Author + information
- Received August 6, 2018
- Revision received October 4, 2018
- Accepted October 23, 2018
- Published online January 7, 2019.
- Janarthanan Sathananthan, MBChB, MPHa,
- Stephanie Sellers, PhDb,c,
- Aaron M. Barlow, BSc, PhDb,
- Viktória Stanová, Dipl-Ingd,
- Rob Fraser, MSce,
- Stefan Toggweiler, MDf,
- Keith B. Allen, MDg,
- Adnan Chhatriwalla, MDg,
- Dale J. Murdoch, BSc, MBBSa,h,
- Mark Hensey, MB BCh, BAOa,
- Karen Laub,c,
- Abdullah Alkhodair, MDa,
- Danny Dvir, MDi,
- Anita W. Asgar, MDj,
- Anson Cheung, MDa,
- Philipp Blanke, MDa,c,
- Jian Ye, MDa,
- Régis Rieu, PhDd,
- Phillippe Pibarot, DVM, PhDk,
- David Wood, MDa,
- Jonathan Leipsic, MDa,c and
- John G. Webb, MDa,∗ ()
- aCentre for Heart Valve Innovation, St. Paul’s Hospital, University of British Columbia, Vancouver, British Columbia, Canada
- bCentre for Heart Lung Innovation, Vancouver, British Columbia, Canada
- cDepartment of Radiology, St. Paul’s Hospital and University of British Columbia, Vancouver, British Columbia, Canada
- dAix-Marseille Univ, IFSTTAR, LBA UMR_T24, Marseille, France
- eViVitro Labs Inc., Victoria, British Columbia, Canada
- fHeart Center Lucerne, Luzerner Kantonsspital, Lucerne, Switzerland
- gSaint Luke’s Hospital, St. Luke’s Mid America Heart Institute, Kansas City, Missouri
- hUniversity of Queensland, Brisbane, Australia
- iUniversity of Washington, Seattle, Washington
- jMontreal Heart Institute, Montreal, Quebec, Canada
- kQuebec Heart & Lung Institute, Laval University, Quebec, Canada
- ↵∗Address for correspondence:
Dr. John G. Webb, St. Paul’s Hospital, 1081 Burrard Street, Vancouver, British Columbia V6Z 1Y6, Canada.
Objectives The authors assessed the effect of valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) followed by bioprosthetic valve fracture (BVF), testing different transcatheter heart valve (THV) designs in an ex vivo bench study.
Background Bioprosthetic valve fracture can be performed to improve residual transvalvular gradients following VIV TAVR.
Methods The authors evaluated VIV TAVR and BVF with the SAPIEN 3 (S3) (Edwards Lifesciences, Irvine, California) and ACURATE neo (Boston Scientific Corporation, Natick, Massachusetts) THVs. A 20-mm and 23-mm S3 were deployed in a 19-mm and 21-mm Mitroflow (Sorin Group USA, Arvada, Colorado), respectively. A small ACURATE neo was deployed in both sizes of Mitroflow tested. VIV TAVR samples underwent multimodality imaging, and hydrodynamic evaluation before and after BVF.
Results A high implantation was required to enable full expansion of the upper crown of the ACURATE neo and allow optimal leaflet function. Marked underexpansion of the lower crown of the THV within the surgical valve was also observed. Before BVF, VIV TAVR in the 19-mm Mitroflow had high transvalvular gradients using either THV design (22.0 mm Hg S3, and 19.1 mm Hg ACURATE neo). After BVF, gradients improved and were similar for both THVs (14.2 mm Hg S3, and 13.8 mm Hg ACURATE neo). The effective orifice area increased with BVF from 1.2 to 1.6 cm2 with the S3 and from 1.4 to 1.6 cm2 with the ACURATE neo. Before BVF, VIV TAVR with the ACURATE neo in the 21-mm Mitroflow had lower gradients compared with S3 (11.3 mm Hg vs. 16 mm Hg). However, after BVF valve gradients were similar for both THVs (8.4 mm Hg ACURATE neo vs. 7.8 mm Hg S3). The effective orifice area increased from 1.5 to 2.1 cm2 with the S3 and from 1.8 to 2.2 cm2 with the ACURATE neo.
