Quantification of perivalvular thrombus formation in blood pumps by polar coordinate mapping

A polar coordinate mapping technique (PCMT) to quantitatively describe perivalvular thrombus formation was applied in the examination of prosthetic valves from paracorporeal assist devices. The method begins by photographing the upstream and downstream views of the freshly retrieved valves using transparency film. The valve images are then projected onto 10 x planforms of the valves, and the boundaries of the observable thrombi are traced. The radial thrombus length is then measured at 5 degrees increments and plotted on Cartesian coordinates as a function of polar coordinate. Mean radial thrombus length and incidence of thrombus are calculated. Statistical analysis can then be used to test for differences in the length, incidence, and pattern of thrombus formation between test groups. The effect of valve selection, anti-coagulant regime, and other factors that influence thrombus formation can be quantitatively compared with the PCMT. Consequently, the PCMT could be a valuable assessment tool for efforts being made to reduce thrombosis in prosthetic blood pumps.