CarboMedics Mechanical Heart Valve: A Carbon-Based Bileaflet Prosthesis
The CarboMedics valve is a bileaflet mechanical heart valve made of pyrolytic carbon that offers excellent mechanical stability, hemodynamic efficiency, and long-term durability with no reported structural failures after 20 years of clinical use. 1
Design and Characteristics
- Type: Bileaflet mechanical valve prosthesis
- Material: Pyrolytic carbon (originally developed to encapsulate nuclear fuel rods, later adapted for heart valves) 2
- Structure: Two semicircular leaflets that pivot on hinges within a carbon housing
- Manufacturer: CarboMedics Inc. (Austin, TX)
The CarboMedics valve belongs to the most common mechanical valve design category used in cardiac surgery. As a bileaflet valve, it features:
- Relatively quiet operation compared to older mechanical valves
- Mechanical stability over long-term use
- Good hemodynamic efficiency
- Standard implantation technique 1
Clinical Performance
Long-term studies demonstrate excellent durability and reliability:
- Structural integrity: No structural valve failures reported in multiple long-term studies spanning up to 20 years 3, 4, 5
- Survival rates: 20-year freedom from valve-related mortality of 78.3% for aortic valve replacement (AVR) and 74.6% for mitral valve replacement (MVR) 3
Valve-Related Complications
Despite excellent durability, the CarboMedics valve shares common complications with other mechanical valves:
- Thromboembolism: 20-year freedom from thromboembolic events of 91.6% for AVR and 88.5% for MVR 3
- Valve thrombosis: 20-year freedom from valve thrombosis of 98.9% for AVR and 91.4% for MVR 3
- Bleeding: Requires lifelong anticoagulation with warfarin, with 20-year freedom from bleeding events of 89.5% for AVR and 88% for MVR 3
- Endocarditis: 20-year freedom from endocarditis of 97.3% for both AVR and MVR 3
Anticoagulation Requirements
Like all mechanical valves, the CarboMedics valve requires lifelong anticoagulation:
- Initial anticoagulation: INR target of 2.5-3.5 for first 3 months after surgery
- Long-term anticoagulation: INR target of 2.0-3.0 beyond 3 months
- Additional therapy: Low-dose aspirin (75-100 mg daily) recommended in addition to warfarin
- Bleeding risk: Approximately 1-2% per year with proper anticoagulation 1
Special Considerations
- Studies specifically examining the hinge region of CarboMedics valves have shown turbulent shear stress of 564 Pa based on laser Doppler velocimetry 1
- The valve is available in different sizes to accommodate various patient anatomies
- In some valve registries, the CarboMedics valve is listed as a "tricomposite" valve when used in certain configurations 1
Comparison to Other Valve Types
- Vs. other mechanical valves: Similar performance to other bileaflet valves like St. Jude, ATS Medical, and On-X valves 1
- Vs. biological valves: More durable than biological valves but requires lifelong anticoagulation (unlike biological valves)
- Vs. tissue-engineered valves: Current research is exploring tissue-engineered valves to overcome limitations of both mechanical and biological valves 6
The CarboMedics mechanical valve remains a reliable option for patients requiring valve replacement who can tolerate long-term anticoagulation therapy, particularly younger patients who would otherwise face multiple reoperations with biological valves.