Left Ventricular Outflow Tract Areas Research Articles

Use of two- and three-dimensional echocardiography for assessment of the left ventricular outflow tract and aortic orifice areas in dogs

Introduction/ObjectivesIn clinical practice, dogs are screened for subaortic stenosis (SAS) using two-dimensional (2DE) and Doppler echocardiography. There is no accepted antemortem diagnostic criterion to distinguish between mild SAS and unaffected, therefore additional means of evaluating the left ventricular outflow tract (LVOT) and aorta may be desirable. This study sought to determine and compare LVOT and aortic orifice areas using 2DE and three-dimensional echocardiography (3DE) in apparently healthy dogs of various breeds and somatotypes. Animals, materials, and methodsSixty-nine healthy, privately-owned dogs. The LVOT and aortic orifice areas were determined using 2DE aortic valve (AV) diameter-derived area; the continuity equation (CE); and 3DE planimetry of the LVOT, AV, sinus of Valsalva, and sinotubular junction. Orifice areas were indexed to body surface area (BSA). ResultsObtaining 3DE images and performing planimetry was feasible in all dogs. The mean indexed area measured using the 2DE AV diameter (2.85 cm2/m2) was significantly lower than that derived from 3DE AV planimetry (3.85 cm2/m2; mean difference, 1.00 cm2/m2; P<0.001). There was poor agreement between effective area calculated using the CE and the anatomic areas calculated using 2DE AV diameter and 3DE planimetry. The area calculated using the CE was less than all other calculations of area. Interobserver and intraobserver repeatability and reproducibility for 3DE planimetry were excellent. ConclusionsMethods for determining aortic orifice areas in dogs are not interchangeable and this must be taken into account if these methods are investigated in the evaluation of dogs with SAS in future.

763 Feasibility and reliability of a comprehensive three-dimensional transesophageal echocardiography screening process for transcatheter mitral valve replacement

Abstract Aims The planning of transcatheter mitral valve replacement (TMVR) requires cardiac imaging assessment to establish patient eligibility according to mitral valve anatomy, device characteristics and risk of left ventricular outflow tract (LVOT) obstruction. In this setting, computed tomography (CT) is considered the reference method. Although recent studies demonstrated that three-dimensional transesophageal echocardiographic (3D-TEE) assessment of mitral anatomy presents a good agreement compared to CT, its potential role in the TMVR planning has never been fully evaluated. To test feasibility and reliability of a comprehensive 3D-TEE screening in candidates for TMVR. Methods We performed a single-centre retrospective observational study including 59 consecutive patients referred to our centre for TMVR due to high surgical risk, who performed a pre procedural CT and 3D-TEE screening. The measurements of mitral annulus (MA), native LVOT and predicted Neo-LVOT, assessed with CT and 3D-TEE were collected in order to evaluate their concordance in the assessment of TMVR eligibility. The final suitability decision was given by the valve manufacturer based on CT measurements and then compared with the screening results obtained with 3D-TEE evaluation. 3D-TEE measurements were obtained with a post processing analysis using a novel automated software platform (3mensio Structural Heart 10.1 - 3mSH, Pie Medical Imaging, Bilthoven, Netherlands). Results Excellent correlation was found between 3D-TEE and CT measurements for MA area (r =0.85), antero-posterior diameters (r= 0.81), native LVOT (r=0.82) and Neo-LVOT areas (r=0.95) (all P-values &amp;lt;0.0001). Among 59 patients screened, 17 did not undergo the intervention because were found ineligible due to small predicted neo-LVOT, too small or too large MA area. Among the 42 patients with a successful screening, 32 underwent TMVR and all of them showed a correct implantation and no LVOT obstruction at post procedural echocardiographic evaluation. An almost perfect agreement among CT and 3D-TEE was found in assessing the eligibility for TMVR implantation (Cohen kappa 0.82, P&amp;lt;0.001). Interobserver and intraobserver agreements were found excellent for the parameters appraised with ICCs &amp;gt;0.80. Conclusions 3D-TEE appraisements of MA dimensions, native LVOT and Neo-LVOT are feasible in patients candidate for TMVR, showing good correlations with CT measurements and high accuracy to predict TMVR screening success.

Assessment of the left ventricular outflow tract during cardiac anaesthesia with biplane transoesophageal echocardiography: An observational study.

