Mapping and Ablation procedure
Mapping and ablation were performed under the guidance of a CARTO system (Biosense Webster, Diamond Bar, CA), Ensite system (Abbott medical, St. Paul, MN), or Rhythmia system (Boston Scientific, Washington, DC). All ablation procedures were performed under deep sedation using propofol, dexmedetomidine, and pentazocine. The bispectral index (BIS) was monitored and maintained at 40-60. Vascular access was obtained from the right and left femoral vein and, if necessary, from right internal jugular vein. 6Fr duodecapolar, 6Fr decapolar, and 4Fr quadripolar electrode catheters were placed into the coronary sinus, His area, and right ventricle respectively. After venous access was secured, intravenous heparin was used to maintain an activated clotting time more than 300 sec. Electrophysiological study was performed to determine the presence of AP. Bolus infusion of adenosine triphosphate (ATP), extra-stimulus from atrium or ventricle, para-Hisian pacing were underwent to confirm that the antegrade or retrograde conduction was via the AP. When the supraventricular tachycardia (SVT) was induced during control or under an isoproterenol infusion, a standard EPS study was performed to confirm that the SVT was via the AP. In the case of left sided AP, the trans septal approach was performed under the fluoroscopic image and the left side mapping was performed through the trans septal catheter.
The dual chamber map was created by using Rhythmia system and Orion catheter. The potential reference of 3D map was obtained from two different cite in the coronary sinus and the maps were obtained from Orion catheter. Rhythmia system has a specific algorism called “V overlap”, which identify the local ventricular potential of mapping catheter. When the V overlap algorism was enabled, the annotation of 3D map focus on the single chamber only (Figure 1A). But the detail connection between atrial and ventricular wasn’t clear of this setting. Once the V overlap algorism was disabled, the annotation of 3D map can focus on the different chamber and show a 3D color map of the atrium and ventricle (Figure 1B), which we call the “atrio-ventricular dual chamber map”9. Each map was obtained during the ventricular pacing. If there was no retrograde conduction, ventricular map of antegrade conduction was obtained during the atrial pacing (Figure 2). The dual chamber map could be created in the case of type C cases (Figure 3). The 3D map of control group was created by using CARTO system or Ensite system with ablation catheter. The potential reference of 3D map was obtained from a single cite in the coronary sinus and the maps were obtained from ablation catheter. Ablation was performed for the earliest activation site while considering the local potential. Non-irrigation 4mm tip catheter or irrigation 3.5mm tip catheter was used for ablation in order to the operator’s decision. The success of ablation was defined as the conduction interruption of APs. After 30 minutes waiting time, the recurrence of APs conduction was confirmed under the isoproterenol infusion and bonus infusion of ATP. The background characteristics and procedure details were compared between the dual chamber mapping group and conventional single chamber mapping group.