2012
DOI: 10.1155/2012/383217
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Nonconvective Forces: A Critical and Often Ignored Component in the Echocardiographic Assessment of Transvalvular Pressure Gradients

Abstract: Echocardiography is routinely used to assess ventricular and valvular function, particularly in patients with known or suspected cardiac disease and who have evidence of hemodynamic compromise. A cornerstone to the use of echocardiographic imaging is not only the qualitative assessment, but also the quantitative Doppler-derived velocity characteristics of intracardiac blood flow. While simplified equations, such as the modified Bernoulli equation, are used to estimate intracardiac pressure gradients based upon… Show more

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Cited by 16 publications
(14 citation statements)
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“…Energy can change form and location but is neither created nor destroyed. According to the Bernoulli principle, there are three forms of energy in the hydraulic state of liquids that can be applied to AS Pressure energy : defined as P and is the left ventricular and aortic pressures Kinetic energy : defined as KE and is the energy of blood flow Potential energy : defined as PE and is the height of the column of blood and is negligible Bernoullibolds0.25emboldprinciple:normalP1+KE1+PE1=normalP2+KE2+PE2 where P1, KE1, and PE1 are the energy components before, while P2, KE2, and PE2 are the energy components after the stenotic orifice.…”
Section: Pathophysiology Of Aortic Stenosismentioning
confidence: 99%
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“…Energy can change form and location but is neither created nor destroyed. According to the Bernoulli principle, there are three forms of energy in the hydraulic state of liquids that can be applied to AS Pressure energy : defined as P and is the left ventricular and aortic pressures Kinetic energy : defined as KE and is the energy of blood flow Potential energy : defined as PE and is the height of the column of blood and is negligible Bernoullibolds0.25emboldprinciple:normalP1+KE1+PE1=normalP2+KE2+PE2 where P1, KE1, and PE1 are the energy components before, while P2, KE2, and PE2 are the energy components after the stenotic orifice.…”
Section: Pathophysiology Of Aortic Stenosismentioning
confidence: 99%
“…Several non invasive formulas exist to account for the pressure recovery either through estimating the recovered pressure gradient (see above) or the estimated AVA after accounting for the recovered pressure gradient (Energy loss coefficient or index, ELCO, ELI): ELCObold-italic=EOA×Ascending Aorta Area/Ascending Aorta Areamonospace−EOA Bernoulli assumptions : utilizing the Bernoulli equation for non‐invasive assessment of transvalvular pressure gradient (Δ P ) omits several assumptions required for the Bernoulli equation to be accurately applied including the full and complete conversion of pressure energy to kinetic energy, the need for steady flow state and negligible friction losses. This leads to several discrepancies between invasive and non‐invasive measures of the measured Δ P even after accounting for the pressure recovery phenomenon . (1) The friction and inertial forces and viscous losses, as expressed with Reynolds' number, are not accounted for in the modified Bernoulli equation and have been shown in experimental and in vivo models to reconcile ECHO and CATH gradients, (2) The omission of the flow acceleration component, which was indeed shown to be negligible when utilizing the modified Bernoulli equation to determine ECHO MG across the mitral valve with mitral stenosis; however, is not negligible in a pulsatile system, especially across the aortic valve and in non restrictive orifices, such as normal functioning TAVR valves, the flow acceleration is presumed to play a significant role in describing overall trans valve gradients,(3) The Bernoulli equation, and its derivative utilized in Doppler‐echocardiography, assumes that the ejection jet is a single stream line and hence a laminar flow system across the aortic valve in patients with severe AS wherein the effective flow velocity equals half of maximum velocity and the average kinetic energy density is one third of the maximum kinetic energy density.…”
Section: Pathophysiology Of Aortic Stenosismentioning
confidence: 99%
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“…[4][5][6][7][8][9][10][11] Several studies have investigated the correlation between MRI measurements and echocardiography with catheterization for the estimation of the pressure drop in pulmonary circulation. The results have been inconsistent.…”
mentioning
confidence: 99%
“…Quantitative assessment of the severity of pulmonary valve stenosis is mainly based on the pulmonary transvalvular pressure drop, commonly estimated by continuous‐wave Doppler and recently by magnetic resonance imaging (MRI) phase contrast flow measurements . The accuracy of noninvasive measurements of the transvalvular pressure drop has been debated . Several studies have investigated the correlation between MRI measurements and echocardiography with catheterization for the estimation of the pressure drop in pulmonary circulation.…”
mentioning
confidence: 99%