Membranous septum length and bicuspid aortic valve
The current study demonstrated similar MS length in BAV and TAV patients, unlike the previous study that revealed shorter MS length in BAV than TAV (24 ). A possible explanation for this discrepancy is the difference in measuring the MS length (18, 24 ). We speculate that it is more difficult to control the deployment of the THV due to challenging anatomical features accompanied with BAV such as eccentric device landing zone calcification, asymmetric geometry of the cusps, and concomitant pathologies of the aorta (severe tortuosity, horizontal aorta, and aneurysms) (31 ). Thus, the implantation might be targeted deeper to avoid valve migration or embolization rather than high implantation when the device manipulation is difficult especially in a trans-femoral case. Also, variation of implantation depth was higher in the BAV group (0.59 vs 0.34), which might reflect the unstable control of implantation depth compared to TAV. Further studies demonstrating the relation between implantation depth and the safety or the efficacy of high implantation for BAV are warranted.