Ventricular Outflow Tract Diameter Research Articles

Right Ventricular Outflow Tract Diameter Change with Exercise: a Prospective Exercise Echocardiography and Invasive CPET study

Abstract While cardiac output reserve with exercise predicts outcomes in cardiac and pulmonary vascular disease, precise quantification of exercise cardiac output requires invasive cardiopulmonary testing (iCPET). To improve the accuracy of cardiac output reserve estimation with transthoracic echocardiography (TTE), this prospective study aims to define changes in right ventricular outflow tract diameter (RVOTd) with exercise and its relationship with invasively measured hemodynamics. 20 subjects underwent simultaneous TTE and iCPET, with data collected at rest, leg-raise, 25W, 50W (n = 16), 75W (n = 14), 100W (n = 6). This was followed by a second exercise study with real-time RV pressure-volume loops at similar stages (except leg-raise). The overall cohort included heart failure with preserved ejection fraction (n = 12), pulmonary arterial hypertension (n = 5), and non-cardiac dyspnea (n = 3).RVOTd was reverse engineered from the TTE-derived RVOT velocity time integral (VTI) and iCPET-derived stroke volume, using the formula: Fick stroke volume = RVOT VTI x RVOT area (wherein RVOT area = π x [RVOTd/2]2). RVOTd increased by nearly 3-4% at every 25W increment. Using linear regression models, where each subject is treated as a categorical variable and adjusting for subject intercept, RVOTd was correlated with hemodynamic variables (cardiac output, heart rate, pulmonary artery and RV pressures). Of all the predictor hemodynamic variables, cardiac output had the highest r2 model fit (adjusted r2 = 0.68), with a unit increase in cardiac output associated with a 0.0678 increase in RVOTd (p < 0.001). Our findings indicate that RVOTd increases by 3-4% with every 25W increment, predominantly correlated with cardiac output augmentation. These results can improve the accuracy of cardiac output reserve estimation by adjusting for RVOTd with graded exercise during noninvasive CPET and echocardiogram. However, future studies are needed to define these relationships for left ventricular outflow tract diameter.

Hemodynamic Comparison of the On-X and Top Hat Mechanical Aortic Valve Prostheses

BackgroundThere are limited data comparing hemodynamic valve function in mechanical aortic valve prostheses. This study compared the hemodynamic function of 2 commonly used mechanical aortic valve (AV) prostheses, the On-X (Artivion) and Top Hat (CarboMedics Inc) valves. MethodsThis study was a retrospective analysis of 512 patients who underwent AV replacement with the On-X (n = 252; 49%) or Top Hat (n = 260; 51%) mechanical valves between 2011 and 2019. Patients were matched on the basis of selected variables. Echocardiographic data were collected preoperatively and postoperatively over a median follow-up of 1.39 years. ResultsA total of 320 patients were matched, 160 patients in each group. Despite being matched for left ventricular outflow tract diameter, patients in the Top Hat group received a greater prevalence of smaller tissue annulus diameter valves (≤21 mm) (83% vs 38%; P < .001). Patients in the On-X group had longer aortic cross-clamp times (78 minutes vs 64 minutes; P < .001) during isolated aortic valve replacement. Discharge echocardiography showed no difference in the AV area index between both groups (1.00 cm2/m2 vs 1.02 cm2/m2; P = .377). During longer-term echocardiographic follow-up, the AV area index remained stable for both valves within their respective tissue annulus diameter groups (P = .060). ConclusionsThere was no difference between the 2 valves with respect to the AV area index at discharge, and hemodynamic function was stable during longer-term follow-up. The longer aortic cross-clamp time observed in the On-X group may indicate increased complexity of implantation compared with the Top Hat group.

Right ventricular assessment of the adolescent footballer’s heart

IntroductionAthletic training can result in electrical and structural changes of the right ventricle that may mimic phenotypical features of arrhythmogenic right ventricular cardiomyopathy (ARVC), such as T-wave inversion and right heart dilatation. An erroneous interpretation may have consequences ranging from false reassurance in an athlete vulnerable to cardiac arrhythmias, to unnecessary sports restriction in a healthy individual. The primary aim of this study was to define normal RV dimension reference ranges for academy adolescent footballers of different ethnicities. Secondary aims include analysis of potential overlap between this adolescent group with ARVC criteria and comparison with normal adult ranges.ResultsElectrocardiographic (ECG) and echocardiographic data of 1087 academy male footballers aged between 13 and 18 years old (mean age 16.0 ± 0.5 years), attending mandatory cardiac screening were analysed. Ethnicity was categorised as white (n = 826), black (African/Caribbean; n = 166) and mixed-race (one parent white and one parent black; n = 95). Arrhythmogenic right ventricular cardiomyopathy major criteria for T-wave inversion was seen in 3.3% of the cohort. This was more prevalent in black footballers (12%) when compared to mixed race footballers (6.3%) or white footballers (1%), P < 0.05. Up to 59% of the cohort exceeded adult reference ranges for some of the right ventricular parameters, although values were similar to those seen in adult footballers. There were no differences in right ventricular dimensions between ethnicities. In particular, the right ventricular outflow tract diameter would fulfil major criteria for ARVC dimension in 12% of footballers. Overall, 0.2% of the cohort would fulfil diagnosis for ‘definite’ arrhythmogenic right ventricular cardiomyopathy and 2.2% would fulfil diagnosis for ‘borderline’ arrhythmogenic right ventricular cardiomyopathy for RV dimensions and ECG changes. This was seen more frequently in black footballers (9.9%) than mixed race footballers (3.9%) or white footballer (0.6%), P < 0.05. Among athletes meeting definite or borderline arrhythmogenic right ventricular cardiomyopathy criteria, no cardiomyopathy was identified after comprehensive clinical assessment, including with cardiac magnetic resonance imaging, exercise testing, ambulatory electrocardiograms and familial evaluation.ConclusionRight heart sizes in excess of accepted adult ranges occurred in as many as one in two adolescent footballers. Structural adaptations in conjunction with anterior T-wave inversion may raise concern for ARVC, highlighting the need for evaluation in expert settings.

