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BACKGROUND AND AIM OF THE STUDY Mechanical heart valve implantation requires long-term anticoagulation because of thromboembolic complications. Recent studies have indicated that the relatively high wall shear stresses and negative pressure transients developed during the valve closing phase may be dominant factors inducing thrombus initiation. The study(More)
  • L J Frazin, G Lanza, +7 authors D McPherson
  • 1990
To determine whether rotational blood flow or chiral asymmetry exists in the human descending thoracic aorta, we established the ability of color Doppler ultrasound to detect rotational flow in a tornado tube model of a vortex descending fluid column. In a model of the human aortic arch with a pulse duplicator, color Doppler was then used to demonstrate(More)
Aortic helical flow may play an important role in plaque deposition, dissection formation, and organ perfusion. The authors have previously demonstrated, using in vitro flow models and transesophageal echocardiography, that helical flow begins in the mammalian aortic arch and continues into the descending thoracic aorta. The purpose of this study was to(More)
Analysis of three-dimensional velocity profiles and wall shear stress distribution in a segment of an artery reconstructed from in vivo imaging data are presented in this study. Cross-sectional images of a segment of the abdominal aorta in dogs were obtained using intravascular ultrasound (IVUS) imaging employing a constant pull back technique. Simultaneous(More)
The wall shear stress induced by the leaflet motion during the valve-closing phase has been implicated with thrombus initiation with prosthetic valves. Detailed flow dynamic analysis in the vicinity of the leaflets and the housing during the valve-closure phase is of interest in understanding this relationship. A three-dimensional unsteady flow analysis(More)
The effect of valve orientation on flow development in a model human aorta was studied by means of a qualitative flow visualization technique. The model replicated the geometry of the human aorta and the experiment simulated a physiologically realistic pulsatile flow. The following valves were studied: Starr-Edwards Stellite, Starr-Edwards silicone,(More)
Atherosclerosis is a diffuse arterial disease developing over many years and resulting in a complicated three-dimensional arterial morphology. The arterial wall material properties have been demonstrated to show regional alterations with atheroma development and growth. We present a mechanical analysis of diseased arterial segments reconstructed from(More)
Flow in the aortic arch is characterized primarily by the presence of a strong secondary flow superimposed over the axial flow, skewed axial velocity profiles and diastolic flow reversals. A significant amount of helical flow has also been observed in the descending aorta of humans and in models. In this study a computational model of the abdominal aorta(More)
A numerical analysis is carried out for oscillatory flow of a viscous incompressible fluid through thin-walled elastic tubes with small curvature. A wave propagation analysis for sinusoidal input pressure disturbance yields a resulting asymmetrical flow pattern and the secondary flow pattern induced by centrifugal effects due to curvature. Essential(More)