Direct Aortic Access Transcatheter Aortic Valve Replacement: Three-Dimensional Computed Tomography Planning and Real-Time Fluoroscopic Image Guidance.

BACKGROUND AND AIM OF THE STUDY

Direct aortic access for transcatheter aortic valve replacement (DA-TAVR) is an important alternative approach in patients with hostile ileo-femoral vessels. Planning the transaortic puncture site and an 'ideal' trajectory towards the annulus plane is important for safe and successful valve implantation. The feasibility of three-dimensional (3D) planning and real-time fluoroscopic image guidance for DA-TAVR was evaluated using pre-procedural multi-detector computed tomography (MDCT) and intra-procedural Dyna CT co-registration approaches.

METHODS

Between May 2012 and August 2014, a total of 44 patients (40 mini-sternotomies, four mini-thoracotomies) was selected for DA-TAVR using the authors' MDCT-Dyna CT co-registration approach (32 CoreValve, 12 SAPIEN). Pre-procedural contrast-enhanced multi-slice CT (MSCT) and intra- procedural non-contrast Dyna CT images were co-registered based on cardiac outline and aortic root calcifications. Using a prototype software, the aortic root was segmented and relevant landmarks identified automatically. The intersection of a virtual perpendicular trajectory from the annulus with the greater curvature of the aorta was marked as the planned DA puncture site. The planned DA puncture site, trajectory and relevant landmarks were overlaid onto real-time fluoroscopic images for image guidance during DA-TAVR.

RESULTS

Real-time fluoroscopic overlay of planned trajectory was feasible in all 44 cases of DA-TAVR. The mean 2D projection distance error between the actual and planned aortic puncture sites was 1.60 +/- 1.1 cm. The mean angular difference error (measure of co-axiality) between actual and planned DA trajectory was 11.86 +/- 9.3. Errors in distance and co-axiality were lower with the mini-thoracotomy than with the mini-sternotomy approach. The Multi-Slice CT (MSCT)-Dyna CT co-registration technique resulted in significantly less contrast usage, and trended towards shorter fluoroscopy and operative times. There was also a trend towards a reduction in acute kidney injury, but no difference was identified in the degree of paravalvular regurgitation or mortality.

CONCLUSION

3D access planning and real-time image guidance for DA-TAVR is feasible using an MDCT/non-contrast Dyna CT image co-registration-based approach. Such image co-registration strategies improve the accuracy of case planning and safety of valve deployment with a direct aortic approach. Further studies are necessary to determine if these enhancements translate into an improvement in clinical outcomes.