Increased cardiac output and left ventricular contractility in pigs paced with vs. without restored respiratory sinus arrhythmia - proof of principle of a newly developed pacing device

Abstract Background Heart rate variability (HRV) correlates with the severity and mortality of heart failure. Respiratory sinus arrhythmia (RSA) is defined by the dynamic increase and decrease in heart rate between breaths. Restoration of RSA might be beneficial in patients with heart failure and/or patients in need of permanent pacing. Purpose The aim of this translational, proof-of-principle study was to investigate the effect of pacing with or without RSA using a newly designed pacing device on the left ventricular contractility and cardiac output. Methods The project was initiated with the aim of designing a new pacing device capable of restoring RSA in paced hearts with the help of lung inflation sensors. Neuronal networks were designed to reconstruct the human brain using ultra-low energy-consuming technology. The lung inflation sensor fed the detected inspiration data back to the pacing device, which paced the heart via pacing leads (DDD) in the right atrium and ventricle. In total, 5 intubated but spontaneously breathing landrace pigs were paced without RSA (fixed-rate pacing) and with restored RSA. Stroke volume and cardiac output were measured by echocardiography (diameter of left ventricular outflow tract and velocity time integral measured by pulsed wave doppler averaged over three heart beats). Preload-independent cardiac contractility was measured via a pressure-volume loop catheter in the left ventricle during occlusion of the inferior vena cava. Fig. 1 indicates the setup of the trial. The trials were conducted according to the relevant rules (NIH Publication no. 85-23 revised 1985) and in accordance with national law. Results Echocardiography (n=5) showed a mean left ventricular outflow tract diameter of 21 ± 0.1 mm. The mean intrinsic heart rate was 87 ± 14 bpm, and the mean paced heart rate was 104 ± 5 bpm in the pigs (65 ± 3 kg). The main outcomes are displayed in Fig. 2: The left ventricular stroke volume increased by 11ml (+21%, p=0.036) with 100% RSA compared to pacing without RSA, while cardiac output increased by 1.14 l/min (+21%, p=0.037). The pressure volume area is proportional to the total myocardial oxygen consumption and decreased by 6234 mmHg*ml (-39%, p=0.004). Cardiac efficiency represents the relative amount of blood being pumped consuming one unit energy and increased by 0.163 (+72%, p=0.033). End-systolic pressure volume relationship demonstrated a non-significant increase by 0.183 mmHg/ml (+45%, p=0.25). Parameters of diastolic function (Tau) did not differ between the groups. Conclusion Restoration of RSA by our newly developed pacing device significantly improved the cardiac contractility/output in our proof-of-principle large animal translational model. Chronic trials will be required to definitively confirm the positive effects of RSA on cardiac remodeling.Fig. 1: Set-up of the animal trials.Fig. 2: Main results (mean/std error)

Real world application of left ventricular outflow tract diameter prediction and clinical implications

