Hydrodynamic Assessment of Explanted Degenerated Transcatheter Aortic Valves: Novel Insights Into Noncalcific and Calcific Mechanisms.

BACKGROUND: The etiology of transcatheter aortic valve (TAV) degeneration is poorly understood, particularly noncalcific mechanisms. OBJECTIVES: The authors sought to investigate noncalcific and calcific mechanisms of TAV degeneration and evaluate their impact on leaflet function by bench testing, imaging, and histology. METHODS: TAV explants were obtained from the EXPLANT THV registry and clinical institutions. Hydrodynamic assessment was performed using a heart valve pulse duplicator system under physiological conditions. Micro-computed tomography, high-resolution photography, high speed video, and hematoxylin and eosin staining were used to evaluate the morphological appearance, leaflet kinematics, and calcium burden of TAVs. RESULTS: A total of 14 explants were evaluated: 10 self-expanding CoreValve/Evolut TAVs (Medtronic), 3 balloon-expandable SAPIEN 3 TAVs (Edwards Lifesciences), and 1 mechanically expandable Lotus TAV (Boston Scientific). The median patient age at explantation was 73.0 years (Q1-Q3: 64.5-80.0 years), with a time to explantation of 4 years 1 month (1 year 5 months to 4 years 11 months). Six TAV explants were found to have leaflet calcification (162.4 mm3; 58.8-603.0 mm3), and 8 had no calcification detectable by micro-computed tomography and histology. All samples had impaired leaflet kinematics. There was no significant difference in the hydrodynamic mean gradient between calcified (47.2 mm Hg; 26.6-74.1 mm Hg) and noncalcified (27.6 mm Hg; 15.2-36.7 mm Hg; P = 0.28) TAVs. Leaflet calcification had a weak but nonsignificant association with the hydrodynamic mean gradient (r = 0.42; P = 0.14). CONCLUSIONS: TAV function can be severely impacted by noncalcific and calcific mechanisms of tissue degeneration. Importantly, functional stenosis can occur in TAVs in the absence of obvious and significant calcification.

Redo-TAVI with SAPIEN 3 in SAPIEN XT or SAPIEN 3 - impact of pre- and post-dilatation on final THV expansion.

BACKGROUND: When a balloon-expandable transcatheter heart valve (THV) is chosen to treat a failed balloon-expandable THV, there is a risk of underexpansion with a potential impact on performance. AIMS: We aimed to assess the impact of pre- and post-dilatation on the expansion of balloon-expandable THVs after redo-transcatheter aortic valve implantation (TAVI). METHODS: Redo-TAVI was performed on the bench with a 23 mm SAPIEN 3 (S3) implanted within a 23 mm SAPIEN XT (SXT) or a 23 mm S3, both of which served as the "failed" THVs. Pre- and/or post-dilatation was performed using a 23 mm non-compliant TRUE balloon. Expansion of the index and redo-THVs were assessed before and after pre-/post-dilatation using microcomputed tomography (micro-CT), and THV hydrodynamic testing was conducted. RESULTS: Without pre- or post-dilatation, the S3 was underexpanded, for all combinations, particularly in the mid-portion of the THV (18.6 mm and 19.7 mm representing 81% and 86% of the nominal diameter inside the SXT and S3, respectively). Pre- and post-dilatation had an additive effect on diameter expansion of the redo-THV, which remained constrained in most combinations. The only combination to achieve nominal expansion was the S3 in S3 when both pre- and post-dilatation were performed. The S3 remained underexpanded inside the SXT despite pre- and post-dilatation (93% in the mid-portion). Improved redo-THV expansion was accompanied by 2.7 mm (12%) overexpansion of the index THV. While all samples had acceptable hydrodynamic performance, the underexpanded samples had worse leaflet pinwheeling. CONCLUSIONS: When performing redo-TAVI with a 23 mm S3 inside a 23 mm SXT or S3, only the S3 in S3 with the use of pre- and post-dilatation reached full expansion. This underlines the importance of CT assessment of THV expansion and the role of pre-/post-dilatation.

