The study is a prospective, multi-center, non-randomized single arm interventional investigation with the TSP Crosser Transseptal Access System, a new complete solution for transseptal puncture and left atrial access and catheter navigation, for patients with atrial fibrillation ablation referred for radiofrequency catheter ablation.

Transseptal (TS) catheterization is a critical step for left atrial (LA) interventions (atrial fibrillation ablation, LA appendage closure, mitral valve interventions). The availability of suitable tools and techniques is essential to safely perform the TS puncture, effectively deliver radiofrequency lesions, deploy LA devices, and anticipate difficult procedural situations in which complications may arise. This study is intended to assess the safety, performance and usability of the TSP Crosser System in facilitating access to the left atrium and catheter navigation to the pulmonary veins (PV) during catheter based ablation procedures for the treatment of atrial fibrillation (AF). Moreover, the study will assess the impact of the TSP Crosser System on procedural times, including time to achieve left atrial accesses, total procedure times, total fluoroscopy time, left atrial mapping time and radiofrequency isolation times. The study is a prospective, multicenter, non-randomized single arm interventional investigation. Enrolled subjects who meet the study inclusion/exclusion criteria will be evaluated during the catheter mapping and ablation procedures and followed until release from hospital post procedure per institutional standard of care. After 30 days, patient will be contacted by telephone to obtain information on their clinical condition and any adverse events; if necessary, a clinic visit may be performed when required by the physician.

Inclusion Criteria:

• Patient is referred to receive a catheter ablation procedure for atrial fibrillation, requiring transseptal access and LA catheterization
• Patient has signed the informed consent form and is willing to participate in the clinical study and data collection
• Patient age is between 18 and 80 years old

Exclusion Criteria (Procedure Related): The use of the TSP Crosser System is contraindicated in patients with the following conditions:

• Atrial thrombus or tumor or myxoma.
• Previous interatrial septal patch or prosthetic atrial septal defect closure device.
• Interruption of inferior vena cava.
• Giant right atrium (70 mm diameter or more).
• Severe rotational anomalies of the heart or great vessels
• Severe kyphoscoliosis.
• Marked dilation of the ascending aorta.
• Inability to lie flat.

Exclusion Criteria (Clinical): Subjects with following conditions will also be considered unsuitable for enrollment:

• Unstable angina or ongoing myocardial infarction.
• History of recent systemic arterial embolization (within 1 month).
• History of recent Cerebral Vascular Accident (CVA) (within 1 month).
• Active infection or sepsis.
• Enrollment in any other ongoing study protocol.
• Female patient is pregnant or lactating.
• Untreatable allergy to contrast media or device materials in contact with blood or skin (Pebax, PTFE, Nitinol, Stainless steel, Polycarbonate, ABS, silicon, acetal, Pet-P (Ertalyte), POM (Delerin), Polycarbonate).
• Unable to tolerate anticoagulation therapy (heparin or warfarin).
• History of blood clotting (bleeding or thrombotic) abnormalities, with increased risk of bleeding.
• Any other health condition that, in the opinion of the investigator, makes the subject unsuitable for transseptal left atrial catheterization
• Participation in concomitant research studies of investigational products.
• Subject will not agree to return to the implant center for the required number of follow-up visits or is geographically unavailable for follow-up.