Abstract Background The Left Ventricular Outflow Tract diameter (LVOTd) measured with transthoracic echocardiogram is crucial for stroke volume, flow and effective orifice area (EOA) assessment in aortic stenosis (AS), but it’s also a source of error. A formula for its prediction has been proposed (Leye’s formula), based on body surface area (BSA). However, it has never been validated externally. Purpose The aim of study is to externally validate the equation by Leye et al. in a retrospective, single-center, large cohort of consecutive non-obese patients with severe symptomatic AS undergoing surgical aortic valve replacement. Methods A population of patients with severe symptomatic AS undergoing surgical aortic valve replacement was analyzed; three different LVOTd values were obtained for each patient: measured-LVOTd (m-LVOTd, from echo database), predicted-LVOTd (p-LVOTd, using Leye’s formula) and surgical-LVOTd (s-LVOTd, obtained by surgical reports). p-LVOTd was used to reevaluate stroke volume and EOA. Results Data from 735 patients were collected; mean age was 75±8 years and 417 patients (57%) were men, mean BMI was 25.6 kg/m2 and mean BSA was 1.8 m2. m-LVOTd was significantly lower than p-LVOTd (20.2±2.4mm and 22.4±1.0mm, respectively; bias 2.1mm; p &amp;lt; 0,001). Moreover the difference between p-LVOTd and s-LVOTd (23.2±1.7mm; bias 0.8 mm) was lower than the difference between m-LVOTd and s-LVOTd (bias 3.0 mm). When the stroke volume index (SVi) was calculated through p-LVOTd, its value increased significantly compared to SVi calculated with m-LVOTd (50.0±10.9 vs 40.9±10.2 mL/m2, p&amp;lt;0.001), leading to a significant decrease in patients classified as low-flow AS, from 216 (29%) to 73 (10%) (p&amp;lt;0.001). EOA calculated with p-LVOTd was significantly wider than that calculated using m-LVOTd, and correlation was weak (0.86±0.22 vs 0.70±0.16 cm2, p&amp;lt;0.001; r=0.599, p&amp;lt;0.001). Using the p-LVOTd instead of m-LVOTd has lead to the reclassification of 188 (26%) patients from EOA≤1 cm2 to EOA&amp;gt;1cm2. Conclusion We found that in non-obese patients with severe AS, LVOTd obtained from the simple formula proposed by Leye et al correlates better with the surgical annulus diameter compared with the echocardiographic measurement of LVOT, and this has relevant consequences on AS assessment.

Abstract 14195: Right Ventricular Outflow Tract Diameter Increase With the Low-Moderate Workload: A Prospective Simultaneous Exercise Echocardiography and Invasive Cardiopulmonary Exercise Testing Study

Background: While cardiac output at rest can be estimated non-invasively with echocardiogram, change in left ventricular or right ventricular outflow tract diameter (RVOTd) with exercise makes the cardiac output estimation inaccurate. Hypothesis: RVOTd increases with exercise proportionally with an incremental workload and is determined by stroke volume augmentation. Aims: 1. Define a workload-based change in RVOTd in subjects undergoing invasive cardiopulmonary exercise test (iCPET). 2. Correlate RVOTd at exercise stages with iCPET metrics. Methods: 20 subjects undergoing simultaneous echocardiogram and iCPET were enrolled in a prospective study. Exercise datapoints were acquired at 25 W (n=20), 50W (n=16), 75W (n=14), 100W (n=6). Three hemodynamic groups included: HFpEF (n=12), PAH (n=5), controls (n=3). Utilizing iCPET-based direct Fick cardiac output and stroke volume, RVOTd was reverse engineered with RVOT velocity time integral, per ASE guidelines. Pearson correlation was used to assess correlation of RVOTd with hemodynamic metrics. p&lt;0.05* Results: In overall cohort, age was 64±12 years, BMI 31.2±4.9 Kg/m 2 , female 60%, peak VO 2 13.7±5.7 mL/Kg.min -1 and V E /VCO 2 37±8. Increase in RVOTd with exercise is represented in the Figure. In comparison to rest, RVOTd increased significantly even at low-25W (+4.1±13.6%*) and moderate-50W (+7.6±17.2%*) workloads. Overall, RVOTd increased by 4-5% every 25W. At high workload (100W), the diameter increased by 24% (n=6). There were no differences in RVOT diameter between subgroups. RVOTd at four exercise stages (25W, 50W, 75W, 100W) correlated significantly with stroke volume index (r=0.68*, 0.80*, 0.23, 0.64) and cardiac output (r=0.50*, 0.80*, 0.08, 0.68), but non-significantly with heart rate (r=-0.15, 0.19, -0.10, 0.68). Conclusion: RVOTd increases by 4-5% every 25W on an incremental workload protocol. This behavior is predominantly associated with an increase in stroke volume index with exercise.

Abstract 16873: Takotsubo Variant is Associated With Worse Right and Left Ventricular Systolic Function Than Other Stress Cardiomyopathy Variants

Introduction: Stress cardiomyopathy (SCM) is usually associated with reduced systolic function on echocardiogram. However, the prevalence of systolic dysfunction between different variables of SCM has not been established. Hypothesis: Whether Takotsubo variant SCM is associated with worse systolic function compared to other SCM variants. Methods: We conducted a retrospective cohort study evaluating echocardiograms of all patients with SCM between 2010 and 2022 at Hennepin Healthcare, MN, USA. The diagnosis of SCM was made based on the International Takotsubo (InterTak) diagnostic criteria. Results: Between January 2010 and December 2022, 296 patients presented with SCM. The majority of patients (N= 173, 58.4%) had the apical (Takotsubo) variant, compared to 78 (26.3%) patients with the midventricular variant and 45 (15.2%) with the basal variant. The three groups had no significant difference in the left ventricular outflow tract and septal diameters. Patients with the apical variant had a lower ejection fraction on presentation compared to mid-ventricular and basal variants (28.1% vs. 36.8% and 35.7%, respectively, p&lt;0.001). Patients with Takotsubo CM had the lowest cardiac output and cardiac index among the three groups ( table 1 ). Right ventricular systolic function, evaluated by Tricuspid Annular Plane Systolic Excursion (TAPSE), was lowest in patients with apical SCM (mean TASPE 1.58 cm, p=0.027). All patients had similar ejection fraction recovery at follow-up (mean EF &gt; 55%, p=0.793, mean follow-up time &lt; 4 weeks, p=0.913). Conclusion: Takotsubo variant is associated with worse right and left ventricular systolic function compared to other SCM variants, with similar systolic function recovery at follow-up.