Conclusions BVF performed after VIV TAVR results in improved residual gradients. Following BVF, residual gradients were similar irrespective of THV design. Use of a small ACURATE neo for VIV TAVR in small (≤21 mm) surgical valves may be associated with challenges in achieving optimum THV position and expansion. BVF could be considered in selected clinical cases.
Recent studies have demonstrated the safety and efficacy of valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) as an alternative to reoperation for failed bioprosthetic surgical valves (1,2). However, high residual gradients following VIV TAVR, particularly in smaller surgical valves, have been associated with worse clinical outcomes (1–3).
Various approaches to minimize transvalvular gradients and reduce the incidence of patient–prosthesis mismatch following VIV TAVR have been used. All focus on facilitating optimal transcatheter heart valve (THV) leaflet function despite the constraints of the surgical valve. THVs with leaflets positioned high within the stented frame may allow for “supra-annular” leaflet opening (4–6). Further, implantation of any THV “higher” within a surgical bioprosthesis may allow for better leaflet excursion above the constraints of the surgical ring. Recently, the safety and efficacy of bioprosthetic valve fracture (BVF) has been demonstrated in a small number of patients to increase the internal dimensions of surgical valves thus allowing for optimal expansion of the THV with a reduction in residual gradient and improved effective orifice area (EOA). Clinical experience with BVF is early, and BVF’s impact on long-term clinical outcomes and on THV durability is unknown (7–11).
We assessed the impact of BVF on THV expansion and hydrodynamic function following VIV TAVR using 2 types of THV design.
The surgical aortic valves tested were a 19-mm and a 21-mm Mitroflow aortic bioprosthesis (Sorin Group USA, Arvada, Colorado). The Mitroflow bioprosthesis consists of an acetyl homopolymer stent frame with bovine pericardial sheets sutured externally to form the leaflets. The sewing ring covers the base of the frame and incorporates a nonrigid radiopaque silicone ring covered by a Dacron mesh (12). The 19-mm and 21-mm Mitroflow valves have true internal diameter of 15.5 and 17 mm, respectively (13).
VIV TAVR was tested with a 20-mm, 23-mm SAPIEN 3 (S3) (Edwards Lifesciences, Irvine, California) and small ACURATE neo (ACn) (Boston Scientific, Natick, Massachusetts) THV. The S3 THV is a balloon-expandable THV made of a cobalt-chromium alloy frame, bovine pericardial leaflets, and internal and external polyethylene terephthalate fabric seals at the inflow level of the valve. The 20-mm and 23-mm S3 valves have heights of 15.5 mm and 18 mm, respectively, when fully expanded as per manufacturer specifications (14). The ACn is a self-expanding THV with a nitinol frame and porcine pericardial leaflets positioned higher within the frame. There are inner and outer pericardial seals at the inflow level of the valve. There are 3 stabilization arches for axial alignment, an upper crown and a lower crown (Figure 1). The total height of the ACn ranges between 48 and 51 mm with the stent body height being 18 to 19 mm. Three sizes (small, medium, and large) are currently available to accommodate an aortic annulus diameter between 21 mm and 27 mm. The small-size ACn was used in this study.
Ex vivo VIV procedure
The S3 THV was positioned in the surgical bioprosthetic valve with an aim to achieve a “high” implantation to maximize the EOA. The Mitroflow bioprosthesis has poorly visible radiopaque markers. Ex vivo VIV TAVR using the S3 THV, was performed with the center marker of the S3 THV positioned just above the level of the sewing ring of the Mitroflow valve. A 20-mm S3 was deployed in the 19-mm Mitroflow and a 23-mm S3 was deployed in the 21-mm Mitroflow. Ex vivo VIV TAVR using the ACn THV was performed by positioning the upper crown adjacent to the top of the acetyl stent frame. A small ACn was deployed in both the 19-mm and 23-mm Mitroflow THVs.