Assessment of left ventricular outflow tract (LVOT) area is a key component of quantification of aortic stenosis and stroke volume. Current international guidelines recommend measurement of the LVOT diameter with two-dimensional (2D) echocardiography and assume a circle. This may lead to erroneous measures of aortic valve area and adversely affect peri-operative decision making. Multiplane orthogonal (biplane) and three-dimensional (3D) echocardiography imaging may allow more accurate calculation of LVOT, aortic valve area and stroke volume. To evaluate the shape and area of the LVOT with conventional 2D diameter, short axis cross-sectional planimetry with biplane imaging and 3D multiplane reconstruction in patients undergoing cardiac surgery with transoesophageal echocardiography (TOE). A retrospective observational study. A single centre university hospital. 119 patients undergoing cardiac surgery with TOE. None. Measurements of the shape and area of the LVOT with standard 2D TOE, short axis biplane imaging and 3D TOE. The LVOT shape is elliptical in 70% of patients. The (mean ± SD, [range]) LVOT cross-sectional area with 2D TOE was 4.29 cm2 ± 0.98, [2.46 to 6.70], with biplane was 4.68 cm2 ± 1.03, [2.92 to 7.30] and with 3D was 4.59 cm2 ± 0.99, [2.78 to 7.10]. There was a statistically significant difference (P < 0.001) in the three pairwise comparisons. 2D LVOT area had large bias (7 to 9%) and wider limits of agreement (LOA) with both biplane and 3D LVOT area (-17 to 36%). Biplane and 3D LVOT areas had small bias (1.8%) with relatively narrow LOA (-8 to 11%). 2D diameter measures of the LVOT assuming a circle underestimate LVOT area, underestimate aortic valve area and increase the apparent severity of aortic stenosis. This may lead to inappropriate aortic valve intervention. In a busy operating room environment, we suggest that for the calculation of stroke volume and aortic valve area, LVOT area is measured with biplane imaging. Observational study with no interventions so trial not registered.

The Left Ventricular Outflow Tract Changes in Size and Shape From Pre- to Post-Cardiopulmonary Bypass: Three-Dimensional Transesophageal Echocardiography

To compare two-dimensional (2D) and 3D imaging of the left ventricular outflow tract (LVOT) and to evaluate geometric changes pre- to post-cardiopulmonary bypass (CPB). Retrospective review of intraoperative transesophageal echocardiographic examinations. Single academic medical center. The study comprised 69 cardiac surgical patients-27 with aortic valve stenosis (AS) and 42 without AS. Two-dimensional and 3D analysis of the LVOT pre- and post-CPB. Pre- and post-CPB 2D assessment of LVOT diameter (2D LVOTd) was compared with 3D analysis of the minor (3D LVOTd-min) and major diameters. LVOT areas (LVOTa) were calculated using LVOTd to yield 2D LVOTa and 3D LVOTa-min. These were compared with LVOTa measured by planimetry (3D LVOTa-plan). An ellipticity ratio (ER) (ER = 3D minor/major axes) was calculated. The 2D LVOTd was larger than the 3D LVOTd-min before (2.12 v 2.02 cm respectively (resp); p < 0.001) and after (1.96 v 1.85 cm resp; p = 0.04) CPB. Compared with pre-CPB, there were significant decreases in the 2D LVOTd (p = 0.003) and the 3D LVOTd-min (p < 0.001) post-CPB. Ellipticity increased after CPB (ER 0.80 v 0.75; p = 0.004), and the 2D LVOTa was larger than the 3D LVOTa-min before CPB (3.60 cm2v 3.28 cm2; p < 0.001) and less so after CPB (3.11 cm2v 2.79 cm2; p = 0.053). Compared with pre-CPB, all LVOTa measurements decreased significantly after CPB (p < 0.001). The 3D LVOTa-plan decreased after CPB by approximately 10% (4.05 cm2v 3.61 cm2; p < 0.001). The 2D LVOTa and 3D LVOTa-min underestimated the 3D LVOTa-plan before and after CPB (p < 0.001) by 11% to 14% and 19% to 23%, respectively. When compared with non-AS patients, patients with AS had a smaller LVOTa pre- and post-CPB (p < 0.05). The LVOT is smaller and more elliptical after CPB. Patients with AS have a smaller LVOT compared with non-AS patients. LVOTa calculated using LVOTd underestimates the 3D LVOTa-plan by as much as 23% depending on patient type and timing of measurement. Accurate assessment of the LVOT requires 3D imaging.

