Aortic Valve Area Measurements Research Articles

Aortic Valve Area and Strain Measurements by Cardiac MRI and Transthoracic Echocardiography in Severe Aortic Stenosis with Normal Left Ventricular Function.

Transthoracic echocardiography (TTE) is the recommended imaging technique for the evaluation of patients with aortic stenosis (AS). However, in cases with inconclusive findings, cardiac magnetic resonance (CMR) planimetry is used to grade AS severity. This study aimed to compare the results derived from TTE and CMR in patients with severe AS with normal left ventricular (LV) function. In a prospective study, 20 patients with severe AS were recruited and data derived from TTE and CMR modalities were compared with the archived records of 28 age- and sex-matched healthy controls. The data included aortic valve area (AVA), MRI-derived biventricular global strains, and TTE-derived global longitudinal strain (GLS). SPSS software was used to analyze the data with independent samples t test, intraclass correlation coefficient (ICC), and Pearson correlation. P<0.05 was considered statistically significant. An excellent agreement was found in AVA values derived from CMR and TTE with an average ICC of 0.932 (95% CI=0.829-0.973). There was a significant difference in LV-GLS, LV global radial strain (GRS), right ventricular (RV) GRS, and RV global circumferential strain between the groups. A good correlation was found between CMR- and TTE-derived GLS with an average ICC of 0.721 (95% C=0.255-0.896). The mean aortic valve pressure gradient in TTE had a significant inverse linear correlation with LV-GRS in CMR (r=-0.537). All P values were <0.05. There was a good agreement between AVA and strain values derived from cardiac MRI and TTE. The myocardial strain was impaired in patients with severe AS and normal LV function and correlated with disease severity.

Slice positioning in phase-contrast MRI impacts aortic stenosis assessment

AimsTo determine the phase-contrast cardiovascular magnetic resonance imaging (PC-CMR) slice-position above aortic leaflet-attachment-plane (LAP) that provides flow-velocity, –volume and aortic valve area (AVA) measurements with best agreement to invasive and echocardiographic measurements in aortic stenosis (AS). Methods and resultsFifty-five patients with moderate/severe AS underwent cardiac catheterization, transthoracic echocardiography (TTE) and CMR. Overall, 171 image-planes parallel to LAP were measured via PC-CMR between 22 mm below and 24 mm above LAP. AVA via PC-CMR was calculated as flow-volume divided by peak-velocity during systole. Stroke volume (SV) and AVA were compared to volumetric SV and invasive AVA via the Gorlin-formula, respectively.Above LAP, SV by PC-CMR showed no significant dependence on image-plane-position and correlated strongly with volumetry (rho: 0.633, p < 0.001, marginal-mean-difference (MMD): 1 ml, 95 % confidence-interval (CI): −4 to 6). AVA assessed in image-planes 0–10 mm above LAP differed significantly from invasive measurement (MMD: −0.14 cm2, 95 %CI: 0.08–0.21). In contrast, AVA-values by PC-CMR measured 10–20 mm above LAP showed good agreement with invasive determination without significant MMD (0.003 cm2, 95 %CI: −0.09 to 0.09). Within these measurements, a plane 15 mm above LAP resulted in the lowest bias (MMD: 0.02 cm2, 95 %CI:-0.29 to 0.33). SV and AVA via TTE correlated moderately with volumetry (rho: 0.461, p < 0.001; bias: 15 ml, p < 0.001) and cardiac catheterization (rho: 0.486, p < 0.001, bias: −0.13 cm2, p < 0.001), respectively. ConclusionPC-CMR measurements at 0–10 mm above LAP should be avoided due to significant AVA-overestimation compared to invasive determination. AVA-assessment by PC-CMR between 10 and 20 mm above LAP did not differ from invasive measurements, with the lowest intermethodical bias measured 15 mm above LAP.

CARDIAC CT DIAGNOSTIC UTILITY IN THE ASSESSMENT OF BICUSPID AORTIC STENOSIS: A COMPARATIVE STUDY WITH ECHOCARDIOGRAPHY AND OPERATIONAL RESULTS

