Laser profiling: a technique for the study of prosthetic heart valve leaflet motion

A detailed understanding of the stresses and strains developed in functioning flexible-leaflet valves is necessary if a durable, non-thrombogenic heart valve replacement is to be realized. A new experimental tool, laser profiling, is presented for the study of flexible-leaflet heart valve dynamics. Profiles of moving leaflet surfaces are obtained by projecting parallel sheets of laser light onto valve leaflets as the valves open and close in a mock circulatory loop. Two versions of laser profiling have been developed. In two-dimensional mode multiple profiles are generated on a fixed plane in space but at discrete intervals in time, whereas in three-dimensional mode multiple profiles are generated across the leaflet surface at (effectively) a single instant in time. Highlighted leaflet profiles are captured by camera and transferred to an image processing system for analysis. A simple algorithm permits digitized profiles to be reconstructed within a computer-aided design software package, providing detailed visualization and quantification of valve motion. Extensive validation studies have been performed using the Medtronic-Hall mechanical prosthetic heart valve. Laser profiling enables computer reconstruction of the rigid occluder to an accuracy of +/- 200 microns from a 0.7 ms exposure taken during the period at which the occluder moves with greatest velocity. The technique has been applied to investigate the leaflet dynamics of a bovine pericardial heart valve prosthesis.