Aortic valve area calculation using 3D transesophageal echocardiography: Implications for aortic stenosis severity grading.

Aortic stenosis (AS) grading by 2D-transthoracic echocardiography (2D-TTE) aortic valve area (AVA) calculation is limited by left ventricular outflow tract (LVOT) area underestimation. The combination of Doppler parameters with 3D LVOT area obtained by multidetector computed tomography (MDCT) can improve AS grading, reconciling discordant 2D-TTE findings. This study aimed to systematically evaluate the role of 3D-transesophageal echocardiography (3D-TEE) in AS grading using MDCT as reference standard. 288 patients (81±6.3years, 52.4% female) with symptomatic AS underwent 2D-TTE, 3D-TEE, and MDCT for transcatheter aortic valve implantation. Doppler parameters were combined with 3D LVOT areas measured by manual and semi-automated software 3D-TEE and by MDCT to calculate AVA, reassessing AS severity. Both 3D-TEE modalities demonstrated good correlation with MDCT, with excellent intra-observer and inter-observer variability. Compared to MDCT, 3D-TEE measurements significantly underestimated AVA (PANOVA <.0001), although the difference was clinically acceptable. Compared to 2D-TTE, 3D-TEE manual and semi-automated software reclassified severe AS in 21.9% and 25.2% of cases, respectively (P<.0001), overcame grading parameters discordance in more than 40% of cases in patients with low-gradient AS (P<.0001) and reduced the proportion of low-flow states in nearly 75% of cases when combined to stroke volume index assessment (P<.0001). 3D-TEE imaging modalities showed a reduction in the proportion of patients with low-gradient and pathological AVA as defined by 2D-TTE, and improved AVA and mean pressure gradient agreement with current guidelines cutoff values. 3D-TEE AVA calculation is a reliable tool for AS grading with excellent reproducibility and good correlation with MDCT measurements.

Impact of anatomical variations of the left ventricular outflow tract on stroke volume calculation by Doppler echocardiography in aortic stenosis.

Accurate calculation of stroke volume (SV) by Doppler echocardiography is important for the assessment of aortic stenosis (AS), which may be impacted by anatomical variations of left ventricular outflow tract (LVOT). Patients with AS (n=64) were studied using computed tomography (CT) and transthoracic echocardiography (TTE). Anatomical variations of LVOT areas were measured at (a) the aortic annulus (Aa ); (b) 5mm (A5 ); and (c) 10mm below the annulus (A10 ) by CT. LVOT diameters were also measured by 2D TTE at these three levels for calculation of LVOT areas. Stroke volumes (SV) were calculated using continuity equation. The impacts of anatomical variations of LVOT on SV calculation were evaluated. Anatomical LVOT area increased from Aa to A10 (5.0±0.9cm2 vs 5.8±1.9cm2 , P<.01). Differences between TTE-calculated LVOT areas and anatomical areas were most significant at A10 due to elongation of mediolateral diameters with variable changes in anteroposterior diameters (5.8±1.9cm2 vs 3.4±1.1cm2 , P<.001). Although mean calculated SV by TTE was not significant at different LVOT levels (Aa 69±22mL, vs A5 66±21mL, vs A10 66±28±22mL, P>.05), the most significant variations in individuals were at A10 levels (ΔSV: 8.2±6.4mL, 12±9%). Variations of LVOT anatomy in individuals with AS significantly impact the SV calculated by Doppler echocardiography. These features should be taken into account for AS diagnosis and a clinical decision-making for intervention.

Aortic valve area using computed tomography-derived correction factor to improve the validity of left ventricular outflow tract measurements.