Bioprosthetic Valve Remodeling in Nonfracturable Surgical Valves: Impact on THV Expansion and Hydrodynamic Performance.

BACKGROUND: There are limited data on the effect of bioprosthetic valve remodeling (BVR) on transcatheter heart valve (THV) expansion and function following valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) in a nonfracturable surgical heart valve (SHV). OBJECTIVES: This study sought to assess the impact of BVR of nonfracturable SHVs on THVs after VIV implantation. METHODS: VIV TAVR was performed using 23-mm SAPIEN3 (S3, Edwards Lifesciences) or 23/26-mm Evolut Pro (Medtronic) THVs implanted in 21/23-mm Trifecta (Abbott Structural Heart) and 21/23-mm Hancock (Medtronic) SHVs with BVR performed with a noncompliant TRUE balloon (Bard Peripheral Vascular Inc). Hydrodynamic assessment was performed, and multimodality imaging including micro-computed tomography was performed before and after BVR to assess THV and SHV expansion. RESULTS: BVR resulted in limited improvement of THV expansion. The largest gain in expansion was observed for the S3 in the 21-mm Trifecta with up to a 12.7% increase in expansion at the outflow of the valve. Minimal change was observed at the level of the sewing ring. The Hancock was less amenable to BVR with lower final expansion dimensions than the Trifecta. BVR also resulted in notable surgical post flaring of up to 17.6°, which was generally more marked with the S3 than with the Evolut Pro. Finally, BVR resulted in very limited improvement in hydrodynamic function. Severe pinwheeling was observed with the S3, which improved slightly but persisted despite BVR. CONCLUSIONS: When performing VIV TAVR inside a Trifecta and Hancock SHV, BVR had a limited impact on THV expansion and resulted in SHV post flaring with unknown consequences on coronary obstruction risk and long-term THV function.

Timing of bioprosthetic valve fracture in transcatheter valve-in-valve intervention: impact on valve durability and leaflet integrity.

BACKGROUND: Bioprosthetic valve fracture (BVF) can be used to improve transcatheter heart valve (THV) haemodynamics following a valve-in-valve (ViV) intervention. However, whether BVF should be performed before or after THV deployment and the implications on durability are unknown.  Aims: We sought to assess the impact of BVF timing on long-term THV durability. METHODS: The impact of BVF timing was assessed using small ACURATE neo (ACn) or 23 mm SAPIEN 3 (S3) THV deployed in 21 mm Mitroflow valves compared to no-BVF controls. Valves underwent accelerated wear testing up to 200 million (M) cycles (equivalent to 5 years). At 200M cycles, THV were evaluated by hydrodynamic testing, second-harmonic generation (SHG) microscopy, scanning electron microscopy (SEM) and histology. RESULTS: At 200M cycles, the regurgitant fraction (RF) and effective orifice area (EOA) for the ACn were 8.03±0.30%/1.74±0.01 cm2 (no BVF), 12.48±0.70%/1.97±0.02 cm2 (BVF before ViV) and 9.29±0.38%/2.21±0.0 cm2 (BVF after ViV), respectively. For the S3 these values were 2.63±0.51%/1.26±0.01 cm2, 2.03±0.42%/1.65±0.01 cm2, and 1.62±0.38%/2.22±0.01 cm2, respectively. Further, SHG and SEM revealed a higher degree of superficial leaflet damage when BVF was performed after ViV for the ACn and S3. However, the histological analysis revealed significantly less damage, as determined by matrix density analysis, through the entire leaflet thickness when BVF was performed after ViV with the S3 and a similar but non-significant trend with the ACn.  Conclusions: BVF performed after ViV appears to offer superior long-term EOA without increased RF. Ultrastructure leaflet analysis reveals that the timing of BVF can differentially impact leaflets, with more superficial damage but greater preservation of overall leaflet structure when BVF is performed after ViV.

Coronary Access Following Redo TAVR: Impact of THV Design, Implant Technique, and Cell Misalignment.

