Prediction of severity of aortic stenosis: Accuracy of multiple noninvasive parameters

Come, Patricia C.; Riley, Marilyn F.; Ferguson, James F.; Morgan, James P.; McKay, Raymond G.

doi:10.1016/0002-9343(88)90499-8

Cited by 36 publications

(24 citation statements)

References 15 publications

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“…16 Come ct al. [4] 95 VAC1 = 0.86 X VAgf + 0.06 Nishimura et al [8] 23 VAc ■ = 0.65 X VAgf + 0.15 Metz ct al. [7] 40 VAC *= 0.75 X VAgf + 0.19 Danielsen et al [2] 100 VAC = = 0.85 X VAgf + 0.08 Wendel et al [13] 15 VA c-= 0.62 X VAgf + 0.18…”

Section: Continuity Equation and Gorlin Formulamentioning

confidence: 99%

Evaluation of the Valve Area Underestimation by the Continuity Equation

Wippermann¹,

Schranz²,

Stopfkuchen³

et al. 1992

Cardiology

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During the last years, noninvasive determination of the aortic valve area by Doppler echocardiography using the continuity equation became popular. However, a systematic valve area underestimation of about 15 % compared to invasive measurements using the Gorlin formula has been reported. The cause therefore is unknown. The purpose of this study was to evaluate whether the valve area underestimation by the Doppler method might be due to differences in the hydrodynamic background of both methods. This comparison is facilitated by the fact that the Gorlin formula is based on the continuity equation. Compared to the continuity equation, there are four changes within the Gorlin formula: (1) the additional use of a discharge coefficient, which leads to valve area overestimation by the factor 1.17; (2) neglect of the prestenotic velocity, causing further overestimation by the factor 1.036 (in mild stenosis this factor may be 1.18 and more); (3) the wrong calculation of the mean pressure drop, which leads to a mean change by the factor 0.95, and (4) the incorrect substitution of the height by the pressure drop in the derivation of the Gorlin formula causes underestimation by the factor 0.97. Combining these four factors results in valve area overestimation of the Gorlin formula compared to the continuity equation by the factor 1.12. This explains to a large extent the valve area underestimation by the continuity equation.

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Section: Continuity Equation and Gorlin Formulamentioning

confidence: 99%

Evaluation of the Valve Area Underestimation by the Continuity Equation

Wippermann¹,

Schranz²,

Stopfkuchen³

et al. 1992

Cardiology

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“…Functional MR is a common finding in patients with AS, with an incidence above 60% [1,7,8]. Its management, therefore, is of great importance as simultaneous repair or replacement of MR is associated with greater postoperative morbidity and mortality [9,10].…”

Section: Introductionmentioning

confidence: 99%

Incidence, associated factors and evolution of non-severe functional mitral regurgitation in patients with severe aortic stenosis undergoing aortic valve replacement

Caballero-Borrego

Gómez‐Doblas

Cabrera-Bueno

et al. 2008

European Journal of Cardio-Thoracic Surgery

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“…The third approach was also based on the continuity equation. This method has been described with echocardiographic data 21,22 and is commonly used in clinical routine. AVA is expressed using peak velocity and flow rate than their time integrals: AVA CMR3 =Qmax LVOT /Vmax AO .…”

Section: Image Analysismentioning

confidence: 99%

Evaluation of Aortic Valve Stenosis Using Cardiovascular Magnetic Resonance

Defrance

Bollache

Kachenoura

et al. 2012

Circ: Cardiovascular Imaging

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Background-Accurate quantification of aortic valve stenosis (AVS) is needed for relevant management decisions. However, transthoracic Doppler echocardiography (TTE) remains inconclusive in a significant number of patients. Previous studies demonstrated the usefulness of phase-contrast cardiovascular magnetic resonance (PC-CMR) in noninvasive AVS evaluation. We hypothesized that semiautomated analysis of aortic hemodynamics from PC-CMR might provide reproducible and accurate evaluation of aortic valve area (AVA), aortic velocities, and gradients in agreement with TTE. Methods and Results-We studied 53 AVS patients (AVA TTE =0.87±0.44 cm 2 ) and 21 controls (AVA TTE =2.96±0.59 cm 2 ) who had TTE and PC-CMR of aortic valve and left ventricular outflow tract on the same day. PC-CMR data analysis included left ventricular outflow tract and aortic valve segmentation, and extraction of velocities, gradients, and flow rates. Three AVA measures were performed: AVA CMR1 based on Hakki formula, AVA CMR2 based on continuity equation, AVA CMR3 simplified continuity equation=left ventricular outflow tract peak flow rate/aortic peak velocity. Our analysis was reproducible, as reflected by low interoperator variability (<4.56±4.40%). Comparison of PC-CMR and TTE aortic peak velocities and mean gradients resulted in good agreement (r=0.92 with mean bias=−29±62 cm/s and r=0.86 with mean bias=−12±15 mm Hg, respectively). Although good agreement was found between TTE and continuity equationbased CMR-AVA (r>0.94 and mean bias=−0.01±0.38 cm 2 for AVA CMR2 , −0.09±0.28 cm 2 for AVA CMR3 ), AVA CMR1 values were lower than AVA TTE especially for higher AVA (mean bias=−0.45±0.52 cm 2 ). Besides, ability of PC-CMR to detect severe AVS, defined by TTE, provided the best results for continuity equation-based methods (accuracy >94%). Conclusions-Our Defrance et al Phase-Contrast Evaluation of Aortic Valve Stenosis 605on phase-contrast (PC) imaging demonstrated the ability of velocity-encoded sequences to characterize AVS by evaluating: peak transvalvular velocity, 12 AVA using the continuity equation, [5][6][7][8][9][10] or Hakki formula 7,11 derived from the Gorlin equation. The evaluation of AVA and hemodynamic parameters in the aforementioned PC-CMR studies was mostly based on manual delineation [5][6][7][8]10,11 of the aortic valve and the LVOT, which is subjective and time-consuming, rendering the usefulness of CMR in clinical routine for AVS evaluation limited. In addition, among these studies, some used the estimation of LVOT area from its diameter. [5][6][7][8] Although this strategy complies with TTE measurements, it does not take full advantage of PC-CMR data, which when combined with an accurate segmentation enable a direct estimation of the LVOT stroke volume (SV LVOT ) while taking into account the shape of the outflow tract. Clinical Perspective on p 612Accordingly, our first objective was to design a semiautomated analysis of LVOT and aortic valve PC-CMR data, which would enable an accurate evaluation of AVA, mean and maximal...

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Prediction of severity of aortic stenosis: Accuracy of multiple noninvasive parameters

Cited by 36 publications

References 15 publications

Evaluation of the Valve Area Underestimation by the Continuity Equation

Evaluation of the Valve Area Underestimation by the Continuity Equation

Incidence, associated factors and evolution of non-severe functional mitral regurgitation in patients with severe aortic stenosis undergoing aortic valve replacement

Evaluation of Aortic Valve Stenosis Using Cardiovascular Magnetic Resonance

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