Membranous interventricular septum aneurysm (MISA) is a rare abnormality occurring in 0.3% of patients with congenital heart disease, which thereby increases anatomical complexity. Transcatheter aortic valve replacement (TAVR) procedure was planned for a 71-year-old female patient from East Asia with a type 1 bicuspid aortic valve diagnosed with severe aortic stenosis by transthoracic echocardiography (TTE). Pre-procedural multidetector computed tomography (MDCT) clearly revealed an extremely horizontal aorta and a MISA originating from the sub-annulus with the upper edge extending 7.2 mm above the annulus. A probable communicating flow between the left ventricle and the aorta was confirmed by reviewing the TTE images. Moreover, there was a calcified raphe between the left- and right-coronary cusps. A downsized balloon-expandable valve (a 23 mm Sapien 3 valve with an additional 2 mL dilation) was therefore chosen and deployed with a 100/0 aortic/ventricular ratio position. The TTE post-implantation indicated a trace perivalvular leakage. The cardiac MDCT performed post-procedure, at the 6-month, and 12-month follow-ups demonstrated complete sealing and significant healing of the aneurysm. Transcatheter aortic valve replacement utilizing a balloon-expandable valve was successfully performed for a case with membranous interventricular septum aneurysm extending above the annulus. Comprehensive imaging analysis before the procedure is crucial for TAVR with challenging anatomical conditions.

An 89-year-old woman with severe aortic regurgitation and an aneurysmal interventricular membranous septum extending into the aortic annulus underwent successful transcatheter aortic valve replacement. A challenging case because of the risk of valve mispositioning complications attributed to the co-occurrence of pure aortic regurgitation (very low calcium burden) with an aneurysmal interventricular membranous septum. (Level of Difficulty: Intermediate.).

We report a challenging case of a 81-year-old male with history of severe calcific aortic valve stenosis and aneurysmal membranous interventricular septum. The presence of anomalies in the sub-annular area can lead to valve malpositioning and its consequences. transcatheter aortic valve implantation (TAVR) in patients with aneurysm of the perimembranous interventricular septum extending into the left ventricular outflow tract has not been previously reported. This case describes a successful transfemoral TAVR with an Edwards SAPIEN XT valve (Edwards Lifesciences, Irvine, CA, United States) with such anomaly.

We present the case of a 34-year-old female who was admitted to our hospital due to community-acquired pneumonia and had a transthoracic echocardiogram which revealed an aneurysm of the membranous interventricular septum. This was further investigated with a transesophageal echocardiogram which showed in detail the anatomical features of this very rare condition.