Differential diagnosis of VT vs. SVT with aberrancy using lead aVR only. Assess each criterion in order: any Yes answer ends at VT.
Step 1
Is there a dominant initial R wave in aVR?
Isolated R or R followed by S (Rs). An rS complex does not count.
A tool to support learning and decision-making. The result does not replace clinical evaluation of the patient.
About: Vereckei algorithm — aVR
The 2008 Vereckei algorithm differentiates VT from SVT with aberrancy by looking only at lead aVR. It simplified the original 2007 version, which had four steps combining several leads.
The rationale: in SVT with aberrancy, initial activation moves away from aVR and is fast; in VT, it is usually slow or directed toward aVR.
How to use
In aVR, check for a dominant initial R wave (R or Rs).
Measure the width of the initial r or q wave: more than 40 ms is positive.
Look for a notch on the descending limb of a QRS with a negative onset and a predominantly negative complex.
Calculate Vi/Vt: the vertical excursion during the initial 40 ms divided by that during the terminal 40 ms.
How to interpret
Any positive criterion: ventricular tachycardia.
All four negative (Vi/Vt > 1): SVT with aberrancy.
Limitations
Wide QRS tachycardia algorithms were derived in selected populations and lose accuracy in the hands of infrequent users. No result safely rules out ventricular tachycardia: when in doubt, or if the patient is unstable, manage as VT.
References
Vereckei A, Duray G, Szénási G, Altemose GT, Miller JM. New algorithm using only lead aVR for differential diagnosis of wide QRS complex tachycardia. Heart Rhythm. 2008;5(1):89–98.
Vereckei A, Duray G, Szénási G, Altemose GT, Miller JM. Application of a new algorithm in the differential diagnosis of wide QRS complex tachycardia. Eur Heart J. 2007;28(5):589–600.
Jastrzebski M, Kukla P, Czarnecka D, Kawecka-Jaszcz K. Comparison of five electrocardiographic methods for differentiation of wide QRS-complex tachycardias. Europace. 2012;14(8):1165–71.
