Effect of the sinus of valsalva on the closing motion of bileaflet prosthetic heart valves.
Conventional bileaflet prosthetic mechanical heart valves close passively with backflow. Naturally, the valve has problems associated with closure, such as backflow, water hammer effect, and fracture of the leaflet. On the other hand, in the case of the natural aortic valve, the vortex flow in the sinus of Valsalva pushes the leaflet to close, and the valve starts the closing motion earlier than the prosthetic valve as the forward flow decelerates. This closing mechanism is thought to decrease backflow at valve closure. In this study, we propose a new bileaflet mechanical valve resembling a drawbridge in shape, and the prototype valve was designed so that the leaflet closes with the help of the vortex flow in the sinus. The test valve was made of aluminum alloy, and its closing motion was compared to that of the CarboMedics (CM) valve. Both valves were driven by a computer controlled hydraulic mock circulator and were photographed at 648 frames/s by a high speed charge-coupled device (CCD) camera. Each frame of the valve motion image was analyzed with a personal computer, and the opening angles were measured. The flow rate was set as 5.0 L/min. The system was pulsed with 70 bpm, and the systolic/diastolic ratio was 0.3. Glycerin water was used as the circulation fluid at room temperature, and polystyrene particles were used to visualize the streamline. The model of the sinus of Valsalva was made of transparent silicone rubber. As a result, high speed video analysis showed that the test valve started the closing motion 41 ms earlier than the CM valve, and streamline analysis showed that the test valve had a closing mechanism similar to the natural one with the effect of vortex flow. The structure of the test valve was thought to be effective for soft closure and could solve problems associated with closure.
Ohta
Y
Y
Department of Mechanical Engineering, Toyo University, Kawagoe, Japan. yuji@eng.toyo.ac.jp
Kikuta
Y
Y
Shimooka
T
T
Mitamura
Y
Y
Yuhta
T
T
Dohi
T
T
D000497:Alloys; D000535:Aluminum; D001021:Aortic Valve; D001794:Blood Pressure; D006339:Heart Rate; D006350:Heart Valve Prosthesis; D018056:Hemorheology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008953:Models, Anatomic; D009068:Movement; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012039:Regional Blood Flow; D012826:Silicone Elastomers; D012850:Sinus of Valsalva / Q000502:physiology*; D014741:Video Recording
D000497:Alloys; D012826:Silicone Elastomers; D000535:Aluminum