Outflow Tract Velocity Time Integral Research Articles

Abstract 13250: Establishing Partition Values and Clinical Phenotype for Heart Failure Patients With Abnormal Left Atrial Function Index: A Cross-Sectional Analytical Study

Introduction: Left atrial function index (LAFI) has recently been validated for global estimation of left atrial (LA) function. LA dysfunction is critical to developing overt heart failure (HF), and getting the best tool for assessing its function is critical to HF prevention. This study attempts to establish cut-off values for LAFI among HF patients and identify which HF phenotype is associated with abnormal LAFI. Hypothesis: Is there any association between abnormal LAFI and changes in LV function? Methods: This cross-sectional study was conducted at the Delta State University Teaching Hospital, Nigeria. We recruited 80 hypertensive HF patients and 40 healthy normotensive controls. LAFI = (LAEF x LVOT-VTI)/LAESVI. (LAEF = left atrial emptying fraction; LAESVI = left atrial end-systolic volume index; LVOT-VTI = left ventricular outflow tract velocity time integral). Relationships between variables were determined using an independent student’s t-test, and a P-value of <0.05 was significant. Results: In the control arm, the LAFI reference range was estimated to be 24.07-76.24. Abnormal LAFI was defined as LAFI < 24 and 77.5% of the individuals with HF were found to have abnormal LAFI. There was no difference in age (61.83±7.48 vs. 63.22±6.75, p=0.46), BMI (28.27±4.47 vs. 29.52±5.91, p=0.33) and systolic BP (127.34±19.28 vs. 120.94±19.94, p=0.22) of hypertensive HF patients with LAFI <24 and LAFI ≥24. Those with abnormal LAFI had lower EF (45.04±11.06 vs. 63.73±14.73, p<0.0001), FS (25.75±8.26 vs 32.49±8.64, p=0.003) and SV (57.16±13.30 vs. 64.99±16.94, p=0.02). However, E/E’ (15.62±5.61 vs. 9.2±3.22, p<0.0001) and LAVI (37.22±5.80 vs. 16.48±5.65, p<0.0001) were higher among patients with lower LAFI. Contrarily, E/A (1.87±0.97 vs. 1.87±0.83, p=0.98) and TAPSE (17.87±3.67 vs. 19.54±2.47, p=0.06) did not show any difference among the groups. Conclusions: This study shows that abnormal LAFI was associated with impaired LV function and it is crucial to deploy this non-invasive modality of cardiac assessment in hypertensive patients. Early identification of abnormal left atrial mechanics is pertinent to preventing overt HF, especially in parts of the world where access to advanced cardiovascular care is limited.

Determinants of right ventricular systolic dysfunction among patients with left heart failure in a Ghanaian hospital.

The presence of right ventricular dysfunction affects outcomes in patients with left heart failure. We assessed the determinants of right ventricular systolic dysfunction (RVSD) among patients with left heart failure presenting to the Korle Bu Teaching Hospital of Ghana. Consecutive patients with left heart failure who were 18 years and above were prospectively enrolled and assessed for evidence of RVSD by measuring the tricuspid annular plane systolic excursion, the peak velocity of the tricuspid annulus in systole (RV S'), the two-dimensional right ventricular fractional area change (RV FAC) and the right ventricular myocardial performance index (RV MPI). Two hundred and seventy participants were enrolled, of whom 75.2% had at least one abnormal index of right ventricular systolic function. The prevalence of RVSD was significantly higher among those with non-hypertensive heart failure (85.3 vs 66.0%, p < 0.001). The left ventricular outflow tract velocity-time integral (LVOT VTI) was strongly correlated with the RV FAC and an LVOT VTI < 9.8 cm predicted the presence of an RV FAC < 35% with a sensitivity of 81.5% and specificity of 81.9% [area under the curve 0.882; 95% confidence interval (CI): 0.838-0.926, p < 0.001]. Independent predictors of the presence of RVSD included a transmitral E/A > 2 [odds ratio (OR) = 4.684, 95% CI: 1.521-14.428, p = 0.007), left ventricular ejection fraction < 40% (OR = 4.205, 95% CI: 1.643-10.760, p = 0.003), pulmonary artery systolic pressure (PASP) ≥ 35 mmHg (OR = 2.434, 95% CI: 1.012-5.852, p = 0.047) and systemic systolic blood pressure (SBP) < 140 mmHg (OR = 2.631, 95% CI: 1.152-6.011, p = 0.022). RVSD was common in these Ghanaian patients with left heart failure. Left ventricular function, SBP and PASP were independent predictors of the presence of RVSD. Pending further validation, the LVOT VTI may serve as a useful surrogate or screening tool for RVSD in these patients.