Ex vivo bioprosthetic valve post-dilatation and fracture
True Dilatation balloon valvuloplasty catheters (Bard Vascular, Tempe, Arizona) of various sizes (18 mm, 20 mm, 21 mm, 22 mm, and 23 mm) were used to post-dilate and fracture the surgical bioprosthetic valve after ex vivo VIV TAVR was performed. The True Dilatation balloon is noncompliant, allowing high-pressure balloon inflation with a consistent balloon diameter. The maximal post-dilatation performed with a noncompliant balloon for the S3 VIV bench samples were matched to the labeled size of the THV (20-mm True balloon for the 19-mm Mitroflow, and a 23-mm True balloon for the 21-mm Mitroflow). The maximal post-dilatation performed for the ACn VIV bench samples were a 20-mm True balloon for the 19-mm Mitroflow and 23-mm True balloon for the 21-mm Mitroflow.
Post-dilatation/BVF of the 19-mm Mitroflow/20-mm S3 and the 19-mm Mitroflow/small ACn VIV was performed sequentially, first with a 18-mm and then a 20-mm True Dilatation balloon. Post-dilatation/BVF of the 21-mm Mitroflow/23-mm S3 and the 21-mm Mitroflow/small ACn VIV was performed sequentially with a 18-mm, 20-mm, 21-mm, 22-mm, and 23-mm True Dilatation balloon.
Multimodality imaging was performed at baseline following ex vivo VIV, and repeated after final balloon post-dilatation. High-resolution photography was performed at the same magnification and same fixed camera height. Micro computed tomography was performed both at baseline and repeated after final balloon dilatation. All images were performed using the Nikon XT H 225 ST micro focus X-ray tomography system (Nikon Metrology, Cambridge, Ontario, Canada). Fluoroscopy was performed using a standard adult cardiac catheterization laboratory (General Electric Healthcare, Chicago, Illinois).
Micro computed tomography measurements for the S3 were made at the inflow, waist, and outflow of the THV. The waist was measured at the most constrained part of the THV within the surgical aortic valve (Figure 1). Measurements for the ACn THV were made at the inflow (level of the adaptive polyethylene fabric seal), nadir of the leaflets (at the level of the lower crown), and coaptation level (base of the stabilization arches) of the leaflets (Figure 1). To account for potential blooming artifact, axial measurements of diameter, perimeter, and area were made using the center of each valve strut as a marker (Figure 1).
The percentage change in THV expansion from pre-BVF was calculated at the 3 measured levels of both the S3 and ACn using the following equation:
Degree of eccentricity was only assessed if a noncircular deployment was noted of the THV. Noncircularity was defined if a difference in diameter was observed across 2 perpendicular measurements of the THV. If eccentricity was noted, both minimum and maximum diameter are reported (i.e., 22.3 to 22.4 mm).
An eccentricity index, which has previously been described in the published reports, was calculated for both the S3 and ACn THV using the following equation (15):
Hydrodynamic testing was performed after each sequential balloon post-dilatation using a commercially available pulse duplicator (ViVitro Labs, Victoria, British Columbia, Canada) (Figure 1). Valves were tested in accordance with ISO 5840-3:2013 guidelines for in vitro pulsatile flow testing for heart valve substitutes implanted by transcatheter techniques (16). Valves were placed in a holder fabricated from silicone with a durometer of scale Shore A hardness of 40 ± 5 (Figure 1). Justification for the selection of sample holder hardness was based on published data on acceptable tissue compliance matched with published data on the silicone material hardness scale (17–19). Test fluid used was 0.9 ± 0.2% sodium chloride test solution maintained at 37 ± 2°C (1 drop of Cosmocil [preservative]/l).
Valves were tested on the aortic side of the pulse duplicator with a spring-loaded disc valve (ViVitro Labs) on the mitral side of the pulse duplicator. Measurements were based on average results taken from 10 consecutive cycles. High-speed video was captured at each step condition. Pulsatile forward flow performance was tested at a nominal beat rate of 70 ± 1 beats/min, systolic duration of 35 ± 5%, mean aortic pressure of 100 ± 2 mm Hg, and simulated cardiac outputs of 5 ± 0.1 l/min. Mean gradient (mm Hg) and EOA (mm2) were assessed.
