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Device Thrombogenicity Emulator (DTE)--design optimization methodology for cardiovascular devices: a study in two bileaflet MHV designs.

ABSTRACT: Patients who receive prosthetic heart valve (PHV) implants require mandatory anticoagulation medication after implantation due to the thrombogenic potential of the valve. Optimization of PHV designs may facilitate reduction of flow-induced thrombogenicity and reduce or eliminate the need for post-implant anticoagulants. We present a methodology entitled Device Thrombogenicty Emulator (DTE) for optimizing the thrombo-resistance performance of PHV by combining numerical and experimental approaches. Two bileaflet mechanical heart valves (MHV) designs, St. Jude Medical (SJM) and ATS, were investigated by studying the effect of distinct flow phases on platelet activation. Transient turbulent and direct numerical simulations (DNS) were conducted, and stress loading histories experienced by the platelets were calculated along flow trajectories. The numerical simulations indicated distinct design dependent differences between the two valves. The stress loading waveforms extracted from the numerical simulations were programmed into a hemodynamic shearing device (HSD), emulating the flow conditions past the valves in distinct 'hot-spot' flow regions that are implicated in MHV thrombogenicity. The resultant platelet activity was measured with a modified prothrombinase assay, and was found to be significantly higher in the SJM valve, mostly during the regurgitation phase. The experimental results were in excellent agreement with the calculated platelet activation potential. This establishes the utility of the DTE methodology for serving as a test bed for evaluating design modifications for achieving better thrombogenic performance for such devices.

SUBMITTER: Xenos M

PROVIDER: S-EPMC2922449 | biostudies-literature | 2010 Aug

REPOSITORIES: biostudies-literature

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Device Thrombogenicity Emulator (DTE)--design optimization methodology for cardiovascular devices: a study in two bileaflet MHV designs.

Xenos Michalis M Girdhar Gaurav G Alemu Yared Y Jesty Jolyon J Slepian Marvin M Einav Shmuel S Bluestein Danny D

Journal of biomechanics 20100521 12

Patients who receive prosthetic heart valve (PHV) implants require mandatory anticoagulation medication after implantation due to the thrombogenic potential of the valve. Optimization of PHV designs may facilitate reduction of flow-induced thrombogenicity and reduce or eliminate the need for post-implant anticoagulants. We present a methodology entitled Device Thrombogenicty Emulator (DTE) for optimizing the thrombo-resistance performance of PHV by combining numerical and experimental approaches ...[more]

PMID: 20483411

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Project description:Mechanical circulatory support (MCS) devices provide both short and long term hemodynamic support for advanced heart failure patients. Unfortunately these devices remain plagued by thromboembolic complications associated with chronic platelet activation--mandating complex, lifelong anticoagulation therapy. To address the unmet need for enhancing the thromboresistance of these devices to extend their long term use, we developed a universal predictive methodology entitled Device Thrombogenicity Emulation (DTE) that facilitates optimizing the thrombogenic performance of any MCS device--ideally to a level that may obviate the need for mandatory anticoagulation. DTE combines in silico numerical simulations with in vitro measurements by correlating device hemodynamics with platelet activity coagulation markers--before and after iterative design modifications aimed at achieving optimized thrombogenic performance. DTE proof-of-concept is demonstrated by comparing two rotary Left Ventricular Assist Devices (LVADs) (DeBakey vs HeartAssist 5, Micromed Houston, TX), the latter a version of the former following optimization of geometrical features implicated in device thrombogenicity. Cumulative stresses that may drive platelets beyond their activation threshold were calculated along multiple flow trajectories and collapsed into probability density functions (PDFs) representing the device 'thrombogenic footprint', indicating significantly reduced thrombogenicity for the optimized design. Platelet activity measurements performed in the actual pump prototypes operating under clinical conditions in circulation flow loops--before and after the optimization with the DTE methodology, show an order of magnitude lower platelet activity rate for the optimized device. The robust capability of this predictive technology--demonstrated here for attaining safe and cost-effective pre-clinical MCS thrombo-optimization--indicates its potential for reducing device thrombogenicity to a level that may significantly limit the extent of concomitant antithrombotic pharmacotherapy needed for safe clinical device use.

Project description:The contraceptive effectiveness of intrauterine devices has been attributed in part to effects of a foreign body reaction on the endometrium. We performed this study to identify compare the effects on the endometrial transcriptome of intrauterine devices and combined oral contraceptives, to better understand their mechanisms of action. We collected endometrial and cervical biopsies from women using the levonorgestrel-intrauterine device, copper intrauterine device or levonorgestrel-containing combined oral contraceptives, and from women not using contraceptives (control group). Transcriptional profiling was performed with Affymetrix arrays, Principal Component Analysis and the bioconductor package limma. Pathway analysis was performed using EnrichR and Reactome 2016. In endometrial samples from copper intrauterine device users (n=13), there were no genes with statistically significant differential expression compared to controls (n=11), whereas in levonorgestrel-intrauterine device users (n=11), 2509 genes were significantly dysregulated and mapped onto several immune and inflammatory pathways. In combined oral contraceptive users (n=12), 133 genes were significantly dysregulated and mapped predominantly onto pathways involving regulation of metal ions. Both levonorgestrel-intrauterine device and combined oral contraceptive use were associated with significant downregulation of members of the metallothionein gene family. In cervical samples, none of the groups showed statistically significant differential gene expression compared to controls. In conclusion, hormonal and copper intrauterine devices differ significantly in their effects on the endometrial transcriptome, with endometrium from copper intrauterine device users being indistinguishable from luteal phase endometrium. These results suggest that the contraceptive mechanisms of intrauterine devices are unlikely to rely on a common pathway involving a foreign body reaction in the endometrium.

Dataset Information

Device Thrombogenicity Emulator (DTE)--design optimization methodology for cardiovascular devices: a study in two bileaflet MHV designs.

Publications

Device Thrombogenicity Emulator (DTE)--design optimization methodology for cardiovascular devices: a study in two bileaflet MHV designs.

Similar Datasets

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