Pin pointing the pathway !

I’m sure that for many budding cardiologists including me, diagnosing accessory pathway based on surface ECG has been herculean task. Neverthless i have seen people doing it with ease, may be fruits of their hard work

Recently i found an article mentioning pathway localisation after atrial pacing during EP study.Amazingly it works well on surface ecg .I’m yet to see if it errs.

In the study, pathway was correct in 90% compared to 63 % with arruda criteria.

Best part is that its a stepwise algorithm

  • step 1-lead V1 polarity -Right when negative and left when positive

Now you know the side, proceed down,

  • step 2-Inferior leads polarity

For right sided pathway- All 3 +ve – Think of anterior locations (RA or NH-nodohisian).If 1-2 +ve think intermediate location RL or Sometimes NH.If all negative think posteriorly RP or RPS

Similarly, for left sided pathway-All 3+ve direct hit on LL.If 1-2 +ve again straight to LPL.If all negative again think back to LPS or LPL or DCS(deep CS) locations

  • step 3 v3 polarity

For right sided only- v3 is negative for all away from septum remember APL -RA,RP AND RL.V3 +ve for septal RPS AND NH

v1/1 ratio-For left sided posterior only-see which is more positive? lead v1 or lead 1 .If ratio more than 1 LPL and less than 1 DCS or LPS.But how to find between dcs and LPS ?

  • step 4 lead 2 QRS notch

ONLY to see between DCS and LPS -If lead 2 QRS notched its DCS Otherwise go for LPS

  • Lets try some examples

ecg -1

ecg 2

Thanks to Thomas pambrun and colleagues.Now pathway localisation is gonna be fun.

See comment section to check your answers to above ecg with EP finding in above 2 patients

Good day!


Pambrun, Thomas, et al. “Maximal Pre-Excitation Based Algorithm for Localization of Manifest Accessory Pathways in Adults.” JACC: Clinical Electrophysiology (2018): 667.

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