III. History: Timing of Syncope
- Most important to distinguish timing of syncopal event
- Syncope during Exercise (Exertional Syncope)
-
Syncope following Exercise (Exercise collapse, Heat Syncope)
- Typically benign cause
- Transient Orthostatic Hypotension
- Often occurs with Exercise in hot environments, with vasodilation and increased sweating
- Worse with prolonged standing that results in lower extremity venous pooling
- Vasovagal episode related to sudden decrease in venous return
- Secondary to volume depletion, post-exercise Bradycardia and peripheral vasodilation
- Heat Syncope
- See Heat Illness
- See Heat Illness Risk Factors (includes Sickle Cell Trait)
- Dizziness or fainting with heat exposure immediately after completing Exercise or with prolonged standing
- Secondary to peripheral vasodilatation and venous pooling with secondary Postural Hypotension
- Seen in persons unaccustomed to extreme heat
- Consider Syncope differential diagnosis
- Exertional Syncope during Exercise is concerning (where as Syncope after Exercise is typically benign)
- Hypoglycemia
- Hyponatremia
IV. Symptoms
- Light Headedness, Orthostasis or Dizziness immediately following Exercise
- Transient loss of consciousness
V. Exam
- See Syncope
- Vital Signs (Identify Hypotension, Tachycardia)
- Thorough examination (especially cardiovascular)
VI. Causes: Exertional Syncope (Syncope during Exercise)
- See Arrhythmias in Athletes
- See Sudden Death in Athletes
- Cardiovascular - Arrhythmia
- Cardiovascular - Valvular disease
- Aortic Stenosis
- Mitral Valve Prolapse
- Ebstein's Anomaly of the Tricuspid Valve
- Cardiovascular - structural
- Miscellaneous causes in athletes
VII. Precautions: Red Flags suggestive of cardiogenic Syncope
VIII. Labs
- Bedside Glucose
- Basic chemistry panel (Serum Electrolytes)
- Complete Blood Count
- Creatinine Kinase (CPK)
IX. Evaluation
- See Syncope
- See Heat Illness
- Electrocardiogram
-
Echocardiogram
- If indicated
X. Management
- Immediate management
- Position patient supine with legs elevated
- Encourage oral hydration
- Anticipate symptom resolution in 15-20 minutes
- Additional measures in Heat Related Illness
- See Heat Illness
- Move to cool, shaded environment, lie supine, and administer oral rehydration with salt containing solutions
- Initiate external cooling if concern for Heat Exhaustion or Heat Stroke
- Reassuring findings consistent with discharge home
- Rapid recovery within 15 minutes
- Normalization of Vital Signs
- Ambulating well without recurrent symptoms
- Further urgent or emergent evaluation needed
- Prolonged recovery time >15 minutes
- Loss of consciousness durin Exercise
- Preceding cardiac symptoms (Chest Pain, Palpitations, Shortness of Breath)
- Cardiovascular Risk Factors
- Follow-up
- Avoid Exercise and avoid return to sport until evaluation is complete
- Evaluate for cardiogenic Syncope if red flags as above
- Cardiology Consultation
XI. References
- Spangler and Baird in Herbert (2014) EM:Rap 14(2): 7-8
- Colivicchi (2004) Eur Heart J 25(19): 1749-53 [PubMed]
- Gauer (2026) Am Fam Physician 113(4): 369-81 [PubMed]