Exercise-Induced Syncope: Diagnosis and Management

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Exercise-Induced SyncopeDiagnosis and Management

• Francis G. OConnor, MD, FACSM
• Primary Care Sports Medicine

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Objectives

• Review the epidemiology of sudden death and
  exercise-induced syncope in athletes
• Discuss the pathophysiology and differential
  diagnosis of exertional collapse
• Discuss the evaluation and management of the
  athlete with exercise-associated collapse

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Definitions

• Syncope a sudden and temporary loss of
  consciousness, in the absence of head trauma,
  that is associated with a loss of postural tone
  with spontaneous recovery not requiring
  electrical or chemical cardioversion
• Exercise-Induced Syncope
• Exercise-Associated Collapse

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Exercise-Induced Syncope

• Syncopal episode during exercise or in the
  immediate post-exertional period the athlete
  normally recovers quickly

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Exercise-Associated Collapse

• Athlete is unable to stand or walk unaided as a
  result of lightheadedness, faintness, dizziness,
  or syncope.

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Epidemiology of Exertional Sudden Death and
Syncope
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Sudden Death in Older Athletes
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Sudden Death in Younger Athletes
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Nontraumatic Sports Death in High School and
College Athletes

• VanCamp SP, et al Medicine and Science in Sports
  and Exercise 1996. Vol 27(5)641-7.

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• estimated death rates in male athletes were
  fivefold higher than in female athletes (7.5 vs.
  1.33)
• estimated death rates were twofold higher in male
  college athletes than in male high school
  athletes
• noncardiac causes of death accounted for 22 of
  the cases
• male football and basketball accounted for the
  majority of deaths (104/160)

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Risk for Sudden Cardiac Death Associated with
Marathon Running

• Maron BJ,et alJournal of the American College of
  Cardiology 199628428-431.

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• 215,413 completed the Marine Corps and the Twin
  Cities Marathon
• four exercise-related sudden deaths occurred
  three during the race, one right after completion
• risk for sudden death with marathon running
  150,000 this was 1/100 the risk of overall
  living for 1 year

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Syncope in Children and Adolescents

• Driscoll DJ, et al Journal of the American
  college of Cardiology 1997291039-45.

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• population-based review of syncope in children
  and adolescents
• 194 cases studied 3 presented with exertional
  syncope, with one subsequent sudden death
• conclusions
• electrocardiography warranted in all patients
  with syncope
• detailed evaluation should be considered for
  patients with syncope with exercise, a family
  history of syncope, premature sudden death or
  arrhythmias

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Screening for Hypertrophic Cardiomyopathy in
Young Athletes

• Corrado D, et al The New England Journal of
  Medicine 1998339364-9.

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• prospective study of sudden death events among
  athletes and nonathletes
• the incidence of sudden death from HCM was
  decreased in the athletes who had PPE screens
• most common cause of sudden death in athletes was
  arrhythmogenic right ventricular dysplasia
• 7 of the 28 athletes who died had complained of
  syncope none of the victims complained about
  exertional chest pain

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Exertional Sudden Death in Soldiers

• Drory Y et al Medicine and Science in Sports
• and Exercise 1991. Vol 23(2) 147-151.

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• All exercise-related sudden unexpected deaths of
  soldiers 18-29 in the IDF during 1974-1986 were
  reviewed
• twenty male soldiers died suddenly within 24hr of
  strenuous exercise
• 70 of the victims had prodromal symptoms within
  one month of their demise with syncope being the
  most common complaint (40)
• syncope was associated with HCM, myocarditis,
  intracranial hemorrhage, and heat stroke

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Clinical and Biochemical Characteristics of
Collapsed Ultramarathon Runners

• Holtzhausen LM, Noakes TD et al Medicine and
  Science in Sports and Exercise 1994. Vol
  26(9)1095-1101.

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• 56 km race 65 controls 46 runners with
  exertional collapse
• most cases of EAC occurred at the finish line
  (85) correlation with cutoff for medals and
  race closure
• 15 collapsing during the event had readily
  identifiable medical diagnoses asthma angina
  hypoglycemia gastroenteritis
• states of dehydration, plasma renin and
  vasopressin concentrations were comparable in
  controls and EAC victims

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Pathophysiology of Exercise-Associated Collapse
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• Multifactorial
• Cardiovascular changes with exercise
• Second Heart
• Orthostatic intolerance in Athletes

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Cardiovascular Regulation with Exercise

• aerobic exercise results in dramatic shifts in
  blood distribution
• cardiac ouput increases to accommodate an
  increase in peripheral oxygen demand
• there is a preferential redistribution of blood
  flow to the working muscles and away from
  non-exercising areas

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The Second Heart

• During exercise the skeletal muscle functions as
  a second heart as the pumping action of
  skeletal muscle maintains venous return
• During muscle contraction, the veins are emptied
  and the driving pressure back to the heart is
  substantially increased
• If the the pumping action of skeletal muscle is
  lost despite a persistent vasodilation, syncope
  may ensue

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Orthostatic Intolerance in Athletes

• Endurance trained athletes have a reduced
  capacity to compensate for any acute hypotensive
  stress
• Luft et al report that the incidence of syncope
  during lower body negative pressure is greater in
  trained than in untrained controls
• Smith et al postulate training induced
  alterations in the autonomic nervous system with
  attenuated sympathetic activity to hypotensive
  stress in athletes

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The Prevalence and Significance of Post-Exercise
Hypotension in Ultramarathon Runners

• Holtzhausen LM, Noakes TD, et al Medicine and
  Science in Sports and Exercise 199527(12)1595-16
  01.

