Aortic valve-in-valve implantation: impact of transcatheter- bioprosthesis size mismatch.
OBJECTIVE
Transcatheter aortic valves (TAVs) provide minimally invasive treatment for high-risk patients with severe native aortic stenosis. While the off-label application of TAV for degenerative bioprosthetic stenosis (valve-in-valve therapy) is attractive, few cases have been reported. If the rigid annulus and stent posts of bioprostheses prevent full expansion of the TAV, the hemodynamic performance may be compromised. The study aim was to evaluate the use of a 23 mm TAV within normal bioprostheses of equivalent or smaller orifice sizes.


METHODS
Twelve TAVs designed to mimic the 23 mm Edwards SAPIEN valve were created using stainless steel stents and trileaflet pericardial valves. A custom-built pulse duplicator was used to measure the hemodynamic performance of the TAV within 19, 21 and 23 mm Edwards pericardial bioprostlieses. The transvalvular gradient, effective orifice area (EOA) and regurgitant volume were used to evaluate valve-in-valve therapy for each valve size.


RESULTS
The TAV demonstrated similar hemodynamics to the Edwards SAPIEN valve (mean pressure gradient 6.68 +/- 2.11 mmHg and EOA 2.07 +/- 0.35 cm2). Acceptable valve-in-valve hemodynamics were achieved only in the 23 mm bioprosthesis after TAV implantation, with no significant change in mean pressure gradient (5.93 +/- 0.87 to 8.27 +/- 1.19 mmHg, p = 0.052) and EOA (2.13 +/- 0.15 to 1.79 +/- 0.15 cm2, p = 0.053). In 19 and 21 mm valves, the excess pericardial tissue relative to the stent EOA resulted in severe and moderate stenosis, respectively. The mean pressure gradient increased from 16.18 +/- 2.20 mmHg to 45.53 +/- 12.54 mmHg (p = 0.004) in 19 mm bioprostheses, and from 11.84 +/- 1.88 mmHg to 28.18 +/- 9.03 mmHg (p = 0.004) in 21 mm bioprostheses. Furthermore, the EOA was reduced from 1.28 +/- 0.1 to 0.78 +/- 0.11 cm2 (p < 0.001) in 19 mm valves, and from 1.51 +/- 0.15 to 1.01 +/- 0.19 cm2 (p < 0.001) in 21 mm bioprostheses. The TAV resulted in an increased regurgitant volume for all valve sizes.


CONCLUSIONS
Oversized TAVs are constrained by rigid bioprostheses, creating hemodynamic complications. Patients with 19 and 21 mm Edwards pericardial bioprostheses may be poor candidates for valve-in-valve therapy with the currently available technology.
Department of Surgery, University of California at San Francisco Medical Center (UCSF), 94143-0118, USA.
Ali N
AN
Azadani
Nicolas
N
Jaussaud
Peter B
PB
Matthews
Timothy A M
TA
Chuter
Liang
L
Ge
T Sloane
TS
Guy
Julius
J
Guccione
Elaine E
EE
Tseng
D001021:Aortic Valve; D001705:Bioprosthesis; D006349:Heart Valve Diseases / Q000503:physiopathology / Q000601:surgery; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000379:methods*; D006439:Hemodynamics; D006801:Humans; D017755:Prosthesis Fitting