Transseptal puncture using the Carto-Merge technique: a fluoroscopy-free and echocardiography-free method for real-time observation of needle position in the left atrium

Background: Transseptal puncture (TSP) is a necessary procedure for radiofrequency ablation of atrial fibrillation.At present, many scholars are exploring safe and radiation-free transseptal puncture methods such as transseptal puncture guided by intracardiac echocardiography (ICE) or transesophageal echocardiography (TEE), transseptal puncture guided by a three-dimensional (3D) mapping system, and transseptal puncture guided by intracardiac ultrasound combined with a 3-Dimensional mapping system.Our center tried to use Carto-Merge to guide transseptal puncture and explore a safe and effective transseptal puncture method that does not need ultrasound and X-ray and can observe the position of the puncture needle in the left atrium in real-time.Methods: We conducted a prospective observational study of patients undergoing left atrial septal puncture requiring atrial fibrillation ablation.We fused cardiac computed tomography (CT) images with 3D electroanatomical images of the heart.Two fusion methods were used in each patient: a multi-site fusion of the right atrium and a single-site fusion of the left main.A multi-point fusion of the right atrium was performed first, followed by a single-point fusion of the left main.According to the CT fusion effect, one of the images was selected to guide the transseptal puncture.Results: 52 patients underwent transseptal puncture under Carto-Merge guidance.The first puncture was successful in 50 cases (96%), the second and third puncture was successful in 1 case each (2%), and the incidence of cardiac tamponade was 0. Comparison of the impedance of ablation catheter in left sinus and left main: the impedance of the left sinus was 138.618.3 and the impedance of the left main was 212.719.4.The impedance of the ablation catheter in the left main was significantly higher than that in the left sinus (P<0.001).Right atrial multi-point fusion had only 70% of points within 2 mm.In 91.2% of patients, the error between three-dimensional electroanatomic and CT anatomy was less than 2 mm with the left main single-point fusion method.Conclusions: Transseptal puncture guided by Carto-Merge is a safe, effective, and radiation-free procedure.The left main single-point fusion can accurately fuse the cardiac CT anatomical structure with the three-dimensional electroanatomic of the heart.Under the guidance of this technology, the atrial septal puncture can observe the position of the puncture needle in the left atrium in real-time, avoiding serious complications such as pericardial tamponade caused by mispunctuation.