High-resolution measurements of leakage flow through bileaflet mechanical heart valve hinges
Klusak, Ewa, Monika
MetadataShow full item record
This item's downloads: 43 (view details)
To restore proper function of the heart, diseased valves require repair or replacement. Mechanical heart valves are one of the treatments available. Despite their superior durability in comparison with biological prostheses, mechanical heart valves are associated with life-threatening complications, known to be induced by non-physiological fluid dynamics, generated by valve geometrical features. The aim of this study is to resolve the turbulent nature of the leakage flow through bileaflet mechanical heart valves, and resolve flow structures that may induce blood damage, to improve future valve designs. Therefore, the objective of this research is to obtain comprehensive knowledge of the fluid dynamics near and inside the hinge cavity of bileaflet mechanical heart to enhance understanding of its role in blood damage, for future design improvements. To study complexity of the flow dynamics at high-resolution, scaling of the key geometrical features of the valve was performed. Scaled-up hinge models were developed and tested in a large-scale heart valve flow simulator. The flow dynamics was investigated utilizing Particle Image Velocimetry technique, a laser-based, non-intrusive measurement method. It has been demonstrated that the leakage flow inside the hinge and downstream of the hinge of a bileaflet mechanical heart valves is highly unsteady. Inside the hinge, flow features indicating that flow perhaps separates from the surface of the hinge cavity has been identified. High velocity fluctuation inside and downstream of the hinge were observed. This features suggest that leakage flow is highly-three dimensional and turbulent, which align with findings from previous studies. This study quantified viscous shear stresses of the leakage flow inside and down- stream of bileaflet mechanical heart valve hinges. It has been demonstrated that shear stress inside and downstream of the hinge exceeds the threshold of platelet activation but it remains below that of haemolysis. Flow features such as stagnation, recirculation zones and perhaps flow separation inside the hinge, were observed. These findings indicate that leakage flow may induce damage to blood elements and be favorable for the formation of the thrombus inside and near hinge of bileaflet mechanical heart valves. In this work it was shown that measurement spatial and temporal resolution has a high impact on ability to resolve flow structures in leakage flow inside and downstream of the hinge cavity of a BMHV. Experiments at higher spatial in-plane and out-of-plane resolution revealed flow structures that have not been measured in experiment with clinical scale MHVs models. This work demonstrated that whole-field, high-spatial resolution measurement offered by PIV along with a novel scaled-up models allow gain better understanding of complex flows.
This item is available under the Attribution-NonCommercial-NoDerivs 3.0 Ireland. No item may be reproduced for commercial purposes. Please refer to the publisher's URL where this is made available, or to notes contained in the item itself. Other terms may apply.
The following license files are associated with this item:
Showing items related by title, author, creator and subject.
Olm, Carsten; Zsély, István Gy; Varga, Tamás; Curran, Henry J. (Elsevier ScienceDirect, 2015-01-22)A large set of experimental data was accumulated for syngas combustion: ignition studies in shock tubes (732 data points in 62 datasets) and in rapid compression machines (492/47), flame velocity determinations (2116/217) ...
Varga, T.; Nagy, T.; Olm, C.; Zsély, I. Gy; Pálvölgyi, R.; Valkó, É; Vincze, G.; Cserháti, M.; Curran, Henry J.; Turányi, T. (Elsevier ScienceDirect, 2014-07-05)The Keromnes et al. (2013) mechanism for hydrogen combustion has been optimized using a large set of indirect experimental data, consisting of ignition measurements in shock tubes (566 datapoints in 43 datasets) and rapid ...
Computational investigation of in situ chondrocyte deformation and actin cytoskeleton remodelling under physiological loading Dowling, Enda P.; Ronan, William; McGarry, J. Patrick (Elsevier, 2012-12-24)Previous experimental studies have determined local strain fields for both healthy and degenerate cartilage tissue during mechanical loading. However, the biomechanical response of chondrocytes in situ, in particular the ...