Dr John Christy

Senior Lecturer
School of Engineering

Recent advances in polyurethane heart-valve technology and in bileaflet valve designs, along with reported failures in the ability of animal trials to identify potential incidence of thrombosis, have led to renewed interest in alternative means of pre-clinical testing of heart valves. Successful development of an ultrasonic imaging technique, coupled with our milk-based, in-vitro, thrombogenicity assessment procedure (the only blood-free thrombogenicity assessment procedure world-wide), offer the scope for real-time analysis of clot deposition. This, along with velocimetry studies using the complementary techniques of PIV and LDV, will offer valve developers new means of pre-clinical evaluation of valves. Currently a wide range of valves are being tested with our milk clotting test to confirm the degree to which this test matches thrombosis in-vivo. This work is to be supplemented by micro-analysis of milk clot and thrombus to determine the relationship between structural aspects of clot deposition and flow phenomena. The availability of cryogenic microscopy facilities in the Division of Biology make Edinburgh the ideal location for this research. Advances in applying PIV to micro-scale systems, in conjunction with Physics (Greated), offers scope for combined PIV/LDV studies of flow in the hinge pockets of tilting disc valves (eg St. Jude Medical Valve) to evaluate the accuracy of current techniques for predicting turbulent shear stresses. This is important in valve development, because high shear is associated with thrombus formation.

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