ECG source localisation

Read the 12-lead ECG and click where the source is: a WPW accessory pathway on the AV rings, an ectopic beat in the ventricles. After your answer you see the correct region, the distance from your click and the algorithm's steps on this ECG.

Draft: not yet reviewed by the doctor. The algorithms come from published papers and are cited in the code; the ECGs are schematic.

How it works

WPW: the Arruda algorithm
Delta-wave polarity is read in the first 20 ms after QRS onset. First I and V1 (left free wall), then II (subepicardial), then V1 (septal or right free wall); finally aVF, III and II place the pathway in its region.
PVC: outflow tracts
A left bundle branch block pattern in V1 with an inferior axis points to an outflow tract. A precordial transition at V4 or later means the right outflow tract, by V2 the left. With the transition at V3, the V2 transition ratio is calculated.
PVC: other regions
A right bundle branch block pattern means the left ventricle; a superior axis means the inferior wall or the apex. Positive concordance points to the base, negative lateral chest leads towards the apex.
Points
A click inside the correct region earns 100 points. Outside it, points fall with distance; the distance is shown in millimetres for a schematic heart. Results are stored only in this browser.

Based on: Arruda 1998 — ECG algorithm for WPW accessory pathway location
Outflow tract and PVC origin criteria (Miller 1988, Ouyang 2002, Dixit 2003, Betensky 2011)
Updated: 11 November 2026

How it works

WPW: the Arruda algorithm

Delta-wave polarity is read in the first 20 ms after QRS onset. First I and V1 (left free wall), then II (subepicardial), then V1 (septal or right free wall); finally aVF, III and II place the pathway in its region.

PVC: outflow tracts

A left bundle branch block pattern in V1 with an inferior axis points to an outflow tract. A precordial transition at V4 or later means the right outflow tract, by V2 the left. With the transition at V3, the V2 transition ratio is calculated.

PVC: other regions

A right bundle branch block pattern means the left ventricle; a superior axis means the inferior wall or the apex. Positive concordance points to the base, negative lateral chest leads towards the apex.

Points

A click inside the correct region earns 100 points. Outside it, points fall with distance; the distance is shown in millimetres for a schematic heart. Results are stored only in this browser.