Given the inherent inaccuracies stemming from the assumption that the left ventricular outflow tract (LVOT) is circular, this study aimed to improve the accuracy of transthoracic echocardiography (TTE)-based aortic valve area (AVA) calculation using continuity equation (CE) by introducing a correction factor (CF) derived from multidetector computed tomography angiography (MDCTA) images and validate it in aortic stenosis (AS) patients. This retrospective study used MDCTA images of 400 patients for modeling and 403 TTE dataset for validation. Echocardiographic parasternal long-axis view was modeled using MDCTA, and LVOT diameter (D1) was measured. Direct planimetry of LVOT area was performed and subsequently converted into a theoretical circle. The assumed circle (D2) diameter was derived, and D2/D1 was calculated and termed as the CF. The CF was 1.13, and it improved the agreement between MDCTA- and TTE-derived LVOT areas and correlation between AVA and peak velocity, mean pressure gradient, and velocity ratio. In discordant subgroups of severe AS, the CF reclassified patients to moderate AS in 40% in the low flow (LF), low gradient (LG), and low ejection fraction (EF) group; 53% in the LF, LG, and normal EF group; and 68% in the LF, high gradient, and normal EF group. CF of 1.13 derived from MDCTA improved the accuracy of TTE-derived LVOT area and AVA and improved correlation with hemodynamic variables in AS patients. Reclassification of AS patients using CF may have clinical applicability for patient selection for early intervention.

P300 Reappraisal of aortic stenosis severity grading inconsistencies using 3D aortic valve area

Abstract Funding Acknowledgements no fundings Background Different 3D imaging modalities have been proposed to overcome the limitations in aortic stenosis (AS) grading derived from underestimation of left ventricular outflow tract (LVOT) area by 2D transthoracic echocardiography (2D-TTE). Transesophageal echocardiography manual and software measurements (3D-TEEm and 3D-TEEs) and multidetector computed tomography (MDCT) have been recently been shown as valuable tools for AS grading using a combined approach incorporating 3D LVOT measurements and 2D Doppler parameters in the continuity equation (CE). This approach results particularly useful in cases of 2D-TTE grading inconsistence. As all these 3D imaging modalities provide larger AVA compared to 2D-TTE, we have recently proposed a 1.2 cm2 AVA cut-off could to define AS severity with 3D-TEE and MDCT. Purpose To compare AVA measurements with 3D-TEEm and 3D-TEEs using MDCT as gold standard in order to assess inconsistencies and evaluate the impact of a 1.2 cm2 AVA cut-off on AS severity grading. Methods 288 patients (80 ± 11 years, 52.4% male) with symptomatic AS underwent 2D-TTE, 3D-TTEm, 3D-TEEs and MDCT within the same hospitalization. 3D-TEE LVOT reconstruction was performed manually and with semi-automated software (EchoPAC version 201). 3D-TEEm, 3D-TEEs and MDCT LVOT areas were combined with 2D-TTE Doppler parameters to calculate AVA by CE. The grading of AS was reassessed in patients with low flow-low gradient AS using a 1.2 cm2 cut-off for severity. Results Patients were classified according to flow state (stroke volume index ≥35 ml/m2 or &amp;lt;35 ml/m2) and mean pressure gradient (MPG ≥40 mmHg or &amp;lt;40 mmHg) into 4 groups: normal flow-high gradient (NF-HG; n 173, 60%), normal flow-low gradient (NF-LG; n 45, 15.5%), low flow-high gradient (LF-HG; n 39, 13.5%), and low flow-low gradient (LF-LG; n 31, 11%) AS. Among patients classified as LF-LG AS, 95%, 55%, 29% and 55% of cases were classified as severe by 2D-TTE, 3D-TEEm, 3D-TEEs and MDCT respectively using a 1.0 cm2 AVA cut-off. When the proposed severity AVA cut-off of 1.2 cm2 was applied using 3D imaging modalities, the proportion of severe AS significantly increased to 84% (p = 0.012) (3D-TEEm), 52% (p = 0.046) (3D-TEEs) and 71% (p &amp;lt; 0.001) (MDCT) respectively. Conclusion The use of a 1.2 cm2 AVA cut-off for 3D-TEE and MDCT significantly reduces the number of cases of inconsistently graded AS, increasing the proportion of patients with severe AS.

The relation of left ventricular geometry to left ventricular outflow tract shape and stroke volume index calculations.