Pin-wheeling, as defined by the International Standards Organization guideline for THV testing, refers to twisting of the leaflet free edges resulting from excessive leaflet redundancy (16). A pin-wheeling index (PWI) as described by Midha et al. (20) was used. We quantitated the degree of pin-wheeling by tracing the contour of the leaflet free edges and compared it to the unconstrained, ideal configuration. The following equation was used to calculate a PWI:
Lactual denotes the length of the leaflet from the valve frame to the coaptation center. Lideal denotes the straight line distance between the endpoints of the leaflet free edge (20). Determination of the PWI was performed using a custom-made MATLAB code (MathWorks, Natick, Massachusetts) after the image calibration.
Hydrodynamic variables are reported as mean ± SD. Hydrodynamic variables at baseline and after final balloon dilatation were compared using the Student’s t-test.
BVF occurred with use of a 20-mm True Dilatation balloon at 12 atm pressure for both the 19-mm and 21-mm Mitroflow valves. An audible, high-pitched “crack” was heard when BVF occurred.
In the S3 VIV TAVR deployments, the most constrained part of the THV was located just above the radio-opaque ring of the Mitroflow valve (Figures 1 and 2). For the ACn VIV TAVR deployments, a high implant (adjacent to the top of the Mitroflow acetyl stent frame) was required to allow full expansion of the upper crown of the ACn and allow favorable THV function. Marked underexpansion of the lower crown of the THV within the surgical valve was also observed (Figure 2). If the upper crown of the ACn was deployed within the Mitroflow valve, there was marked underexpansion of the upper crown and compromise to THV leaflet function.
The S3 and ACn were both underexpanded following VIV TAVR. Underexpansion of the S3 occurred particularly within the Mitroflow valve with a waist observed to the THV.
Following VIV TAVR, the 20-mm S3 implanted in the 19-mm Mitroflow had inflow, waist, and outflow diameters of 18.7 mm, 14.9 mm, and 19.5 mm, respectively. Following BVF with a 20-mm balloon, the inflow, waist, and outflow diameters increased to 19.9 to 20.8 mm, 16.3 mm, and 19.2 to 19.9 mm, respectively. Following VIV TAVR the 23-mm S3 implanted in the 21-mm Mitroflow had inflow, waist, and outflow diameters of 21 mm, 16.5 mm, and 22.3 to 22.4 mm, respectively. Following BVF, the inflow, waist, and outflow diameters increased to 23.2 to 23.6 mm, 20.1 mm, and 23.1 to 23.5 mm, respectively. Perimeter and area measurements before and after BVF, for the S3 THV are reported in Figure 3. Following VIV TAVR and before BVF, the 20-mm S3 had inflow, waist, and outflow area of 274.2 mm2, 175.1 mm2, and 300.3 mm2, respectively. Following BVF, the inflow, waist, and outflow area increased to 301.4 mm2, 208.0 mm2, and 330.0 mm2, respectively. Following VIV TAVR and before BVF, the 23-mm S3 had inflow, waist, and outflow areas of 347.6 mm2, 213.4 mm2, and 392.6 mm2, respectively. Following BVF, the inflow, waist, and outflow areas increased to 431.3 mm2, 318.9 mm2, and 426.9 mm2, respectively (Figure 3).
Following VIV TAVR in the 19-mm Mitroflow, and before BVF, the small ACn had inflow, leaflet nadir, and leaflet coaptation level perimeters of 41.8 mm, 56.8 mm, and 71.3 mm, respectively. Following BVF, the inflow, leaflet nadir, and leaflet coaptation level perimeters increased to 46.7 mm, 60.2 mm, and 73.6 mm, respectively. Following VIV TAVR in the 21-mm Mitroflow, and before BVF, the small ACn had inflow, leaflet nadir, and leaflet coaptation level perimeters of 48.1 mm, 59.2 mm, and 71.0 mm, respectively. Following BVF, the inflow, leaflet nadir, and leaflet coaptation level perimeters increased to 60.0 mm, 67.1 mm, and 74 mm, respectively. Diameter measurements before and after BVF, for the small ACn THV are reported in Figure 3. Following VIV TAVR in the 19-mm Mitroflow, and before BVF, the small ACn had inflow, leaflet nadir, and leaflet coaptation level area of 129.7 mm2, 238.4 mm2, and 404.1 mm2, respectively. Following BVF, the inflow, leaflet nadir, and leaflet coaptation level area increased to 173.5 mm2, 288.8 mm2, and 430.7 mm2, respectively. Following VIV TAVR in the 21-mm Mitroflow, and before BVF, the small ACn had inflow, leaflet nadir, and leaflet coaptation level area of 173.0 mm2, 279.0 mm2, and 400.5 mm2, respectively. Following BVF, the inflow, leaflet nadir, and leaflet coaptation level area increased to 286.2 mm2, 358.5 mm2, and 435.4 mm2, respectively.
