Impact of Pressure Recovery Adjustment on Aortic Valve Area Classification of Disease Severity in Transcatheter Aortic Valve Replacement Patients.

OBJECTIVES: To determine the impact of pressure recovery (PR) adjustment on disease severity grading in patients with severe aortic stenosis. The authors hypothesized that accounting for PR would result in echocardiographic reclassification of aortic stenosis severity in a significant number of patients. DESIGN: A retrospective observational study between October 2013 and February 2021. SETTING: A single-center, quaternary-care academic center. PARTICIPANTS: Adults (≥18 years old) who underwent transcatheter aortic valve implantation (TAVI). INTERVENTIONS: TAVI. MEASUREMENTS AND MAIN RESULTS: A total of 342 patients were evaluated in this study. Left ventricle mass index was significantly greater in patients who continued to be severe after PR (100.47 ± 28.77 v 90.15 ± 24.03, p = < 0.000001). Using PR-adjusted aortic valve area (AVA) resulted in the reclassification of 81 patients (24%) from severe to moderate aortic stenosis (AVA >1.0 cm2). Of the 81 patients who were reclassified, 23 patients (28%) had sinotubular junction (STJ) diameters >3.0 cm. CONCLUSION: Adjusting calculated AVA for PR resulted in a reclassification of a significant number of adult patients from severe to moderate aortic stenosis. PR was significantly larger in patients who reclassified from severe to moderate aortic stenosis after adjusting for PR. PR appeared to remain relevant in patients with STJ ≥3.0 cm. Clinicians need to be aware of PR and how to account for its effect when measuring pressure gradients with Doppler.

Wall shear rate and energy loss coefficient measures using conventional Doppler ultrasound do not predict carotid plaque progression.

Background: The rate of carotid plaque progression is believed to be related to blood flow hemodynamics and shear stress. Our objective was to determine if wall shear rate (WSR) and the energy loss coefficient (ELC) measured by Doppler ultrasound could predict atherosclerotic carotid disease progression. Patients and methods: Patients at a large tertiary center with an initial ultrasound between 2016 and 2018 with a significant carotid plaque were included if they had at least one 6 months follow-up comparative study. Stenosis progression was assessed according to the NASCET (The North American Symptomatic Carotid Endarterectomy Trial) percentage criterion. Results: The average annual progression rate for the 74 plaques included was 5.7% NASCET per year. We identified 18 plaques with ≥10% NASCET progression and 56 plaques without significant progression <10% NASCET. Among the plaques with progression, only four plaques had progression greater than 20% NASCET. Median WSR was 6266 s-1 [5813-8974] in plaques with progression and 6564 s-1 [5285-8766] in stable plaques (p=0.643). Median ELC was 3.86 m2 [2.78-5.53] in plaque with progression and 4.32 m2 [3.42-6.81] in stable plaques (p=0.296). Conclusions: Although it is a widely accepted hypothesis that shear stress and hemodynamics of the carotid bifurcation contribute to plaque progression, we found that WSR and ELC estimated by Doppler ultrasound do not reliably predict atherosclerotic plaque progression in the carotid artery. Other ultrasound modalities, such as 3D imaging, may be used to assess the influence of plaque geometry and hemodynamics in plaque progression.

Correction and laboratory investigation for energy loss coefficient of square-edged orifice plate.

A lot of studies have shown that the hydraulic characteristics of orifice plate are mainly controlled by its contraction ratio, but the thickness of square-edged orifice plate also has many impacts on energy loss characteristics. The primary objective of this study was to investigated the effects of square-edged orifice plate thickness on energy loss characteristics. In this paper, the effects of square-edged orifice plate thickness on energy loss characteristics are investigated by numerical simulation using CFD. Orifice plate discharge tunnel is axial symmetric, two dimensional numerical simulations of orifice plate discharge tunnel flow was used. The equation (9) for calculating energy loss coefficient of square-edged orifice plate energy dissipater considering the influence of thickness is proposed. The results of the present research demonstrate that energy loss coefficient decreases with increase of the orifice plate thickness. The results of model experiment are consistence with the results calculated by using rectified equation in present paper. The CFD simulations and Model experiment for the flow through an orifice plate are carried out. For square-edged orifice plate energy dissipater, the relative orifice plate thickness T/D has remarkable impacts on its energy loss coefficient ξ. The Traditional equation (8) is corrected by numerical results. The equation (9) for calculating energy loss coefficient of square-edged orifice plate energy dissipater considering the influence of thickness is proposed and this equation is available in the condition of d/D = 0.4-0.8, T/D = 0.05-0.25, and Re > 105(Re is Reynolds number). Comparing with the physical model experimental data, the relative errors of equation (9) is smaller than 15%.

Prognostic Value of Energy Loss Coefficient for Predicting Asymptomatic Aortic Stenosis Outcomes: Direct Comparison With Aortic Valve Area.

