Quantification Of Aortic Valve Area Research Articles

P2399Applying 3D echocardiography derived stroke volume for quantification of aortic valve area in low-flow aortic stenosis: The superiority of a hybrid approach

P2399Applying 3D echocardiography derived stroke volume for quantification of aortic valve area in low-flow aortic stenosis: The superiority of a hybrid approach

Three-Dimensional Morphology of the Left Ventricular Outflow Tract: Impact on Grading Aortic Stenosis Severity

Left ventricular outflow tract (LVOT) measurement is a critical step in the quantification of aortic valve area. The assumption of a circular morphology of the LVOT may induce some errors. The aim of this study was to assess the three-dimensional (3D) morphology of the LVOT and its impact on grading aortic stenosis severity. Fifty-eight patients with aortic stenosis were studied retrospectively. LVOT dimensions were measured using 3D transesophageal echocardiography at three levels: at the hinge points (HP) of the aortic valve and at 4 and 8mm proximal to the annular plane. Results were compared with standard two-dimensional echocardiographic measurements. Three-dimensional transesophageal echocardiography showed a funnel shape that was more circular at the HP and more elliptical at 4 and 8mm proximal to the annular plane (circularity index=0.92 vs 0.83 vs 0.76, P<.001). Cross-sectional area was smaller at the HP and larger at 4 and 8mm from the annular plane (3.6 vs 3.9 vs 4.1cm2, P=.001). The best correlation between two-dimensional and 3D transesophageal echocardiographic dimensions was at the HP (intraclass correlation coefficient=0.75; 95% CI, 0.59-0.86). When the HP approach was selected, there was a reduction in the percentage of patients with low flow (from 41% to 29%). A large portion of patients with aortic stenosis have funnel-shaped and elliptical LVOTs, a morphology that is more pronounced in the region farther from the annular plane. Two-dimensional LVOT measurement closer to the annular plane has the best correlation with 3D measurements. Measurement of the LVOT closer to the annular plane should be encouraged to reduce measurement errors.

3T CMR for quantification of aortic valve area - A comparison between continuity equation via phase contrast sequences and planimetric analysis

Assessment of aortic valve area (AVA) is primarily carried out by echocardiography in clinical routine. In cases of insufficient acoustic window, discrepant medical findings or suboprimal Doppler conditions, 1.5 T magnetic resonance imaging (MRI) is discussed as an non-invasive alternative imaging method for planimetry of AVA. If quantification of AVA is also possible at higher magnetic field strength had not been investigated until now. The aim of the present study was to quantify AVA using planimetry and continuity equation and correlate them with each other.

Quantification of aortic valve area at 256-slice computed tomography: Comparison with transesophageal echocardiography and cardiac catheterization in subjects with high-grade aortic valve stenosis prior to percutaneous valve replacement

Purpose The purpose of this study was to compare planimetric aortic valve area (AVA) measurements from 256-slice CT to those derived from transesophageal echocardiography (TEE) and cardiac catheterization in high-risk subjects with known high-grade calcified aortic stenosis. Methods and materials The study included 26 subjects (10 males, mean age: 79 ± 6; range, 61–88 years). All subjects were clinically referred for aortic valve imaging prior to percutaneous aortic valve replacement from April 2008 to March 2009. Two radiologists, blinded to the results of TEE and cardiac catheterization, independently selected the systolic cardiac phase of maximum aortic valve area and independently performed manual CT AVA planimetry for all subjects. Repeated AVA measurements were made to establish CT intra- and interobserver repeatability. In addition, the image quality of the aortic valve was rated by both observers. Aortic valve calcification was also quantified. Results All 26 subjects had a high-grade aortic valve stenosis (systolic opening area <1.0 cm 2) via CT-based planimetry, with a mean AVA of 0.62 ± 0.18. In four subjects, TEE planimetry was precluded due to severe aortic valve calcification, but CT-planimetry was successfully performed with a mean AVA of 0.46 ± 0.23 cm 2. Mean aortic valve calcium mass score was 563.8 ± 526.2 mg. Aortic valve area by CT was not correlated with aortic valve calcium mass score. A bias and limits of agreement among CT and TEE, CT and cardiac catheterization, and TEE and cardiac catheterization were −0.07 [–0.37 to 0.24], 0.03 [−0.49 to 0.55], 0.12 [−0.39 to 0.63] cm 2, respectively. Differences in AVA among CT and TEE or cardiac catheterization did not differ systematically over the range of measurements and were not correlated with aortic valve calcium mass score. Conclusion Planimetric aortic valve area measurements from 256-slice CT agree well with those derived from TEE and cardiac catheterization in high-risk subjects with known high-grade calcified aortic stenosis.