The bicuspid aortic valve is the most prevalent congenital cardiac abnormality, often leading to symptoms in middle-aged individuals. It is a significant determinant of aortic valve dysfunction in the young population. This study aimed to assess the diagnostic utility of cardiac CT in evaluating individuals with bicuspid aortic valve disease. Thirty consecutive individuals with aortic stenosis who underwent surgical valve repair from January 2021 to July 2022 at Chaudhary Pervez Ellahi Institute of Cardiology Multan, Pakistan, were included in the study. ECG-gated CT and echocardiography were performed utilising a 64-MDCT scanner. Imaging findings regarding the number of aortic valve leaflets (bicuspid or tricuspid) were compared with intraoperative observations. Statistical analysis was conducted using one-way univariate analysis of variance. The aortic valve area (AVA) was assessed using CT and echocardiography, and the results were statistically analysed using a paired Student's t-test.: Eleven 30 patients had bicuspid aortic valves, while nineteen had tricuspid aortic valves. Echocardiography failed to determine the type of aortic valve in five patients due to severe calcification. The sensitivity, specificity, positive predictive value, and negative predictive value for detecting a bicuspid aortic valve were 75.5%, 60.3%, 67.6%, and 93.5%, respectively, for echocardiography, and 93.7%, 100%, 100%, and 96.7%, respectively, for CT. CT findings were not significantly different from perioperative observations (p = 0.87), while echocardiographic results were (p &lt; 0.05). CT and echocardiography yielded AVA measurements of 0.931 ± 0.42 cm2 and 0.649 ± 0.241 cm2, respectively, with a significant difference (p &lt; 0.05). ECG-gated cardiac CT provides a reliable morphologic diagnosis of bicuspid aortic stenosis, especially in individuals with significant valve calcification.

Concomitant mitral regurgitation in patients with low-gradient aortic stenosis: an analysis from the German Aortic Valve Registry

BackgroundPatients with severe aortic stenosis (AS) frequently presented mitral regurgitation (MR), which may interfere with the standard echocardiographic measurements of mean pressure gradient (MPG), flow velocity, and aortic valve area (AVA).AimsHerein we investigated the prevalence and severity of MR in patients with severe AS and its role on the accuracy of the standard echocardiographic parameters of AS quantification.MethodsOf all patients with severe AS undergoing transcatheter or surgical aortic valve replacement enrolled in the German Aortic Registry from 2011 to 2017, 119,641 were included in this study. The population was divided based on the values of left ventricular ejection fraction ([LVEF] > 50%, LVEF 31–50%, and LVEF ≤ 30%] and AVA (0.80 to ≤ 1.00 cm2, 0.60 to < 0.80 cm2, 0.40 to < 0.60 cm2, and 0.20 to < 0.40 cm2).ResultsOverall, 77,890 (65%) patients with mild to-moderate and 4262 (4%) with severe MR were compared with 37,489 (31%) patients without MR. Patients with mild-to-moderate and severe MR presented significantly lower mPG (ΔmPG [95%CI] − 1.694 mmHg [− 2.123 to − 1.265], p < 0.0001 and − 6.954 mmHg [− 7.725 to − 6.183], p < 0.0001, respectively), that increased with LVEF impairment. Conversely, AVA did not differ (severe versus no MR: ΔAVA [95%CI]: − 0.007cm2 [− 0.023 to 0.009], p = 0.973). Increasing MR severity was associated with significant mPG reduction throughout all AVA strata, causing a low-gradient pattern, that manifested since the early stages of severe AS (LVEF > 50%: AVA 0.80 to 1.00 cm2; LVEF 31–50%: AVA 0.60 to 0.80 cm2).ConclusionsIn patients with severe AS, concomitant MR is common, contributes to the onset of a low-gradient AS pattern, and affects the diagnostic accuracy of flow-dependent AVA measurements. In this setting, a multimodality, AVA-centric approach should be implemented.Graphical abstractIn patients with severe aortic stenosis, concomitant mitral regurgitation contributes to the onset of a low-gradient pattern, warranting a multimodality, and AVA-centric diagnostic approach.

Implementation of a CT-derived correction factor to refine the measurement of aortic valve area and stroke volume using Doppler echocardiography improves grading of severity and prediction of prognosis in patients with severe aortic stenosis

AimsTo assess rates of reclassification of severity and associated 5-year survival in patients with severe aortic stenosis (AS) and preserved left ventricular ejection fraction (LVEF) after application of a CT-derived correction factor (CF) to refine the measurement of aortic valve area (AVA) and stroke volume index (SVi) using Doppler echocardiography. Methods and resultsWe enrolled 1450 patients with severe AS and preserved LVEF from a French registry. Multiplication of echocardiographic LV outflow tract diameter by a CT-derived CF of 1.13 to calculate the AVA and SVi using the continuity equation resulted in reclassification of 39% of patients from severe to moderate AS (AVA > 1 cm2) and 77% from low flow (LF, SVi < 35 ml/m2) to normal flow (NF, SVi ≥ 35 ml/m2). After application of the CF, 5-year survival with conservative management was 50 ± 4% for severe AS compared to 62 ± 4% for moderate AS (p < 0.001). A strategy of medical management followed by intervention for severe AS was associated with higher risk of mortality over 5-year follow-up after adjustment for covariates and application of the CF (HR 1.35 [1.10–1.55], p = 0.015). Five-year survival was also poorer in patients remaining in the LF group after application of the CF, even after valve intervention (72%, 66% and 47% for NF to NF, LF to NF and LF to LF, respectively). After adjustment for covariates (including intervention), risk of mortality was higher in LF to LF patients compared to NF to NF (HR 1.78 [1.25–2.56]), but similar for NF to NF and LF to NF (HR 1.20 [0.90–1.60]). ConclusionRefined accuracy of echocardiographic LV outflow tract diameter measurement using a CF of 1.13 before derivation of AVA and SVi in patients with severe AS and preserved LVEF allows improved grading of severity, and prediction of prognosis. We recommend implementation of the CF during routine echocardiography when using the continuity equation for Doppler haemodynamic measurements.

