II. Findings
- Supraventricular rhythm (narrow complex) similar to sinus rhythm
- Regular rhythm typically at 50 to 100 bpm
- Unlike sinus rhythm
- Focus external from the Sinoatrial Node (SA)
- Although P Waves are present, they are a different configuration from typical P Waves
- Often inverted in I, II, III, aVF (if focus is lower in the atrium than the SA Node)
- Short PR Interval may be present (<0.12 sec)
III. Causes
- Common
- Increased vagal tone (e.g. young, athlete)
- During sleep
- Acute significant pain
- Emesis
- Medications
- Other
- Hyperkalemia
- Hypoxia
- Myocarditis
- Sick Sinus Syndrome or other underlying chronic conduction abnormality
IV. Management
- Benign in most young patients, athletes, acute pain or Emesis
- Stable and asymptomatic patients require no intervention
- Manage Electrolyte abnormalities (e.g. Potassium, Magnesium)
- Caution, telemetry and consider Consultation in symptomatic patients (e.g. Syncope) with risk factors
- Older patients (esp. with known heart disease)
- Suspected ingestion
V. References
- Smith, Brady and Vendersteenhoven (2026) Crit Dec Emerg Med 40(1): 13-4