Accurate determination of the ventricular insertion sites of accessory AV connections in the Wolff-Parkinson-White syndrome with electrocardiographic body surface potential mapping

The following conclusions were made: 1. BSPM using QRS analysis accurately predicts the ventricular insertion of accessory bypass tracts in the presence of antegrade conduction. 2. The ventricular insertion sites of accessory AV connections determined by BSPM and surgical mapping were identical or within one mapping site (<1.5 cm) in all but four of 18 cases. Three of the four exceptions had more than one accessory AV connection and the other a very broad ventricular insertion. 3. BSPM and EPS mapping locations of the accessory AV connections correlated very well in the 34 cases despite the fact that the BSPM determines ventricular insertion of the accessory AV connection, and EPS determines the atrial insertion site of the accessory AV connection. The latter explains why BSPM is somewhat more accurate. 4. As suggested by the three cases of multiple accessory AV connections, EPS and BSPM may be complementary, since BSPM identified one pathway and EPS the other. In the case of the broad connection, BSPM and EPS demonstrated different areas of that connection. (One of those with two accessory AV connections later demonstrated a third, but conduction was retrograde only, not identifiable by noninvasive methods.) 5. BSPM using ST-T is inaccurate in predicting the ventricular insertion site of accessory connections. 6. Standard ECG using the Gallagher methodology (but with no attempt at stimulating more preexcitation) was not as accurate connection as was the QRS of the BSPM. 7. BSPM using QRS analysis appears to be accurate in predicting right ventricular versus left ventricular posteroseptal accessory connections. 8. Typical epicardial right ventricular breakthrough, indicative of conduction via the specialized AV conduction system occurs in all patients with left ventricular free wall accessory connections. 9. Epicardial right ventricular breakthrough was not observed in cases with right ventricular free wall or anteroseptal accessory connections. 10. Epicardial right ventricular breakthrough can occur in the presence of posteroseptal accessory connections, whether right or left ventricular. 11. The delay in RV breakthrough in cases of LV insertion may provide a marker to estimate the degree of ventricular preexcitation.