Over the past decade there has been a rise in left heart procedures necessitating transseptal puncture. Prior to that, interventional cardiologists did transseptal punctures for diagnostic purposes, or perform balloon mitral valvuloplasty for rheumatic mitral stenosis. Occasionally, a transeptal puncture might be done, somewhat paradoxically, to treat a patent foramen ovale (rather than placing a device in a long tunnel). Electrophysiologists more commonly did transseptal punctures, for mapping and for atrial fibrillation ablations. However, now interventional cardiologists rely on transseptal punctures to access the mitral valve, for TEER, mitral valve replacements, and to treat paravalvular leaks of the mitral valve. Occasionally ventricular septal defect closures are performed via a transseptal puncture (antegrade approach). Both interventional cardiologists and electrophysiologists perform transseptal punctures to access the left atrial appendage to place closure devices.