Figure 5. The S-curve of different fluoroscopic working views for transcatheter aortic valve deployment.

The S-curve identifies infinite patient-specific fluoroscopic projections in which the 3 aortic cusps are aligned on the same plane. Among them, there are 3 projections where the 3 cusps are equidistant (NRL, LNR and RLN) and 3 other projections where 2 of 3 cusps are overlapping (RL cusp overlap, LN cusp overlap, NR cusp overlap). The most widely used implanting views are the 3-cusp coplanar view NRL and the RL cusp overlap view. CAU: caudal; CRA: cranial; L: left coronary cusp; LAO: left anterior oblique; LCA: left coronary artery; N: non-coronary cusp; R: right coronary cusp; RAO: right anterior oblique; RCA: right coronary artery