Abstract 17783: Improved Aortic Valve Area Calculation Using a Novel Biplane Echo Continuity Equation

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Thorsten M Leucker ◽  
Edward P Shapiro
Keyword(s):  
Aortic Valve ◽  
Continuity Equation ◽  
Simple Calculation ◽  
Ventricular Outflow Tract ◽  
Left Ventricular ◽  
Aortic Valve Area ◽  
Single Plane ◽  
Chamber View ◽  
Transcatheter Aortic Valve ◽  
Valve Area

The aim of this study was to improve the accuracy of transthoracic echo- cardiographic (TTE) assessment of the aortic valve area (AVA) in patients with aortic stenosis (AS). The traditional continuity equation (CE) for determining AVA requires a measurement of left ventricular outflow tract (LVOT) area, which is calculated from a linear LVOT dimension using the parasternal long axis view, assuming circular geometry. However, routine use of multidetector computed tomography (MDCT) in patients undergoing evaluation for transcatheter aortic valve replacement (TAVR) has shown that the LVOT is elliptical rather than round. Assumption of circular geometry may introduce inaccuracies into AVA assessment. A total of 61 patients (76 ± 11 years of age, 61% men) with isolated calcific AS (mean gradient 42 ± 9 mm Hg; ejection fraction 56 ± 11%) underwent Doppler TTE as part of pre TAVR or aortic valvuloplasty evaluation. AVA was calculated by TTE using two near- perpendicular planes (parasternal long axis and apical five chamber view) to evaluate the LVOT. A modified CE was used to calculate AVA (cm2) = (π((D1 x D2)/4)x LVOT VTI)/(AV VTI) in order to account for the elliptical rather than round shape of the LVOT. AVA measurements from the traditional and modified CE were compared to invasive AVA assessment. Biplane (Figure, Panel B+D) vs. traditional single plane (Panel A+C) TTE measurement of the LVOT yielded a significantly improved positive correlation between TTE and invasive AVA assessment (r2=0.861 vs. 0.296) and a markedly reduced mean error (0.07 cm2 vs. 0.18 cm2), p<0.001. Utilizing the proposed modified continuity equation greatly improves the accuracy of TTE guided AVA measurements. This simple calculation can be performed using standard TTE without additional costly equipment (ie, biplane transducers), without additional echo views (ie, more sonographer time), and without the need to subject patients to further invasive or non- invasive testing (ie, TEE or MDCT).

scholarly journals Impact of left ventricular outflow tract flow acceleration on aortic valve area calculation in patients with aortic stenosis

2019 ◽  
Vol 6 (4) ◽  
pp. 97-103 ◽  
Author(s):  
Andaleeb A Ahmed ◽  
Robina Matyal ◽  
Feroze Mahmood ◽  
Ruby Feng ◽  
Graham B Berry ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Aortic Stenosis ◽  
Continuity Equation ◽  
Ventricular Outflow Tract ◽  
Left Ventricular ◽  
Area Measurement ◽  
Aortic Valve Area ◽  
Flow Acceleration ◽  
The Impact ◽  
Valve Area

Objective Due to its circular shape, the area of the proximal left ventricular tract (PLVOT) adjacent to aortic valve can be derived from a single linear diameter. This is also the location of flow acceleration (FA) during systole, and pulse wave Doppler (PWD) sample volume in the PLVOT can lead to overestimation of velocity (V1) and the aortic valve area (AVA). Therefore, it is recommended to derive V1 from a region of laminar flow in the elliptical shaped distal LVOT (away from the annulus). Besides being inconsistent with the assumptions of continuity equation (CE), spatial difference in the location of flow and area measurement can result in inaccurate AVA calculation. We evaluated the impact of FA in the PLVOT on the accuracy of AVA by continuity equation (CE) in patients with aortic stenosis (AS). Methods CE-based AVA calculations were performed in patients with AS once with PWD-derived velocity time integral (VTI) in the distal LVOT (VTILVOT) and then in the PLVOT to obtain a FA velocity profile (FA-VTILVOT) for each patient. A paired sample t-test (P < 0.05) was conducted to compare the impact of FA-VTILVOT and VTILVOT on the calculation of AVA. Result There were 46 patients in the study. There was a 30.3% increase in the peak FA-VTILVOT as compared to the peak VTILVOT and AVA obtained by FA-VTILVOT was 29.1% higher than obtained by VTILVOT. Conclusion Accuracy of AVA can be significantly impacted by FA in the PLVOT. LVOT area should be measured with 3D imaging in the distal LVOT.