BACKGROUND: The implications and potential challenges of coronary access after redo transcatheter aortic valve replacement (TAVR) are unknown. OBJECTIVES: The authors sought to evaluate the impact of different transcatheter heart valve (THV) designs, neoskirt height, implant technique, and cell misalignment on coronary access after redo TAVR. METHODS: Different THV designs (Sapien 3 [Edwards Lifesciences LLC], Evolut Pro [Medtronic], ACURATE neo [Boston Scientific Corporation], and Portico [Abbott Structural Heart]) and sizes were implanted inside Sapien XT (Edwards Lifesciences LLC) and Evolut R (Medtronic) THVs, which were modeled as the "failed" THVs, at different implant depths. Valve combinations underwent micro-computed tomography to determine the neoskirt height and dimensions of the lowest accessible cell for potential coronary access. This was compared with dimensions of 6-F/7-F/8-F coronary guiding catheters. RESULTS: Redo TAVR combinations resulted in a wide range of neoskirt heights (15.4-31.6 mm) and a variable diameter of the lowest accessible cell (1.9-21.8 mm). An ACURATE neo implanted in a Sapien XT resulted in the largest accessible cells, whereas a Portico implanted in a Sapien XT resulted in the lowest neoskirt heights. The smallest accessible cell was observed in the Evolut Pro-in-Evolut R configuration with higher neoskirt heights. Redo TAVR in a tall frame valve with supra-annular leaflets caused a taller neoskirt height. In Evolut-in-Evolut combinations, misalignment of the cells of the 2 THVs reduced the cell area by 30% to 50% compared with an aligned configuration. CONCLUSIONS: This study demonstrates that different redo TAVR combinations are not equivalent in terms of future coronary access. Redo TAVR using a tall frame valve in a failed tall frame valve and misaligned cells may lead to potentially challenging coronary access.

Evaluation of an Explanted Tiara Transcatheter Mitral Valve.

Post-explant (ex vivo) evaluation of medical devices is an essential part of quality assurance, quality improvement, and further device development. Central to this is detailed pathological analysis. Here, we provide the first such evaluation of an explanted Tiara transcatheter mitral valve prosthesis. (Level of Difficulty: Advanced.).

Bioprosthetic Valve Leaflet Displacement During Valve-in-Valve Intervention: An Ex Vivo Bench Study.

OBJECTIVES: The aim of this study was to examine the effect of different transcatheter heart valves (THVs) on valve leaflet displacement when deployed within bioprosthetic surgical valves and, thereby, risk for coronary obstruction. BACKGROUND: Coronary obstruction is a potentially devastating complication during valve-in-valve (ViV) transcatheter aortic valve replacement. Strategies such as provisional stenting and intentional bioprosthetic valve leaflet laceration have been developed to mitigate this risk. Alternatively, the use of a THV that retracts the bioprosthetic leaflet away from the coronary ostium may prevent coronary obstruction. METHODS: A 25-mm J-Valve, a 26-mm Evolut Pro, and a 23-mm JenaValve were implanted into both a 25-mm Trifecta surgical valve and a 25-mm Mitroflow surgical valve. A 23-mm and a 26-mm SAPIEN 3 were deployed into the Trifecta and Mitroflow, respectively. Displacement of the surgical valve leaflets (retraction vs. expansion) was measured with implantation of each THV by measuring displacement angle and maximal displacement distance. RESULTS: Within both the Trifecta and Mitroflow valves, implantation of the J-Valve and JenaValve resulted in retraction of the surgical valve leaflets, and placement of the Evolut Pro and SAPIEN 3 resulted in tubular expansion of the surgical valve leaflets. There were significant differences in displacement angles and distances between both the J-Valve and JenaValve and the SAPIEN 3 and Evolut Pro (p < 0.0001). CONCLUSIONS: ViV implantation with new-generation THVs that directly interact with bioprosthetic valve leaflets results in surgical valve leaflet retraction. This might mitigate the risk for coronary obstruction in selected cases of ViV transcatheter aortic valve replacement and also facilitate coronary reaccess after ViV TAVR.