Association of Shock Index with Echocardiographic Parameters in Cardiac Intensive Care Unit

BackgroundA high shock index (SI), the ratio of heart rate (HR) to systolic blood pressure (SBP), has been associated with unfavorable outcomes. We sought to determine the hemodynamic underpinnings of an elevated SI using 2-D and doppler Transthoracic Echocardiography (TTE) in unselected cardiac intensive care unit (CICU) patients. MethodsWe included Mayo Clinic CICU admissions from 2007 to 2018 who were in sinus rhythm at the time of TTE. The SI was calculated using HR and SBP at the time of TTE. Patients were grouped according to SI: <0.7, 4012 (64%); 0.7–0.99, 1764 (28%); and ≥ 1.0, 513 (8%). Pearson's correlation coefficient was used to assess associations between continuous variables. ResultsWe included 6289 unique CICU patients, 58% of whom had acute coronary syndrome. The median age was 67.9 years old and 37.8% were females. The mean SI was 0.67 BPM/mmHg. As the SI increased, markers of left ventricular (LV) systolic function and forward flow decreased, including left ventricular ejection fraction (LVEF), fractional shortening, left ventricular outflow tract (LVOT) velocity time integral (VTI), stroke volume, LV stroke work index, and cardiac power output. Biventricular filling pressures increased, and markers of right ventricular function worsened with rising SI. Most TTE measurements reflecting LV function and forward flow were inversely correlated with SI, including LV stroke work index (r = −0.59) and LVOT VTI (r = −0.41), as were both systemic vascular resistance index (r = −0.43) and LVEF (r = −0.23). ConclusionCICU patients with elevated SI have worse biventricular function and systemic hemodynamics, particularly decreased stroke volume and related calculated TTE parameters. The SI is an easily available marker that can be used to identify CICU patients with unfavorable hemodynamics who may require further assessment.

Reliability of point-of-care ultrasound to evaluate fluid tolerance performed by critical care residents

BackgroundPatients with hypotension usually receive intravenous fluids, but only 50% will respond to fluid administration. We aimed to assess the intra and interobserver agreement to evaluate fluid tolerance through diverse ultrasonographic methods.MethodsWe prospectively included critically ill patients on mechanical ventilation. One trained intensivist and two intensive care residents obtained the left ventricular outflow tract velocity–time integral (VTI) variability, inferior vena cava (IVC) distensibility index, internal jugular vein (IJV) distensibility index, and each component of the venous excess ultrasound (VExUS) system. We obtained the intraclass correlation coefficient (ICC) and Gwet’s first-order agreement coefficient (AC1), as appropriate.ResultsWe included 32 patients. In-training observers were unable to assess the VTI-variability in two patients. The interobserver agreement was moderate to evaluate the IJV-distensibility index (AC1 0.54, CI 95% 0.29–0.80), fair to evaluate VTI-variability (AC1 0.39, CI 95% 0.12–0.66), and absent to evaluate the IVC-distensibility index (AC1 0.19, CI 95% − 0.07 to 0.44). To classify patients according to their VExUS grade, the intraobserver agreement was good, and the interobserver agreement was moderate (AC1 0.52, CI 95% 0.34–0.69).ConclusionsPoint-of-care ultrasound is frequently used to support decision-making in fluid management. However, we observed that the VTI variability and IVC-distensibility index might require further training of the ultrasound operators to be clinically useful. Our findings suggest that the IJV-distensibility index and the VExUS system have acceptable reproducibility among in-training observers.

