[Revision of criteria for locating the accessory pathway by electrocardiogram in Wolff-Parkinson-White syndrome. A new algorithm].

A new algorithm has been developed for locating the anomalous conduction pathway from the ECG which is based on 62 cases of Wolff-Parkinson-White syndrome with a single anomalous conduction pathway, located by epicardial mapping, i.e. 28 on the free edge of the left ventricle (FL), 22 posterior septal, including 11 left (LPS) and 11 right (RPS), 8 right lateral (RL) and 4 right anterior septal (RAS). Criteria use the orientation of the delta wave and the QRS complex in the right precordial leads and the frontal plane, combined with the presence or absence of left or right ventricular hypertrophy. The algorithm is worked out in 15 steps, each criterion being applied only if the preceding criterion has not been observed. It identifies 100 per cent of the study population. This high specificity has been checked on independent series which include 55 FL pathways, 9 LPS, 17 RPS, 10 RL and 5 RAS. Only 2 LPS pathways were identified as FL and 1 RPS pathway as RL corresponding, perhaps, to "borderline" cases. The ECG thus remains the simplest non invasive examination for locating the ventricular origin of anomalous conduction pathways.