New Perspectives Provided by Merging Computed Tomographic Scanning and Electroanatomical Mapping of Koch’s Pyramid

Figure 4. Merging of the electroanatomical mapping with the reconstructed computed tomographic dataset. As shown in the figures, the electroanatomical map was overlaid with scans obtained before the procedure, resulting in a combined image with anatomical markers of the boundaries of the pyramid of Koch. Left: The left anterior oblique view shows, with an external view, the location of the His bundle recording site, the transition between His and the AV node (NH) and the area of the compact AV node, continuing along the tricuspid annulus with the right inferior nodal extension, identified on the basis of the Jackmann slow pathway potential preceding a low frequency humped potential. The conduction axis is directed towards the infero-septal recess of the left ventricle at the apex of Koch’s pyramid [3]. Right: The right anterior oblique view shows the view of the septal surface of Koch’s triangle area as seen from the right atrium. The electrograms recorded in these areas using the settings described in the text are shown below. The specified measurements of the atrial components of the conduction axis, including the depth to endocardial surface and the location of the slow pathway, has…

Figure 1. Recordings of AV node potential in Koch’s triangle during AVNRT. (A) In the mid-septal region of Koch’s triangle, a long-duration, low-frequency, low-amplitude AV node potential not preceded by a Jackmann slow pathway potential, was recorded without any near-field or far-field His electrogram. The potential was annotated in the middle of its duration. (B) Recording of AV node potential in the slow pathway region of Koch’s triangle during AVNRT. Left side: in the infero para-septal region of Koch’s triangle, a long-duration, low-frequency, low-amplitude AV node potential was recorded together with a Jackmann slow pathway potential slightly before its onset. The potential was annotated at the peak of the Jackmann slow pathway potential. (C) Electrogram recorded in the supero-septal region of Koch’s triangle during AVNRT: the low-frequency His-like potential was presumed to represent the compact node-His transition zone potential or the lower nodal bundle electrogram.

Figure 2. AV node potential recorded by spline F 5-6 during a Wenckebach cycle induced by incremental atrial pacing. The compact AV node potential completely disappears after the atrial non-conducted beat.

Figure 3. Merged acquisition from 3D mapping and reconstruction of computed tomographic datasets: step per reconstruction. Once the RA Rhythmia™ map has been acquired using Orion catheter, we aligned it with the reconstructed segmentations. This alignment allows us to clearly identify the aortic root relative to Koch’s pyramid. Lower panels: The position of the non-branching atrioventricular bundle inside the His cloud was identified at the site where the infero-septal recess of the aortic root meets the apex of the pyramid of Koch. The inferior right panel shows the electrograms recorded in Koch’s triangle. CTI = cavo-tricuspid isthmus, CS = coronary sinus, AVN = atrioventricular node, LCS = left coronary sinus, RCS = right coronary sinus, NCS = non-coronary sinus.

Figure 5. Flowchart of the proposed method to localize on the map the components of the atrioventricular conduction axis.