ABC | Volume 114, Nº6, June 2020

Original Article Saad et al. Zero Fluoroscopy Catheter Ablation for Atrial Fibrillation and Supraventricular Arrhythmias Arq Bras Cardiol. 2020; 114(6):1015-1026 Methods Description of the technique All procedures were performed under general anesthesia, and venous access was obtained using ultrasound guidance, according to the specific need of the procedure, but generally consisted of two or three right femoral vein punctures, one left femoral vein puncture (for the ICE catheter), and one internal jugular vein puncture (in atrial fibrillation cases, for coronary sinus duodecapolar catheter placing). Monitoring during the procedure included 12-lead electrocardiogram and EA mapping cutaneous patches (Ensite NavX - St. Jude Medical, St. Paul, MN, USA or CARTO 3 – Biosense Webster Inc., Diamond Bar, CA, USA). Navigation through the intravascular space From the left femoral vein, an ICE catheter (ViewFlex Xtra – Abbott or Acunav – Biosense Webster) was advanced to the right atrium (RA), guided by visualization of echo-free spaces in the vascular system. The ICE catheter was advanced through the left iliac vein while keeping an “echo-free space” close to the near-field of the ultrasound image (representing an absence of tissue contact at the tip of the ICE catheter). This technique allows the operator to discriminate between a free-advancement of the ICE catheter tip through the vascular lumen when echo- free space is visible and a palpable resistance to advancement when this image pattern is not obtained. Whenever the path to the inferior vena cava was not so clear, a retained guidewire technique, using long wires from the left femoral vein allowed advancing the ICE catheter following a clear wire image in the lumen. That is of particular value in patients with thin iliac veins, where echo-free space is not very clear. Upon reaching the inferior vena cava, it is possible to identify the cavoatrial junction where, at the level of the liver, and a parenchymatous image with clearly visible intrahepatic veins is appreciated. At this moment, it is essential to identify and avoid the inadvertent progression of the ICE catheter through the hepatic veins and correctly direct it to the right atrium (RA), which can be done with gentle anterior deflection. Once in the RA, all standard views can be obtained using the conventional technique of clockwise or counterclockwise torque from the home view. The catheter is then prolapsed to the right ventricle using anterior deflection, while keeping the tricuspid valve visible, and sectional views of the pericardial space were obtained to rule out any baseline pericardial effusion. Back to the RA, a posterior deflection with a gentle clockwise torque allows a longitudinal view of the superior vena cava (SVC). This view allows adequate visualization of catheters coming from superior veins and is the standard view to start advancing transseptal guidewires and sheaths (figure 1). A long guidewire was then inserted through the right femoral vein, and smooth progression to the SVC was confirmed by ICE imaging. It is possible to visualize the right atrial appendage near the SVC ostium, and the inadvertent misplacement of the guidewire in this structure can then be avoided. A long transeptal sheath was advanced over the wire and placed in the SVC (using ICE, one can see the sheath itself “covering” the guidewire, while the distal, unsheathed part of the guidewire remains bright). When multipolar catheters are inserted through the femoral veins using short sheaths, it is possible to see catheter advancement using EA mapping and ICE image, until electrical potentials appear in the distal poles, confirming “arrival” at the RA. Catheter positioning When the CARTO system was used, an irrigated ablation catheter with contact force sensor was then advanced under EA and ICE visualization and a limited right atrial map was constructed, mostly to create a matrix (allowing other catheters to be visualized in EA maps) and to delineate the septum and coronary sinus (CS) anatomy (video 1). This step is not needed when the NAVx system is used, where any catheter can be visualized without the need for matrix creation. The CS was then cannulated with the multipolar catheter, under EA and ICE visualization (ICE can clearly visualize the proximal CS and the ostium, as well as the catheter going in). The progression of these multipolar catheters was monitored and confirmed using EA mapping (if the catheter is coming from the femoral vein, the inferior vena cava geometry is created) or ICE imaging (if the catheter is coming from the internal jugular vein, it can be clearly seen coming from the SVC). If a duodecapolar catheter was used, the distal 10 poles were placed in the CS and the proximal poles in the RA. A quadripolar catheter was placed in the RV using the same technique. AF Cases In AF cases, once a limited RA geometry was created (CARTO system only), two guidewires were inserted from the right femoral vein and advanced to the SVC, with adequate positioning being visualized on ICE. Two long transseptal sheaths (fixed curve and deflectable) were advanced over the wire to the SVC. Importantly, heparin was given as soon peripheral access was obtained, before any catheter insertion, aiming at an activated clotting time (ACT) > 350s. Those levels were maintained until left atrial instrumentation ended by continuous infusion and rebolus as needed. Two transseptal punctures were separately performed under ICE visualization, coming down to the septum from the SVC (figure 1 and video 2). After each septal perforation, a guidewire was advanced to the left superior pulmonary vein (PV), thus allowing for safe passage over the wire sheath positioning in the left atrial (LA) cavity. The ablation catheter and a multipolar mapping catheter were then positioned in the PVs. All these steps were clearly visualized on ICE, which could also be placed in the LA cavity through one of the transseptal accesses for a very high definition visualization (done in the last 15 cases of these series). A multipolar esophageal catheter was placed, and its position guided by ICE visualization. The LA and PV anatomies were reconstructed with a high-density map using the multipolar catheter (video 3). In particular, the ridge between the left superior PV and left atrial 1016