Deep learning for automated left ventricular outflow tract diameter measurements in 2D echocardiography

BackgroundMeasurement of the left ventricular outflow tract diameter (LVOTd) in echocardiography is a common source of error when used to calculate the stroke volume. The aim of this study is to assess whether a deep learning (DL) model, trained on a clinical echocardiographic dataset, can perform automatic LVOTd measurements on par with expert cardiologists.MethodsData consisted of 649 consecutive transthoracic echocardiographic examinations of patients with coronary artery disease admitted to a university hospital. 1304 LVOTd measurements in the parasternal long axis (PLAX) and zoomed parasternal long axis views (ZPLAX) were collected, with each patient having 1–6 measurements per examination. Data quality control was performed by an expert cardiologist, and spatial geometry data was preserved for each LVOTd measurement to convert DL predictions into metric units. A convolutional neural network based on the U-Net was used as the DL model.ResultsThe mean absolute LVOTd error was 1.04 (95% confidence interval [CI] 0.90–1.19) mm for DL predictions on the test set. The mean relative LVOTd errors across all data subgroups ranged from 3.8 to 5.1% for the test set. Generally, the DL model had superior performance on the ZPLAX view compared to the PLAX view. DL model precision for patients with repeated LVOTd measurements had a mean coefficient of variation of 2.2 (95% CI 1.6–2.7) %, which was comparable to the clinicians for the test set.ConclusionDL for automatic LVOTd measurements in PLAX and ZPLAX views is feasible when trained on a limited clinical dataset. While the DL predicted LVOTd measurements were within the expected range of clinical inter-observer variability, the robustness of the DL model requires validation on independent datasets. Future experiments using temporal information and anatomical constraints could improve valvular identification and reduce outliers, which are challenges that must be addressed before clinical utilization.Graphical

Incremental Value of Right Ventricular Outflow Tract Diameter in Risk Assessment of Chronic Heart Failure Patients with Implantable Cardioverter Defibrillators: Development of RVOTD-ICD Benefit Score in Real-World Setting

Incremental Value of Right Ventricular Outflow Tract Diameter in Risk Assessment of Chronic Heart Failure Patients with Implantable Cardioverter Defibrillators: Development of RVOTD-ICD Benefit Score in Real-World Setting

CARDIAC OUTPUT IN CRITICALLY ILL PATIENTS CAN BE ESTIMATED EASILY AND ACCURATELY USING THE MINUTE DISTANCE OBTAINED BY PULSED-WAVE DOPPLER.

Background: Cardiac output (CO) assessment is essential for management of patients with circulatory failure. Among the different techniques used for their assessment, pulsed-wave Doppler cardiac output (PWD-CO) has proven to be an accurate and useful tool. Despite this, assessment of PWD-CO could have some technical difficulties, especially in the measurement of left ventricular outflow tract diameter (LVOTd). The use of a parameter such as minute distance (MD) which avoids LVOTd in the PWD-CO formula could be a simple and useful way to assess the CO in critically ill patients. Therefore, the aim of this study was to evaluate the correlation and agreement between PWD-CO and MD. Methods: A prospective and observational study was conducted over 2 years in a 30-bed intensive care unit (ICU). Adult patients who required CO monitoring were included. Clinical echocardiographic data were collected within the first 24 h and at least once more during the first week of ICU stay. PWD-CO was calculated using the average value of three LVOTd and left ventricular outflow tract velocity-time integral (LVOT-VTI) measurements, and heart rate. Minute distance was obtained from the product of LVOT-VTI × heart rate. Pulsed-wave Doppler cardiac output was correlated with MD using linear regression. Cardiac output was quantified from the MD using the equation defined by linear regression. Bland-Altman analysis was also used to evaluate the level of agreement between CO calculated from MD (MD-CO) and PWD-CO. The percentage error was calculated. Results: A total of 98 patients and 167 CO measurements were analyzed. Sixty-seven (68%) were male, the median age was 66 years (interquartile range [IQR], 53-75 years), and the median Acute Physiology and Chronic Health Evaluation II score was 22 (IQR, 16-26). The most common cause of admission was shock in 81 patients (82.7%). Sixty-nine patients (70.4%) were mechanically ventilated, and 68 (70%) required vasoactive drugs. The median CO was 5.5 L/min (IQR, 4.8-6.6 L/min), and the median MD was 1,850 cm/min (IQR, 1,520-2,160 cm/min). There was a significant correlation between PWD-CO and MD-CO in the general population ( R2 = 0.7; P < 0.05). This correlation improved when left ventricular ejection fraction (LVEF) was less than 60% ( R2 = 0.85, P < 0.05). Bland-Altman analysis showed good agreement between PWD-CO and MD-CO in the general population, the median bias was 0.02 L/min, the limits of agreement were -1.92 to +1.92 L/min. The agreement was better in patients with LVEF less than 60% with a median bias of 0.005 L/min and limits of agreement of -1.56 to 1.55 L/min. The percentage error was 17% in both cases. Conclusion: Measurement of MD in critically ill patients provides a simple and accurate estimate of CO, especially in patients with reduced or preserved LVEF. This would allow earlier cardiovascular assessment in patients with circulatory failure, which is of particular interest in difficult clinical or technical conditions.

