Aortic annulus sizing in stenotic bicommissural non-raphe-type bicuspid aortic valves: reconstructing a three-dimensional structure using only two hinge points

Bicuspid aortic valve (BAV) anatomy is becoming an increasingly frequently encountered challenge in transcatheter aortic valve implantation (TAVI). Bicommissural non-raphe-type BAV (Sievers and Schmidtke Type 0) is composed morphologically of two aortic cusps with no raphe and is less common than the tricommissural or bicommissural raphe-type configurations. Precise annular sizing is a key step for successful TAVI in BAV. The challenge in bicommissural non-raphe-type BAV is that a three-dimensional structure has to be reconstructed using only two anatomical hinge points. For this reason, available software are limited when it comes to bicommissural non-raphe-type BAV. We propose that manual assessment of the aortic root in bicommissural non-raphe-type BAV using multi-planar reconstruction (MPR) software can be performed successfully by aligning the two available hinge points and measuring the smallest identifiable annular dimensions in the transverse plane (Fig.1). We identified 12 patients with bicommissural non-raphe-type BAV undergoing TAVI between January 2013 and December 2017 in our high-volume institution. Our novel sizing strategy was employed prospectively in three patientswith good clinical outcomesand evaluated retrospectively in the remainder (Table 1). No patient suffered a central major vascular complication or required new permanent pacemaker implantation. Device success occurred in all patients except one (post-procedural echocardiographic transvalvular gradient of 23mmHg). In the retrospectively assessed cases, the novel annulus measure was concordant with the implanted THV size in 7 out of 9 procedures and, importantly, did not overestimate the annulus dimensions in any case. Furthermore, in two balloon-expandable THV cases the new measure may, in retrospect, have prompted consideration of a smaller implant size. To be noted, balloon sizing of the aortic annulus has additional value when selecting the valve size in BAV anatomy. Further prospective validation of this novel MDCT sizing technique is required.