Vereckei Algorithm: A simplified, lead aVR-only algorithm to differentiate Ventricular Tachycardia (VT) from Supraventricular Tachycardia (SVT) with aberrancy.
Examine Lead aVR Only
Guidelines & Evidence
Clinical Details
Section 1
When to Use
When to Use
Differential diagnosis of wide complex tachycardia (WCT) where the underlying rhythm is unclear.
Particularly useful when precordial leads (V1-V6) are unavailable or difficult to interpret.
Clinical Caveat
Any wide complex tachycardia in an unstable patient should be treated as VT regardless of algorithm results. Synchronized cardioversion is the priority.
Section 2
Formula & Logic
Why lead aVR?
During SVT with bundle branch block, the initial activation of the ventricles occurs via the normal specialized conduction system, which typically moves AWAY from lead aVR (creating a negative QRS). In VT, activation often starts in the inferior/apical regions and moves TOWARD aVR, or is slowed by muscle-to-muscle conduction.
The 4 Steps
01
Presence of an initial R wave: Highly specific for VT.
02
Initial r or q wave width > 40 ms: Suggests slow muscle-to-muscle conduction diagnostic of VT.
03
Notch on the descending limb of a negative QRS: Indicates fragmented ventricular activation.
04
Vi/Vt ratio ≤ 1: Measures the velocity of initial activation (Vi) vs terminal activation (Vt) in the last 40ms. SVT is fast initially (Ratio > 1), VT is slow initially (Ratio ≤ 1).
Section 3
Pearls/Pitfalls
Accuracy vs Brugada
The Vereckei algorithm has shown slightly higher overall accuracy than Brugada in some head-to-head trials, mainly due to its better performance in diagnosing VT in patients with pre-existing bundle branch blocks or cardiomyopathy.
Section 4
Evidence Appraisal
Original Publication
New algorithm using only lead aVR for differential diagnosis of wide QRS complex tachycardia.
Vereckei A et al. • Heart Rhythm.. 2008;5(1):89-98. The landmark paper introducing the 4-step aVR algorithm.