The degree of eccentricity for both the S3 and ACn THV are detailed in Figure 3.
The transvalvular gradients following VIV TAVR in the 19-mm Mitroflow were 22.0 ± 0.2 mm Hg and 19.1 ± 0.3 mm Hg for the 20-mm S3 and small ACn, respectively, and decreased significantly to 14.2 ± 0.1 mm Hg (p < 0.0001) and 13.8 ± 0.1 mm Hg (p < 0.0001) following BVF (Figure 4). The transvalvular gradient following VIV TAVR in the 21-mm Mitroflow were 16.0 ± 0.2 mm Hg and 11.3 ± 0.1 mm Hg for the 23-mm S3 and small ACn, respectively. With sequential post-dilatation using larger noncompliant balloons, there was a reduction in the transvalvular gradient, which was observed for both the 23-mm S3 and small ACn THVs. After final post-dilatation and BVF, the gradients decreased significantly to 7.8 ± 0.1 mm Hg (p < 0.0001) and 8.4 ± 0.1 mm Hg (p < 0.0001) for the 23-mm S3 and small ACn, respectively (Figure 4).
The EOA following VIV TAVR in the 19-mm Mitroflow were 1.2 cm2 and 1.4 cm2 for the 20-mm S3 and small ACn, respectively. Following BVF the EOA increased significantly to 1.6 cm2 (p < 0.0001) and 1.6 cm2 (p < 0.0001) for both the 20-mm S3 and small ACn (Figure 4). The EOAs following VIV TAVR in the 21-mm Mitroflow were 1.5 cm2 and 1.8 cm2 for the 23-mm S3 and small ACn, respectively. With sequential post-dilatation using larger noncompliant balloons, there was an increase in the EOA, which was observed for both the 23-mm S3 and small ACn. After final post-dilatation and BVF, the EOA increased significantly to 2.1 cm2 (p < 0.0001) and 2.2 cm2 (p < 0.0001) for the 23-mm S3 and small ACn, respectively (Figure 4).
There was significant pin-wheeling noted for both the 20-mm (PWI 15.4%) and 23-mm S3 (PWI 15.0%) before BVF. After BVF, there was an improvement in pin-wheeling in both the 20-mm (PWI 8.1%) and 23-mm S3 (PWI 6.8%) THVs. The degree of pin-wheeling was similar before and after BVF for the ACn THV (Figures 5 and 6⇓⇓, Online Videos 1, 2, 3, 4, 5, 6, 7, and 8).
BVF following VIV TAVR was effective in reducing transvalvular gradients in both sizes of Mitroflow valves tested. Following VIV TAVR and before BVF, transvalvular gradients were high irrespective of THV design for the 19-mm Mitroflow, but in the 21-mm Mitroflow, lower residual gradients were achieved with the ACn THV. However, following BVF, residual transvalvular gradients were similar, with no superiority seen on the basis of THV design.
