EKG Changes in Syncope due to Arrhythmia
Aka: EKG Changes in Syncope due to Arrhythmia, Electrocardiogram in Syncope
II. Precautions
- Intervals and duration (PR interval, QRS Duration, QTc Interval) are critical to evaluate in Syncope
III. Interpretation: EKG changes suggestive of Syncope due to arrhythmia
- Abnormal Heart Rate
- Sinus Bradycardia <50 bpm (consider Sick Sinus Syndrome)
- Prolonged PR Interval
- Short PR Interval
- Abnormal QRS
- Left Bundle Branch Block, anterior or posterior hemiblock or Bifascicular Heart Block
- Associated with a 3 fold higher risk of serious cardiac cause
- QRS Duration > 120 ms
- Q Waves
- Left Bundle Branch Block, anterior or posterior hemiblock or Bifascicular Heart Block
- Prolonged QTc Interval
- See QT Prolongation
- See Prolonged QT Interval due to Medication
- Long QT Syndrome
IV. Interpretation: EKG changes related to specific syndromes
- EKG in Acute Coronary Syndrome
- ST Segment Elevation
- Deep T Wave inversion
- EKG in Tachy-Brady Syndrome (Sick Sinus Syndrome)
- Tachycardia or Bradycardia
- Atrioventricular Block (especially Mobitz II or third degree AV Block)
- EKG changes seen in Wolff-Parkinson-White Syndrome (WPW Syndrome)
- Short PR Interval (<120 ms)
- Delta Waves
- EKG changes seen in Brugada Syndrome
- Right Bundle Branch Block (RSR’)
- ST Elevation in leads V1-V3
- EKG in Arrhythmogenic Right Ventricular Dysplasia (ARVD)
- T Wave inversion in leads V1-V3
- QRS Complex duration > 110 ms in leads V1-V3
- Right Bundle Branch Block
- Terminal notch at end of QRS (Epsilon Wave)
- Septal T Wave inversion (V1-3)
- EKG in Hypertrophic Cardiomyopathy
- High voltage
- Lateral and inferior Q waves (deep, needle-like narrow)
- Septal, deep, symmetric T inversion (variable)
- Abnormal QT Interval
- Prolonged QT Segment >500 ms
- Short QT Segment <300 ms
- Autosomal Dominant condition associated with Sudden Cardiac Death
- EKG with right ventricular strain pattern (e.g. Pulmonary Embolism)
- See Right Ventricular Strain EKG Pattern
- Right Bundle Branch Block
- T Wave Inversion in anterior (V1-3) or inferior (II, III, avF) leads
- Prominent P Waves
- S1-Q3-T3 Pattern (S in I, Q in III, T inversion in III)
- EKG in Hyperkalemia
- Initial: Peaked T Waves in V2-3, II, III
- Next: ST depression, First degree AV Block, QT Interval shortening
- Next: QRS Widening with loss of P Waves
- EKG in Increased Intracranial Pressure
- Very large amplitude T Waves
- Prolonged QT
V. Efficacy
- EKG is low yield in syncopal patients under age 40 years old (however most warrant EKG in ED evaluation)
VI. References
- Herbert (2014) EM:Rap 14(7): 15-6
- Brignole (2001) Eur Heart J 22:1256-306 [PubMed]