A case study on implantation strategies to mitigate coronary obstruction in a patient receiving transcatheter aortic valve replacement

Abstract

Coronary obstruction is a life threatening complication during and post-transcatheter aortic valve replacement (TAVR). The objective of this preliminary work is to investigate the mechanisms underlying coronary obstruction in a patient after TAVR, in whom coronary obstruction was confirmed in addition to highlighting the importance of pre-procedural planning. The aortic root of an 80-year old male patient with coronary obstruction during TAVR-where a 29 mm SAPIEN 3 was deployed-was segmented from Computed Tomography scans and 3D-printed with compliant material. Flow and pressure data were acquired in this 3D-printed model in-vitro using a pulse duplicator under physiological conditions for the cases: a 29 mm SAPIEN 3, a 26 mm SAPIEN 3 expanded with a 29 mm balloon, and a 31 mm Medtronic-CoreValve deployed annularly, supra and sub-annularly respectively. Only the CoreValve in sub-annular axial position and the 29 mm SAPIEN 3 yielded pressure gradients (PG) lower than 10 mmHg (6.76 ± 0.52 and 5.72 ± 0.13 mmHg respectively) while the 26 mm SAPIEN 3, CoreValve in normal and supra-annular positions yielded higher PGs (15.5 ± 0.48, 12.2 ± 0.15 and 10.8 ± 0.24 mmHg respectively). 29 mm SAPIEN 3 implantation yielded an FFR value of 45.7 ± 0.6%. However, 31 mm CoreValve in any of the three different annular positions yielded FFR values going from 89.6 ± 1.1% in supra-annular position to 98.3 ± 1.1% in sub-annular position. Implantation with a 26 mm SAPIEN 3 expanded with a 29 mm balloon also yielded an FFR of 92.1 ± 1.2%. Coronary obstruction in this patient could have been prevented through usage of different valve types and/or through usage of a different combination of valve size-balloon sizes.

Keywords: Coronary obstruction; FFR; Fractional flow reserve; TAVR; Transcatheter aortic valve replacement.

Fig.1:

Coronary obstruction at the time of the procedure.

Fig.2:

Representative 3D printed patient-specific aortic root model.

Fig.3:

Pressure Gradient and FFR results for the different valves.

Fig.4:

Schematic showing the 5 different TAV cases in relation with the coronary ostium with (a) SAPIEN 3 29, (b) SAPIEN 3 26 expanded with a 29mm balloon, (c) CoreValve in supra-annular position, (d) CoreValve in normal position and (e) CoreValve in sub-annular position. The images of Medtronic CoreValve and Edwards SAPIEN 3 are taken from Refs and respectively.