Introduction to Arrhythmias

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Author(s) J.S.S.G. de Jong
Moderator J.S.S.G. de jong
some notes about authorship
Arrhythmias can be subdivided into supraventricular, nodal and ventricular arrhythmias

Arrhythmias (non-normal heart rhythms) can be a challenge to understand, but with a systematic approach, diagnosis is often less difficult than it may appear at first.

A good stepwise approach to interpret the heart rhythm is to follow these steps:

  • Is this my patient's ECG or is this an artifact? (applies especially in stressfull situations)
  • What is the ventricular heart rate?
    • >100 bpm = tachycardia
    • <60 bpm = bradycardia
    • Are there extra beats? -> Ectopic Beats
  • Cherchez le P, French for find the P waves.
    • Do you see P waves? Leads II and V1 are often most suitable to find P waves.
    • What is the rate of the P waves?
    • What is the P wave morphology?
  • What is the relationship between P waves and QRS complexes?
  • What is the QRS width?
  • What is the Heart Axis and did it change?
    • If the heart axis turns significantly when compared to the heart axis during sinus rhythm a ventricular origin of the rhythm is more likely.
  • What is the clinical setting?
    • A wide complex tachycardia in a hemodynamically unstable 70-year-old man with previous myocardial infarction should be considered a ventricular tachycardia until proven otherwise
    • A wide complex tachycardia in a 24-year-old woman with recurrent spells of tachycardia that respond to vagal maneuvers is most likely an AVNRT with aberrant conduction.


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All Medline abstracts: PubMed | HubMed