In-vitro measurements of the regurgitation of mechanical mitral heart valve prostheses in case of atrial fibrillation.
OBJECTIVE
The characterization of heart valve prostheses requires regurgitation tests to be conducted in pulsatile flow. Although tests are generally conducted in accordance with hemodynamic conditions of a healthy young man, heart valve implantation is often associated with other pathology, such as atrial fibrillation. To run more realistic trials, four mechanical heart valve prostheses were tested with, and then without, atrial contraction.


METHODS
The dual activation simulator (DAS) allow simulation of physiologically normal and pathological flows through the mitral valve. The DAS comprises silicon-based cavities, is activated by pumps, and was equipped successively with monoleaflet (Björk-Shiley, Medtronic Hall) and bileaflet (St. Jude Medical, CarboMedics) valves. Each valve (mitral, size 27 mm) was tested under two conditions (with and without atrial contraction) at a mean flow rate of 3 l/min of glycerol/water solution (analog blood viscosity).


RESULTS
Leakage volumes were of the same magnitude as the precision of the instruments. Respectively, closing volumes increased from normal conditions to atrial fibrillation from 3.2 to 5.1 ml for Björk-Shiley, from 4.6 to 6.3 ml for Medtronic Hall, from 5 to 6.6 ml for St. Jude Medical, and from 5.2 to 5.4 ml for CarboMedics. The standard deviation was below the precision of measurements (+/- 0.5 ml).


CONCLUSIONS
Without atrial contraction, the valves seemed to be closed by backward flow only, thus confirming earlier reports. This study showed that different heart valves behave differently in pathological situations with regard to their design; this must be considered when selecting a valve for implantation.
Mouret
F
F
Cardiovascular Biomechanics Laboratory, Mechanical Engineering School, Marseilles, France.
Garitey
V
V
Fuseri
J
J
Rieu
R
R
D001281:Atrial Fibrillation / Q000503:physiopathology*; D001783:Blood Flow Velocity / Q000502:physiology; D006350:Heart Valve Prosthesis; D006801:Humans; D066298:In Vitro Techniques; D008944:Mitral Valve Insufficiency / Q000503:physiopathology*; D008955:Models, Cardiovascular; D011475:Prosthesis Failure; D011673:Pulsatile Flow / Q000502:physiology