A novel approach to determine aortic valve area with phase-contrast\xa0cardiovascular magnetic resonance

BackgroundTransthoracic echocardiography (TTE) is the diagnostic routine standard for assessing aortic stenosis (AS). However, its inaccuracies in determining stroke volume (SV) and aortic valve area (AVA) call for a more precise and dependable method. Phase-contrast cardiovascular magnetic resonance imaging (PC-CMR) is a promising tool to push these boundaries. Thus, the aim of this study was to validate a novel approach based on PC-CMR against the gold-standard of invasive determination of AVA in AS compared to TTE.MethodsA total of 50 patients with moderate or severe AS underwent TTE, cardiac catheterization and CMR. AVA via PC-CMR was determined by plotting momentary flow across the valve against flow-velocity. SV by CMR was measured directly via PC-CMR and volumetrically using cine-images. Invasive SV and AVA were determined via Fick-principle and Gorlin-formula, respectively. TTE yielded SV and AVA using continuity equation. Gradients were calculated via the modified Bernoulli-equation.ResultsSV by PC-CMR (85 ± 31 ml) correlated strongly (r: 0.73, p < 0.001) with cine-CMR (85 ± 19 ml) without significant bias (lower and upper limits of agreement (LLoA and ULoA): − 41 ml and 44 ml, p = 0.83). In PC-CMR, mean pressure gradient correlated significantly with invasive determination (r: 0.36, p = 0.011). Mean AVA, as determined by PC-CMR during systole (0.78 ± 0.25 cm2), correlated moderately (r: 0.54, p < 0.001) with invasive AVA (0.70 ± 0.23 cm2), resulting in a small bias of 0.08 cm2 (LLoA and ULoA: − 0.36 cm2 and 0.55 cm2, p = 0.017). Inter-methodically, AVA by TTE (0.81 ± 0.23 cm2) compared to invasive determination showed similar correlations (r: 0.58, p < 0.001 with a bias of 0.11 cm2, LLoA and ULoA: − 0.30 and 0.52, p < 0.001) to PC-CMR. Intra- and interobserver reproducibility were excellent for AVA (intraclass-correlation-coefficients of 0.939 and 0.827, respectively).ConclusionsOur novel approach using continuous determination of flow-volumes and velocities with PC-CMR enables simple AVA measurement with no bias to invasive assessment. This approach highlights non-invasive AS grading through CMR, especially when TTE findings are inconclusive.

Valvulo-Arterial Impedance and Dimensionless Index for Risk Stratifying Patients With Severe Aortic Stenosis.

The hemodynamic effects of aortic stenosis (AS) consist of increased left ventricular (LV) afterload, reduced myocardial compliance, and increased myocardial workload. The LV in AS patients faces a double load: valvular and arterial loads. As such, the presence of symptoms and occurrence of adverse events in AS should better correlate with calculating the global burden faced by the LV in addition to the transvalvular gradient and aortic valve area (AVA). The valvulo-arterial impedance (Zva) is a useful parameter providing an estimate of the global LV hemodynamic load that results from the summation of the valvular and vascular loads. In addition to calculating the global LV afterload, it is paramount to estimate the stenosis severity accurately. In clinical practice, the management of low-flow low-gradient (LF-LG) severe AS with preserved LV ejection fraction requires careful confirmation of stenosis severity. In addition to the Zva, the dimensionless index (DI) is a very useful parameter to express the size of the effective valvular area as a proportion of the cross-section area of the left ventricular outlet tract velocity-time integral (LVOT-VTI) to that of the aortic valve jet (dimensionless velocity ratio). The DI is calculated by a ratio of the sub-valvular velocity obtained by pulsed-wave Doppler (LVOT-VTI) divided by the maximum velocity obtained by continuous-wave Doppler across the aortic valve (AV-VTI). In contrast to AVA measurement, the DI does not require the calculation of LVOT cross-sectional area, a major cause of erroneous assessment and underestimation of AVA. Hence, among patients with LG severe AS and preserved LV ejection fraction, calculation of DI in routine echocardiographic practice may be useful to identify a subgroup of patients at higher risk of mortality who may derive benefit from aortic valve replacement. This article aims to elucidate the Zva and DI in different clinical situations, correlate with the standard indexes of AS severity, LV geometry, and function, and thus prove to improve risk stratification and clinical decision making in patients with severe AS.

