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Pivot design in bileaflet valves
F Vallana1, S Rinaldi, P M Galletti
1Sorin Biomedica S.p.A., Saluggia (VC), Italy.
ASAIO Journal (American Society for Artificial Internal Organs : 1992)
|July 1, 1992
Summary
The novel Sorin Bicarbon bileaflet valve features a unique rolling-contact hinge design. This innovation minimizes friction and wear, preventing thrombotic events in both animal and early human clinical studies.
Area of Science:
- Biomaterials Engineering
- Cardiovascular Surgery
- Medical Device Design
Background:
- Bileaflet heart valves are critical medical devices.
- Hinge design significantly impacts valve performance, durability, and thrombogenicity.
- Existing prostheses have limitations in fluid dynamics, wear, and thrombus formation.
Purpose of the Study:
- To develop a new bileaflet valve (Sorin Bicarbon) with improved functional requirements and performance.
- To address critical hinge design elements affecting fluid dynamics, durability, and thrombus formation.
- To leverage advanced carbon coating technology (Carbofilm) for enhanced valve design.
Main Methods:
- Comparative analysis of three existing bileaflet valve models.
- Development of a novel hinge design utilizing coupled spheric surfaces with different radii of curvature.
- Electroerosion fabrication of the hinge into a Carbofilm-coated metallic housing.
- In vivo studies in sheep (tricuspid implantation without anticoagulation) and clinical evaluation in humans (mitral position with standard anticoagulation).
- Assessment of valve performance using transesophageal echocardiography and echo Doppler (diastolic gradient, functional area).
Main Results:
- The new hinge design features continuous rolling contact, minimizing friction and wear.
- Uninterrupted washing of blood-exposed surfaces was observed, even during diastole.
- No thrombotic events occurred in 33 sheep over 40-400 days post-implantation without anticoagulation.
- In 36 human implants, no leaflet fracture, thrombotic, or embolic complications were observed over 15 months.
- Clinical data showed a mean diastolic gradient of 4 +/- 1.25 mmHg and a functional area of 3.2 +/- 0.6 cm2.
Conclusions:
- The Sorin Bicarbon bileaflet valve demonstrates promising performance and safety profiles.
- The novel rolling-contact hinge design contributes to reduced friction, wear, and thrombogenicity.
- The valve shows potential for reduced anticoagulation requirements or improved outcomes in clinical use.