Evaluation of the Proximal Flow Field to Circular and Noncircular Orifices of Different Aspect Ratios

Myers, Jerry G.; Fox, James F.; Elmahdi, Abdelaziz M.; Perry, Gilbert J.

doi:10.1115/1.2796100

Cited by 10 publications

(3 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…3 2 Myers et al showed that the PISA shape was particularly related to the ori ce aspect ratio. 28 The ori ce aspect ratio loses its effect on the PISA shape when at a distance of more than 1.4 times the diameter of the ori ce.…”

Section: Figure 3 a The Regression Analysis Between The Qp-qs P Is mentioning

confidence: 99%

Proximal Isovelocity Surface Area (PISA) as a Noninvasive Method for the Estimation of the Shunt Quantification in Perimembranous Ventricular Septal Defects

et al. 2001

View full text Add to dashboard Cite

This study was designed to assess the reliability of the proximal isovelocity surface area (PISA) method for the estimation of shunt quantification in perimembranous ventricular septal defects (PVSD). The study group was composed of 30 patients (age 11 +/- 7 years, 13 female) with PVSD. The shunt flow (Qp-Qs) and the ratio of the pulmonary flow to the systemic flow (Qp/Qs) were calculated by spectral Doppler and catheterization. The Qp-Qs, the defect area (DA), and the shunt volume (SV) were obtained by the PISA method. The PISA method estimated the DA (cm(2)/m(2)), the SV (cm(3)/m(2)), and the Qp-Qs (L/min/m(2)) to be equal to (2 x pi x R(2) x NL)/(V(max) x Body surface area), DA x TVI(shunt), and to SV x Heart rate, respectively (R is the distance of the maximal PISA from the first aliasing line to the left ventricular side of the defect, NL is the nyquist limit, and V(max) and TVI(shunt) are the peak velocity and time-velocity integral of transdefect Doppler tracing obtained by continuous-wave Doppler). The PISA method (3.4 +/- 1.5 L/min/m(2)) underestimated the Qp-Qs according to spectral Doppler (r = 0.96, P < 0.001; mean difference -0.74 +/- 0.61 L/min/m(2); SEE = 0.11 L/min/m(2), P < 0.001) and catheterization (r = 0.92, P < 0.001; mean difference -0.45 +/- 0.7 L/min/m(2); SEE = 0.13 L/min/m(2), P < 0.001). The correlations between the PISA findings (Qp-Qs, DA, SV) and the catheterization Qp/Qs (r = 0.86, 0.84, and 0.86; P < 0.001, respectively), or between these and the spectral Doppler Qp/Qs (r = 0.80, 0.80, and 0.79; P < 0.001, respectively) were significant. The accuracies of the PISA findings in identifying large defects were high (0.90, 0.93, and 0.90 for cut-off values of Qp-Qs = 3.67 L/min/m(2), DA = 0.44 cm(2)/m(2), and SV = 43 cm(3)/m(2), respectively). As a result, the PISA method can be a simple and reliable alternative to the spectral Doppler method in the identification of large shunts in PVSD.

show abstract

Section: Figure 3 a The Regression Analysis Between The Qp-qs P Is mentioning

confidence: 99%

Proximal Isovelocity Surface Area (PISA) as a Noninvasive Method for the Estimation of the Shunt Quantification in Perimembranous Ventricular Septal Defects

et al. 2001

View full text Add to dashboard Cite

show abstract

“…Vandervoort et al 1,14 used multiple correlations to determine the location of the ori ce and to subsequently calculate the regurgitant ow. Anayiotos et al and Myers et al [26][27][28] have proposed a remarkable approach based on a precise description of the isovelocity surfaces and excluding any simpli cation in terms of velocity elds. Schwammenthal et al 13 validated a detailed analysis of the velocity pro le that allowed determination of the aliasing velocity, allowing an accurate evaluation of the regurgitant ow.…”

