The relationship between intraoperatively assessed atrial and ventricular insertions of accessory pathways

To gain insight into the complex problems regarding the extension of the atrial and ventricular insertions of anomalous pathways, the activation patterns obtained from intraoperative epicardial mapping in 23 patients with Wolff-Parkinson-White syndrome were carefully analyzed. The atrial and ventricular activation times along the atrioventricular groove were measured at 15 predefined anatomical landmarks. The width of the region of earliest atrial and ventricular activation times and the extent of atrial and ventricular overlap were assessed. The relationship between the atrial and ventricular insertions was studied by predicting the ventricular insertions from the observed atrial insertions and vice versa. The mean extension of an atrial and a ventricular insertion at surgery was 1.9 +/- 0.2 (SE) and 1.6 +/- 0.2 (SE) anatomical landmarks, respectively. The width of the region of early atrial and ventricular activation times measured 2.7 +/- 0.3 (SE) landmarks, thus indicating an overlap of the atrial and ventricular insertions. The lateral distance between the sites of earliest atrial and ventricular activation times was, on average, 1.7 +/- 0.3 (SE) landmarks. The predicted atrial insertion from a known ventricular insertion, and vice versa was found to cover 4 to 6 anatomical landmarks. These observations suggest that wide surgical dissections along the atrioventricular groove are warranted even if epicardial mapping discloses only a single accessory pathway.