Stroke volume (SV) and aortic valve area calculations require the left ventricular (LV) outflow tract (LVOT) or aortic annular area calculations that involve squaring the respective diameters. Area calculation errors became evident with transcatheter aortic valve replacement where areas were underestimated due to an elliptical annulus. We hypothesized that LVOT and annular shape are more elliptical in patients with greater relative LV wall thickness (RWT) leading to underestimation of SV index using 2D Doppler echocardiography. We studied 203 consecutive patients referred to an outpatient noninvasive laboratory for Doppler echocardiograms which included acceptable 3-dimensional images. 3-dimensional assessment of the LVOT at 3-5mm from the valve insertion, at the site of valve insertion, and at the sinus of Valsalva (SOV) was performed with assessment of the minor axis (MN), major axis (MJ), and areas at mid-systole. SV index was calculated from LVOT and annular diameters obtained from 2-dimensional echo and from 3-dimensional LVOT areas. An inverse relation of RWT with MN/MJ at mid-systole for the LVOT (r=0.5812, P<0.0001) and annulus (r=0.6865, P<0.0001) was noted. LVOT and annulus areas were similar among groups at mid-systole. SV index calculated from 2D LVOT dimensions was significantly smaller than using 3D LVOT areas (35.6±8.9 vs 53.6±16.1mL, P<0.0001). There is an inverse relation between MN/MJ and RWT at the LVOT and aortic annulus despite the LVOT and annular areas being similar across most geometries resulting in SV index underestimation calculated using LVOT diameters vs 3D LVOT areas.

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

Aortic valve area (AVA) is usually estimated by the continuity equation (CE) in which the left ventricular outflow tract (LVOT) area is calculated assuming a circular shape. This study aimed to compare measurements of LVOT area using standard 2D transthoracic echocardiography (2DTTE), 3D transesophageal echocardiography (3DTEE), and multidetector computed tomography (MDCT) and assess their relative impact on AVA estimated by the CE. We prospectively enrolled 60 patients with severe aortic stenosis (AS) referred for transcatheter aortic valve replacement (TAVR) who systematically underwent 2DTTE, 3DTEE, and MDCT. Mean LVOT areas obtained by 2DTTE (3.28±0.66cm2 ) and 3DTEE (3.95±0.90cm2 ) were significantly underestimated when compared to the mean MDCT LVOT area (4.31±0.99cm2 ). LVOT was rather elliptical than round, with a mean eccentricity index of 1.47 (ratio of maximum to minimum LVOT diameters) assessed by MDCT. Mean TTE AVA estimated by the CE was 0.62±0.20cm2 . Substitution of 2DTTE LVOT area by 3DTEE LVOT area in the CE resulted in AVA of 0.74±0.24cm2 , while using MDCT LVOT area held an AVA of 0.80±0.24cm2 . MDCT-derived AVA was similar to MDCT planimetric AVA and allowed 24% of patients to be reclassified from severe to moderate AS. 2DTTE and 3DTEE underestimate LVOT area when compared to MDCT with significant impact on AVA estimation. Assessment through MDCT fusion AVA may be of incremental value in patients with discrepant severity criteria for AS.

Abstract 20012: Measuring the Sinuses of Valsalva and Left Ventricular Outflow Tract by Cardiac Computed Tomographic Angiography: Incremental Value for Sizing the Valve for Transcatheter Aortic Valve Replacement?

Background: Accurate assessment of aortic annulus size (AoA) is critical for insuring successful transcatheter aortic valve replacement (TAVR) as well as to minimize para-valvular regurgitation. However, the AoA is occasionally difficult to assess due to challenges caused by annular calcification, motion artifact and improper CT gating. Proper TAVR valve size and sealing is dependent more than just AoA, but rather multiple other measurements including the left ventricular outflow tract (LVOT) diameters and sinuses of Valsalva. We hypothesized that the measurement of sinuses of Valsalva and LVOT by cardiac computed tomographic angiography (CCTA) imaging are important adjunctive measurements in determining the ideal valve size for TAVR. Methods: Consecutive patients evaluated for TAVR underwent single phase, prospective ECG gated CCTA with contrast to evaluate the aortic valve anatomy. Measurements of annular, coronary height, left ventricular outflow tract diameters and areas were performed. Findings were analyzed using ANOVA and regression models. Results: CCTA was performed on 87 patients being evaluated for TAVR. Increasing body surface area (BSA) is weakly associated with AoA and somewhat correlated with sinotubular junction measurements. Sinuses of Valsalva and LVOT are strongly predictive of AoA and the ideal valve size (r 2 =0.66, r 2 =0.86, respectively). Sinuses of Valsalva and LVOT are helpful predictive adjuncts along with AoA in determining the ideal valve size for TAVR, specifically in those with the smallest and largest annular areas (figure 1). Coronary heights were not associated with AoA or BSA. Conclusion: There is a strong association between the annulus size and sinuses of Valsalva diameter and LVOT measured by CCTA. This finding is particularly useful in determining the appropriate valve size in those borderline cases or when accurate aortic annulus dimensions are difficult to obtain.

