Conformational Pulsatile Changes of the Aortic Annulus: Potential Implications for Prosthesis Sizing for Transcatheter Aortic Valve Implantation by Computed Tomography

Abstract

Ziele: To evaluate the potential influence of the cardiac reconstruction phase on aortic annulus dimension and prosthesis selection by dual-source computed tomography (DSCT) in patients undergoing trans-catheter aortic valve replacement (TAVI). Methode: One-hundred-and-twelve patients with severe aortic stenosis (mean age 81±8 years, mean aortic valve area 0.69±0.18cm2) and sinus rhythm underwent retrospectively gated DSCT for evaluation for potential TAVI. Aortic annulus dimensions were quantified by cross-sectional area assessment by means of planimetry and average diameter calculation (calculated average annulus diameter, CAAD=2 x √(A/pie)) at the level of the basal attachment points of the aortic cusps throughout the cardiac phase at 5% intervals. Eccentricity index (EI) was calculated as EI=1 – (minimal diameter/maximum diameter). Prosthesis selection was CAAD-based (23mm prosthesis for CAAD <22mm, 26mm prosthesis for CAAD 22–25mm, 29mm prosthesis for CAAD >25mm), hypothetically at either 40% and 75% of the cardiac cycle. Agreement was calculated by kappa-statistics. Ergebnis: CAAD was found to be larger during early- and mid-systole than during diastole, with maximum CAAD found between 20–30% in 91% of patients. Average difference between minimum and maximum CAAD was 1.9±0.6mm and between 40% and 75% 0.7±0.6mm. Agreement for prosthesis selection was found in 98/112 patients (κ=0.78). EI was reduced during early- and mid-systole and peaked in early- and end-diastole, corresponding to phases of rapid ventricular filling and atrial contraction. Schlussfolgerung: The aortic annulus is subject to conformational pulsatile changes, with increased cross-sectional area but reduced eccentricity during early- and mid-systole. Difference in diameter between traditional reconstruction phases at 40% and 75% is limited, with agreement in prosthesis selection in the vast majority of patients.