Discrepancy of Aortic Valve Area Measurements by Doppler vs. Biplane Stroke Volume Measurements and Utility of Combining the Different Areas in Aortic Valve Stenosis - The Asian Valve Registry.

The aortic valve area index (AVAI) in aortic stenosis (AS) is measured by echocardiography with a continuity equation using the stroke volume index by Doppler (SVIDoppler) or biplane Simpson (SVIBiplane) method. AVAIDopplerand AVAIBiplaneoften show discrepancy due to differences between SVIDopplerand SVIBiplane. The degree of discrepancy and utility of combined AVAIs have not been investigated in a large population of AS patients, and the characteristics of subjects with larger discrepancies are unknown.Methods and Results:We studied 820 patients with significant AS (AVADoppler<1.5 cm2) enrolled in the Asian Valve Registry, a prospective multicenter registry at 12 Asian centers. All-cause death and aortic valve replacement were defined as events. SVIDopplerwas significantly larger than SVIBiplane(49±11 vs. 39±11 mL/m2, P<0.01) and AVAIDopplerwas larger than AVAIBiplane(0.51±0.15 vs. 0.41±0.14 cm2/m2, P<0.01). An increase in (AVAIDoppler- AVAIBiplane) correlated with shorter height, lower weight, older age, smaller left ventricular (LV) diameter and increased velocity of ejection flow at the LV outflow tract. Severe AS by AVAIDoppleror AVAIBiplaneenabled prediction of events, and combining these AVAIs improved the predictive value of each. Discrepancy in AVAI by Doppler vs. biplane method was significantly more pronounced with increased LV outflow tract flow velocity, shorter height, lower weight, older age and smaller LV cavity dimensions. Combining the AVAIs enabled mutual and incremental value in predicting events.

A New Method for Aortic Valve Planimetry with High-Resolution 3-Dimensional MRI and Its Comparison with Conventional Cine MRI and Echocardiography for Assessing the Severity of Aortic Valvular Stenosis.

ObjectiveWe aimed to compare the aortic valve area (AVA) calculated using fast high-resolution three-dimensional (3D) magnetic resonance (MR) image acquisition with that of the conventional two-dimensional (2D) cine MR technique.Materials and MethodsWe included 139 consecutive patients (mean age ± standard deviation [SD], 68.5 ± 9.4 years) with aortic valvular stenosis (AS) and 21 asymptomatic controls (52.3 ± 14.2 years). High-resolution T2-prepared 3D steady-state free precession (SSFP) images (2.0 mm slice thickness, 10 contiguous slices) for 3D planimetry (3DP) were acquired with a single breath hold during mid-systole. 2D SSFP cine MR images (6.0 mm slice thickness) for 2D planimetry (2DP) were also obtained at three aortic valve levels. The calculations for the effective AVA based on the MR images were compared with the transthoracic echocardiographic (TTE) measurements using the continuity equation.ResultsThe mean AVA ± SD derived by 3DP, 2DP, and TTE in the AS group were 0.81 ± 0.26 cm2, 0.82 ± 0.34 cm2, and 0.80 ± 0.26 cm2, respectively (p = 0.366). The intra-observer agreement was higher for 3DP than 2DP in one observer: intraclass correlation coefficient (ICC) of 0.95 (95% confidence interval [CI], 0.94–0.97) and 0.87 (95% CI, 0.82–0.91), respectively, for observer 1 and 0.97 (95% CI, 0.96–0.98) and 0.98 (95% CI, 0.97–0.99), respectively, for observer 2. Inter-observer agreement was similar between 3DP and 2DP, with the ICC of 0.92 (95% CI, 0.89–0.94) and 0.91 (95% CI, 0.88–0.93), respectively. 3DP-derived AVA showed a slightly higher agreement with AVA measured by TTE than the 2DP-derived AVA, with the ICC of 0.87 (95% CI, 0.82–0.91) vs. 0.85 (95% CI, 0.79–0.89).ConclusionHigh-resolution 3D MR image acquisition, with single-breath-hold SSFP sequences, gave AVA measurement with low observer variability that correlated highly with those obtained by TTE.

Cardiac Imaging of Aortic Valve Area From 34 287 UK Biobank Participants Reveals Novel Genetic Associations and Shared Genetic Comorbidity With Multiple Disease Phenotypes.