Comparison of Left Ventricular Outflow Geometry and Aortic Valve Area in Patients With Aortic Stenosis by 2-Dimensional Versus 3-Dimensional Echocardiography

The present study sought to elucidate the geometry of the left ventricular outflow tract (LVOT) in patients with aortic stenosis and its effect on the accuracy of the continuity equation-based aortic valve area (AVA) estimation. Real-time 3-dimensional transesophageal echocardiography (RT3D-TEE) provides high-resolution images of LVOT in patients with aortic stenosis. Thus, AVA is derived reliably with the continuity equation. Forty patients with aortic stenosis who underwent 2-dimensional transthoracic echocardiography (2D-TTE), 2-dimensional transesophageal echocardiography (2D-TEE), and RT3D-TEE were studied. In 2D-TTE and 2D-TEE, the LVOT areas were calculated as π × (LVOT dimension/2)(2). In RT3D-TEE, the LVOT areas and ellipticity ([diameter of the anteroposterior axis]/[diameter of the medial-lateral axis]) were evaluated by planimetry. The AVA is then determined using planimetry and the continuity equation method. LVOT shape was found to be elliptical (ellipticity of 0.80 ± 0.08). Accordingly, the LVOT areas measured by 2D-TTE (median 3.7 cm(2), interquartile range 3.1 to 4.1) and 2D-TEE (median 3.7 cm(2), interquartile range 3.1 to 4.0) were smaller than those by 3D-TEE (median 4.6 cm(2), interquartile range 3.9 to 5.3; p <0.05 vs both 2D-TTE and 2D-TEE). RT3D-TEE yielded a larger continuity equation-based AVA (median 1.0 cm(2), interquartile range 0.79 to 1.3, p <0.05 vs both 2D-TTE and 2D-TEE) than 2D-TTE (median 0.77 cm(2), interquartile range 0.64 to 0.94) and 2D-TEE (median 0.76 cm(2), interquartile range 0.62 to 0.95). Additionally, the continuity equation-based AVA by RT3D-TEE was consistent with the planimetry method. In conclusion, RT3D-TEE might allow more accurate evaluation of the elliptical LVOT geometry and continuity equation-based AVA in patients with aortic stenosis than 2D-TTE and 2D-TEE.

Assessment of the Aortic Root Using Real-Time 3D Transesophageal Echocardiography

Precise evaluation of the aortic root geometry prior to transcatheter aortic valve implantation is important for procedural success in patients with aortic stenosis (AS). To determine the potential for 3-dimensional transesophageal echocardiography (3DTEE), the aims of the present study were: (1) to assess the accuracy of 3DTEE measurements of the aortic root using multidetector computed tomography (MDCT) as a reference, and (2) to examine whether aortic root geometry differs between patients with and without AS. 3DTEE and contrast-enhanced MDCT were performed in 35 patients. Multiplanar reconstruction was used to measure the left ventricular outflow tract (LVOT) and aortic annulus diameter/area, aortic valve area (AVA), and distances between the annulus and coronary artery ostium. The same 3DTEE measurements were performed in patients with (n=71) and without AS (n=80). Aortic annular and LVOT areas measured by 3DTEE were slightly but significantly smaller compared with values obtained with MDCT. Both methods revealed that the aortic annulus and LVOT have an oval shape. Aortic annular and LVOT area, AVA and the distances between the aortic annulus and the coronary ostia correlated well between the 2 modalities. Only minor differences in aortic root geometry were observed between patients with AS and those without. The geometry of the aortic annulus can be reliably evaluated using 3DTEE as an alternative to MDCT for the assessment of aortic root.