Quantification of aortic valve area with ECG-gated multi-detector spiral computed tomography in patients with aortic stenosis and comparison of two image analysis methods

Thirty-three consecutive patients with aortic stenosis underwent a 16-row spiral CT scan. Aortic valve planimetry was performed using two methods: double-oblique reformation (DO) and 2D-curved multiplanar reconstruction using advanced vessel analysis software (VA). The mean aortic valve area determined by transthoracic echocardiography was 0.88 ± 0.34 [0.53–1.88] and did not differ significantly from that determined by CT (DO): 0.87 ± 0.38 [0.42–1.93] ( p = 0.75) or CT (VA): 0.87 ± 0.38 [0.44–2.00] ( p = 0.69). This study demonstrates that 16-row spiral CT scan is a feasible, accurate and reproducible method for aortic valve planimetry in patients with aortic stenosis. Both methods show similar accuracy but the VA method takes slightly longer.

Aortic Stenosis: Evaluation with Multidetector CT Angiography and MR Imaging

Aortic valvular stenosis (AS) is the most common valve disease which results in the need for a valve replacement. Although a Doppler echocardiography is the current reference imaging method, the multidetector computerized tomograpghy (MDCT) and magnetic resonance imaging (MRI) have recently emerged as a promising method for noninvasive valve imaging. In this study, we briefly describe the usefulness and comparative merits of the MDCT and MRI for the evaluation of AS in terms of valvular morphology (as the causes of AS), quantification of aortic valve area, pressure gradient of flow (for assessment severity of AS), and the evaluation of the ascending aorta and cardiac function (as the secondary effects of AS). The familiarity with the MDCT and MRI features of AS is considered to be helpful for the accurate diagnosis and proper management of patients with a poor acoustic window.

Quantification of Aortic Valve Area Using Three-Dimensional Echocardiography

To determine whether the reproducibility of left ventricular outflow tract (LVOT) area measurement is greater with three-dimensional echocardiographic (3D-echo) planimetry than with conventional 2D-echo. To determine the LVOT circularity index by means of 3D-echo. To determine the usefulness of measuring the LVOT area by 3D-echo for quantifying the severity of valvular aortic stenosis. The study included 40 patients, of whom 22 had an aortic stenosis. The LVOT area was measured using both 2D-echo and 3D-echo, and the circularity index, using 3D-echo alone. In addition, the severity of valvular aortic stenosis was categorized using both 2D-echo and 3D-echo. The levels of inter- and intra-observer agreement on LVOT area measurements were better with 3D-echo. The circularity index was 1.50 (0.25), and there was a very poor linear correlation with LVOT area (r=-0.34; P=.47). Patients with valvular aortic stenosis were categorized according to the severity of their stenoses using both 2D-echo and 3D-echo. The level of agreement between the two techniques was poor (kappa=0.36). Measurements of the LVOT area made using 3D-echo were more reproducible than those made using 2D-echo. Consequently, 3D-echo may be a better technique for assessing the LVOT area. In addition, 3D-echo showed that the LVOT is elliptical in form and that its size is not related to its circularity. Moreover, 3D-echo could also be helpful in classifying the severity of valvular aortic stenosis.

Multislice Computed Tomography for Detection of Patients With Aortic Valve Stenosis and Quantification of Severity

The purpose of this study was to evaluate whether multislice computed tomography (MSCT) provides a reliable, noninvasive imaging modality for identification of patients with degenerative aortic valve stenosis (AS) by quantifying the aortic valve area (AVA) in comparison to the accepted diagnostic standard transthoracic echocardiography (TTE). Management of patients with degenerative AS is based on the severity of disease. The severity of AS in clinical practice is assessed by TTE and classified as mild, moderate, or severe according to the AVA. Forty-six patients were examined with contrast-enhanced, electrocardiogram-gated, 16-row MSCT for the evaluation of the diagnostic accuracy. In 30 patients, quantification of the AVA with MSCT was compared to TTE using the continuity equation with Doppler velocity-time integral for calculation of the AVA. Sensitivity of MSCT for the identification of patients with degenerative AS was 100%, and the specificity was 93.7%. Thirty of 46 patients had AS determined by TTE. Quantification of AVA by MSCT (mean AVA = 0.94 cm2) in patients with AS showed a good correlation to TTE (r = 0.89; p < 0.001). Bland-Altman plot illustrated good intermodality agreement between the two methods (limits of agreement, 0.20; 0.29). Multislice computed tomography may provide an accurate, noninvasive imaging technique for detection of patients with AS and quantification of AVA.