A new experimental method for the determination of the effective orifice area based on the acoustical source term

Kadem, Lyes; Knapp, Yannick; Bertrand, Éric; Garcia, Damien; Durand, Louis-Gilles; Rieu, Régis

doi:10.1007/s00348-005-0038-0

Cited by 8 publications

(13 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This new method is based on the acoustical source term (AST) computed from the velocity field [ 14 , 29 ]. Briefly, flow disturbance and separation downstream of an aortic stenosis produce high vorticity field which is responsible for sound generation [ 24 ].…”

Section: Methodsmentioning

confidence: 99%

“…This method provides an accurate and simple way of separating the jet-like zone from the recirculation zone right downstream of the stenotic valve and defines then the area of the vena contracta, i.e. the EOA [ 14 ] (Figure 2 ). This is due to the amplification of the vorticity by the magnitude of the local velocity.…”

Section: Methodsmentioning

confidence: 99%

“…This velocity profile was normalized with respect to peak velocity and then used to compute vorticity and AST shear layers profiles (Figure 2B and 2C ). The CMR JSLD EOA was measured by a semi-automated algorithm that detects the peaks of normalized AST profiles corresponding to maximal noise production due to vorticity [ 14 ] (Figure 2D and 3A ). An animation showing step-by-step how AST is determined from CMR velocity maps is included as Additional file 1.…”

Section: Methodsmentioning

confidence: 99%

“…There is thus an important need for the development and validation of new simpler, more reproducible but still highly accurate CMR methods to estimate the EOA in AS patients. In a previous in vitro study, using particle image velocimetry measurements, we have shown that EOA can be directly determined using velocity measurements downstream of the stenosis and the application of acoustical source term concept (AST) [ 14 ]. Briefly, the fundamental idea behind this concept is that the flow jet created by the stenotic valve generates acoustic noise and the major sources of this sound generation can be determined by computing the acoustical source term.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Cardiovascular magnetic resonance evaluation of aortic stenosis severity using single plane measurement of effective orifice area

García

Marrufo

Rodrı́guez

et al. 2012

Journal of Cardiovascular Magnetic Resonance

View full text Add to dashboard Cite

BackgroundTransthoracic echocardiography (TTE) is the standard method for the evaluation of the severity of aortic stenosis (AS). Valve effective orifice area (EOA) measured by the continuity equation is one of the most frequently used stenotic indices. However, TTE measurement of aortic valve EOA is not feasible or not reliable in a significant proportion of patients. Cardiovascular magnetic resonance (CMR) has emerged as a non-invasive alternative to evaluate EOA using velocity measurements. The objectives of this study were: 1) to validate a new CMR method using jet shear layer detection (JSLD) based on acoustical source term (AST) concept to estimate the valve EOA; 2) to introduce a simplified JSLD method not requiring vorticity field derivation.Methods and resultsWe performed an in vitro study where EOA was measured by CMR in 4 fixed stenoses (EOA = 0.48, 1.00, 1.38 and 2.11 cm2) under the same steady flow conditions (4-20 L/min). The in vivo study included eight (8) healthy subjects and 37 patients with mild to severe AS (0.72 cm2 ≤ EOA ≤ 1.71 cm2). All subjects underwent TTE and CMR examinations. EOA was determinated by TTE with the use of continuity equation method (TTECONT). For CMR estimation of EOA, we used 3 methods: 1) Continuity equation (CMRCONT); 2) Shear layer detection (CMRJSLD), which was computed from the velocity field of a single CMR velocity profile at the peak systolic phase; 3) Single plane velocity truncation (CMRSPVT), which is a simplified version of CMRJSLD method. There was a good agreement between the EOAs obtained in vitro by the different CMR methods and the EOA predicted from the potential flow theory. In the in vivo study, there was good correlation and concordance between the EOA measured by the TTECONT method versus those measured by each of the CMR methods: CMRCONT (r = 0.88), CMRJSLD (r = 0.93) and CMRSPVT (r = 0.93). The intra- and inter- observer variability of EOA measurements was 5 ± 5% and 9 ± 5% for TTECONT, 2 ± 1% and 7 ± 5% for CMRCONT, 7 ± 5% and 8 ± 7% for CMRJSLD, 1 ± 2% and 3 ± 2% for CMRSPVT. When repeating image acquisition, reproducibility of measurements was 10 ± 8% and 12 ± 5% for TTECONT, 9 ± 9% and 8 ± 8% for CMRCONT, 6 ± 5% and 7 ± 4% for CMRJSLD and 3 ± 2% and 2 ± 2% for CMRSPVT.ConclusionThere was an excellent agreement between the EOA estimated by the CMRJSLD or CMRSPVT methods and: 1) the theoretical EOA in vitro, and 2) the TTECONT EOA in vivo. The CMRSPVT method was superior to the TTE and other CMR methods in terms of measurement variability. The novel CMR-based methods proposed in this study may be helpful to corroborate stenosis severity in patients for whom Doppler-echocardiography exam is inconclusive.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Cardiovascular magnetic resonance evaluation of aortic stenosis severity using single plane measurement of effective orifice area

García

Marrufo

Rodrı́guez

et al. 2012

Journal of Cardiovascular Magnetic Resonance

View full text Add to dashboard Cite

show abstract

“…In this theory (Appendix) (19), the term (ٌ · ជ ٙ V ជ ), where ٌ is the nabla operator, is the vorticity field, and V is the velocity field, is called the acoustical source term and is responsible of the sound generated by unsteady fluid motion. This method provides an accurate and simple way of separating the jet-like zone from the recirculation zone at the level of the vena contracta (14).…”

Section: Asmentioning

confidence: 99%

Flow-Dependent Changes in Doppler-Derived Aortic Valve Effective Orifice Area Are Real and Not Due to Artifact

Kadem

Rieu

Dumesnil

et al. 2006

Journal of the American College of Cardiology

View full text Add to dashboard Cite

show abstract

Assessment of left heart and pulmonary circulation flow dynamics by a new pulsed mock circulatory system

et al. 2009

View full text Add to dashboard Cite

show abstract

A new experimental method for the determination of the effective orifice area based on the acoustical source term

Cited by 8 publications

References 28 publications

Cardiovascular magnetic resonance evaluation of aortic stenosis severity using single plane measurement of effective orifice area

Cardiovascular magnetic resonance evaluation of aortic stenosis severity using single plane measurement of effective orifice area

Flow-Dependent Changes in Doppler-Derived Aortic Valve Effective Orifice Area Are Real and Not Due to Artifact

Assessment of left heart and pulmonary circulation flow dynamics by a new pulsed mock circulatory system

Contact Info

Product

Resources

About