Ultra Simple Brugada Criteria

VT vs SVT with Aberrancy – ECG Criteria for Accurate Diagnosis

Wide complex tachycardia (WCT) is VT unless proven otherwise. Correct differentiation between ventricular tachycardia (VT) and supraventricular tachycardia (SVT) with aberrancy is critical because management differs significantly and misdiagnosis can be dangerous.

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1. Basic Definitions

Ventricular Tachycardia (VT)

A tachycardia originating below the His bundle (ventricular myocardium or Purkinje system), usually with wide QRS ≥ 120 ms.

SVT with Aberrancy

A supraventricular rhythm conducted through abnormal ventricular conduction (e.g., bundle branch block or accessory pathway), producing a wide QRS.

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2. Why It Matters

Treating VT as SVT (e.g., giving AV nodal blockers in unstable VT) can cause hemodynamic collapse.

Treating SVT as VT is generally safer (e.g., amiodarone).

In structural heart disease, ischemic heart disease, or prior MI → assume VT.

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Stepwise ECG Approach to Wide Complex Tachycardia

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Step 1: Clinical Clues

Suggests VT:

Age > 35 years

Structural heart disease

Previous MI

Cardiomyopathy

History of ventricular arrhythmia

Suggests SVT:

Known SVT history

Young patient without structural disease

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Step 2: AV Dissociation (Most Specific Sign of VT)

Findings:

P waves independent of QRS

Capture beats

Fusion beats

If AV dissociation present → VT until proven otherwise

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Step 3: QRS Duration

QRS ≥ 140 ms (RBBB morphology) → favors VT

QRS ≥ 160 ms (LBBB morphology) → favors VT

Very wide QRS (> 180 ms) → strongly VT

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Step 4: Concordance in Chest Leads

Definition: All precordial leads either entirely positive or entirely negative

Positive concordance → VT

Negative concordance → VT

Concordance is highly specific for VT.

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Step 5: Brugada Criteria

Developed by Pedro Brugada.

Four-step algorithm:

1. Absence of RS complex in all precordial leads → VT

2. RS interval > 100 ms in any precordial lead → VT

3. AV dissociation present → VT

4. Morphologic criteria for VT in V1–V2 and V6

If any step positive → VT

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Step 6: Vereckei (aVR) Algorithm

Developed by László Vereckei.

Focuses mainly on lead aVR:

Initial R wave in aVR → VT

Initial r or q > 40 ms in aVR → VT

Notching on downstroke of QRS in aVR → VT

Vi/Vt ratio ≤ 1 → VT

Useful when bundle branch morphology is unclear.

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Step 7: Morphologic Criteria

If RBBB Pattern in V1

Suggests VT if:

Monophasic R

qR pattern

Broad R (> 40 ms)

R/S ratio < 1 in V6

Suggests SVT if:

rSR' typical pattern

Narrow initial r wave

If LBBB Pattern in V1

Suggests VT if:

Broad initial R in V1

Notched S in V1

Q wave in V6

Suggests SVT if:

Typical LBBB morphology

Narrow initial r wave

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Comparative Table

Feature VT SVT with Aberrancy

AV dissociation Present Absent

Capture/Fusion beats Present Absent

QRS width Very wide Moderately wide

Concordance Often present Rare

Structural heart disease Common Less common

Response to adenosine No termination May terminate

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Special Situations

1. Pre-excited SVT (WPW with AF)

Irregular wide tachycardia

Very fast ventricular rate

Avoid AV nodal blockers

2. Fascicular VT

Relatively narrow QRS

RBBB morphology

Responds to verapamil

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Practical Emergency Rule

If unsure → treat as VT

Unstable → immediate synchronized cardioversion

Stable → amiodarone or procainamide

Avoid verapamil in undifferentiated WCT (risk of collapse in VT).

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Key Take-Home Points

AV dissociation is the most specific ECG sign of VT.

Concordance strongly favors VT.

Use Brugada or Vereckei algorithm systematically.

Wide complex tachycardia in structural heart disease = VT until proven otherwise.

When in doubt, manage as VT.