuralgia (and other painful
  • panic
  • exercise in athletes without heart disease

Neurally-mediated Syncope (cont.)
  • Mechanism is poorly understood
  • emotional upset may trigger CNS fainting
  • activation of receptors in wall of bladder,
    esophagus, heart, respiratory tract, and carotid
    sinus lead to reflex vagal efferent activity and
    sympathetic withdrawal
  • Net effect is a vicious cycle of inappropriate
    peripheral vasodilitation and relative
    bradycardia ? progressive hypotension and
    syncope (reversible by a supine posture or
    elevation of legs)
  • Possible role of neurohormonal factors (e.g.
    serotonin, vasopressin, endorphins, epinephrine)

Cardiac Syncope
  • Organic heart disease with reduced cardiac
  • Obstruction to LV outflow (e.g. aortic
    stenosis, hypertrophic obstructive
    cardiomyopathy, mitral stenosis, left atrial
    myxoma, ball-valve thrombus)
  • Obstruction to pulmonary flow (e.g. pulmonic
    stenosis, primary pulmonary hypertension,
    pulmonary emboli)
  • Myocardial massive MI with pump failure
  • Pericardial cardiac tamponade
  • Aortic dissection
  • Reduced venous return Valsalva maneuver

Cardiac Syncope (cont.)
  • Arrhythmias
  • Bradyarrhythmias
  • Atrioventricular block (2nd or 3rd degree)
    with Stokes Adams attacks
  • Sinus bradycardia, sinoatrial block,
    transient sinus arrest, sick sinus syndrome
  • Pacemaker malfunction
  • Tachyarrhythmias
  • Episodic ventricular tachycardia with or
    without associated bradyarrhythmias
  • Supraventricular tachycardia without AV block

Neurologic Diseases
  • Primary autonomic disturbances with CNS signs
    (e.g. Shy Drager syndrome, Parkinsons Disease)
    or with peripheral nerve signs (e.g. GBS, and
  • Secondary autonomic dysfunction (e.g. chronic
    ethanol, diabetes)
  • Surgical sympathectomy
  • Spinal cord disorders (e.g. syringobulbia)
  • Posterior fossa tumors
  • Cerebrovascular disturbance (e.g. TIAs,
    vertebral-basilar or carotid insufficiency, spasm
    of cerebral arterioles)

Orthostatic (Postural) Hypotension
  • Defined as low blood pressure induced upon
    standing upright
  • Criteria a decrease in systolic BP of gt20 mm
    Hg, or diastolic BP gt 10 mm Hg, after standing
    for at least 2 minutes
  • Causes
  • Volume depletion (e.g. acute illness,
    dehydration, GI bleeding, Addisons disease)
  • Medications that alter vascular tone and HR
  • Dysfunction of the vasoconstrictive
    reflexes in the blood vessels of the lower

Medications Causing Syncope
  • Vasodilators
  • Nitrates
  • ACE inhibitors
  • Ca Channel blockers
  • Hydralazine
  • Alpha-adrenergic blockers
  • Psychoactive Drugs
  • Phenothiazines
  • Tricyclic Antidepressants
  • Barbiturates
  • Narcotics
  • Diuretics
  • Drugs associated w/ Torsades de pointes
  • Quinidine
  • Procainamide
  • Amioderone
  • Sotolol
  • Others
  • Digitalis
  • Insulin
  • Marijuana
  • Ethanol
  • Cocaine

Psychiatric disorders
  • Generalized anxiety disorder
  • Panic disorder
  • Major depression
  • Alcohol and substance abuse
  • Hysteria
  • Conversion disorders
  • predispose to neurally-mediated reaction

Diagnosing the Cause of Syncope
  • Careful history and physical exam (56-85)
  • Electrocardiography is recommended, despite low
    yield because it can lead to decisions about
    immediate treatment (5)
  • Routine use of basic laboratory tests
    (electrolytes, blood counts, renal function,
    glucose level) is not recommended because of low
    yield use only when specifically indicated by
    the H P (2)
  • This initial assessment may lead to the diagnosis

Initial Assessment Suggesting a Diagnosis
  • Episodes occur after sudden unexpected pain,
    fear, or unpleasant sight, sound, or smell
  • Episodes occur after prolonged standing at
  • Episodes occur in well-trained athletes without
    heart disease after exertion
  • Episodes occur during or immediately after
    micturition, cough, swallowing, or defecation
  • Vasovagal syncope
  • Vasovagal syncope
  • Vasovagal syncope
  • Situational syncope

