Introduction to Arrhythmias

Author(s)	J.S.S.G. de Jong
Moderator	J.S.S.G. de jong
Supervisor
some notes about authorship

Morphologic criteria to differentiate between SVT vs. VT in a wide complex tachycardia. This is part of the wide complex tachycardia flowchart

Arrhythmias (non-normal heart rhythms) can be a challenge to the person who tries to understand them. But with a systematical approach, diagnosis is often less difficult than it seems at the beginning.

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

• 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?
  • Is there a 1:1 relation between P waves and QRS complexes? If not there may be AV dissociation due to a Ventricular arrhythmia or AV block
  • Is every P wave followed by a QRS complex? And every QRS preceded by a P wave?
  • What is the PR interval and does it change?
• What is the QRS width?
  • If the QRS < 120ms (i.e. a narrow complex), then it is either a sinus arrhythmia, supraventricular rhythm or a junctional tachycardia. In tachycardias, this flowchart will lead to the right diagnosis.ESCnarrowQRS
  • If the QRS > 120ms it is either a ventricular tachycardia or a supraventricular rhythm with additional bundle branch block. This is a challenging difficulty in arrhythmia diagnosis, therefore a flowchart might help, which incoporates the Brugada criteria for VT.Brugada Another method to discriminate VT from SVT has been proposed by Vereckei et al.vereckei In the editorial on that paper an excellent review is given on the subject by Dendi and Josephson.dendi
• What is the clinical setting?
  • A wide complex tachycardia in a hemodynamically instable 70 year old man with previous myocardial infarction should be concidered a ventricular tachycardia until proven otherwise
  • A wide complex tachycardia in a 24 year old women with recurrent spells of tachycardia the respond to vagal manouevres is most likely an AVNRT with aberrant conduction.

References

<biblio>

1. ESCnarrowQRS pmid=14563598
2. Brugada pmid=2022022
3. vereckei pmid=17272358
4. dendi pmid=17317697

</biblio>