Clinical and bench studies have suggested that the use of supra-annular THVs may result in lower residual gradients following VIV TAVR, particularly in patients with small surgical bioprostheses (2,3,20). However, our bench study suggests that this may not necessarily apply to all combinations of bioprosthetic surgical valve sizes and THV types. In the 19-mm Mitroflow, hydrodynamic function was similar between the S3 and ACn THVs, both before and after BVF. The large core lab–adjudicated PARTNER 2 ViV (PARTNER II Trial: Placement of AoRTic TraNscathetER Valves) and CoreValve U.S. Expanded Use studies, also showed similar mean gradients at 30 days between SAPIEN and CoreValve THVs (average mean gradient at 30 days was 17.1 and 17.0 mm Hg, respectively) (1,21). VIV TAVR in small (<21 mm) surgical valves were excluded in these 2 studies. There was a clear difference by THV design in the 21-mm Mitroflow with lower residual gradients using the ACURATE neo THV, compared with the 23-mm S3. Following BVF of the 21-mm Mitroflow, the reduction in gradients across the ACn THV was also not dramatic. Ultimately the smallest residual area will influence valvular gradients, rather than specific THV design differences. If THV leaflets are positioned at the point of greatest THV constraint, then this will reduce the final area. Therefore, achieving a “supra-annular” leaflet position relative to the area of maximal constraint is favorable. A THV design that has leaflets positioned high (supra-annular) can still be positioned low within a surgical valve, and the leaflets placed in an intra-annular position. Similarly, a THV design with intra-annular leaflet position, can be positioned high relative to the surgical valve, so that the THV leaflets are in a supra-annular position. Clinicians may favor performing BVF, particularly when THV leaflets are positioned intra-annular, to potentially facilitate THV expansion and function. However, the role of BVF when transvalvular gradients are low remains unknown. In the smaller 19-mm Mitroflow, gradients were high at ∼20 mm Hg following VIV TAVR that clinically is associated with higher mortality at 1 year (1). This would favor consideration of BVF in these situations to lower residual gradients.
VIV TAVR can result in THV underexpansion, which may subsequently have an impact on leaflet coaptation and durability, particularly in small bioprosthetic valves. In this study, we observed evidence of pin-wheeling of both types of THV, which was particularly evident in the S3 THV. In our bench study, we observed an improvement in pin-wheeling after performing BVF. Pin-wheeling can lead to localized leaflet strain that may accelerate leaflet fatigue and premature THV failure. Pin-wheeling as demonstrated on ex vivo testing has been shown to cause asymmetrical leaflet strain in THVs (15,20,22). Pin-wheeling has also been observed in bioprosthetic surgical valves and has been shown to impact durability, as was reported with the Ionescu-Shiley valve (15). We observed an improvement in pin-wheeling after performing BVF. Although speculative, performing BVF regardless of the residual transvalvular gradient, may optimize leaflet coaptation and reduce pin-wheeling, which may result in improved THV durability.
Of some concern is that BVF performed following VIV TAVR has the potential for THV leaflet injury, which may have an impact on both short- or long-term durability. An alternative approach is to perform BVF before VIV TAVR, but this runs the risk of acute bioprosthetic valve failure, embolization, and incomplete THV expansion. In this ex vivo study, we did not observe any significant change in position of the THVs following BVF; however, BVF was not performed under physiological conditions. Additional concerns with post-dilation include the possibility of ACn THV malposition due to interaction of the lower crown with the bioprosthetic frame or expansion of the conical annular portion of the THV frame leading to a “pop-up.” Similarly, the S3 valve will shorten as it is expanded. Currently, the risk of BVF are poorly understood and may include potential risk of stroke or damage to the aortic root. Of note, prior bench studies have also demonstrated that Trifecta (St. Jude Medical, Minneapolis, Minnesota) and Hancock II (Medtronic, Minneapolis, Minnesota) bioprosthetic valves are unable to be fractured (7).
Experience with ACn in VIV TAVR is limited, and there are currently no published clinical cases in small bioprosthetic valves (≤21 mm) (23). The commonly used aortic VIV app, available for download on smartphones, does not recommend use of ACn for VIV TAVR in Mitroflow valves <25 mm. When ACn is used for VIV TAVR in larger Mitroflow valves, the VIV app recommends an implant depth of 15% to 20% below the fluoroscopic marker in the sewing ring (13). In our bench study, in order to facilitate full expansion of the upper crown and optimize leaflet function, a higher implant technique was used. An almost 0% implant depth was used in relation to the fluoroscopic marker in the small Mitroflow valves tested. However, achieving a similar implant depth safely in a clinical case in a degenerated surgical valve may be extremely challenging. In smaller bioprosthetic valves, there are also concerns regarding incomplete expansion of the THV, which was demonstrated in our bench study. The long-term implications of underexpansion of the ACn lower crown is unknown. Currently, clinical experience is limited, and use of ACn for VIV TAVR in small surgical valves should be performed with caution due to potential challenges in achieving optimum THV expansion and deployment.
