What are the differences between balloon-expandable and self-expanding Transcatheter Aortic Valve Replacement (TAVR) valves?

Differences Between Balloon-Expandable and Self-Expanding TAVR Valves

Self-expanding valves provide superior hemodynamic performance, particularly in patients with small aortic annuli, while balloon-expandable valves offer more precise positioning and lower rates of paravalvular leak and pacemaker implantation. 1, 2

Structural and Design Differences

Self-Expanding Valves

• Made of porcine pericardium mounted in a taller, nitinol stent with adaptive shape and supra-annular design 1
• Taller frame with more flexible structure
• Deployed by gradual release from delivery catheter
• Require minimum vessel diameter of 5mm for newer models
• Provide continued outward radial force after deployment

Balloon-Expandable Valves

• Made of bovine pericardium mounted in a cylindrical, relatively short cobalt-chromium stent 1
• Shorter frame with more rigid structure
• Deployed by balloon inflation
• Require minimum vessel diameter of 6mm
• Only option for transapical approach

Clinical Performance Differences

Hemodynamic Performance

• Self-expanding valves demonstrate:
  • Lower mean pressure gradients (7.7 mmHg vs 15.7 mmHg at 12 months) 2
  • Larger effective orifice areas (1.99 cm² vs 1.50 cm²) 2
  • Lower rates of prosthesis-patient mismatch (11.2% vs 35.3%) 2, 3
  • Superior performance in small aortic annuli (≤430 mm²) 2, 4

Paravalvular Leak and Positioning

• Balloon-expandable valves show:
  • Lower incidence of paravalvular leak ≥ mild (OR: 0.19; 95% CI: 0.14-0.26) 4
  • More precise positioning during deployment 1
  • Better sealing against the annulus

Conduction Disturbances

• Balloon-expandable valves have lower rates of permanent pacemaker implantation (OR: 0.53; 95% CI: 0.33-0.86) 4
• Self-expanding valves have higher pacemaker implantation rates due to deeper extension into the left ventricular outflow tract 4, 3

Patient Selection Considerations

Anatomical Factors Favoring Self-Expanding Valves

• Severe calcification of aortic annulus/LV outflow tract with risk of rupture 1
• Extremely oval-shaped annulus 1
• Small aortic annulus (≤430 mm²) 1, 2
• Low coronary ostia 1
• Valve-in-valve procedures for small failed bioprostheses 3, 5

Anatomical Factors Favoring Balloon-Expandable Valves

• Dilated ascending aorta (>43 mm) 1
• Severely angulated aorta (aorto-ventricular angle >70°) 1
• Need for future coronary access (large cell design facilitates easier coronary re-access) 1, 3
• When precise positioning is critical 1

Special Considerations

Valve-in-Valve Procedures

• Self-expanding valves show superior hemodynamics in valve-in-valve procedures for small failed bioprostheses 5
• In patients with small failed aortic bioprostheses (≤23 mm), self-expanding valves demonstrated:
  • Lower mean transvalvular gradients (15 ± 8 mmHg vs 23 ± 8 mmHg) 5
  • Lower maximal transvalvular gradients (28 ± 16 mmHg vs 40 ± 13 mmHg) 5
  • Trend toward lower rates of severe prosthesis-patient mismatch (44% vs 64%) 5

Long-Term Considerations

• Early reports suggest potentially lower rates of structural valve dysfunction with supra-annular self-expanding valves 3
• Long-term durability data beyond 3-4 years remains limited for both valve types 1
• Future coronary access may be easier with balloon-expandable valves, an important consideration for younger patients 1, 3

Clinical Pitfalls to Avoid

• Underestimating the importance of accurate pre-procedural imaging and sizing for both valve types 1
• Overlooking the higher risk of prosthesis-patient mismatch with balloon-expandable valves in small aortic annuli 2, 4
• Failing to consider future coronary access needs, especially in younger patients 1, 3
• Not accounting for the higher pacemaker implantation rates with self-expanding valves 4
• Disregarding the potential benefits of self-expanding valves in valve-in-valve procedures 3, 5