Effect of assessing velocity time integral at different locations across ventricular outflow tracts when calculating cardiac output in neonates

This study aims to evaluate the effect of assessing velocity time integral at different locations across ventricular outflow tracts for calculating cardiac output (CO) in neonates. Velocity time integral (VTI) and CO were measured at 3 different locations across right and left ventricular outflow tracts using transthoracic echocardiography in healthy term neonates without any major congenital heart disease. ANOVA with Bonferroni correction was used to determine the differences between the VTI and CO sampled at these three locations. Forty-one neonates met inclusion criteria with mean gestational age of 38.6 ± 1 weeks and mean birth weight of 3155 ± 463 g. The median hours after birth when echocardiography was obtained was 23 h (range 11–68 h after birth). Left CO were 121 ± 30 mL/kg/min, 155 ± 38 mL/kg/min, and 176 ± 36 mL/kg/min measured below the valve, hinges of the valve, and tip of the valve, respectively. Right CO were 197 ± 73 mL/kg/min, 270 ± 83 mL/kg/min, and 329 ± 104 mL/kg/min measured below the valve, hinges of the valve, and tip of the valve, respectively. A statistically significant difference (P < 0.001) was found in the VTI and CO measured at the 3 different locations across both left and right ventricular outflow tracts. Conclusions: There is a significant difference in measurements of VTI and CO depending on the location of Doppler gate sampling across the ventricular outflow tracts. Consistency and precision in Doppler gate location are essential for measuring VTI and calculating CO while assessing changes in hemodynamic status in critically ill infants.What is Known:• Targeted Neonatal Echocardiography is increasingly applied to measure cardiac output in critically ill neonates and serial assessments are performed to assess the trend in changes in cardiac output.• Noninvasive measurement using velocity time integral to calculate cardiac output is commonly performed. However, location of Doppler sample gate to measure ventricular outflow tract velocity time integral is not consistent.What is New:• Statistically significant changes in measured velocity time integral and cardiac output are noted based on the location of Doppler gate sampling.• To monitor the cardiac output for trending, it is important to be consistent with regards to the location of the Doppler sample gate to assess changes in cardiac output in critically ill newborns.

Fluid Responsiveness in Critically Ill Patients Using Carotid Peak Systolic Velocity Variability: A New Frontier.

Background and objectives A fluid responder is a patient who can increase his stroke volume/ cardiac output by more than 10%-15% after a fluid bolus. Left ventricular outflow tract (LVOT) velocity time integral (VTI) variability is widely used as an adynamic parameter of fluid responsiveness, but a transthoracic echo view of LVOT VTI is often time-consuming and, at times, difficult to achieve. So, in the quest for another parameter that might equally be a good surrogate marker of stroke volume variation, carotid peak systolic velocity (CPSV) variation has been studied. The objective was to assess CPSV variation in patients who are already fluid responders. Methods The sample size was calculated considering a minimum correlation coefficient of 0.5. Adult patients in whom the physician wanted to give a fluid bolus and whose average LVOT VTI was more than 15% over 3 respiratory cycles were included in the study. Demographic variables, along with hemodynamic parameters such as heart rate, blood pressure, the need for vasopressors, mode of breathing (spontaneous or mechanical ventilation), andCPSV variation,were noted and averaged over three respiratory cycles. Fluid bolus (Plasmalyte) 6 ml/kg bolus over 10-15 minutes. Post-fluid hemodynamic variables, along with averaged LVOT VTI over three respiratory cycles and averaged CPSV variation over three respiratory cycles, are noted. Results Thirty adult patients were evaluated in the study. In spontaneously breathing patients (n=12), the average CPSV variation expressed as mean + standard deviation before and after fluid administration of 6ml/kg of ideal body weight was 14.1 ± 3.4 and 5.4 ± 2.6, respectively (p < 0.05). In mechanically ventilated patients (n=18), the average CPSV variation expressed as mean + standard deviation before and after fluid administration of 6ml/kg of ideal body weight fluid was 15 ± 5.3 and 6.5 ± 3.1, respectively (p <0.005). Overall, there was a statistically significant positive correlation between LVOT VTI variation and CPSV variation before fluid therapy (correlation coefficient 0.56 and p-value 0.001) and a statistically significant moderate positive correlation post-fluid therapy (correlation coefficient 0.37 and p-value 0.043). Conclusion We found a significant decrease in CPSV variation post-fluid administration in patients who are fluid responders, which mimics a decrease in stroke volume variation after fluid administration in patients who are fluid responsive.