The aortic valve is an important determinant of cardiovascular physiology and anatomic location of common human diseases. From a sample of 34 287 white British ancestry participants, we estimated functional aortic valve area by planimetry from prospectively obtained cardiac magnetic resonance imaging sequences of the aortic valve. Aortic valve area measurements were submitted to genome-wide association testing, followed by polygenic risk scoring and phenome-wide screening, to identify genetic comorbidities. A genome-wide association study of aortic valve area in these UK Biobank participants showed 3 significant associations, indexed by rs71190365 (chr13:50764607, DLEU1, P=1.8×10-9), rs35991305 (chr12:94191968, CRADD, P=3.4×10-8), and chr17:45013271:C:T (GOSR2, P=5.6×10-8). Replication on an independent set of 8145 unrelated European ancestry participants showed consistent effect sizes in all 3 loci, although rs35991305 did not meet nominal significance. We constructed a polygenic risk score for aortic valve area, which in a separate cohort of 311 728 individuals without imaging demonstrated that smaller aortic valve area is predictive of increased risk for aortic valve disease (odds ratio, 1.14; P=2.3×10-6). After excluding subjects with a medical diagnosis of aortic valve stenosis (remaining n=308 683 individuals), phenome-wide association of >10 000 traits showed multiple links between the polygenic score for aortic valve disease and key health-related comorbidities involving the cardiovascular system and autoimmune disease. Genetic correlation analysis supports a shared genetic etiology with between aortic valve area and birth weight along with other cardiovascular conditions. These results illustrate the use of automated phenotyping of cardiac imaging data from the general population to investigate the genetic etiology of aortic valve disease, perform clinical prediction, and uncover new clinical and genetic correlates of cardiac anatomy.

Computed tomography aortic valve calcium scoring for the assessment of aortic stenosis progression

ObjectiveCT quantification of aortic valve calcification (CT-AVC) is useful in the assessment of aortic stenosis severity. Our objective was to assess its ability to track aortic stenosis progression compared with...

Estimation of Stroke Volume and Aortic Valve Area in Patients with Aortic Stenosis: A Comparison of Echocardiography versus Cardiovascular Magnetic Resonance

In aortic stenosis, accurate measurement of left ventricular stroke volume (SV) is essential for the calculation of aortic valve area (AVA) and the assessment of flow status. Current American Society of Echocardiography and European Association of Cardiovascular Imaging guidelines suggest that measurements of left ventricular outflow tract diameter (LVOTd) at different levels (at the annulus vs 5 or 10mm below) yield similar measures of SV and AVA. The aim of this study was to assess the effect of the location of LVOTd measurement on the accuracy of SV and AVA measured on transthoracic echocardiography (TTE) compared with cardiovascular magnetic resonance (CMR). One hundred six patients with aortic stenosis underwent both TTE and CMR. SV was estimated on TTE using the continuity equation with LVOTd measurements at four locations: at the annulus and 2, 5, and 10mm below annulus. SV was also determined on CMR using phase contrast acquired in the aorta (SVCMR-PC), and a hybrid AVACMR-PC was calculated by dividing SVCMR-PC by the transthoracic echocardiographic Doppler aortic velocity-time integral. Comparison between methods was made using Bland-Altman analysis. Compared with the referent method of phase-contrast CMR for the estimation of SVCMR-PC and AVACMR-PC (SVCMR-PC 83±16mL, AVACMR-PC 1.27±0.35cm2), the best agreement was obtained by measuring LVOTd at the annulus or 2mm below (P= NS), whereas measuring 5 and 10mm below the annulus resulted in significant underestimation of SV and AVA by up to 15.9±17.3mL and 0.24±0.28cm2, respectively (P<.01 for all). Accuracy for classification of low flow was best at the annulus (86%) and 2mm below (82%), whereas measuring 5 and 10mm below the annulus significantly underperformed (69% and 61%, respectively, P<.001). Measuring LVOTd at the annulus or very close to it provides the most accurate measures of SV and AVA, whereas measuring LVOTd 5 or 10mm below significantly underestimates these parameters and leads to significant overestimation of the severity of aortic stenosis and prevalence of low-flow status.

Bioprosthetic valve fracture during valve-in-valve transcatheter aortic valve replacement

Transcatheter aortic valve replacement (TAVR) valve-in-valve (VIV) therapy has been approved for select patients with surgically inoperable bioprosthetic valves that need replacement. Bioprosthetic valve fracturing (BVF) used in conjunction with VIV TAVR can reduce transvalvular gradients and increase the aortic valve area. Twelve patients who underwent BVF VIV TAVR at a single center were retrospectively analyzed. Measurements of hemodynamics and aortic valve area were performed at baseline, after VIV TAVR, after BVF, and at 30-day follow-up. The mean Society of Thoracic Surgeons Predicted Risk of Mortality score was 7.12 ± 3.5%, with 75% of patients deemed high risk by the heart team. Mean gradients decreased from 44 mm Hg to 15 mm Hg following VIV TAVR, and to 7 mm Hg following BVF. The mean aortic valve area increased from 0.6 cm2 to 1 cm2 following VIV TAVR, and to 1.3 cm2 following BVF. There were no postoperative permanent pacemaker implantations or vascular complications, and at 30 days, only one patient had died. While we report intraoperative mortality, BVF with VIV TAVR can be performed to reduce transvalvular gradients and increase effective aortic valve area in high-surgical-risk patients with failed bioprosthetic valves.