Section: Comparison With Similar Studiesmentioning

confidence: 99%

“…None of these studies simultaneously addressed the two sources of errors: the positioning of the ori ce and the selection of the velocity at which the radius is measured. Anayiotos et al and Myers et al [26][27][28] have proposed a remarkable approach based on a precise description of the isovelocity surfaces and excluding any simpli cation in terms of velocity elds. The hemiellipses were either directly imaged or calculated after several ttings of the observed centerline velocity pro les with theoretical data derived from numerical simulations including "a priori" informations.…”

Section: Comparison With Similar Studiesmentioning

confidence: 99%

In Vitro Validation of a New Approach for Quantitating Regurgitations Using Proximal Isovelocity Surface Area

et al. 2000

View full text Add to dashboard Cite

The present work has been designed to validate the calculation of the effective regurgitant orifice (ERO) area with the use of a new formula that takes into account the velocity profile (V(r) vs r) and that is insensitive to errors in the determination of the position of the orifice. Assuming a hemispheric model, ERO = 2 pi r(2). V(r)/V(o) (with V(o) = velocity at the orifice) and (V(o)/V(r))(0.5) = (2 pi/ERO)(0.5) r. Thus, the slope of the corresponding linear regression allows ERO to be calculated as: ERO = 2 pi/slope(2). This approach was tested in vitro in pulsatile conditions on circular, conical, and slit-like orifices. The calculated ERO was compared with the actual jet cross sectional area derived from the transverse velocity profile at the jet origin. For the purpose of comparison, the "classical" ERO was calculated for all the configurations, angulations, and threshold velocities. The relationship between (V(o)/V(r))(0.5) was linear (r > 0.98) over a wide range of velocities. The nonhemispheric components were found to modify the constant and not the slope. The mean variation of the calculated ERO was 6.5%. The correlation between the calculated and the actual ERO was very close (>0.97) with slope equal to 0.96. By comparison with the new method, the classical formula gave an underestimation of the ERO that dramatically increased when studying the flow closer to the orifice or in the case of error on the measurement of r. In conclusion, a method using velocity profiles instead of isolated values improves the accuracy of the proximal isovelocity surface area (PISA) method for measuring the ERO.

show abstract

Developments in cardiovascular ultrasound. Part 2: Arterial applications

Moran

McDicken

Hoskins

et al. 1998

Med. Biol. Eng. Comput.

View full text Add to dashboard Cite

Many of the changes resulting from arterial disease can be measured, using Doppler ultrasound for measurement of blood velocity and B-scan imaging for measurement of tissue structure and composition. Wall thickness, the degree of arterial narrowing and plaque volume can be measured using B-scan imaging, and 3D ultrasound can be used to improve the accuracy of measurements of plaque volume and for improved visualisation of complex arterial geometries. Measurement of the dynamic properties of the arterial wall permits estimation of wall elasticity and plaque motion. From the Doppler signal, measurements of blood velocity are used to estimate the degree of arterial narrowing and volumetric flow, although measurement errors can be large. Wall shear stress can be estimated by measuring the velocity gradient at the vessel wall. The problems of inadequate spatial resolution and interference from overlying tissue are largely removed when intravascular systems are used, and these have superior capability in the assessment of arterial structure and tissue composition. However, measurement of quantities relating to blood flow is more difficult using the intravascular approach, as the indwelling cather disturbs the blood flow pattern, and currently, assessment of flow and vessel cross-section are not performed at the same site.

show abstract

Evaluation of the Proximal Flow Field to Circular and Noncircular Orifices of Different Aspect Ratios

Cited by 10 publications

References 15 publications

Proximal Isovelocity Surface Area (PISA) as a Noninvasive Method for the Estimation of the Shunt Quantification in Perimembranous Ventricular Septal Defects

Proximal Isovelocity Surface Area (PISA) as a Noninvasive Method for the Estimation of the Shunt Quantification in Perimembranous Ventricular Septal Defects

In Vitro Validation of a New Approach for Quantitating Regurgitations Using Proximal Isovelocity Surface Area

Developments in cardiovascular ultrasound. Part 2: Arterial applications

Contact Info

Product

Resources

About