Correlation of Common Carotid Artery Blood Flow Parameters With Transthoracic Echocardiographic Cardiac Output for Assessing Fluid Responsiveness After Passive Leg Raising (PLR) Test in Critically Ill Patients.

Introduction The passive leg raising (PLR) test is a simple, non-invasive method of knowing fluid responsiveness by acting as an internal-fluid challenge. The PLR test coupled with a non-invasive assessment of stroke volume would be the ideal method to assess fluid responsiveness. This study aimed to determine the correlation between transthoracic echocardiographic cardiac output (TTE-CO)and common carotid artery blood flow(CCABF) parameters in determining fluid responsiveness with the PLR test. Methods We performed a prospective observational study on 40 critically ill patients. Patients were evaluated with a 7-13 MHz linear transducer probe for CCABFparameters calculated using time-averaged mean velocity (TAmean) and with a 1-5 MHz cardiac probe equipped with tissue doppler imaging (TDI) for TTE-CO calculated using left ventricular outflow tract velocity time integral (LVOT VTI) with an apical five-chamber view. Two separate PLR tests (five minutes apart) were done within 48 hours of ICU admission. The first PLR test was to assess the effects on TTE-CO. The second PLR test was performed to assess the effects on CCABF parameters. Patients were designated as fluid responders (FR) if changes in TTE-CO (Δ TTE-CO) ≥ 10 %. Results A positive PLR test was observed in 33% of patients. A strong correlation was present between absolute values of TTE-CO calculated using LVOT VTI and the absolute values of CCABF calculated using TAmean (r=0.60, p<0.05). However, a weak correlation was found between Δ TTE-CO and changes in CCABF (Δ CCABF) during the PLR test (r=0.05, p<0.74). A positive PLR test response could not be detected by Δ CCABF (area under the curve (AUC): 0.59 ± 0.09). Conclusions We found a moderate correlation between TTE-CO and CCABF at baseline. However,Δ TTE-COhad a very poor correlation with Δ CCABF, during the PLR test. Considering this, CCABF parameters may not be recommended as a means to detect fluid responsiveness with PLR tests in critically ill patients.

End-tidal carbon dioxide's change to fluid challenge versus internal jugular vein dispensability index for predicting fluid responsiveness in septic patients: A prospective, observational study.

The prediction of fluid responsiveness is crucial for the fluid management of septic shock patients. This prospective, observational study was conducted to compare end-tidal carbon dioxide (ETCO2) change due to fluid challenge (FC-induced ΔETCO2) versus internal jugular vein distensibility index (IJVDI) as predictors of fluid responsiveness in such patients. Septic hypoperfused mechanically ventilated patients were classified as fluid responders (Rs) and non-responders (NRs) according to the improvement of left ventricular outflow tract-velocity time integral (ΔLVOT-VTI) after fluid challenge (FC). The receiver operating characteristic (ROC) curves of FC-induced ΔETCO2, pre-(FC) IJVDI and their combination for prediction of fluid responsiveness were compared to that of ΔLVOT-VTI% as a gold standard. Of 140 patients who completed the study, 51 (36.4%) patients were classified as Rs and 89 (63.6%) patients as NRs. With regard to the prediction of fluid responsiveness, no significant difference (P. 0. 384) was found between the diagnostic accuracy of FC-induced ΔETCO2 >2 mmHg (area under the ROC curve [AUC] 0.908, P < 0.001) and that of pre-(FC) IJVDI >18% (AUC 0.938, P < 0.001), but a prediction model combining both markers, ΔETCO2 ≥3 mmHg and IJVDI ≥16%, achieved significantly higher accuracy (AUC 0.982, P < 0.001) than each independent one (P < 0.05). Under stable ventilatory and metabolic conditions, the predictivity of FC-induced ΔETCO2 >2 mmHg can be comparable to that of pre-(FC) IJVDI >18%. A predictive model combining both FC-induced ΔETCO2 ≥3 mmHg and IJVDI ≥16% can provide higher accuracy than that recorded for each one independently.

