European Journal of Cardio-Thoracic Surgery, Vol 10, 422-427, Copyright © 1996 by European Association for Cardio-thoracic Surgery
Hydrodynamic function of tilting disc prostheses and bileaflet valves in double valve replacement
M Struber, A Campbell, G Richard and J Laas
Dept. of Cardiovascular Surgery, Christian-Albrechts University, Kiel, Germany.
OBJECTIVE: To determine the energy loss attributable to prosthetic valve
size and design in double valve replacement, energy consumption of mitral
valves (size #25 to #29), of two different designs (Bjork Shiley tilting
disc and Carbomedics bileaflet valves), in combination with a small (#21)
and large sized (#27) aortic prosthesis, were analyzed in a flow simulator.
METHODS: A pulsatile flow simulator was used to reproduce physiological
ventricular dynamics and to match the input and output impedances of the
human left ventricle. Hydrodynamic performance was determined as stroke
work, closing work and leak work for each combination of valves at low flow
(5 liters per minute) and high flow (9 liters per minute) conditions.
RESULTS: At low flow no decrease of energy requirement was found with the
use of a mitral valve larger than #25. At high flow the #27 and #29 mitral
valves required less energy compared to a #25 mitral valve, in combination
with a large aortic prosthesis. The #29 mitral prosthesis revealed similar
results as the #27. With the use of a large aortic prosthesis a remarkable
reduction of total flow work was shown. These results were found in both
designs. In comparison of the two designs, tilting disc valves required
more energy for stroke and closure of the valve, although less energy for
leakage. In total, energy requirements were higher for tilting disc valves.
COMMENTS: A hydrodynamic advantage for the use of a mitral valve larger
than #25 was found only with the combination of a large aortic prosthesis
and high flow. Hydrodynamic data favor the use of bileaflet prosthesis
especially for a patient who is expected to exercise.
