Type of Document	Master's Thesis
Author	Simon, Helene A
URN	etd-04012004-192539
Title	Influence of the Implant Location on the Hinge and Leakage Flow Fields Through Bileaflet Mechanical Heart Valves
Degree	Master of Science
Department	Chemical Engineering
Advisory Committee	Advisor Name Title Yoganathan Ajit Committee Chair Sambanis Athanassios Committee Member Sotiropoulos Fotis Committee Member
Keywords	Laser Doppler Velocimetry thrombosis hinge implant location CarboMedics valve St. Jude Medical Regent valve leakage jets
Date of Defense	2003-12-09
Availability	unrestricted
Abstract Native heart valves that have limited functionality due to cardiovascular disease or congenital birth defects are commonly replaced by prosthetic heart valves. Bileaflet mechanical heart valves (BMHV) are the most commonly implanted valve design due to their long-term durability. However, their unnatural hemodynamics promote thrombosis and thromboembolic events. Clinical reports and in vitro experiments suggest that the thrombogenic complications in bileaflet valves are related to the stress imposed on blood by the valves during the closing phase. Additionally, animal and clinical studies have shown that BMHV in the aortic position demonstrate reduced failure rates compared to identical valves in the mitral position. The present study aimed to investigate the leakage, hinge, and near hinge flow fields of two BMHV under simulated physiologic aortic flow conditions and to compare these results with previous findings in the mitral position to better understand how the implant location influences the valve performance and the subsequent risk of blood damage. Two and three-component Laser Doppler Velocimetry techniques were used to quantify the velocity and turbulent shear stress fields in both the hinge and the upstream leakage flow regions. The study focused on the 23 mm St. Jude Medical Regent (SJM) and the 23 mm CarboMedics (CM) valves. Although they were tested under similar physiologic conditions, shape and location of the leakage jets were dependent on valve design. Nevertheless, turbulent shear stress levels recorded within all jets were well above the threshold shear stress for the onset of blood cell damage. Within the hinge region, the flow fields were complex and unsteady. The angulated hinge recess of the CM valve appeared to promote blood damage while the streamlined geometry of the SJM valve contributed to better washout of the hinge region. Animations of the velocity flow fields are given in QuickTime or MPEG format. Comparison of the present findings with previously published results for the mitral position suggests that the superior clinical results of the mechanical valves in the aortic position may be due to less severe leakage flow upon valve closure as well as to enhanced hinge washout during the forward flow phase.
Files	Filename       Size       Approximate Download Time (Hours:Minutes:Seconds)     28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access    helene_simon_a_200405_mast.pdf 9.09 Mb 00:42:05 00:21:38 00:18:56 00:09:28 00:00:48   simon_helene_a_200405_mast_hinge_cm_195micronslevel.mov 535.49 Kb 00:02:28 00:01:16 00:01:06 00:00:33 00:00:02   simon_helene_a_200405_mast_hinge_cm_1mmlevel.mov 534.21 Kb 00:02:28 00:01:16 00:01:06 00:00:33 00:00:02   simon_helene_a_200405_mast_hinge_cm_390micronslevel.mov 419.65 Kb 00:01:56 00:00:59 00:00:52 00:00:26 00:00:02   simon_helene_a_200405_mast_hinge_cm_flatlevel.mov 522.33 Kb 00:02:25 00:01:14 00:01:05 00:00:32 00:00:02   simon_helene_a_200405_mast_hinge_sjm_195micronslevel.mov 457.75 Kb 00:02:07 00:01:05 00:00:57 00:00:28 00:00:02   simon_helene_a_200405_mast_hinge_sjm_1mmlevel.mov 615.87 Kb 00:02:51 00:01:27 00:01:16 00:00:38 00:00:03   simon_helene_a_200405_mast_hinge_sjm_390micronslevel.mov 578.27 Kb 00:02:40 00:01:22 00:01:12 00:00:36 00:00:03   simon_helene_a_200405_mast_hinge_sjm_3mmlevel.mov 602.59 Kb 00:02:47 00:01:26 00:01:15 00:00:37 00:00:03   simon_helene_a_200405_mast_hinge_sjm_500micronslevel.mov 617.66 Kb 00:02:51 00:01:28 00:01:17 00:00:38 00:00:03   simon_helene_a_200405_mast_hinge_sjm_flatlevel.mov 611.62 Kb 00:02:49 00:01:27 00:01:16 00:00:38 00:00:03   simon_helene_a_200405_mast_leakagejets_cm_space.mpg 925.83 Kb 00:04:17 00:02:12 00:01:55 00:00:57 00:00:04   simon_helene_a_200405_mast_leakagejets_cm_time.mov 1.01 Mb 00:04:40 00:02:24 00:02:06 00:01:03 00:00:05   simon_helene_a_200405_mast_leakagejets_sjm_space.mpg 976.93 Kb 00:04:31 00:02:19 00:02:02 00:01:01 00:00:05   simon_helene_a_200405_mast_leakagejets_sjm_time.mov 780.18 Kb 00:03:36 00:01:51 00:01:37 00:00:48 00:00:04