Evaluation of aortic stenosis using cardiovascular magnetic resonance: a systematic review & meta-analysis

BackgroundAs the average age of patients with severe aortic stenosis (AS) who receive procedural intervention continue to age, the need for non-invasive modalities that provide accurate diagnosis and operative planning is increasingly important. Advances in cardiovascular magnetic resonance (CMR) over the past two decades mean it is able to provide haemodynamic data at the aortic valve, along with high fidelity anatomical imaging.MethodsElectronic databases were searched for studies comparing CMR to transthoracic echocardiography (TTE) and transoesophageal echocardiography (TEE) in the diagnosis of AS. Studies were included only if direct comparison was made on matched patients, and if diagnosis was primarily through measurement of aortic valve area (AVA).ResultsTwenty-three relevant, prospective articles were included in the meta-analysis, totalling 1040 individual patients. There was no significant difference in AVA measured as by CMR compared to TEE. CMR measurements of AVA size were larger compared to TTE by an average of 10.7% (absolute difference: + 0.14cm2, 95% CI 0.07–0.21, p < 0.001). Reliability was high for both inter- and intra-observer measurements (0.03cm2 +/− 0.04 and 0.02cm2 +/− 0.01, respectively).ConclusionsOur analysis demonstrates the equivalence of AVA measurements using CMR compared to those obtained using TEE. CMR demonstrated a small but significantly larger AVA than TTE. However, this can be attributed to known errors in derivation of left ventricular outflow tract size as measured by TTE. By offering additional anatomical assessment, CMR is warranted as a primary tool in the assessment and workup of patients with severe AS who are candidates for surgical or transcatheter intervention.

Effect of General Endotracheal Anesthesia and Mechanical Ventilation on the Echocardiographic Measurements in Severe Aortic Stenosis

Introduction: We measured the peak pressure gradient (pPG) and mean pressure gradient (mPG) obtained by transesophageal echocardiography (TEE) after induction of anesthesia and compared it with the preoperative pPG and mPG by transthoracic echocardiography (TTE) in adults with aortic stenosis (AS). We also compared the aortic valve area (AVA) measurements as obtained preoperatively by TTE versus those by TEE following induction of general endotracheal anesthesia (GETA) during the inspiratory phase, expiratory phase of the ventilatory cycle and with incremental increases in tidal volume. Materials and Methods: All patients had preoperative TTE within 1 month of surgery and was reviewed 1 day before the surgery. After anesthetic induction, precardiopulmonary bypass (CPB) TEE evaluation was done to measure mPG and pPG across AV, under steady-state conditions. Three different controlled tidal volumes: 8 ml, 10 ml, and 12 ml per kg body weight were utilized during the TEE measurements. Results: A total of 90 adults underwent aortic valve replacement from 2017 to 2018. The preoperative pPG and mPG across the AV by TTE was 96.7 ± 23.27 mmHg and 60.7 ± 18.1 mmHg, respectively. Compared to preoperative TTE, pre-CPB TEE pressure gradient during both phases of ventilation under GETA was significantly lower. The pPG and mPG were higher during inspiration as compared to those in the expiratory cycle during mechanical ventilation under GETA (pPG during inspiration = 66.63 ± 22.15 mmHg; mPG during inspiration = 38.24 ± 13.65 mmHg; pPG during expiration = 52.49 ± 19.10 mmHg; mPG during expiration = 30.76 ± 12.66 mmHg). There were no significant changes in AVA between TTE/TEE and inspiration/expiration. Conclusions: The findings of this study demonstrate that the TEE pre-CPB PGs underestimated the severity of AS; hence, the severity of AS must be interpreted with caution during GETA and mechanical ventilation (MV). In addition, PGs must be done at similar points in the respiratory cycle.