Evaluating the Utility of Portal Vein Pulsatility Index for Detecting Fluid Unresponsiveness in the Intensive Care Unit

The primary aim of the authors' study was to evaluate the capacity of the portal vein pulsatility index (PVP) to detect fluid unresponsiveness in patients admitted to intensive care. This was a retrospective, diagnostic accuracy study SETTING: At a tertiary medical-surgical intensive care unit in Buenos Aires, Argentina. Patients were included during usual care in the intensive care unit, who were evaluated by ultrasonography for the flow of the portal vein, calculating their PVP prior to fluid expansion. Patients who exhibited an increase of <15% in left ventricle outflow tract velocity-time integral after receiving 500 mL of Ringer Lactate were considered non-responders to fluids. The authors included a total of 63 patients between January 2022 and October 2022. The area under the receiver operating characteristic curve for PVP to predict fluid unresponsiveness was 0.708 (95% CI 0.580 to 0.816). A value of the PVP >32% predicted fluid unresponsiveness with a sensitivity of 30.8% (95% CI 17% to 47.6%) and specificity of 100% (95% CI 85.8 to 100). The positive predictive value was 100%, and the negative predictive value was 47.1% (95% CI 41.9% to 52.3%). Although PVP has limited value as the sole indicator for fluid management decisions, it can be used as a stopping rule or combined with other diagnostic tests to improve the accuracy of fluid responsiveness assessment.

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.

Comparison of echocardiographic pulmonary flow Doppler markers in patients with massive or submassive acute pulmonary embolism and control group: A cross-sectional study.

Computed tomography angiography (CTA) is the gold standard for the diagnosis of massive (MPE) and submassive pulmonary embolism (SMPE). Ultrasound has not been accepted as a diagnostic tool. We aim to evaluate the pattern of pulmonary Doppler echocardiography in patients with pulmonary embolism (PE). From 2020 to 2022, 30 patients with acute MPE or SMPE confirmed by CTA and normal pulmonary pressures were selected. A control group was created with 30 individuals without PE. All patients had an echocardiography Doppler study of the pulmonary flow with a focus on early systolic notching (ESN), McConnell's (MC) sign, Right ventricular outflow tract velocity time integral (RVOTVTI), segmental thickness variability (STV), right ventricular end-diastolic diameter (RVEDD), tricuspid regurgitation (TR) gradient, pulmonary artery pressure (PAP), and acceleration (AT) or ejection time (ET). ESN was identified in 96.6% of PE patients and 0% of the control group (p < 0.001). In comparison with the control group, STV (p < 0.001), RVOT VTI (p < 0.001), ET (p = 0.04), and AT (p < 0.001) values were lower in patients with PE while RVEDD, TR gradient, PAP, ESN, MC sign, and d-shape were higher (p < 0.001). Identification of the ESN pattern and AT/ET < 0.4 showed excellent predictive ability for MPE and SMPE with a sensitivity of 97.0% and 100%, specificity of 99.0% and 97%, and an area under the ROC curve of 0.967 (95% CI 0.914-1.00) and 0.933 (95% CI 0.844-1.00), respectively. Doppler echocardiography with particular attention to ESN, may be a suitable noninvasive method for the diagnosis of MPE and SMPE. Further studies with more sample sizes are needed to confirm its diagnostic benefit.

Echocardiographic Correlates of Left Atrial Function Index Among Hypertensive Heart Failure Patients: A Cross-Sectional Study.

