Carto mapping system

A staged electrophysiology study was performed after totally thoracoscopic ablation median 6 days after surgery during hospitalization. The electrophysiological study was performed under sedation, and detailed electroanatomical data were obtained from the CARTO mapping system (Biosense Webster, Diamond Bar, CA, USA). Single or double trans-septal access was performed with an SL1 sheath (St. Jude Medical, St. Paul, MN, USA). The circular mapping catheter and the ablation catheter were introduced into the left atrium. Bidirectional block was confirmed for both PVs with entrance block and exit block. We applied radiofrequency catheter ablation (RFCA) if a residual PV gap was present. Additional CTI ablation was performed after PVI. Other linear lesions were created by discretion of the physician. All patients underwent catheter ablation with an open irrigated catheter (Thermocool, Biosense Webster). RF energy up to 25–35 W was used. Patients were administered anticoagulant during procedures with intravenous heparin. The infusion was adjusted to maintain an activated coagulation time of 300–400 sec.

Detailed 3‐dimensional electroanatomical mapping of the left ventricle via direct insertion of catheters through the left atrium and mitral valve was performed using the CARTO Mapping System (Biosense Webster, Inc, Diamond Bar, CA). Intracardiac mapping was performed using a Navistar ablation catheter with a 3.5‐mm tip and electrode spacing of 2‐5‐2 mm (Biosense Webster). Three‐dimensional electroanatomical maps were created, and mapping was performed in the ventricle, in addition to annotation of the His bundle, as well as fascicular and Purkinje signals. Fascicular potentials were labeled if a high‐frequency electrogram occurred before the ventricular electrogram but with a short isoelectric period intervening. Purkinje potentials were derived from the noninsulated portion of the conduction system, which were recognized by no isoelectric period between the high‐frequency Purkinje potential and the ventricular electrogram. The left bundle was assumed to be a direct extension of the His potential, without any atrial electrogram visible on the proximal pair of electrodes.

The ablation procedure protocol at our institution was implemented as previously described.14 15 (link) In brief, antiarrhythmic drugs (AADs) were stopped five half-lives before ablation procedure. Pulmonary vein (PV) angiography was performed to verify the ostia and antrum of PV, CARTO mapping system (Biosense Webster, Irvine, California, USA) was constructed for building a LA three-dimensional electroanatomic map and intracardiac electrogram recordings. The integration module of CARTO system was used to integrate of PV CT images with the constructed eletroanatomy to navigate the ablation catheter in real time. The endpoint of extensive circumferential PV isolation was the abolition or dissociation of PV potential or failure to induce AF. Patients with persistent AF received the additional ablation procedures, including linear ablation of the LA roof and isolation of superior vena cava.

Our CA technique has been described previously.⁹ (link) Procedures were performed under general anaesthesia or conscious sedation. Patients taking warfarin continued uninterrupted anticoagulation, while patients taking non-vitamin K oral anticoagulants had 0–2 doses omitted at the operator’s discretion. Patients who had not maintained therapeutic anticoagulation for 4 weeks pre-procedure underwent transoesophageal echocardiography. Ultrasound-guided vascular access was obtained via the right femoral vein.¹⁰ (link) Two trans-septal punctures were performed and unfractionated heparin was used to maintain an activated clotting time of >250 s. A 3.5 mm contact force-sensing irrigated tip ablation catheter (Smarttouch™) was used with the CARTO mapping system (Biosense Webster, Irvine, CA, USA) aiming for contact force of 5–40 g for each lesion. Since December 2014, minimum ablation index values of 550 on the anterior wall and 400 on the posterior wall were targeted.⁹ (link) Pulmonary vein isolation (PVI) was mandatory for all patients while additional ablation was performed at operator’s discretion. Successful PVI was defined as entrance block confirmed with a 20-pole spiral catheter, and successful linear lesions were defined as bidirectional block. Details of the CA procedure were prospectively captured in a bespoke electronic AF ablation database.