Protocol for rheumatoid arthritis complicated with cardiovascular damage treated with Guanxining tablet with a randomized controlled trial

BackgroundCardiovascular disease (CVD) is the main cause of death in patients with rheumatoid arthritis (RA). Apart from traditional cardiovascular risk factors, immune dysfunction and chronic inflammation of RA are also risk factors for complex cardiovascular damage. Although methotrexate (MTX) is beneficial to CVD in RA patients by inhibiting inflammation, its adverse effects limit its clinical application. Therefore, it is essential to seek safer and more effective drugs. ObjectiveWe aimed to assess the efficacy of Guanxining Tablet (GXNT) for rheumatoid arthritis complicated with cardiovascular damage. MethodsWe will conduct a prospective single-center randomized trial. We will randomly divide 56 eligible patients into two groups. The treatment group will take GXNT and MTX treatment, and the control group will receive MTX and the placebo. The primary outcome measure will be aortic distensibility (AD). Secondary outcome measures will be Cardiac function which will contain right ventricular outflow tract diameter (RVOTD), aortic diameter (AOD), left atrium diameter (LAD), right ventricular end diastolic diameter (RVDD), left ventricular end diastolic diameter (LVDD), ejection fraction (EF%), fractional shortening (FS%), stroke volume (SV). Adverse events will be closely monitored during the entire trial period. DiscussionThis trial is intended to determine whether the addition of GXNT will improve the prognosis of patients with rheumatoid arthritis and cardiovascular damage without severe adverse reactions. Completing this clinical trial might provide these patients with a novel and effective drug while avoiding adverse reactions similar to methotrexate. Trial registrationChiCTR2000030247.

Tidal volume challenge-induced hemodynamic changes can predict fluid responsiveness during one-lung ventilation: an observational study.

To evaluate the ability of tidal volume challenge (VTC)-induced hemodynamic changes to predict fluid responsiveness in patients during one-lung ventilation (OLV). 80 patients scheduled for elective thoracoscopic surgery with OLV were enrolled. The inclusion criteria were: age ≥ 18 years, American Society of Anesthesiologists physical status I-III, normal right ventricular function, normal left ventricular systolic function (ejection fraction ≥55%), and normal or slightly impaired diastolic function. The study protocol was implemented 15 min after starting OLV. Simultaneous recordings were performed for hemodynamic variables of diameter of left ventricular outflow tract, velocity time integral (VTI) of aortic valve, and stroke volume (SV), and ΔSV-VTC, ΔVTI-VTC, and ΔMAP-VTC were calculated at four time points: with VT 5 mL/kg (T1); after VT increased from 5 mL/kg to 8 mL/kg and maintained at this level for 2 min (T2); after VT was adjusted back to 5 mL/kg for 2 min (T3); and after volume expansion (250 mL of 0.9% saline infused over 10-15 min) (T4). Patients were considered as responders to fluid administration if SV increased by ≥10%. Receiver operating characteristic (ROC) curves for percent decrease in SV, VTI, and MAP by VTC were generated to evaluate their ability to discriminate fluid responders from nonresponders. Of the 58 patients analyzed, there were 32 responders (55%) and 26 nonresponders (45%). The basic characteristics were comparable between the two groups (p > 0.05). The area under the curve (AUC) for ΔSV-VTC, ΔVTI-VTC, and ΔMAP-VTC to discriminate responders from nonresponders were 0.81 (95% CI: 0.68-0.90), 0.79 (95% CI: 0.66-0.89), and 0.56 (95% CI: 0.42-0.69). The best threshold for ΔSV-VTC was -16.1% (sensitivity, 78.1%; specificity, 84.6%); the best threshold for ΔVTI-VTC was -14.5% (sensitivity, 78.1%; specificity, 80.8%). Tidal volume challenge-induced relative change of stroke volume and velocity time integral can predict fluid responsiveness in patients during one-lung ventilation.Clinical Trial Registration: Chinese Clinical Trial Registry, No: chictr210051310.

Pitfalls and Tips in the Assessment of Aortic Stenosis by Transthoracic Echocardiography.