Initial Assessment Suggesting Diagnosis (cont.)
  • Syncope is accompanied by throat or facial pain
    (glossopharyngeal or trigeminal neuralgia)
  • Episodes occur with head rotation or pressure on
    carotid sinus (tumors, shaving, tight collars)
  • Episodes occur immediately upon standing
  • Patients take medications that may lead to a long
    QT interval or orthostasis and bradycardia
  • Neurally mediated syncope with neuralgia
  • Carotid sinus syncope
  • Orthostatic hypotension
  • Drug-induced syncope

Initial Assessment Suggesting Diagnosis (cont.)
  • Syncope is associated with headaches
  • Patient is confused after episode, or loss of
    consciousnes lasts more than 5 minutes
  • Syncope is associated with vertigo, dysarthria,
    or diplopia
  • Episodes occur with arm exercise
  • Migraines, seizures
  • Seizure
  • TIA, subclavian steal
  • Subclavian steal

Initial Assessment Suggesting Diagnosis (cont.)
  • Differences are found in BP or pulse between two
  • Syncope and murmur occur with changes in position
    (from sitting to lying, bending, turning over in
  • Syncope occurs with exertion
  • Subclavian steal or aortic dissection
  • Atrial myxoma or thrombus
  • Aortic stenosis, pulmonary hypertension, mitral
    stenosis, HOCM, CAD

Initial Assessment Suggesting Diagnosis (cont.)
  • Patient has a family history of sudden death
  • Patient has a brief loss of consciousness with no
    prodrome, and has heart disease
  • Patient has frequent syncope with no symptoms,
    but no heart disease
  • Long-QT syndrome, the Brugada syndrome
  • Arrhythmia
  • Psychiatric Illness

Importance of Heart Disease
  • In evaluating syncope, the presence of structural
    heart disease is the most important factor for
    predicting the risk of death, and likelihood of
  • Patients with structural heart disease or an
    abnormal ECG have an increased risk of death in 1
  • Early studies showed that cardiac causes of
    syncope are associated with increased mortality
    and an increased risk of sudden death. It was
    later shown that underlying heart disease,
    despite the cause of the syncope, is the factor
    associated with increased risk of death.
  • (Ann Emerg Med, 1997 29 459-66 Am J Med,
    1996 100 646-55)

Patients with Structural Heart Disease or ECG
  • Concern is arrhythmia
  • If cannot confirm structural heart disease (e.g.
    elderly) or syncope during exercise or known
    disease of undetermined severity echocardiography
    (5-10) and stress testing is recommended
  • 24 hour ECG monitoring is recommended as well as
    consultation with a cardiologist
  • Symptoms in conjunction with arrhythmias?
    arrhythmia is cause
  • Symptoms without accompanying arrhythmia ?
    excludes arrhythmias
  • In the remaining patients if arrhythmic syncope
    is still suggested by symptoms then
    electrophysiologic testing and/or continuous-loop
    event monitoring is recommended

Patients with Normal ECG Findings and No Heart
  • Majority of patients without heart disease have
    neurally-mediated syncope (includes carotid sinus
    syncope and psych illnesses)
  • Tilt table testing is recommended in patients
    with recurrent syncope or those with severe
    episodes (e.g. severe injury or MVA) or high-risk
    occupations (e.g. pilots)
  • Perform carotid sinus massage in elderly patients
    to rule out carotid sinus syncope (but not in
    those with a carotid bruit or known
    cerebrovascular disease) (vasodepressor gt 3sec
    cardioinhibitory gt50 mmHg fall)
  • If syncope and other somatic complaints consider
    psychiatric assessment

Testing for Arrhythmia
  • Think arrhythmia in patients with structural
    heart disease or abnormal ECG if the symptoms
    suggest cardiac syncope
  • (sudden brief loss of consciousness without a
  • The only way to include or exclude arrhythmia as
    the cause is to obtain a rhythm strip during

Ambulatory (Holter) Monitoring
  • Symptoms found in conjunction with arrhythmia in
    4 of patients ? diagnosis of arrhythmic syncope
  • Symptoms occur without arrhythmia in 17 of
    patients ? rules out arrhythmic syncope
  • The remaining 79 of patients either brief
    arrhythmias or no arrhythmias are found ? cannot
    exclude because may be episodic
  • (Ann Intern Med 1990 113-53-68)
  • Increasing the duration of monitoring to 72 hours
    does not increase the yield
  • (Arch Int. Med 1990 150 1073-78)

ContinuousLoop Event Recorders
  • Provides long-term monitoring-weeks to months
  • Patient or an observer can activate the monitor
    after symptoms occur, thereby freezing in its
    memory the readings from the previous 2-5 minutes
    and the subsequent 60 seconds
  • In patients with recurring syncope (gt 15
    episodes) arrhythmias were found during syncope
    in 8-20 normal rhythm found during symptoms in
  • (Am J Cardiol 1990 66 214-19 Br. Heart J.
    1987 58 251-253
  • Limitations compliance, potential for errors in
    using device, and in transmission

