A note on the blood analog for in-vitro testing of heart valve bioprostheses

Glycerol solution with the viscosity coefficient similar to that of blood is used in evaluating the performance characteristics of prosthetic heart valves in the laboratory. However, physiological saline solution is used as a test fluid in testing tissue heart valves even though the viscosity coefficient does not match that of human blood. It is commonly believed that glycerol is absorbed by the tissue valves and hence the leaflets become stiff, making the test results invalid. However, in our laboratory a comparison of tissue valves exposed to glycerine solution at various times does not indicate any difference in the leaflet opening characteristics. Hence, it is suggested that glycerine solution be used as a test fluid for the evaluation of tissue valves also.