Introduction to Arrhythmias
|Author(s)||J.S.S.G. de Jong|
|Moderator||J.S.S.G. de jong|
|some notes about authorship|
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.
- What is the relationship between P waves and QRS complexes?
- 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.
- 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. Another method to discriminate VT from SVT has been proposed by Vereckei et al. In the editorial on that paper an excellent review is given on the subject by Dendi and Josephson.
- 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 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.