Ex vivo bench testing may not entirely reflect how a THV will expand in a patient’s native annulus, within a degenerated surgical bioprosthesis, or under physiological conditions. The Mitroflow valve was only tested in this bench study, and it would be desirable to assess other bioprosthetic surgical heart valves and THVs. Assessment of hydrodynamic function when BVF is performed first, before VIV TAVR, would also be of importance.
BVF, performed after VIV TAVR for both the 19-mm and 21-mm Mitroflow valves, results in improved hydrodynamic function. Use of the ACURATE neo resulted in lower gradients before BVF in the 21-mm, but not the 19-mm, Mitroflow valve. After BVF, high residual gradients were significantly reduced irrespective of THV design, in both sizes of surgical bioprostheses tested. Use of a small ACURATE neo for VIV TAVR in small (≤21 mm) surgical valves may be associated with challenges in achieving optimum THV position and expansion. Bioprosthetic valve fracture could be considered in selected patients to aid improvement in residual transvalvular gradients and THV function. However, the impact of BVF on long-term clinical outcomes and THV durability is currently unknown.
WHAT IS KNOWN? Early clinical experience has demonstrated that bioprosthetic valve fracture can successfully reduce transvalvular gradients following valve-in-valve TAVR. However, the impact of bioprosthetic valve fracture on hydrodynamic function with different THV designs has not been studied.
WHAT IS NEW? Bioprosthetic valve fracture performed after valve-in-valve TAVR results in improved residual transvalvular gradients. After bioprosthetic valve fracture, residual transvalvular gradients were similar by THV design.
WHAT IS NEXT? The impact of valve-in-valve TAVR on THV expansion and function using other commercially available THVs and bioprosthetic valves is important to ascertain. The impact of bioprosthetic valve fracture on long-term THV durability is also important to understand.
Dr. Leipsic is supported by a Canadian Research Chair in Advanced CardioPulmonary Imaging. Mr. Fraser is an employee of ViVitro Labs. Dr. Toggweiler has been a consultant and proctor for Boston Scientific and New Valve Technology; and has received an institutional research grant from Boston Scientific. Dr. Allen has received research grants from Edwards Lifesciences, Abbott Vascular, and Medtronic; has been a proctor for and received speaker fees from Edwards Lifesciences and Medtronic; and has been a consultant to Abbott Vascular. Dr. Chhatriwalla is on the Speakers Bureau for and received travel reimbursement from Medtronic, Edwards Lifesciences, and Abbott Vascular; and has been a proctor for Medtronic. Dr. Dvir has been a consultant to Edwards Lifesciences, Medtronic, and St. Jude Medical. Dr. Asgar has been a consultant to and has received research support from Abbott Vascular. Dr. Cheung has been a consultant to Abbott Vascular, Medtronic, and Neovasc. Dr. Blanke has been a consultant to Edwards Lifesciences. Dr. Ye has been a consultant to Edwards Lifesciences. Dr. Pibarot has received funding from Edwards Lifesciences; and is a grant recipient from Medtronic. Dr. Wood has been a consultant to and received grant support from Edwards Lifesciences. Dr. Leipsic has been a consultant to Edwards Lifesciences, Circle Cardiovascular Imaging Inc., and HeartFlow; provides CT core lab services for Edwards Lifesciences, Medtronic, Neovasc, GDS, and Tendyne Holdings, for which no direct compensation is received; has stock options in Circle Cardiovascular Imaging Inc. and HeartFlow; and receives institutional research support from HeartFlow. Dr. Webb is a consultant to and has received research funding from Edwards Lifesciences, Abbott Vascular, Boston Scientific, and ViVitro Labs. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Abbreviations and Acronyms
- ACURATE neo
- bioprosthetic valve fracture
- effective orifice area
- pin-wheeling index
- SAPIEN 3
- transcatheter aortic valve replacement
- transcatheter heart valve
- Received August 6, 2018.
- Revision received October 4, 2018.
- Accepted October 23, 2018.
- 2019 American College of Cardiology Foundation
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