Abstract 18065: Combining Echo Doppler and CT Derived LVOT Measurements Improve Accuracy of Continuity Equation Based Aortic Valve Area Determination

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Sami Alnasser ◽  
Asim Cheema ◽  
Vamshi Kotha ◽  
Djeven Deva ◽  
Jeremy Edwards ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Aortic Stenosis ◽  
Correlation Coefficient ◽  
Continuity Equation ◽  
Severe Aortic Stenosis ◽  
Ventricular Outflow Tract ◽  
Left Ventricular ◽  
Aortic Valve Area ◽  
Left Ventricular Outflow ◽  
Valve Area

Background: Left ventricular outflow tract (LVOT) measurement by Echo falsely assumes circular LVOT with implications for aortic valve area (AVA) determined using continuity equation. In this study, we investigated the utility of combining Echo Doppler and computed tomography (CT) based LVOT area for precise AVA assessment. Methods: AVA-echo was calculated using continuity equation and standard echocardiography techniques. CT-LVOT area was measured by 3 independent readers. Blinded measurements were obtained in candidates for percutaneous aortic valve replacement. AVA-CT was calculated using CT-LVOT area and echo Doppler measurements. The inter-observer variability for CT-LVOT area and correlation between AVA-echo and AVA-CT was analyzed using intra-class (ICC) and Spearman correlation coefficient. Results: Complete data for 66 patients was analyzed. The ICC for CT derived LVOT measurement by three observers was 0.96 demonstrating excellent reliability. The LVOT area by echo was significantly smaller than that obtained by CT (3.43±0.8 vs. 4.45±1.2 cm2, p<0.0001) and showing moderate correlation (r=0.66, p=0.006). Similarly, the AVA-echo was significantly lower compared to AVA-CT (0.76±0.46 vs. 0.97±0.53 cm2, p<0.0001). The correlation coefficient for AVA-echo and AVA-CT was 0.7 (p < 0.0001), 0.4 (p=0.06) and 0.9 (p<0.0001) for AVA-echo of 0.8 cm2 respectively. The regression analysis showed that AVA-CT could be predicted by applying a correction factor to the AVA-echo as AVA-CT = AVA-echo x 1.1+0.14. Conclusion: CT provides accurate and reliable LVOT assessment. Combining CT-LVOT and echo Doppler measurements result in a larger AVA compared to AVA-echo representing a true anatomic measurement. These findings have important implications for grading of aortic stenosis and management of patients with moderate to severe aortic stenosis.

scholarly journals Modified continuity equation using left ventricular outflow tract three-dimensional imaging for aortic valve area estimation

2017 ◽  
Vol 34 (7) ◽  
pp. 978-985 ◽  
Author(s):  
Pedro Pinto Teixeira ◽  
Ruben Ramos ◽  
Pedro Rio ◽  
Luísa Moura Branco ◽  
Guilherme Portugal ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Continuity Equation ◽  
Left Ventricular Outflow Tract ◽  
Three Dimensional ◽  
Ventricular Outflow Tract ◽  
Left Ventricular ◽  
Aortic Valve Area ◽  
Area Estimation ◽  
Left Ventricular Outflow ◽  
Valve Area

Abstract 18192: Aortic Stenosis: The Effect of Spectral Broadening in the Left Ventricular Outflow Tract on Stroke Volume and Calculated Aortic Valve Area

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Jeremy J Thaden ◽  
Michael Y Tsang ◽  
Saki Ito ◽  
Sorin V Pislaru ◽  
Vuyisile T Nkomo ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Aortic Stenosis ◽  
Ventricular Outflow Tract ◽  
Left Ventricular ◽  
Uniform Flow ◽  
Aortic Valve Area ◽  
Spectral Broadening ◽  
Volumetric Assessment ◽  
Left Ventricular Outflow ◽  
Valve Area

Introduction: Accurate stroke volume (SV) calculation is critical for calculating aortic valve area by echocardiography. 2D-Doppler estimation of SV (SV 2D ) assumes uniform blood flow velocities through the left ventricular outflow tract (LVOT). Non-uniform flow through the LVOT, appreciated as spectral broadening of the LVOT Doppler signal, could result in inaccurate SV calculation. Hypothesis: Increased spectral broadening in the LVOT will result in overestimation of SV by the SV 2D method compared to 3D volumetric assessment of SV (SV 3D ). Methods: Fifty-one consecutive patients with aortic stenosis underwent comprehensive 2D-TTE and assessment of SV 3D . Patients with ≥ moderate mitral or aortic regurgitation were excluded. An LVOT pulse-wave Doppler signal with > 0.4 m/s difference between outer and inner edge of velocity spectral display (at time of peak velocity) was considered non-uniform flow (i.e., spectral broadening). Results: Spectral broadening was present in 33% of the cohort. These patients were commonly female with smaller ventricles and higher ejection fraction. Spectral broadening was associated with a significant overestimation of SV on Doppler-based measurements (101±20 ml vs 78±15 mL, SV 2D vs SV 3D , respectively; r=0.83, p<0.0001); such differences were not seen in patients with uniform flow velocities (82±15 vs 79±14 mL, r=0.83, p=0.03). Patient characteristics by spectral broadening are shown in table 1. Conclusion: In aortic stenosis patients with non-uniform flow, Doppler-based methods overestimated SV by 29.5% on average (maximum 64%) when compared to 3D methods. This results in a proportional increase in calculated valve area despite a similar mean gradient between groups. Substituting SV 3D resulted in similar SV, valve area, and mean gradient between uniform and non-uniform groups. When spectral broadening >0.40 cm/s is present, 3D volumetric assessment of SV should be considered for accurate estimation of aortic valve area.

Sign in / Sign up

Export Citation Format

Share Document