Background Heart failure contributes to the global burden of cardiovascular diseases, with hypertensive heart failure affecting individuals in their productive age group and leading to high economic losses and disability-adjusted life years. The left atrium, on the other hand, contributes significantly to left ventricular filling in heart failure patients, and the left atrial function index is an excellent tool for assessing left atrial function among heart failure patients. The study aimed to evaluate some parameters of systolic and diastolic function as correlates and potential predictors of the left atrial function index among hypertensive heart failure cohorts. Materials and methods The study was conducted at Delta State University Teaching Hospital, Oghara. Eighty (80) patients with hypertensive heart failure who met the inclusion criteria were enrolled in the cardiology outpatient clinics. The left atrial function index was calculated using the following formula: LAFI = (LAEF x LVOT-VTI)/LAESVI. (LAFI = left atrial function index; LAEF = left atrial emptying fraction; LAESVI = left atrial end-systolic volume index; LVOTVTI = outflow tract velocity time integral). The data were analysed using IBM Statistical Product and Service Solution Version 22. Relationships between variables were determined using analysis of variance, Pearson correlation, and multiple linear regressions. Significance was assessed at p<0.05. Result It was discovered that the left atrial function index correlated with ejection fraction (r = 0.616, p = 0.001), fractional shortening (r = 0.462, p = 0.001), and the ratio of early transmitral flow to early myocardial contractility, E/E' (r =-0.522, p = 0.001). However, there was no correlation with stroke volume (r = 0.38, p = 0.11); the ratio of early transmitral flow to late transmitral flow, E/A (r = -0.10, p = 0.11); isovolumetric relaxation time, IVRT (r = -0.171, p = 0.11);and tricuspid annular plane systolic excursion, TAPSE (r =0.185, p = 0.10). Of the variables that correlated with left atrial function index, left ventricular ejection fraction and the ratio of early transmitral flow to early myocardial contractility (E/E') were found to be independent predictors of left atrial function index. Conclusion Left ventricular ejection fraction and the ratio of early transmitral flow to early myocardial contractility reflect changes in the left atrial function index, and as such, they should be used as surrogates for its assessment, especially in low- and medium-income countries where left atrial function index estimation is not routinely done.

Effects of varying blood flow rate during peripheral veno-arterial extracorporeal membrane oxygen (V-A ECMO) on left ventricular function measured by two-dimensional strain.

We evaluated the effects of varying blood flow rate during peripheral veno-arterial extracorporeal membrane oxygen (V-A ECMO) on left ventricular function measured by two-dimensional strain. Adult patients who were supported by peripheral V-A ECMO were recruited. Serial hemodynamic and cardiac performance parameters were measured by transthoracic echocardiogram within the first 48 h after implementation of V-A ECMO. Measurements at 100%, 120%, and 50% of target blood flow (TBF) were compared. A total of 54 patients were included and the main indications for V-A ECMO were myocardial infarction [32 (59.3%)] and myocarditis [6 (11.1%)]. With extracorporeal blood flow at 50% compared with 100% TBF, the mean arterial pressure was lower [66 ± 19 vs. 75 ± 18 mmHg, p < 0.001], stroke volume was greater [23 (12-34) vs. 15 (8-26) ml, p < 0.001], and cardiac index was higher [1.2 (0.7-1.7) vs. 0.8 (0.5-1.3) L/min/m2, p < 0.001]. Left ventricular contractile function measured by global longitudinal strain improved at 50% compared with 100% TBF [-2.8 (-7.6- -0.1) vs. -1.2 (-5.2-0) %, p < 0.001]. Similarly, left ventricular ejection fraction increased [24.4 (15.8-35.5) vs. 16.7 (10.0-28.5) %, p < 0.001] and left ventricular outflow tract velocity time integral increased [7.7 (3.8-11.4) vs. 4.8 (2.5-8.5) cm, p < 0.001]. Adding echocardiographic parameters of left ventricular systolic function to the Survival After Veno-arterial ECMO (SAVE) score had better discriminatory value in predicting eventual hospital mortality (AUROC 0.69, 95% CI 0.55-0.84, p = 0.008) and successful weaning from V-A ECMO (AUROC 0.68, 95% CI 0.53-0.83, p = 0.017). In the initial period of V-A ECMO support, measures of left ventricular function including left ventricular ejection fraction and global longitudinal strain were inversely related to ECMO blood flow rate. Understanding the heart-ECMO interaction is vital to interpretation of echocardiographic measures of the left ventricle while on ECMO.

