New Laboratory Technique Measures Projected Dynamic Area of Prosthetic Heart Valves

Lawrence N. Scotten Dipl T, David K. Walker PhD 
 

Background and aim of the study: Fluid dynamic forces, valve design factors and gravity interactively determine the complex motion of prosthetic heart valve occluders. Although motion has been investigated, in vitro, using high-speed image recording, the technique has significant cost and limitations on resolution.
Methods: The kinematics of mechanical and biological valve occluders in the aortic and mitral positions were assessed by measuring projected dynamic valve area (PDVA). Valves were tested in a pulse duplicator system simulating normal cardiac conditions. To quantify PDVA, light passage through back-illuminated valves was measured by a calibrated photo-sensor with high-frequency response up to 150 kHz. Ten consecutive cycles were sampled using a PC data acquisition system. The system was calibrated under static conditions using reference areas.

 Results: Several characteristics can be obtained from PDVA measurement including: maximum and minimum PDVA; rate of change of valve opening and closing PDVA; occluder rebound; and oscillatory open occluder behavior. Biological valves open more rapidly, close more gently, and exhibit no occluder rebound. They are also unaffected by gravity, and vary little in behavior from cycle to cycle compared with mechanical valves.
Conclusion: A new method for measuring PDVA has been developed. Distinct differences in performance between valves were identified. It is hypothesized that, aside from patient factors and differences in materials, mechanical valves that mimic the PDVA behavior of biological valves, will lead to reduction of thrombogenicity, cavitation and high-intensity transient signals (HITS), and also reduce sound level and regurgitation.
 
Untitled Document
Registered Users
Click here to view the file in pdf format or click here to logout from the site

Subscribers

You must be a subscriber and registered with the site to view these files. If you are a subscriber but have not yet registered with the site please click here.


Not yet subscribed?
Click here to subscribe using our simple online system