Balloon-Expandable Valve for Treatment of Evolut Valve Failure: Implications on Neoskirt Height and Leaflet Overhang.

OBJECTIVES: This study sought to determine the degree of Evolut (Medtronic) leaflet pinning, diameter expansion, leaflet overhang, and performance at different implant depths of the balloon-expandable Sapien 3 (S3, Edwards Lifesciences LLC) transcatheter heart valve (THV) within the Evolut THV. BACKGROUND: Preservation of coronary access and flow is a major factor when considering the treatment of failed Evolut THVs. METHODS: An in vitro study was performed with 20-, 23-, 26-, and 29-mm S3 THVs deployed within 23-, 26-, 29-, and 34-mm Evolut R THVs, respectively. The S3 outflow was positioned at various depths at node 4, 5, and 6 of the Evolut R. Neoskirt height, leaflet overhang, performance, and Evolut R valve housing diameter expansion were assessed under physiological conditions as per ISO 5840-3 standard. RESULTS: The neoskirt height for the Evolut R was shorter when the S3 outflow was positioned at node 4 compared with node 6 (node 4 height for 23 mm = 16.3 mm, 26 mm = 17.1 mm, 29 mm = 18.3 mm, and 34 mm = 19.9 mm vs node 6 height for 23 mm = 23.9 mm, 26 mm = 23.4 mm, 29 mm = 24.7 mm, and 34 mm = 27 mm Evolut R). All configurations exhibited acceptable hydrodynamic performance irrespective of the degree of leaflet overhang, except the 29-mm S3 implanted in 34-mm Evolut R at node 4 (regurgitant fraction >20%). The valve housing radius of the index Evolut R increased when the S3 was implanted, with the increase ranging from 0 to 2.5 mm. CONCLUSIONS: Placement of the S3 at a lower implant position within an index Evolut R reduces the neoskirt height with no significant compromise to S3 valve function despite a higher degree of leaflet overhang. Low S3 implantation may facilitate future coronary access after redo transcatheter aortic valve replacement.

Crestal remodelling and osseointegration at surface-modified commercially pure titanium and titanium alloy implants in a canine model.

BACKGROUND: Ti-6Al-7Nb alloys exhibit enhanced mechanical properties and corrosion resistance and may represent an improvement to present commercially pure (CP) titanium oral implant technology. OBJECTIVES: To evaluate crestal remodelling and osseointegration at CP titanium compared with Ti-6Al-7Nb alloy oral implants using a canine model. METHODS: Two threaded anodized CP titanium and two Ti-6Al-7Nb alloy anodized oral implants (ø4.5 × 6.1 mm) were placed into each jaw quadrant in the edentulated posterior mandible in six adult male Hound Labrador mongrel dogs. Abutments were placed onto the implants, and the mucogingival flaps were adapted and sutured for transmucosal wound healing. Block biopsies were collected for histometric analysis following an 8-week healing interval. RESULTS: Healing was uneventful. Bone density outside and within the root of the threads averaged (± SE) 49.0 ± 4.5% and 38.7 ± 5.1% for CP titanium implants and 43.2 ± 3.6% and 34.2 ± 4.8% for Ti-6Al-7Nb alloy implants. Mean osseointegration reached 68.0 ± 4.4% and 62.8 ± 2.5% for CP titanium and Ti-6Al-7Nb alloy implants, respectively. Although crestal resorption at lingual sites averaged 0.2 ± 0.1 mm for both technologies, crestal resorption at buccal sites averaged 0.9 ± 0.2 and 1.0 ± 0.6 mm for CP titanium and Ti-6Al-7Nb alloy implants, respectively. There were no statistically significant differences between implant technologies for any parameter assessed. Notably, advanced/advancing buccal crestal resorption exposing the implant threads was observed in 50% of the implants (four of six animals) regardless of implant technology; osteoclastic resorption still observed at 8 weeks following implant placement. CONCLUSION: Within the limitations of study, anodized Ti-6Al-7Nb alloy implants may represent a feasible alternative to benchmark anodized CP titanium implants. Remodelling of the buccal crestal plate resulting in advanced bone loss appears a major impediment to oral implant osseointegration and possibly, in extension, implant maintenance.