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• Study involving 31/240 runners in an 80k
  ultramarathon (mean age 38.9 years)
• Pre- and Post-race weights, supine and erect
  blood pressures, and blood samples
• osmolality
• chemistries
• glucose

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• Average weight loss was 3.5 kg (4.6)
• Large increase in supine-erect blood pressure
  differences after the race
• 81 of runners demonstrated a posture-related
  difference in systolic blood pressure in excess
  of 20mmHg
• No significant correlation was found with weight
  loss, or plasma volume with systolic blood
  pressure differences

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• Systolic and diastolic BP were decreased after
  exercise, but to a much greater extent in the
  erect versus supine position
• Level of dehydration was unrelated to the degree
  of postural hypotension
• EAC should initially be treated with pelvic and
  lower limb elevation, not IV rehydration

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Exercise Associated Collapse

• Postulated Mechanism for EAC
• redistribution of blood flow to working muscle
  and skin
• reliance of skeletal muscle pump to maintain
  atrial filling pressure
• sudden cessation of exercise of exercise promotes
  peripheral pooling

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Exercise Associated Collapse

• Postulated Mechanism for EAC
• contractions of empty ventricle stimulate
  mecchanoreceptors
• afferent vagal C-fibers transmit these signals to
  the CNS with efferent reflexes result in
  vasodilatation and bradycardia with syncope

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Exercise Associated Collapse

• In summary, syncope after exercise is
  multifactorial but can usually be explained by
  predictable hemodynamic responses
• heat stress
• extraordinary effort
• standing quietly in an upright position

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Differential Diagnosis of Exertional Syncope
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Differential Diagnosis of Syncope
Mean Arterial Pressure
Cerebral Metabolism

• Heart Rate
• Stroke Volume
• Peripheral Resistance

• Tissue Oxygen
• Substrate Delivery

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Differential Diagnosis

• Cerebral Metabolism
• seizure
• hypocapnia
• hypoxia
• hypoglycemia
• hyperthermia

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Differential Diagnosis

• Heart Rate too Slow
• bradyarrhythmia
• cardioinhibitory reflex (neurocardiogenic)
• conduction abnormality

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Differential Diagnosis

• Heart Rate too Fast
• supraventricular
• pre-excitation
• atrial fibrillation
• ventricular
• ventricular tachycardia
• ventricular fibrillation

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Differential Diagnosis

• LVEDV too Low
• pulmonary hypertension
• pulmonic stenosis
• dehydration
• hemorrhage

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Differential Diagnosis

• LVESV too High
• aortic stenosis
• hypertrophic cardiomyopathy
• ischemia

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Differential Diagnosis

• TPR too Low
• vasodepressor reflex
• anaphylaxis
• functional sympatholysis

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Evaluation and Management of the Athlete with a
History of Exertional Syncope
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Assessment

• History and Physical Examination
• Electrocardiogram
• Special Tests
• Echocardiography
• Exercise Stress Testing
• Putting it All Together

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History

• True syncope versus exercise associated
  collapse
• During versus immediately after exercise
• Prodromal symptoms
• Post-event state
• Medications
• High risk behaviors
• Family history

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Physical Examination

• Vital signs supine and upright (at least 5
  minutes standing)
• BP in arms/legs
• Body habitus
• Cardiac murmurs at rest and during Valsalva or
  rise from squatting position

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Electrocardiogram

• QTc
• Pre-excitation
• ST-T wave abnormalities
• Ischemic changes
• T wave inversion v1 -v3
• Ectopy, inparticular with LBBB

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Echocardiogram

• LV and RV size and function
• Valve structure
• Left main coronary ostial position
• Aortic annulus size
• Pulmonary systolic pressure

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Exercise Stress Test

• Designed to reproduce conditions which provoked
  the event e.g.
• start-stop
• prolonged high intensity
• Appropriate QT shortening

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Putting it All Together
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Evaluation and Management of the Athlete with
Acute Exercise-Associated Collapse
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Collapsed Ultraendurance Athlete Proposed
Mechanisms and an Approach to Management

• Holtzhausen LM, Noakes TD Clinical Journal of
  Sports Medicine 19977292-301.