Efficacy and Safety of Leadless Pacemakers for Atrioventricular Synchronous Pacing: A Systematic Review and Meta-Analysis

Leadless pacemakers with an atrioventricular synchrony algorithm represent a novel technology for patients qualified for VDD pacing. The current evidence of their performance is limited to several small-scale observational studies. This systematic review and meta-analysis aimed to evaluate the efficacy and safety of this new technology. We systematically searched the PubMed, Embase, and Cochrane library databases from their inception to 12 September 2022. The primary efficacy outcome was atrioventricular synchrony after implantation, whereas the secondary efficacy outcome was the change in cardiac output represented by the left ventricular outflow tract velocity time integral (LVOT-VTI). The primary safety outcome was major complications related to the procedures and the algorithm. Means or mean differences with 95% confidence interval (95% CI) were combined using a random-effects model or a fixed-effects model. Finally, 8 published studies with 464 participants were included in the qualitative analysis. The pooled atrioventricular synchrony proportion was 78.9% (95% CI 71.9-86.0%), and a further meta-regression did not screen factors that contributed significantly to the heterogeneity. Additionally, a significant increase in atrioventricular synchrony of 11.3% (95% CI 7.0-15.7%, p < 0.01) was achieved in patients experiencing programming optimization. LVOT-VTI was significantly increased by 1.9 cm (95% CI 1.2-2.6, p < 0.01), compared with the VVI pacing mode. The overall incidence of complications was approximately 6.3%, with major complications related to the algorithm being extremely low. Overall, leadless pacemakers with atrioventricular synchronous pacing demonstrated favorable safety and efficacy. Future data on their long-term performance are required to facilitate their widespread adoption in clinical practice.

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.

Possibilities of a portable electrocardiogram and pulse wave recorder in detecting left ventricular systolic dysfunction

Highlights. The article presents a novel and unique method for assessment of left ventricular systolic disfunction using electrocardiography and photoplethysmography data. This method will improve and simplify the detection of cardiovascular diseases.Aim. To evaluate left ventricular (LV) systolic function using electrocardiogram (ECG) and photoplethysmogram (PPG) signals recorded by a single-channel ECG and PPG-based monitor.Methods. The prospective study included 489 patients over 18 years old with various cardiovascular diseases. All participants underwent echocardiography to determine the main indicators of LV systolic function: LV ejection fraction (EF), LV outflow tract velocity time integral (LVOT VTI), and global longitudinal strain (GLS). Moreover, all patients underwent 1-lead ECG and PPG recording using a single-channel ECG and PPG-based monitor (CardioQvark). The obtained data were analyzed, and ROC curve analysis was performed.Results. We have identified ECG and PPG parameters associated with a decrease in LV contractile function. During the analysis, the ECG, T-wave amplitude (TA) and RonsF parameters showed the highest diagnostic accuracy. With EF below 55%, the area under the ROC curve (AUC) was 0.822, sensitivity (Se) 80%, specificity (Sp) 69% in EF below 55% in TA; in RonsF AUC was 0.743, Se 81%, Sp 77%. With EF below 40%, AUC was 0.915, Se 85%, Sp 83% in TA, and in RonsF AUC was 0.844, Se 82%, Sp 82%. Diagnostic accuracy of ECG signals in case of LVOT VTI lower than 16 cm was measured: TA (AUC 0.755, Se 82%, Sp 70%), RonsF (AUC 0.620, Se 77%, Sp 72%). PPG signals were not significantly associated with reduced EF; however, the pulse wave parameters were associated with lower LVOT VTI: in DP-B0 AUC was 0.687, Se 71%, Sp 74%. The combination of ECG and PPG signals was significantly associated with EF below 40% (RonsF * DP-SEP (AUC 0.877, Se 86%, Sp 85%). ECG and PPG signals were not associated with LV GLS.Conclusion. Assessment of LV systolic function can be performed by analyzing ECG and PPG signals recorded using a portable single-channel CardioQvark monitor.