P755 Aortic valve area calculation by 3D transesophageal echocardiography: new insights in severity grading of aortic stenosis

Abstract Background Aortic stenosis (AS) grading is mainly based on aortic valve area (AVA) calculation by 2D transthoracic echocardiography (2D-TTE), using continuity equation (CE). However, 2D-TTE shows several limits, mainly due to left ventricular outflow tract (LOVT) underestimation. Different 3D imaging modalities have been proposed to overcome 2D-TTE limitations, including 3D transesophageal echocardiography manual and software measurements (3D-TEEm and 3D-TEEs) and multidetector computed tomography (MDCT). The AVA cut-off value generally used to define severe AS has been established and validated by outcome studies in which AVA was measured by 2D-TTE. This cut-off value cannot be directly extrapolated to the 3D-TEE combined approach that systematically measures larger LVOT compared with 2D-TTE. Purpose.To evaluate the diagnostic accuracy of 3D transesophageal echocardiography manual and software measurements (3D-TEEm and 3D-TEEs) in AS grading, compared with multidetector computed tomography (MDCT) as gold standard, and to identify a new cut-off for AS severity assessment. Methods 218 patients (81 ± 5.4 years, 54% male) with symptomatic normal-flow 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. Using Doppler parameters (Vmax &amp;gt;4 m/s and MPG &amp;gt;40 mmHg) to define AS severity, a receiving-operating curve (ROC) was calculated for AVA obtained with different 3D imaging modalities. Results There was a good correlation between both 3D-TEEm and 3D-TEEs and MDCT measurements (r = 0.800 and r = 0.814, respectively) and excellent agreement between 3D-TEEm and 3D-TEEs with minimum bias. 2D-TTE significantly underestimated AVA compared to 3D-TEEm, 3D-TEEs and MDCT. On the other hand, both 3D-TEEm and 3D-TEEs underestimated AVA compared to MDCT (mean AVA difference = 0.13 and =0.06 cm2, respectively). ROC curve analysis demonstrated 91% sensibility and 34% specificity for 2D-TTE AVA using a cut-off of 1 cm2 (AUC 0.732). For 3D-TEEm and 3D-TEEs, a 1 cm2cut-off resulted in 74% sensibility and 59% specificity, while a 1.2 cm2cut-off resulted in 91% sensibility and 31% specificity (AUC 0.715). MDCT showed 59% sensibility and 70% specificity using a 1 cm2 cut-off and 83% sensibility and 45% specificity using a 1.2 cm2 cut-off (AUC 0.708). Conclusion 3D-TEE represents a valuable tool for AS grading using a combined approach incorporating 3D LVOT measurements and 2D Doppler parameters in the CE. Both 3D-TEEm and 3D-TEEs AVA measurements demonstrated good correlation with MDCT and excellent reproducibility. 3D-TEE measurements underestimate AVA compared to MDCT. Given the multiparametric assessment of AS severity, a 1.2 cm2 AVA cut-off could be considered to define AS severity with emerging 3D imaging modalities.

Expert consensus document on the assessment of the severity of aortic valve stenosis by echocardiography to provide diagnostic conclusiveness by standardized verifiable documentation.

According to recent recommendations on echocardiographic assessment of aortic valve stenosis direct measurement of transvalvular peak jet velocity, calculation of transvalvular mean gradient from the velocities using the Bernoulli equation and calculation of the effective aortic valve area by continuity equation are the appropriate primary key instruments for grading severity of aortic valve stenosis. It is obvious that no gold standard can be declared for grading the severity of aortic stenosis. Thus, conclusions of the exclusive evaluation of aortic stenosis by Doppler echocardiography seem to be questionable due to the susceptibility to errors caused by methodological limitations, mathematical simplifications and inappropriate documentation. The present paper will address practical issues of echocardiographic documentation to satisfy the needs to analyze different scenarios of aortic stenosis due to various flow conditions and pressure gradients. Transesophageal and multidimensional echocardiography should be implemented for reliable measurement of geometric aortic valve area and of cardiac dimensions at an early stage of the diagnostic procedure to avoid misinterpretation due to inconsistent results.

Impact of concomitant mitral regurgitation on transvalvular gradient and flow in severe aortic stenosis: a systematic ex vivo analysis of a subentity of low-flow low-gradient aortic stenosis.

