Brugada Algorithm for Wide-Complex Tachycardia
VT vs SVT with Aberrancy
Why the Brugada Algorithm Matters
Wide-complex tachycardia (WCT) is ventricular tachycardia (VT) until proven otherwise. Mislabeling VT as supraventricular tachycardia (SVT) with aberrancy can lead to inappropriate therapy and hemodynamic collapse.
The Brugada algorithm provides a stepwise, ECG-based approach to rapidly differentiate VT from SVT with aberrancy using standard 12-lead ECG features.
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When to Apply the Algorithm
Regular WCT (QRS ≥ 120 ms)
Stable or unstable patient (do not delay cardioversion in instability)
No obvious pacing spikes or polymorphic rhythms
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Step-by-Step Brugada Algorithm
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Step 1: Absence of RS Complexes in All Precordial Leads (V1–V6)
Look for RS complexes (an R wave followed by an S wave).
If no RS complex in any precordial lead → VT
Interpretation
Pure monophasic R or S waves across V1–V6 strongly favor VT.
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Step 2: RS Interval > 100 ms in Any Precordial Lead
Measure from onset of R wave to nadir of S wave.
RS interval > 100 ms → VT
Physiology
Slow myocardial conduction in VT prolongs ventricular activation compared with fast His–Purkinje conduction in SVT.
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Step 3: Atrioventricular (AV) Dissociation
Look for:
P waves marching through QRS
Fusion beats
Capture beats
If AV dissociation present → VT
Pearl
AV dissociation is highly specific for VT, even if subtle.
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Step 4: Morphologic Criteria (V1–V2 and V6)
Apply bundle-branch-block–like morphology rules.
If RBBB-like pattern:
Monophasic R or qR in V1
Broad or slurred S in V6
→ VT favored
If LBBB-like pattern:
Broad initial R (>30–40 ms) in V1
Notched or slurred downstroke of S
Delayed nadir of S
→ VT favored
If morphology consistent with VT → VT
If none of the above → SVT with aberrancy
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Final Diagnosis Logic
Any positive step = VT
Only if all four steps are negative, consider SVT with aberrancy
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Practical Clinical Pearls
VT accounts for ≈80% of WCT in adults, especially with structural heart disease.
The Brugada algorithm prioritizes specificity over sensitivity—designed to avoid missing VT.
When in doubt, treat as VT.
Anti-VT therapy is generally safer than AV-nodal blockers in undifferentiated WCT.
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Common Pitfalls
Missing subtle RS complexes
Incorrect RS interval measurement
Over-reliance on morphology alone
Assuming young age excludes VT (it does not)
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Comparison With Other Algorithms
Brugada: Stepwise, easy bedside use
Vereckei (aVR): Single-lead focus, helpful when precordials unclear
Wellens criteria: Older, morphology-heavy
No algorithm is perfect—clinical context + ECG together provide the best accuracy.
Bottom Line
The Brugada algorithm is a practical, high-yield tool for differentiating VT from SVT with aberrancy in wide-complex tachycardia.
If any step suggests VT, manage as VT—when uncertain, VT is the safest assumption.
Good job guys
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