TAVR Uses Bioprosthetic Valves Exclusively
TAVR (Transcatheter Aortic Valve Replacement) exclusively uses bioprosthetic valves, not mechanical valves. 1
Valve Composition and Design
All TAVR devices consist of bioprosthetic tissue mounted on expandable frames 1:
- Pericardial tissue leaflets (typically bovine or porcine) are mounted on self-expanding or balloon-expandable frames made of nitinol or other biocompatible materials 1
- The tissue valves are designed to mimic native valve function without requiring long-term anticoagulation 1
- Current TAVR platforms include devices with repositionable prostheses consisting of pericardial tissue on nitinol frames 1
Why Bioprosthetic Rather Than Mechanical
The exclusive use of bioprosthetic valves in TAVR is driven by several technical and clinical factors 1:
- Deliverability: Bioprosthetic tissue can be crimped and compressed onto catheters for minimally invasive delivery, whereas mechanical valves cannot be collapsed in this manner 1
- Anticoagulation avoidance: TAVR patients are typically elderly with high surgical risk, making the bleeding risks associated with mandatory warfarin anticoagulation for mechanical valves particularly problematic 1
- Conformability: Bioprosthetic leaflets can adapt to the irregular, calcified native valve anatomy better than rigid mechanical valve components 1
Emerging Bioprosthetic Technologies
Novel TAVR valve designs continue to refine bioprosthetic technology 1:
- Tissue-engineered valves (Lutter valve) aim to create more physiological heart valves 1
- Nanotechnology approaches (PercValve) use elastic nitinol frames with leaflets designed to allow endothelial cell growth, potentially converting to living tissue and eliminating anticoagulation needs within 10 days in animal studies 1
- Flexible sealing membranes are being developed to reduce paravalvular leaks by conforming better to calcified native annuli 1
Clinical Implications
The bioprosthetic nature of TAVR valves has specific consequences 1, 2:
- No mandatory anticoagulation: Unlike mechanical valves requiring lifelong warfarin, TAVR bioprosthetic valves typically require only dual antiplatelet therapy or anticoagulation based on other indications 1
- Durability concerns: Bioprosthetic valves have limited durability (10-18 years depending on patient age), though long-term TAVR durability data beyond 5-10 years remains incomplete 1, 2
- Valve-in-valve capability: When TAVR bioprosthetic valves fail, another TAVR can be deployed within the failed bioprosthesis, which would not be possible with mechanical valves 1