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Conditions Associated with Collapse during or
after Prolonged Exercise

• Hypothermia
• Hyponatremia
• Cardiac arrest
• Other medical conditions
• Orthopedic conditions

• Exercise-associated collapse
• Muscle cramps
• Heat stroke
• Hypoglycemia

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Initial Management of Collapsed Athletes

• Noakes Fallacy 1 All persons who collapse after
  exercise have dehydration-induced hyperthermia
• Treatment by necessity is most often initiated in
  the absence of a diagnosis
• Appropriate Triage
• level of consciousness
• site of collapse
• vital signs HR, BP, rectal temp

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Severity of the Collapsed Athlete

• Nonsevere
• Immediate Assessment
• conscious
• alert
• rectal temp lt40C
• systolic BP gt100 mmHg
• heart rate lt100 bpm
• Specialized Assessment
• glucose 4 -10 mmol/L
• sodium 135 -148 mmol/l
• wt loss 0 -5

• Severe
• Immediate Assessment
• unconscious or altered mental state
• confused, disoriented
• rectal temp gt40C
• systolic BP lt100mmHg
• heart rate gt100 bpm
• Specialized
• glucose lt4 or gt10 mmol/L
• sodium lt130 or gt148 mmol/l
• wt loss gt10

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Management of Collapsed Athletes who are
Unconscious

• Universal Algorithm for Adults
• ABCs
• Differential Diagnosis
• Medical vs. Exercise-related
• Vital Signs
• Clinical Judgement

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Universal Algorithm for Adults
Assess Responsiveness

• Responsive
• Observe
• Treat as Indicated

• Not Responsive
• Activate EMS
• Call for defibrillator
• Assess breathing

• Not Breathing
• Give 2 slow breaths
• Assess circulation

• Breathing
• Place in recovery position

• Rescue breathing
• Oxygen, endotracheal intubation
• Vital signs, IV, Monitor
• History and Physical

Pulse
No Pulse
Start CPR
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Management of Collapsed Athletes who are
Unconscious

• Medical Condition not Necessarily Related to
  Exercise
• cardiac arrest
• diabetic coma
• subarachnoid hemorrhage
• grand mal epilepsy

• Exercise-Related Disorder
• hyponatremia
• heat stroke
• severe hypoglycemia

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Differential Diagnosis

• Heat Stroke
• unconscious
• altered mental state
• T gt41C
• tachycardia
• hypotension

• Hyponatremia
• unconscious
• altered mental state
• Tlt40C
• NL V/S

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Initial Management

• Heat Stroke
• ABCs
• IV, monitor
• Immediate cooling to 38C
• Normal saline
• Transfer

• Hyponatremia
• ABCs
• IV, monitor
• Isotonic/hypertonic saline lt50ml/hr
• avoid overhydration
• transfer

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Management of Collapsed Athletes who are
Conscious

• Clinical Assessment
• altered mental status
• pertinent history
• state of hydration
• vital signs
• rectal temp
• blood pressure
• heart rate
• orthostatics

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Management of Collapsed Athletes who are
Conscious

• Pertinent History
• amount of fluid ingested during the race
• amount of urine passed during the race
• vomiting and/or diarrhea
• carbohydrate ingested before and during the race
• drugs taken during the race
• recent illness
• race preparation

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Management of Collapsed Athletes who are
Conscious

• Exercise-Associated Collapse
• diagnosis of exclusion
• ingest oral fluids
• elevate legs and pelvis
• cool as indicated
• monitor vital signs
• most athletes asymptomatic within 30 minutes

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Management of Collapsed Athletes who are
Conscious

• Who needs an IV?
• unconscious
• suspected heat stroke, hyponatremia, hypoglycemia
• physical exam c/w dehydration
• persistent emesis
• persistent tachycardia and hypotension when
  lying supine with legs and pelvis elevated gt10 to
  15 minutes

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Conclusions

• EAC is common, and most often benign
• Exercise-induced syncope, however, particularly
  during exercise, may be a harbinger of a sudden
  death event
• Management of the young athlete requires an
  astute clinician who incorporates judgement with
  an appropriate history and physical
• Always treat the patient first and the athlete
  second

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You find what you look for, and diagnose what
you know!

• Jack Hughston, MD

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Compression

• No RCTs isolating effect of compression
• Compression wraps with malleolar horseshoes to
  decrease swelling
• When combined with appropriate elevation, thought
  to limit swelling and result in a faster recovery

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Putting it All Together

• Assessment
• History
• Physical Examination
• Electrocardiogram
• Selected Laboratory Tests

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Putting it All Together

• Diagnostic
• Suggestive
• Unexplained

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Putting it All Together

• Diagnostic or Suggestive
• Potentially life-threatening
• Restriction vs. treat or evaluate
• Consider Referral

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Putting it All Together

• Unexplained
• Restriction
• ECHO/GXT
• Reassurance vs. Referral
• Post-exertional
• Non-recurrent
• Normal family history
• Normal cardiac examination
• Normal ECG, ECHO, GXT