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A pulsatile flow study comparing the Hancock porcine xenograft aortic valve prostheses models 242 and 250.

A modified version of the Hancock porcine xenograft aortic valve bioprosthesis has recently been introduced into clinical use. In this valve, the leaflet containing the septal shelf has been replaced by a leaflet from another valve, thus increasing the effective orifice area of the prosthesis without changing its external dimensions. Modified valves (model 250) have been subjected to pulsatile flow studies and compared to similar studies carried out on the current aortic valve xenografts (model 242) over a range of sizes (19-25 mm). The new model 250 valves caused significantly lower pressure drops or gradients than those of the previous model. They also allowed between 33 percent and 45 percent more flow (depending on size) at a gradient of 20 mmHg than did the model 242 valves. These results indicate that the new valves hould have clear clinical advantages over the current prostheses.