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Exercise-Induced Syncope: Diagnosis and Management

Exercise-Induced Syncope: Diagnosis and Management. Francis G. O’Connor, MD, FACSM Primary Care Sports Medicine. Objectives. Review the epidemiology of sudden death and exercise-induced syncope in athletes Discuss the pathophysiology and differential diagnosis of exertional collapse

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Exercise-Induced Syncope: Diagnosis and Management

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  1. Exercise-Induced Syncope:Diagnosis and Management Francis G. O’Connor, MD, FACSM Primary Care Sports Medicine

  2. 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

  3. 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

  4. Exercise-Induced Syncope • Syncopal episode during exercise or in the immediate post-exertional period; the athlete normally recovers quickly

  5. Exercise-Associated Collapse • Athlete is unable to stand or walk unaided as a result of lightheadedness, faintness, dizziness, or syncope.

  6. Epidemiology of Exertional Sudden Death and Syncope

  7. Sudden Death in Older Athletes

  8. Sudden Death in Younger Athletes

  9. 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.

  10. 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)

  11. Risk for Sudden Cardiac Death Associated with Marathon Running Maron BJ,et al:Journal of the American College of Cardiology 1996;28:428-431.

  12. 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: 1:50,000; this was 1/100 the risk of overall living for 1 year

  13. Syncope in Children and Adolescents Driscoll DJ, et al: Journal of the American college of Cardiology 1997;29:1039-45.

  14. 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

  15. Screening for Hypertrophic Cardiomyopathy in Young Athletes Corrado D, et al: The New England Journal of Medicine 1998;339:364-9.

  16. 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

  17. Exertional Sudden Death in Soldiers Drory Y et al: Medicine and Science in Sports and Exercise 1991. Vol 23(2) 147-151.

  18. 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

  19. 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.

  20. 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

  21. Pathophysiology of Exercise-Associated Collapse

  22. Multifactorial • Cardiovascular changes with exercise • “Second Heart” • Orthostatic intolerance in Athletes

  23. 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

  24. 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

  25. 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

  26. The Prevalence and Significance of Post-Exercise Hypotension in Ultramarathon Runners Holtzhausen LM, Noakes TD, et al: Medicine and Science in Sports and Exercise 1995;27(12):1595-1601.

  27. 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

  28. 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

  29. 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

  30. 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

  31. 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

  32. 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

  33. Differential Diagnosis of Exertional Syncope

  34. Differential Diagnosis of Syncope Mean Arterial Pressure Cerebral Metabolism • Heart Rate • Stroke Volume • Peripheral Resistance • Tissue Oxygen • Substrate Delivery

  35. Differential Diagnosis • Cerebral Metabolism • seizure • hypocapnia • hypoxia • hypoglycemia • hyperthermia

  36. Differential Diagnosis • Heart Rate too Slow • bradyarrhythmia • cardioinhibitory reflex (neurocardiogenic) • conduction abnormality

  37. Differential Diagnosis • Heart Rate too Fast • supraventricular • pre-excitation • atrial fibrillation • ventricular • ventricular tachycardia • ventricular fibrillation

  38. Differential Diagnosis • LVEDV too Low • pulmonary hypertension • pulmonic stenosis • dehydration • hemorrhage

  39. Differential Diagnosis • LVESV too High • aortic stenosis • hypertrophic cardiomyopathy • ischemia

  40. Differential Diagnosis • TPR too Low • vasodepressor reflex • anaphylaxis • functional sympatholysis

  41. Evaluation and Management of the Athlete with a History of Exertional Syncope

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

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

  44. 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

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

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

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

  48. “Putting it All Together”

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