Transseptal

Transseptal is an anatomical and procedural term describing passage through a septum, most often the interatrial septum of the heart. It denotes approaches that create or utilize a communication between the right and left atria, allowing access to the left atrium from the venous circulation. In medicine, transseptal puncture is a standard technique used in interventional cardiology and electrophysiology to reach the left atrium for diagnostic or therapeutic purposes.

Technique and guidance: The procedure typically begins with venous access, usually through the femoral vein. A guiding sheath is advanced to the right atrium, and the fossa ovalis is identified by fluoroscopy and imaging modalities such as transesophageal or intracardiac echocardiography. A transseptal needle (often a Brockenbrough needle) and dilator are used to puncture the interatrial septum, after which the sheath is advanced into the left atrium. Real-time imaging helps confirm position and monitor for complications. The puncture site is chosen to optimize safety and subsequent instrumentation for the intended procedure.

Applications and risks: Transseptal access is essential for many left atrial interventions, including catheter ablation of atrial fibrillation, percutaneous mitral valvotomy, and left atrial appendage occlusion, as well as diagnostic sampling of the left atrium. Possible complications include cardiac perforation with pericardial effusion or tamponade, air or thromboembolism, residual septal defect, and vascular or access-site bleeding. Relative contraindications depend on patient factors and specific procedural context, and decisions are guided by imaging and operator experience.