Aortic stenosis (AS) is a valvular heart disease that significantly contributes to cardiovascular morbidity and mortality worldwide. The condition is characterized by calcification and thickening of the aortic valve leaflets, resulting in a narrowed orifice and increased pressure gradient across the valve. AS typically progresses from a subclinical phase known as aortic sclerosis, where valve calcification occurs without a transvalvular gradient, to a more advanced stage marked by a triad of symptoms: heart failure, syncope, and angina. Echocardiography plays a crucial role in the diagnosis and evaluation of AS, serving as the primary non-invasive imaging modality. However, to minimize misdiagnoses, it is crucial to adhere to a standardized protocol for acquiring echocardiographic images. This is because, despite continuous advances in echocardiographic technology, diagnostic errors still occur during the evaluation of AS, particularly in classifying its severity and hemodynamic characteristics. This review focuses on providing guidance for the imager during the echocardiographic assessment of AS. Firstly, the review will report on how the echo machine should be set to improve image quality and reduce noise and artifacts. Thereafter, the review will report specific emphasis on accurate measurements of left ventricular outflow tract diameter, aortic valve morphology and movement, as well as aortic and left ventricular outflow tract velocities. By considering these key factors, clinicians can ensure consistency and accuracy in the evaluation of AS using echocardiography.

Comparative Analysis of “Improved” 2D Transthoracic Echocardiographic Left Ventricular Outflow Tract Diameter (LVOTd) Measurements for Aortic Valve Area (AVA) Calculations By the Continuity Equation (CE): Do We Still Need 3D?

Comparative Analysis of “Improved” 2D Transthoracic Echocardiographic Left Ventricular Outflow Tract Diameter (LVOTd) Measurements for Aortic Valve Area (AVA) Calculations By the Continuity Equation (CE): Do We Still Need 3D?

A simplified echocardiographic formula to estimate cardiac index in the intensive care unit

Abstract Funding Acknowledgements Type of funding sources: None. Background Measurement of cardiac index (CI) is crucial in the hemodynamic assessment of critically ill patients. Pulmonary artery catheterization (PAC) remains the gold standard for CI evaluation, but it's invasive. Doppler trans-thoracic echocardiography (TTE) has been proposed as an accurate bedside non-invasive alternative to PAC for CI estimation, based on measurement of left ventricular outflow tract velocity time integral (LVOT-VTI) and diameter (LVOT-d). However, intrinsic limits of geometrical assumptions and practical limitations related to the intensive care unit (ICU) setting may lead to inaccurate CI calculation, mainly due to errors in LVOT-d. A body surface area (BSA)-based formula to predict LVOT-d has been proposed and validated. Including the predicted LVOT-d in the CI equation we obtained a new "simplified formula" for TTE CI estimation: CI=2,17*LVOT-VTI*HR/1000. Purpose This study aimed to assess the accuracy of a new TTE-based simplified formula, only requiring LVOT-VTI and HR, for TTE estimation of CI. Methods We prospectively enrolled all consecutive patients admitted to the ICU requiring PAC from January to December 2021 (n=74). We measured TTE-based CI method using both the "traditional formula" (traditional CI TTE) and the new "simplified formula" (simplified CI TTE), and compared the accuracy of both with the PAC-derived CI (CI PAC) as the reference method. Results As shown in Figure 1a, there was a moderate correlation (r = 0.70, p &amp;lt; 0.001) between traditional CI TTE and the CI PAC. A plot of the differences between traditional CI TTE and the CI PAC is illustrated in Figure 2a, resulting in a mean difference of -0.18 ± 0.58 L/min/m2, and 95% limits of agreement of -1.32 to +0.96 L/min/m2. The correlation between simplified CI TTE and CI PAC was strong (r = 0.81, p &amp;lt; 0.001) (Figure 1b) and resulted significantly greater than the traditional CI TTE and CI PAC correlation (p &amp;lt; 0.05). On Bland-Altman plot analysis (Figure 2b), the mean difference between simplified CI TTE and CI PAC was +0.19 ± 0.48 L/min/m2 with 95% limits of agreement of -0.74 to +1.13 L/min/m2. Conclusion In this study, we validated an easy-to-use and practical approach, leveraging on TTE LVOT-VTI and HR only, for non-invasive estimation of CI in ICU patients. In this peculiar setting, our formula was more reliable than the traditional CI TTE formula. However, despite the strong correlation with CI PAC, our formula introduces a slight but systematic overestimation of CI (+0.19 L/min/m2), as illustrated in the Bland-Altman plot. Therefore, this formula may be particularly useful in longitudinal CI assessment rather than precisely quantifying CI on a single measurement. This approach may thus be apt to quickly assess the hemodynamic response to pharmacological and mechanical supports during longitudinal assessment.

