Transcatheter valve-in-valve implantation for degenerated bioprosthetic aortic and mitral valves - an update on indications, techniques, and clinical results.

: Aortic and mitral bioprosthesis are the gold standard treatment to replace a pathological native valve. However, bioprostheses are prone to structural valve degeneration, resulting in limited long-term durability. During the past decade, the implantation of transcatheter stent-valves within degenerated aortic and mitral bioprostheses, (the so-called 'valve-in-valve' procedure), represents a valid alternative to redo surgery in patients with high-risk surgical profiles.: We reviewed the clinical outcomes and the procedural details of transcatheter aortic and mitral valve-in-valve series according to current published literature and include a practical guide for valve sizing and stent-valve positioning and strategies to prevent complications.: In both aortic and mitral positions meticulous planning is fundamental in these procedures to avoid serious complications including patient prosthesis mismatch, coronary obstruction and left ventricular outflow tract obstruction.