Griffith Algorithm (VT vs SVT, default-to-VT)
Griffith algorithm (Lancet 1994) for wide-complex tachycardia.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Bundle branch pattern
- Right bundle pattern (V1 mainly positive)
- rSR prime in V1
- Yes
Result: Griffith: VT by default - the right bundle pattern is not textbook (RS in V6 with R taller than S).
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Default
- VT unless the QRS is a textbook bundle branch block. This is the reverse of Brugada and Vereckei, which look for features of VT.
- Right bundle
- SVT only if BOTH: rSR prime in V1, and RS in V6 with the R taller than the S.
- Left bundle
- SVT only if ALL THREE: rS or QS in V1 and V2; delay to the S nadir under 70 ms; an R wave in V6 with no Q wave.
- Performance
- Sensitivity for VT about 94%, specificity about 40%. VT here is a safe default, not a positive finding; RVOT tachycardias are known to be misread as SVT.
- Caution
- An unstable wide-complex tachycardia is treated as VT and cardioverted regardless of any algorithm.
What you enter
- Bundle branch pattern
- rSR prime in V1 (right bundle)
- RS in V6, R taller than S (right bundle)
- rS or QS in V1 and V2 (left bundle)
- S nadir under 70 ms (left bundle)
- R with no Q in V6 (left bundle)
How this is calculated
Griffith MJ, Garratt CJ, Mounsey P, Camm AJ. Ventricular tachycardia as default diagnosis in broad complex tachycardia. Lancet. 1994;343(8894):386-388. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.