Fully Automated Artificial Intelligence Assessment of Aortic Stenosis by Echocardiography

Aortic stenosis (AS) is a common form of valvular heart disease, present in over 12% of the population age 75years and above. Transthoracic echocardiography (TTE) is the first line of imaging in the adjudication of AS severity but is time-consuming and requires expert sonographic and interpretation capabilities to yield accurate results. Artificial intelligence (AI) technology has emerged as a useful tool to address these limitations but has not yet been applied in a fully hands-off manner to evaluate AS. Here, we correlate artificial neural network measurements of key hemodynamic AS parameters to experienced human reader assessment. Two-dimensional and Doppler echocardiographic images from patients with normal aortic valves and all degrees of AS were analyzed by an artificial neural network (Us2.ai) with no human input to measure key variables in AS assessment. Trained echocardiographers blinded to AI data performed manual measurements of these variables, and correlation analyses were performed. Our cohort included 256 patients with an average age of 67.6±9.5years. Across all AS severities, AI closely matched human measurement of aortic valve peak velocity (r=0.97, P<.001), mean pressure gradient (r=0.94, P<.001), aortic valve area by continuity equation (r=0.88, P<.001), stroke volume index (r=0.79, P<.001), left ventricular outflow tract velocity-time integral (r=0.89, P<.001), aortic valve velocity-time integral (r=0.96, P<.001), and left ventricular outflow tract diameter (r=0.76, P<.001). Artificial neural networks have the capacity to closely mimic human measurement of all relevant parameters in the adjudication of AS severity. Application of this AI technology may minimize interscan variability, improve interpretation and diagnosis of AS, and allow for precise and reproducible identification and management of patients with AS.

Automatic Prediction of Paediatric Cardiac Output From Echocardiograms Using Deep Learning Models

<h2>Abstract</h2><h3>Background</h3> Cardiac output (CO) perturbations are common and cause significant morbidity and mortality. Accurate CO assessment is crucial for guiding treatment in anaesthesia and critical care, but measurement is difficult, even for experts. Artificial intelligence methods show promise as alternatives for accurate, rapid CO assessment. <h3>Methods</h3> We reviewed paediatric echocardiograms with normal CO and a dilated cardiomyopathy patient group with reduced CO. Experts measured the left ventricular outflow tract diameter, velocity time integral, CO, and cardiac index (CI). EchoNet-Dynamic is a deep learning model for estimation of ejection fraction in adults. We modified this model to predict the left ventricular outflow tract diameter and retrained it on paediatric data. We developed a novel deep learning approach for velocity time integral estimation. The combined models enable automatic prediction of CO. We evaluated the models against expert measurements. Primary outcomes were root-mean-squared error, mean absolute error, mean average percentage error, and coefficient of determination (<i>R</i>²). <h3>Results</h3> In a test set unused during training, CI was estimated with the root-mean-squared error of 0.389 L/min/m², mean absolute error of 0.321 L/min/m², mean average percentage error of 10.8%, and <i>R</i>² of 0.755. The Bland-Altman analysis showed that the models estimated CI with a bias of +0.14 L/min/m² and 95% limits of agreement -0.58 to 0.86 L/min/m². <h3>Conclusions</h3> Our model estimated CO with strong correlation to ground truth and a bias of 0.17 L/min, better than many CO measurements in paediatrics. Model pretraining enabled accurate estimation despite a small dataset. Potential uses include supporting clinicians in real-time bedside calculation of CO, identification of low-CO states, and treatment responses.

1082 LEFT VENTRICULAR FUNCTION ESTIMATION: WHEN VOLUMES MEASUREMENT IS NOT FEASIBLE

Abstract Background Contrast echocardiography is mainly performed for the assessment of global left ventricular (LV) function, left ventricular ejection fraction (LVEF) and stroke volume (SV) thanks to improved visualization of endocardial LV borders. Neverless in some patients estimation of ventricular volumes could be difficult also with contrast and assessment of LVEF can be really hard. The aim of the study was to find alternative methods for LV function evaluation independent from volume assessment. Methods Patients who underwent a contrast echocardiography between October 2015 and September 2022 were enrolled in the study. A complete transthoracic echocardiography was performed and Sonovue contrast was then injected. End-diastolic and end-systolic LV volume in apex 4 and 2 chamber views, were measured prior and after injecting contrast. Left ventricular outflow tract diameter (LVOTd) was measured and LVOT velocity time integral was traced in order to calculate LVOT VTI Stroke Volume (product of LVOT cross sectional area to the LVOT VTI). LVOT VTI SV obtained during traditional echocardiography was then compared to LV SV calculated as the difference between end-diastolic and end-systolic volume traced after contrast. After intravenous bolus injection of Sonovue pulmonary transit time (PTT) was recorded as contrast agent's transit time from right to left ventricle in apex 4 chamber view (seconds). PTT was then compared to measures of LV function: LVEF with and without Sonovue and LV SV with contrast. Results 149 patients were enrolled in the study, 86 had history of CAD, 31 presented dilatative cardiomyopathy, 5 hypertrophic cardiomyopathy (HMC), 113 had arterial hypertension, and 37 diabetes. Medium BMI was 28. The main indications for contrast echocardiography were measurement of EF and exclusion of thrombi in LV apex. LVOT VTI SV was calculated in 126 patients. In the same patients LVEF Stroke Volume was calculated. A strong correlation (P value &amp;lt; 0.0001) between LVOT VTI SV and LV SV was found (Figure 1). PPT was calculated in 74 patient and in the same patients LVEF with and without contrast (Figure 2) and LV SV were calculated. A strong correlation (P-value &amp;lt;0.048, p-value&amp;lt;0.006 and p-value &amp;lt; 0.046 respectively) was found. Conclusion This study demonstrates that, besides extremely poor acoustic windows, bedside echocardiography, with and without contrast, can be used to estimate LV function using volume-independent methods like PTT and LVOT VTI SV.