Evaluation of aortic stenosis (AS) is based on echocardiographic measurement of mean pressure gradient (MPG), flow velocity (Vmax) and aortic valve area (AVA). The objective of the present study was to analyse the impact of systemic haemodynamic variables and concomitant mitral regurgitation (MR) on aortic MPG, Vmax and AVA in severe AS. A pulsatile circulatory model was designed to study function and interdependence of stenotic aortic (AVA: 1.0 cm², 0.8 cm² and 0.6 cm²) and insufficient mitral prosthetic valves (n=8; effective regurgitant orifice area [EROA] <0.2 cm² vs. >0.4 cm²) using Doppler ultrasound. In the absence of severe MR, a stepwise increase of stroke volume (SV) and a decrease of AVA was associated with a proportional increase of aortic MPG. When MR with EROA <0.2 cm² vs. >0.4 cm² was introduced, forward SV decreased significantly (70.9±1.1 ml vs. 60.8±1.6 ml vs. 47.4±1.1 ml; p=0.02) while MR volume increased proportionally. This was associated with a subsequent reduction of aortic MPG (57.1±9.4 mmHg vs. 48.6±13.8 mmHg vs. 33.64±9.5 mmHg; p=0.035) and Vmax (5.09±0.4 m/s vs. 4.91±0.73 m/s vs. 3.75±0.57 m/s; p=0.007). Calculated AVA remained unchanged (without MR: AVA=0.53±0.04 cm² vs. with MR: AVA=0.52±0.05 cm²; p=ns). In the setting of severe AS without MR, changes of vascular resistance (SVR) and compliance (C) did not impact on aortic MPG (low SVR and C: 66±13.8 mmHg and 61.1±20 mmHg vs. high SVR and C: 60.9±9.2 mmHg and 71.5±13.5 mmHg; p=ns) In concomitant severe MR, aortic MPG and Vmax were not significantly reduced by increased SVR (36.6±2.2 mmHg vs. 34.9±5.6 mmHg, p=0.608; 3.89±0.18 m/s vs. 3.96±0.28 m/s; p=ns). Systemic haemodynamic variables and concomitant MR may potentially affect diagnostic accuracy of echocardiographic AS evaluation. As demonstrated in the present study, MPG and Vmax are flow-dependent and significantly reduced by a reduction of forward SV from concomitant severe MR, resulting in another entity of low-flow low-gradient aortic stenosis. In contrast, calculated AVA appears to be a robust parameter of AS evaluation if severe MR is present. Changes of SVR and C did not affect the diagnostic accuracy of AS evaluation.

Echocardiographic Assessment of Cardiac Structural and Functional Abnormalities in Patients With End-Stage Renal Disease Receiving Chronic Hemodialysis.

The aim of this study was to assess the echocardiographic characteristics of chronic hemodialysis (HD) patients with end-stage renal disease (ESRD) in a multicenter prospective cohort study.Methods and Results:Three hundred and fifteen patients with ESRD (67.9±10.6 years, 47.6% male) on chronic HD for ≥1 year were examined on transthoracic echocardiography, including Doppler-derived aortic valve area (AVA) measurement. Only 11.5% and 3.4% of all patients had normal left ventricular (LV) geometry and normal LV filling pattern, respectively. The majority of patients had aortic and mitral valvular calcification, and approximately 50% of all 315 patients had aortic valve narrowing with AVA <2.0 cm2. Patients were divided into 3 groups according to AVA index tertile: group 1, highest tertile; group 2, middle tertile; and group 3, lowest tertile. Group 3 was older, had a greater cardiothoracic ratio on chest X-ray, higher plasma brain natriuretic peptide and total LV afterload, and lower stroke volume index than the other 2 groups. Age and intact parathyroid hormone (PTH) level were independently associated with low AVA index. Patients with ESRD on chronic HD have a high prevalence of cardiac structural and functional abnormalities including calcified aortic sclerosis. High age and PTH were associated with aortic valve narrowing in these patients.

The effect of aortic area measurement site on the energy loss coefficient: a comparison between echocardiography and cardiac computed tomography angiography in patients with aortic stenosis.

The energy loss coefficient (ELCo) has been suggested as a more accurate indicator of aortic stenosis (AS) severity as compared to transthoracic echocardiography (TTE) aortic valve area (AVA). There are little data regarding the optimal location for aortic area (Aa) measurement needed for ELCo calculation and the agreement of ELCo with direct anatomical AVA measurement. The aim of this study was to determine the optimal site of Aa measurement for calculation of the ELCo, using cardiac computed tomography angiography (CCTA) AVA planimetry as the reference standard. We analyzed 69 patients with AS who underwent both CCTA and TTE. ELCo and CCTA planimetry AVA were compared using multiple sites for CCTA Aa measurement (sinus, sinotubular junction, or ascending aorta). CCTA AVA was 0.96±0.46cm2 . ELCo was 0.95±0.43cm2 using sinotubular junction Aa, 0.92±0.41cm2 using sinus Aa, and 0.91±0.4cm2 using the ascending aorta (P=.84, P=.13, and P=.08 compared to CCTA AVA). There was good agreement between CCTA AVA and ELCo using all Aa locations (0.89-0.90). On subgroup analysis of 16 patients most likely to be affected by pressure recovery (aortic diameter<3cm and AVA ≥1cm2 ), ELCo using the sinotubular junction Aa showed the best agreement with CCTA AVA as compared to the other Aa locations (0.84 vs 0.75-0.77). ELCo using Aa measurement at the sinotubular junction showed the best agreement with CCTA AVA. We therefore recommend using the sinotubular junction Aa for ELCo calculation.