Sigmoid Septum and Balloon-Expandable Transcatheter Aortic Valve Replacement: A Cautionary Tale.

Transcatheter aortic valve replacement (TAVR) continues to garner considerable attention, especially as the commercial use of the procedure grows. Herein is highlighted an under-reported, underappreciated challenge in TAVR--that of a sigmoid septum. The two cases reported constitute the first discussion in the contemporary literature of this unique geometry in the setting of TAVR. Specifically, the report addresses how such a bulging septum may preclude safe TAVR with a balloon- expandable prosthesis, and also reinforces the importance of thoroughly evaluating all aspects of the subvalvular anatomy prior to valve deployment.