The Journal of Thoracic and Cardiovascular Surgery, Vol 83, 610-617, Copyright © 1982 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Open versus closed position fixation of bioprosthesis. Comparative in vitro studies from the viewpoint of durability
E Imamura, H Ohteki, T Tsutsui, Y Nishiya, S Ishihara and H Koyanagi
In an effort to normalize the dynamic leaflet behavior of a porcine
bioprosthesis, an experimental attempt was made to treat a tissue heart
valve with 0.625% glutaraldehyde in the open position ("open-type valve").
Eighteen open-type valves, having fixed openings of various sizes, were
examined with our pulse simulators. Eight closed-type valves, which were
treated in the closed position, were studied for comparison. The results
showed that closed-type valve tended to offer an immobile cusp at a low
flow state; at a pump pressure of 90 mm Hg in a pulsatile flow or under
steady flows of no more than 10 L/min. By contrast, the open-type valve
showed the symmetric cusps opening with circular orifices at any given flow
rates. Analysis of the pressure loss coefficient revealed that the leaflets
prepared in the open position produced only a minimal impediment to the
forward flow. One half of the anatomic orifice of a valve was considered to
be the optimal size for the fixed opening. It is concluded that open
position fixation is expected to provide the bioprosthesis with improved
fatigue durability in patients with low cardiac output syndrome and in
small children.