The new St. Jude Medical Regent (TM) mechanical heart valve: Laboratory measurements of hydrodynamic performance

Background and aim of the study: The St. Jude Medical(R) (SJM) mechanical h eart valve was the first bileaflet valve with leaflets and orifice all fabr icated from pyrolytic carbon. In 1992, a supra-annular cuff configuration, the SJM mechanical heart valve Hemodynamic Plus Series (HP), was introduced , which gave a one-size gain in orifice area over the standard valve. In a continuing effort to improve hydrodynamic performance, a new enhanced confi guration of the mechanical valve - the SJM Regent(TM) valve - has been deve loped. The blood-contacting components of the SJM Regent valve have the sam e design features as those of the standard or HP valve, but the orifice lum en area has been increased, without compromising structural integrity, by a shift in the cuff-retaining orifice rims. Methods: Valve performance has been measured using a laboratory simulation of the left heart system. Three samples of both valve types (SJM Regent, HP ) for sizes 17 mm to 27 mm, were tested at a cardiac output of 5 l/min. Sup plementary steady-flow measurements were made at flow rates between 5 and 3 0 l/min. Pressure and flow signals were recorded and several performance pa rameters, including pressure gradient, effective orifice area (EOA), insuff iciency (regurgitant volume as a percent of forward flow volume) and energy loss, were computed. Results: All sizes of the SJM Regent valve showed improved hydrodynamic per formance compared with the HP valve. For the small sizes (17, 19, 21 mm), t he pressure gradient of the SJM Regent decreased by 37%, 36% and 39%, respe ctively; the EOA increased by 22%, 22% and 21%; and the total transaortic e nergy loss decreased by 33%, 31% and 31% compared with the HP valve. The re gurgitation for both valves ranged between 4% and 8% of forward flow volume over the 17-27 mm size range. Conclusions: Hydrodynamic measurements confirm the gain of the SJM Regent v alve over the HP valve that is expected based on the increased geometric or ifice area. Given its basic similarity of design, but with an increased EOA as demonstrated in vitro, the SJM Regent valve is anticipated to provide a n increased level of clinical benefit.