Abstract 14857: Usefulness of Invasive Hemodynamics in the Evaluation of Patients With Paradoxical Low Gradient Severe Aortic Stenosis

Background: Management of patients with paradoxical (ejection fraction &gt; 50%) low gradient (&lt; 40 mm Hg mean) severe (valve area &lt; 1 cm 2 ) aortic stenosis (PLAS) on ECHO is controversial. We studied the role of invasive hemodynamics (CATH) in evaluating these patients. Methods: In this single center retrospective cohort study, patients who underwent CATH for evaluation of PLAS on ECHO were divided into a “concordant” group (CG) when CATH aortic valve area (AVA) was &lt; 1.0 cm 2 and a “discordant” group (DG) when CATH AVA was &gt; 1.0 cm 2 . ECHO features, aortic valve replacement (AVR), and all-cause mortality were compared between the two groups. T-test, Chi-square test, and Kaplan-Meier analysis were performed. P-value of &lt; 0.05 was considered statistically significant. Results: Among 76 PLAS patients who underwent CATH, the AVA was discordant in 21/76 (27.6%). DG patients were younger (72.2 vs. 78.7 y, p = 0.008). Other demographics including the Charlson comorbidity index (CCI) were similar. Dimensionless index (DI) was lower in CG than in DG (0.24 ±0.042 vs. 0.274 ± 0.041, p = 0.002) and % with DI &lt; 0.25 was higher in CG (55.6% vs. 28.7%, p = 0.03). Other ECHO parameters including mean gradient, left ventricular outflow tract (LVOT) diameter, Vmax LVOT, AVA i , stroke volume index, and flow rate (AVA x mean velocity) were not different. More patients underwent AVR in CG (49/55, 89%) compared to DG (12/21, 57%, p = 0.001). Overall survival based on all-cause mortality was similar after AVR in both groups (p = 0.695, median follow up 1105.5 days). In DG, survival was better with AVR than with medical therapy alone (p = 0.049). CCI was not different in patients with AVR versus those without (p = 0.102). Conclusion: ¼ of patients with PLAS on ECHO had discordant AVA on CATH. DI &lt; 0.25 occurred more frequently in the CG cohort. Even in the DG, survival was better with AVR. Clinical Implication: AVR confers a survival advantage in patients with PLAS on ECHO, and should be considered regardless of AVA on CATH.

Abstract 13173: Impact of Bicuspid Aortic Valve Morphology on Computed Tomography Valvular Calcification in Aortic Stenosis and Sex Differences

Introduction: Aortic valve calcification (AVC) is the key pathophysiology underlying aortic stenosis (AS). We aimed to assess computed tomography AVC in AS by valve morphology (bicuspid [BAV] vs. tricuspid aortic valve[TAV]) and sex. Methods: Retrospective study of patients with echocardiographic AS severity and AVC assessments within six months. Patients with &gt; moderate aortic regurgitation, prosthetic aortic valve, or indeterminate aortic valve morphology were excluded. Severe AS with high mean gradient (MG) was defined as aortic valve area (AVA)≤1cm2 or indexed AVA≤0.6 cm2/m2 + MG≥40 mmHg. Results: Of 2647 patients, 361(65% men) had BAV and 2286(59% men) had TAV, age 65±11 vs. 80±9 years(p&lt;0.001), AVA 1.07±0.42 vs. 0.90±0.25 cm2(p&lt;0.001), MG 41±16 vs.42±14 mmHg(p=0.4) for BAV and TAV, respectively. For both BAV and TAV groups, age, MG, and severe AS frequency were similar between women and men(all p≥0.06). BAV morphology affected AVC-AS severity and AVC-sex associations (p for interactions &lt;0.001): as AS severity increased, mean AVC difference became larger between BAV-men and TAV-men, but smaller between BAV-women and TAV-women. Similar patterns were observed in AVC density (AVCd, AVC divided by left ventricular outflow tract diameter)-AS severity and AVCd-sex associations (p for interactions &lt; 0.001). In patients with concordant AS severity and MG levels, the best BAV AVC-cutoff for detecting severe AS + high MG by area-under-the-curve analysis was 924 AU for BAV-women and 2851 AU for BAV-men, different from guideline-recommended AVC-thresholds (1200 for women and 2000 for men). The best BAV AVCd cutoff was 289 for BAV-women and 476 for BAV-men, similar to the cutoffs for patients predominantly with TAV (292 for women and 476 for men from Clavel MA JACC 2013). The BAV-AVC threshold identified more patients with severe AS than guideline-recommended threshold in BAV-women (84% vs 74%, p&lt;0.001), but not in BAV-men. Conclusions: Valvular calcium accretion in AS was different by valve morphology and sex. As compared to TAV, BAV-women exhibited the least calcification while BAV-men exhibited the highest. Such patterns may impact the sensitivity of guideline-recommended AVC thresholds for detecting severe AS in BAV patients.