Coaxial Angle Prediction for TAVR: CT

Procedural success in transcatheter aortic valve replacement (TAVR) depends on precise positioning and deployment of the valve in the three-dimensional aortic annulus and root. Fluoroscopy is the imaging modality typically relied on during valve positioning and deployment in TAVR. Accurate coaxial positioning of the valve with this method is best achieved by selecting a fluoroscopic deployment projection that is perpendicular to the native aortic valve plane. The use of a suboptimal “off-axis” fluoroscopic deployment projection may result in incorrect valve positioning and in turn lead to paravalvular aortic regurgitation, valve embolization, coronary ostium obstruction, heart block, or interference with the mitral valve apparatus [1–3]. Traditionally the native aortic plane has been assessed by invasive aortic root angiography, often requiring a number of aortograms be performed until a satisfactory projection is obtained. Frequently, however, such perpendicular projections are difficult to determine with significant contrast media utilized in attempts to do so in patients who often have significant renal dysfunction. More recently, multislice computed tomography (MDCT) has emerged as an accurate and practical alternative to repeated aortograms, providing operators with precise implant projections that can be determined prior to the procedure (Box 26.1). This chapter will outline the practical uses of MSCT to help predict the correct implant projection and review the available evidence with this technique.