Vereckei Algorithm for Ventricular Tachycardia (VT)

Vereckei Algorithm for Ventricular Tachycardia (VT)

A Detailed ECG-Based Diagnostic Guide

Wide complex tachycardia (WCT) is a common and critical ECG challenge. The most important rule in clinical cardiology is: any WCT should be considered VT until proven otherwise. The Vereckei algorithm is a simplified, stepwise ECG approach developed to differentiate VT from supraventricular tachycardia with aberrant conduction (SVT-A), using mainly lead aVR and avoiding complex morphological criteria.

This algorithm is especially useful in emergency settings, critical care, and examinations.

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Background and Rationale

Traditional algorithms (Brugada, Wellens) rely on multiple precordial lead patterns and can be difficult to apply quickly. Vereckei et al. proposed a simpler method based on the observation that initial ventricular activation during VT is abnormal, whereas SVT conducts rapidly through the His–Purkinje system.

The algorithm answers one question at each step. If the answer is “yes,” the diagnosis is VT and the evaluation stops.

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The Vereckei Algorithm – Stepwise Approach

Step 1: Is there an initial R wave in lead aVR?

Look specifically at lead aVR.

• Presence of a dominant initial R wave in aVR strongly favors VT

• Normal supraventricular activation produces an initial negative deflection in aVR

If YES → VT

If NO → go to Step 2

Why this works:

VT often originates away from the His–Purkinje system, producing an abnormal initial vector directed toward aVR.

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Step 2: Is the initial r or q wave width ≥ 40 ms in aVR?

Measure the duration of the first deflection (either r or q wave) in lead aVR.

• ≥ 40 ms (1 small ECG box) → VT

• < 40 ms → go to Step 3

Rationale:

In VT, myocardial cell-to-cell conduction is slow, prolonging the initial ventricular activation.

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Step 3: Is there a notch on the descending limb of a negative QRS in aVR?

Look for notching or slurring on the downstroke of a predominantly negative QRS complex in aVR.

• Presence of notch → VT

• Absence → go to Step 4

Rationale:

Notching reflects delayed and heterogeneous ventricular activation, typical of VT.

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Step 4: Vi/Vt Ratio (Velocity of Initial vs Terminal Activation)

This is the most important and most specific step.

• Vi = voltage change during the first 40 ms of the QRS

• Vt = voltage change during the last 40 ms of the QRS

Calculate visually (no exact measurement required).

• If Vi/Vt ≤ 1 → VT

• If Vi/Vt > 1 → SVT with aberrancy

Interpretation:

– VT: slow initial activation (low Vi), faster terminal activation

– SVT: fast initial activation via His–Purkinje (high Vi), slower terminal spread

This step reflects the fundamental electrophysiological difference between VT and SVT.

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Final Diagnosis

If ANY step is positive → diagnose VT

Only if ALL steps are negative → consider SVT with aberrancy

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Sensitivity and Specificity

• Sensitivity for VT: ~90–95%

• Specificity: ~85–90%

• Particularly accurate in patients with structural heart disease

Multiple studies have validated its reliability and ease of use.

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Clinical Pearls

• Structural heart disease + WCT = VT until proven otherwise

• AV dissociation, fusion beats, capture beats always favor VT (outside algorithm but critical)

• Algorithm is applicable even when bundle branch block pattern is unclear

• Do not delay treatment in unstable patients for ECG analysis

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Limitations

• Less reliable in pre-excited tachycardias (antidromic AVRT)

• Requires careful inspection of lead aVR

• Not a substitute for clinical judgment

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Comparison with Brugada Algorithm

Vereckei Algorithm

• Fewer steps

• Relies mainly on lead aVR

• Easier for emergency use

Brugada Algorithm

• Uses multiple precordial leads

• More complex morphology analysis

Both are acceptable; Vereckei is often preferred for rapid bedside decision-making.

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Key Takeaway

The Vereckei algorithm is a practical, physiology-based method to diagnose VT in wide complex tachycardia. By focusing on lead aVR and ventricular activation velocity, it allows fast, accurate decision-making in both clinical practice and exams.

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References

• Vereckei A et al. New algorithm using only lead aVR for differential diagnosis of wide QRS complex tachycardia. Heart Rhythm. 2008

• ACC/AHA/HRS Guidelines on Ventricular Arrhythmias

• Braunwald’s Heart Disease, 12th Edition

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