CT-Guided Transcatheter Aortic Valve Replacement in Bicuspid Aortic Stenosis With a Large Membranous Ventricular Septal Aneurysm: Challenges in Annular Sizing and Valve Selection.

Membranous ventricular septal aneurysm (MSA) is an uncommon anatomical finding that may significantly alter the geometry of the aortic annulus and left ventricular outflow tract, creating challenges for transcatheter aortic valve replacement (TAVR). We report the case of a 78-year-old woman with symptomatic severe bicuspid aortic stenosis and a large MSA who underwent successful TAVR following CT-guided procedural planning. Cardiac computed tomography demonstrated interruption of annular continuity by the aneurysmal cavity, making conventional annular sizing unreliable. A virtual annular plane excluding the aneurysm was reconstructed to estimate the effective landing zone, yielding an annular area of 387 mm2 and a perimeter of 71.4 mm. Given the large aneurysmal neck and bicuspid valve with a calcified raphe, a 29-mm Evolut FX+ self-expanding valve was selected. Following balloon valvuloplasty, valve implantation was successfully performed with excellent positioning and minimal residual aortic regurgitation. At 2-month follow-up, the patient reported marked symptomatic improvement. Cardiac CT demonstrated stable prosthesis positioning, absence of leaflet thrombosis, and reduction of MSA systolic volume from 2.81 cm3 to 1.55 cm3. This case highlights the importance of multimodality imaging, CT-based virtual annular reconstruction, and individualized valve selection in patients with complex structural anatomy undergoing TAVR.