AI Article Synopsis

Article Abstract

Objectives: We sought to determine whether the flow-dependent changes in Doppler-derived valve effective orifice area (EOA) are real or due to artifact.

Background: It has frequently been reported that the EOA may vary with transvalvular flow in patients with aortic stenosis. However, the explanation of the flow dependence of EOA remains controversial and some studies have suggested that the EOA estimated by Doppler-echocardiography (EOA(Dop)) may underestimate the actual EOA at low flow rates.

Methods: One bioprosthetic valve and three rigid orifices were tested in a mock flow circulation model over a wide range of flow rates. The EOA(Dop) was compared with reference values obtained using particle image velocimetry (EOA(PIV)).

Results: There was excellent agreement between EOA(Dop) and EOA(PIV) (r2 = 0.94). For rigid orifices of 0.5 and 1.0 cm2, no significant change in the EOA was observed with increasing flow rate. However, substantial increases of both EOA(Dop) and EOA(PIV) were observed when stroke volume increased from 20 to 70 ml both in the 1.5 cm2 rigid orifice (+52% for EOA(Dop) and +54% for EOA(PIV)) and the bioprosthetic valve (+62% for EOA(Dop) and +63% for EOA(PIV)); such changes are explained either by the presence of unsteady effects at low flow rates and/or by an increase in valve leaflet opening.

Conclusions: The flow-dependent changes in EOA(Dop) are not artifacts but represent real changes in EOA attributable either to unsteady effects at low flow rates and/or to changes in valve leaflet opening. Such changes in EOA(Dop) can be relied on for clinical judgment making.

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jacc.2005.05.100DOI Listing

Publication Analysis

Top Keywords

flow-dependent changes
12
low flow
12
flow rates
12
changes doppler-derived
8
valve effective
8
effective orifice
8
orifice area
8
flow
8
eoadop
8
bioprosthetic valve
8

Similar Publications

Article Synopsis
  • Atrial fibrillation (AF) significantly increases the risk of stroke due to thrombus formation in the left atrial appendage (LAA), which can have varied morphologies impacting blood flow dynamics.
  • The study used advanced non-Newtonian computational fluid dynamics (CFD) models to analyze blood viscosity in the LAA, confirming that fibrinogen levels substantially influence this viscosity across different patient groups, particularly in AF patients with Covid-19.
  • Gaussian process emulators (GPEs) showed promise for predicting blood viscosity in the LAA quickly and effectively, with the chicken wing morphology displaying the highest viscosity levels among the LAA types analyzed.
View Article and Find Full Text PDF

Development and Validation of a Flow-Dependent Endothelialized 3D Model of Intracranial Atherosclerotic Disease.

Transl Stroke Res

November 2024

Department of Neurology, David Geffen School of Medicine, Gordon Neuroscience Research Building, The University of California, 635 Charles E. Young Dr. South, Room 415, Los AngelesLos Angeles, CA, USA.

Intracranial atherosclerotic disease (ICAD) is a major cause of stroke globally, with mechanisms presumed to be shared with atherosclerosis in other vascular regions. Due to the scarcity of relevant animal models, testing biological hypotheses specific to ICAD is challenging. We developed a workflow to create patient-specific models of the middle cerebral artery (MCA) from neuroimaging studies, such as CT angiography.

View Article and Find Full Text PDF

Root morphology, an important determinant of nutrient absorption and plant growth, can adapt to various growth environments to promote survival. Solution flow under hydroponic conditions provides a mechanical stimulus, triggering adaptive biological responses, including altered root morphology and enhanced root growth and surface area to facilitate nutrient absorption. To clarify these mechanisms, we applied untargeted metabolomics technology, detecting 1737 substances in lettuce root samples under different flow rates, including 17 common differential metabolites.

View Article and Find Full Text PDF

The innermost layer of the vessel wall is constantly subjected to recurring and relenting mechanical forces by virtue of their direct contact with blood flow. Endothelial cells of the vessel are exposed to distension, pressure, and shear stress; adaptation to these hemodynamic forces requires significant remodeling of the cytoskeleton which includes changes in actin, intermediate filaments, and microtubules. While much is known about the effect of shear stress on the endothelial actin cytoskeleton; the impact of hemodynamic forces on the microtubule network has not been investigated in depth.

View Article and Find Full Text PDF

Background: Meniere disease, characterized by intermittent episodes of vertigo, fluctuating sensorineural hearing loss, tinnitus, and aural pressure, is a common cause of vertigo in humans. The pathogenesis of Meniere disease remains unknown. The current study aimed to describe a novel pathological change discovered in the inner ears of patients with Meniere disease who underwent labyrinthectomy.

View Article and Find Full Text PDF

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!