Fluid dynamics of the CarboMedics kinetic bileaflet prosthetic heart valve.

OBJECTIVE

To compare hydrodynamic characteristics of a new bileaflet heart valve, the CarboMedics kinetic cardiac valve prosthesis, with those of a St. Jude Medical (SJM) heart valve.

METHODS

Hydrodynamic characteristics were determined in the mitral and aortic positions of a Vivitro Systems pulse duplicator for size 23 Kinetic aortic values, size 23 SJM aortic valves, size 29 Kinetic mitral valves and size 29 SJM mitral valves. Test conditions were 72 beats per min with cardiac outputs of 2, 5 and 7 l/min. Values of forward flow pressure drop (delta P), regurgitant and energy loss were determined for each valve. The test results for the two valve designs were compared by valve size.

RESULTS

The test results show that both the size 23 and size 29 Kinetic valves have 8-14% lower delta P values and 5-10% greater effective orifice area (EOA) values. The size 29 Kinetic mitral valve has a 1-2 ml lower regurgitant volume, while the size 23 Kinetic aortic valve has a 0.5 ml greater regurgitant volume than the corresponding SJM values. These factors combine to provide a 5-10% lower energy loss for size 23 Kinetic aortic valves and a 15-25% lower energy loss for size 29 Kinetic mitral valves over the cardiac cycle than for corresponding sizes of SJM valves.

CONCLUSIONS

The Kinetic valve's fluid dynamics are superior to equivalent sizes of SJM valves. This is especially impressive considering that the tissue annulus diameters for Kinetic valves are approximately 0.5 mm less than equivalent size SJM valves. The primary reasons for the superior hydrodynamic performance of Kinetic valves are (1) the larger orifices which result in lower forward flow delta P values and (2) the opening angles, which have been customized for each valve size to minimize energy loss.