Transseptal puncture in cardiovascular interventions: a clinical consensus statement of the European Heart Rhythm Association, the Heart Failure Association, the European Association of Percutaneous Cardiovascular Interventions, the European Association of Cardiovascular Imaging of the ESC, and the Association for European Paediatric and Congenital Cardiology.

With the rapid increase in percutaneous left heart interventions, transseptal access to the left atrium has become a widely used procedure. This technique is crucial for electrophysiological procedures, particularly for atrial fibrillation ablation, which is estimated to be performed in more than 250 000 patients per year worldwide, as well as for various structural heart interventions, like percutaneous mitral valve repair. Although transseptal puncture (TSP) is generally considered a simple technique, it is associated with a small risk of potentially life-threatening complications. To ensure a successful and safe procedure, a thorough understanding of TSPs' clinical use, and the anatomy of the interatrial septum-including the fossa ovalis and its anatomical variants-is critical. Since the first fluoroscopy-guided TSP, advancements in echocardiographic imaging have enhanced the precision of the puncture, allowing targeting of specific regions of the fossa ovalis and facilitating difficult procedures. While most TSPs are performed using a Brockenbrough needle and a (steerable) sheath, wide variation in technique exists, and alternative methods have been developed initially aiming for complex cases but now routinely used. Understanding potential complications-such as cardiac tamponade, aortic puncture, and embolism-is essential for prevention, early recognition, and effective management, ultimately improving patients' outcomes. Finally, understanding how to approach specific complex scenarios is crucial for procedural success.