BACKGROUND: The pressure recovery-adjusted aortic valve area (AVA), called the energy loss coefficient (ELCo), is theoretically a more accurate parameter for evaluating aortic stenosis (AS) severity. The aim of this study was to compare the prognostic value of ELCo with that of conventional AVA. METHODS: Indexed AVA (iAVA) was measured using Doppler echocardiography in 301 asymptomatic Japanese patients with AS and preserved left ventricular ejection fractions. Sinotubular junction diameter was also measured, and the indexed ELCo (iELCo) was calculated. Patients were followed for major cardiac events, including cardiac death, ventricular fibrillation, myocardial infarction, heart failure requiring admission, and aortic valve replacement. RESULTS: The mean sinotubular junction diameter was 2.5 ± 0.3 cm, and >90% of patients had sinotubular junction diameters < 3 cm. There was a quadratic correlation between iAVA and iELCo (r = 0.97, P < .001). During a median of 17.4 months of follow-up, 90 patients had major cardiac events. Statistical analysis failed to show any superiority of iELCo over iAVA for predicting major cardiac events. However, iELCo stratified high-risk patients for cardiac outcome in a subset of patients whose AS grades were classified as severe using iAVA and in those whose AS severity was inconsistent (iAVA < 0.6 cm2/m2 but mean pressure gradient < 40 mm Hg). CONCLUSIONS: The calculation of iELCo may not be always required, even in patients with asymptomatic AS with small aortic roots. However, this index should be calculated in patients whose AS grading assessed by iAVA is severe and in those in whom AS severity criteria are inconsistent.

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.

AIM: 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. METHODS: 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). RESULTS: CCTA AVA was 0.96±0.46 cm2 . ELCo was 0.95±0.43 cm2 using sinotubular junction Aa, 0.92±0.41 cm2 using sinus Aa, and 0.91±0.4 cm2 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<3 cm and AVA ≥1 cm2 ), 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). CONCLUSIONS: 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.

Impact of energy loss index on left ventricular mass regression after aortic valve replacement.

BACKGROUND: Recently, the energy loss index (ELI) has been proposed as a new functional index to assess the severity of aortic stenosis (AS). The aim of this study was to investigate the impact of the ELI on left ventricular mass (LVM) regression in patients after aortic valve replacement (AVR) with mechanical valves. METHODS: A total of 30 patients with severe AS who underwent AVR with mechanical valves was studied. Echocardiography was performed to measure the LVM before AVR (pre-LVM) (n = 30) and repeated 12 months later (post-LVM) (n = 19). The ELI was calculated as [effective orifice area (EOA) × aortic cross sectional area]/(aortic cross sectional area - EOA) divided by the body surface area. The LVM regression rate (%) was calculated as 100 × (post-LVM - pre-LVM)/(pre-LVM). A cardiac event was defined as a composite of cardiac death and heart failure requiring hospitalization. RESULTS: LVM regressed significantly (245.1 ± 84.3 to 173.4 ± 62.6 g, P < 0.01) at 12 months after AVR. The LVM regression rate negatively correlated with the ELI (R = -0.67, P < 0.01). By receiver operating characteristic (ROC) curve analysis, ELI <1.12 cm(2)/m(2) predicted smaller (<-30.0 %) LVM regression rates (area under the curve = 0.825; P = 0.030). Patients with ELI <1.12 cm(2)/m(2) had significantly lower cardiac event-free survival. CONCLUSION: The ELI as well as the EOA index (EOAI) could predict LVM regression after AVR with mechanical valves. Whether the ELI is a stronger predictor of clinical events than EOAI is still unclear, and further large-scale study is necessary to elucidate the clinical impact of the ELI in patients with AVR.

Aortic root geometry in patients with aortic stenosis assessed by real-time three-dimensional transesophageal echocardiography.

BACKGROUND: The authors hypothesized that aortic root geometry is different between bicuspid and tricuspid aortic stenosis (AS) that can be assessed using real-time three-dimensional (3D) transesophageal echocardiography. The aims of this study were (1) to validate the accuracy of 3D transesophageal echocardiographic measurements of the aortic root against multidetector computed tomography as a reference, (2) to determine the difference of aortic root geometry between patients with tricuspid and bicuspid AS, and (3) to assess its impact on pressure recovery. METHODS: In protocol 1, 3D transesophageal echocardiography and contrast-enhanced multidetector computed tomography were performed in 40 patients. Multiplanar reconstruction was used to measure the aortic annulus, the sinus of Valsalva, and the sinotubular junction area, as well as the distance and volume from the aortic annulus to the sinotubular junction. In protocol 2, the same 3D transesophageal echocardiographic measurements were performed in patients with tricuspid AS (n = 57) and bicuspid AS (n = 26) and in patients without AS (n = 32). The energy loss coefficient was also measured in patients with AS. RESULTS: In protocol 1, excellent correlations of aortic root geometric parameters were noted between the two modalities. In protocol 2, compared with patients without AS, those with tricuspid AS had smaller both sinotubular junction areas and longitudinal distances, resulting in a 23% reduction of aortic root volume. In contrast, patients with bicuspid AS had larger transverse areas and longitudinal distances, resulting in a 30% increase in aortic root volume. The energy loss coefficient revealed more frequent reclassification from severe AS to moderate AS in patients with tricuspid AS (17%) compared with those with bicuspid AS (10%). CONCLUSIONS: Three-dimensional transesophageal echocardiography successfully revealed different aortic root morphologies between tricuspid and bicuspid AS, which have different impacts on pressure recovery.