Comparison of Aortic Root Dimensions and Geometries Before and After Transcatheter Aortic Valve Implantation by 2- and 3-Dimensional Transesophageal Echocardiography and Multislice Computed Tomography

3D transesophageal echocardiography (TEE) may provide more accurate aortic annular and left ventricular outflow tract (LVOT) dimensions and geometries compared with 2D TEE. We assessed agreements between 2D and 3D TEE measurements with multislice computed tomography (MSCT) and changes in annular/LVOT areas and geometries after transcatheter aortic valve implantations (TAVI). Two-dimensional circular (pixr(2)), 3D circular, and 3D planimetered annular and LVOT areas by TEE were compared with "gold standard" MSCT planimetered areas before TAVI. Mean MSCT planimetered annular area was 4.65+/-0.82 cm(2) before TAVI. Annular areas were underestimated by 2D TEE circular (3.89+/-0.74 cm(2), P<0.001), 3D TEE circular (4.06+/-0.79 cm(2), P<0.001), and 3D TEE planimetered annular areas (4.22+/-0.77 cm(2), P<0.001). Mean MSCT planimetered LVOT area was 4.61+/-1.20 cm(2) before TAVI. LVOT areas were underestimated by 2D TEE circular (3.41+/-0.89 cm(2), P<0.001), 3D TEE circular (3.89+/-0.94 cm(2), P<0.001), and 3D TEE planimetered LVOT areas (4.31+/-1.15 cm(2), P<0.001). Three-dimensional TEE planimetered annular and LVOT areas had the best agreement with respective MSCT planimetered areas. After TAVI, MSCT planimetered (4.65+/-0.82 versus 4.20+/-0.46 cm(2), P<0.001) and 3D TEE planimetered (4.22+/-0.77 versus 3.62+/-0.43 cm(2), P<0.001) annular areas decreased, whereas MSCT planimetered (4.61+/-1.20 versus 4.84+/-1.17 cm(2), P=0.002) and 3D TEE planimetered (4.31+/-1.15 versus 4.55+/-1.21 cm(2), P<0.001) LVOT areas increased. Aortic annulus and LVOT became less elliptical after TAVI. Before TAVI, 2D and 3D TEE aortic annular/LVOT circular geometric assumption underestimated the respective MSCT planimetered areas. After TAVI, 3D TEE and MSCT planimetered annular areas decreased as it assumes the internal dimensions of the prosthetic valve. However, planimetered LVOT areas increased due to a more circular geometry.

Direct measurement of left ventricular outflow tract by transthoracic real-time 3D-echocardiography increases accuracy in assessment of aortic valve stenosis

Background Evaluation of aortic valve stenosis is a major clinical application of echocardiography. The widely employed continuity equation requires determination of the left ventricular outflow tract (LVOT) area. We aimed at testing whether direct area measurement in a volume data set is superior to conventional calculation from the LVOT diameter. Methods We performed LVOT measurement in 20 normal subjects and 83 patients with moderate to severe aortic stenosis with a transthoracic real-time three-dimensional echocardiography (3D-TTE) technique in two systolic frames. The off-line 3D-evaluation allows full choice of section planes within the acquired volume data set. The aortic valve area was calculated from systolic LVOT areas. These results were compared to area values obtained by M-mode LVOT-diameters (area = π ⁎ ( d / 2) 2). In addition, the calculated aortic valve orifices were compared to invasive measurements or direct planimetry in the transthoracic or transesophageal examination. Results Two independent observers found a reduction in LVOT area during systole ( p < 0.001). Often a more ellipsoid-like shaped LVOT resulted at end-systole which was shown by a reduction ( p < 0.001) of the LVOT longitudinal to oblique axis ratio. 3D-TTE determination of aortic valve orifice areas (mean difference: − 0.04 ± 0.09 cm 2) showed a lesser deviation from the invasively or planimetrically measured areas than conventionally calculated LVOT areas (mean difference: − 0.1 ± 0.1 cm 2) using the continuity equation ( p < 0.001). Conclusions The tested transthoracic 3D-echocardiography technique offers non-invasive measurement of the LVOT and aortic valve area based on the continuity equation during systole and thus improves accuracy and, additionally, agreement of aortic valvular area determination with invasive and direct measurements.