Electrophysiologic Studies
  • Yield of EP tests depends on whether there is
    structural heart disease or abnormal ECG

Induced V. Tach
Structural heart disease
Abnormal ECG
Normal heart
(Ann Intern Med 1997 127 76-86)
Tilt table Testing
  • Most common response in patients with unexplained
    syncope is sudden hypotension, bradycardia, or
  • Tilt tesing is believed to provoke vasovagal
    syncope in susceptible persons symptoms,
    hemodynamic response, and release of
    catecholamines are similar
  • ACC Guidelines on methods and indications in
    assessing syncope with tilt testing
    1996 28 263-75)
  • Commonly use provocative agents such as
    isoproterenol or nitroglycerin
  • The specificity of positive tilt test with
    chemical stimulation is near 90

  • (PACE 1997 20 Pt

Neurologic Testing
  • EEG provides diagnostic information in lt 2 of
    syncope cases
  • Head CT scan provides new diagnostic information
    in only 4 of cases
  • All of these patients had focal neurologic signs
    or symptoms suggestive of a seizure
  • TIAs involving the carotid or vertebrobasilar
    arteries rarely result in syncope (drop
    attacksvertebrobasilar ischemia)
  • No studies demonstrate the usefulness of cranial
    or carotid Doppler studies in evaluating syncope
  • These studies are not recommended unless the
    patient has neurologic symptoms or signs of a TIA

  • For rapid diagnosis of the cause of syncope, or
    for treatment when the cause is known
  • Recommendations for hospital admission are based
    on the potential for adverse outcomes if
    evaluation is delayed
  • (no studies that focus on this issue)

  • Examples
  • CAD, CHF, valves, CHD, V. arrhythmias, P.E.
  • Syncope w/ palpitation, chest pain, exertional
  • Ischemia, BBB, AV block, NSVT, Prolonged QT,
    accessory pathway, RBBB w/ ST elevation V1-V3,
    pacemaker malfunction
  • New stroke or focal signs
  • For diagnostic evaluation
  • Structural heart disease
  • Symptoms suggestive of arrhythmia or ischemia
  • Electrocardiographic abnormalities
  • Neurologic Disease

  • For treatment
  • Structural heart disease
  • Orthostatic hypotension
  • Older age
  • Adverse drug reactions
  • Examples
  • Acute MI, PE, aortic stenosis, HOCM
  • Acute, severe, volume loss, dehydration, GI
    bleeding severe chronic
  • Multiple coexisting abnormalities
  • Torsades de pointes, long QT interval,
    anaphylaxis, orthostasis, bradyarrhythmias

  • Patients with neurally mediated syncope, and
    those who do not have heart disease or an
    abnormal ECG can be evaluated as outpatients

  • Patients encountered during an episode should be
    placed in a position that will maximize cerebral
    blood flow
  • Prevent aspiration by turning head to side and
    give nothing by mouth until patient has regained
  • Dont permit patient to arise until physical
    weakness has passed and patients should be
    observed for few minutes after rising
  • Avoidance of circumstances that provoke event,
    (e.g. excitement, fatigue, arising rapidly from
    bed, medications)

Treatment (cont.)
  • Treat the primary disorder in structural cardiac
    disease, arrhythmia, or neurologic conditions
  • For orthostatic hypotension volume replacement
    and discontinuation of inciting drugs
  • For autonomic failure increase salt and fluid
    intake, waist high support stockings, and drugs
    such as fludrocortisone and midodrine

Treatment (cont.)
  • In neurocardiogenic syncope (positive tilt tests)
    prophylaxis with beta-blockers or disopyramide
    are used. A randomized controlled study showed
    benefit of atenolol after 1 month

  • (Am Heart J 1995 130 1250-3)
  • Permanent pacemakers in those with recurrent
    symptoms and bradycardia on tilt table test
    resulted in 85 reduction in recurrent syncope

  • (JACC 1999 99 1452-7)
  • Paroxetine was found in a randomized, blinded,
    placebo-controlled study to improve symptoms in
    patients with vasovagal syncope unresponsive to
    traditional medications

  • (JACC 1999 331227-30)

  • Syncope is a symptom not a disease, thus
    evaluation focuses on physiologic states that may
    cause the loss of consciousness-there is no gold
    standard test
  • In evaluating syncope utilizing directed history
    taking and physical exams and directed diagnostic
    testing will lead to the diagnosis in the
    majority of patients
  • Treatment focuses on improving patient quality of
    life and decreasing hospital admissions