Echocardiographic Assessment of the Left Ventricular Outflow Tract in the Boxer

Background: Soft, variable ejection murmurs are common in Boxers and are associated with increased left ventricular outflow tract (LVOT) ejection velocities. Whether these murmurs are physiologic or indicate mild aortic stenosis is controversial. Ejection velocity is impacted by LVOT area and ventricular stroke volume (SV), suggesting that these variables are pertinent to murmur development. Hypothesis: Boxers with ejection murmurs have a smaller LVOT and equivalent SV indices, compared with values in dogs without murmurs. Animals: Three age‐and weight‐matched groups of dogs—15 Boxers with soft ejection murmurs (group I); 15 Boxers without murmurs (group II); and 15 nonBoxer dogs without murmurs (group III) — were studied. Methods: All dogs underwent 2‐dimensional and Doppler echocardiographic examinations. The LVOT size at multiple levels; LVOT ejection velocity, stroke distance, and SV index; and right ventricular SV index were determined and compared by analysis of variance. Results: Indexed LVOT areas in Boxer groups were not different, but were significantly smaller than those of non‐Boxer dogs. Ejection velocities and stroke distances were significantly different across all groups, with group I having the highest and group III having the lowest values. Doppler SV indices (ml/m2) for group‐I versus group‐II Boxers were 70±16(SD) versus 62±12 for the LVOT (P= .27) and 58±12 versus 48±9 for the right ventricle (P= .14). Conclusions and clinical importance: These data suggest that a relatively smaller LVOT in Boxers predisposes them to increased ejection velocity and development of murmurs. The contribution of SV to the genesis of these often labile murmurs requires additional study.

Echocardiographic Assessment of the Left Ventricular Outflow Tract in the Boxer

Soft, variable ejection murmurs are common in Boxers and are associated with increased left ventricular outflow tract (LVOT) ejection velocities. Whether these murmurs are physiologic or indicate mild aortic stenosis is controversial. Ejection velocity is impacted by LVOT area and ventricular stroke volume (SV), suggesting that these variables are pertinent to murmur development. Boxers with ejection murmurs have a smaller LVOT and equivalent SV indices, compared with values in dogs without murmurs. Three age- and weight-matched groups of dogs--15 Boxers with soft ejection murmurs (group I); 15 Boxers without murmurs (group II); and 15 nonBoxer dogs without murmurs (group III)--were studied. All dogs underwent 2-dimensional and Doppler echocardiographic examinations. The LVOT size at multiple levels; LVOT ejection velocity, stroke distance, and SV index; and right ventricular SV index were determined and compared by analysis of variance. Indexed LVOT areas in Boxer groups were not different, but were significantly smaller than those of non-Boxer dogs. Ejection velocities and stroke distances were significantly different across all groups, with group I having the highest and group III having the lowest values. Doppler SV indices (ml/m2) for group-I versus group-II Boxers were 70 +/- 16(SD) versus 62 +/- 12 for the LVOT (P = .27) and 58 +/- 12 versus 48 +/- 9 for the right ventricle (P = .14). These data suggest that a relatively smaller LVOT in Boxers predisposes them to increased ejection velocity and development of murmurs. The contribution of SV to the genesis of these often labile murmurs requires additional study.

838 Direct measurement of left ventricular outflow tract by newly developed transthoracic real-time-3D-echocardiography increases accuracy in assessment of aortic valve stenosis

Background: Evaluation of aortic valve stenosis is a major clinical application of echocardiography. The widely employed continuity equation requires determination of the left ventricular outflow tract (LVOT) area. We aimed at testing whether direct area measurement in a volume data set is superior to conventional calculation from the LVOT diameter. Methods: We performed LVOT measurement in 20 normal subjects and 83 patients with moderate to severe aortic stenosis with a transthoracic real-time three-dimensional echocardiography (3D-TTE) technique in two systolic frames. The off-line 3D-evaluation allows full choice of section planes within the acquired volume data set. The aortic valve area was calculated from systolic LVOT areas. These results were compared to area values obtained by M-mode LVOT-diameters (area= π ⁎(d/2) 2 ). In addition, the calculated aortic valve orifices were compared to invasive measurements or direct planimetry in the transthoracic or transesophageal examination. Results: Two independent observers found a reduction in LVOT area during systole (pb0.001). Often a more ellipsoid-like shaped LVOT resulted at end-systole which was shown by a reduction (pb0.001) of the LVOT longitudinal to oblique axis ratio. 3D-TTE determination of aortic valve orifice areas (mean difference: −0.04±0.09 cm 2 ) showed a lesser deviation from the invasively or planimetrically measured areas than conventionally calculated LVOT areas (mean difference: −0.1±0.1 cm 2 ) using the continuity equation (pb0.001). Conclusions: The tested transthoracic 3D-echocardiography technique offers non-invasive measurement of the LVOT and aortic valve area based on the continuity equation during systole and thus improves accuracy and, additionally, agreement of aortic valvular area determination with invasive and direct measurements. © 2008 Elsevier Ireland Ltd. All rights reserved.