Right ventricular cardiac resynchronization therapy in patients with right ventricular conduction delay and heart failure

Right ventricular cardiac resynchronization therapy in patients with right ventricular conduction delay and heart failure

Systemic ventricular function in Fontan patients at rest and after exercise at altitude.

Physical activity at high altitude is expected to pose risks for patients with Fontan circulation and to impair systemic ventricular function. This study aims to determine the effect of high-altitude hypoxia on ventricular function in Fontan patients at rest and after exercise. We hypothesize that systemic ventricular function deteriorates under hypoxic conditions in Fontan patients. In this prospective study, 21 Fontan patients (NYHA class I-II) and 21 age-, gender- and body mass index-matched healthy controls were enrolled (median age 17.9 and 16.9 years). Transthoracic echocardiography was performed at rest, after peak (PE) and after continuous exercise (CE) in normoxia and hypoxia at simulated altitude (2,500 m above sea level). The effect of hypoxia on echocardiographic parameters was quantified by linear mixed-effects models and the difference between normoxia and hypoxia (Δ= hypoxia-normoxia). At rest, cardiac output (CO) estimated by outflow tract velocity time integral × heart rate and annular plane systolic excursion (APSE) were lower in hypoxia compared to normoxia in Fontan patients (CO: Δ = -12.0%, n.s.; APSE: Δ = -9.6%, p < 0.001), an increase was observed in controls (CO: Δ = 8.5%, n.s.; APSE: Δ = 2.5%, n.s.). Other parameters of systolic and diastolic function did not show relevant changes. After exercise under hypoxic conditions, Fontan patients did not show relevant deterioration of systolic function compared to normoxia. Late, active diastolic filling reflected by A-wave velocity remained unchanged in Fontan patients, but increased in controls. Under hypoxic conditions, CO and workload were higher after CE than PE in Fontan patients (CO: PE Δ = 1,530 vs. CE 1630), whereas controls showed higher work load and CO estimates after PE than CE as expected (CO: PE Δ = 2,302 vs. CE 2149). Fontan patients clinically tolerated short-term altitude exposure up to two hours and exercise and showed no consistent deterioration of systolic systemic ventricular function, but parameters of myocardial contractility, heart rate and cardiac output did not increase as observed in controls. This is likely to be multifactorial and may include intrinsic cardiac dysfunction as well as preload inadequacy and the lack of augmented atrial contraction. CE may be better tolerated than PE.

Fibrinolytic Status and Risk of Death After Acute Pulmonary Embolism.

Acute pulmonary embolism (PE) is a heterogeneous disease process with variable presentation and outcomes. The endogenous fibrinolytic system is a complex framework of regulatory pathways that maintains homeostasis by dissolving overabundant thrombi. We sought to investigate phenotypic profiles of the endogenous fibrinolytic system among patients presenting with acute PE and their impact on mortality. We enrolled all consecutive patients with acute PE in our institutional Pulmonary Embolism Response Team registry. We collected blood samples at the time of PE diagnosis and analyzed concentrations of plasminogen activator inhibitor 1 (PAI-1), thrombin-activatable fibrinolysis inhibitor (TAFI), and alpha-2-antiplasmin (A2A). We assessed the association of concentration of fibrinolytic inhibitors and 1-year all-cause mortality and various echocardiographic markers of right ventricular (RV) dysfunction. There is significant variability of PAI-1, A2A, and TAFI concentrations across the spectrum of PE risk profiles with high PAI-1, low TAFI, and low A2A (herein referred to as a high-risk biomarker profile) correlating with worse PE severity. High-risk biomarker profile correlated with high-risk echocardiographic features of RV dysfunction, including increased RV/left ventricular (LV) ratio, low tricuspid annular plane systolic excursion, and low right ventricular outflow tract velocity time integral. Higher-risk biomarker profile was able to discriminate and independently identify patients at high risk of all-cause mortality (Group 2 HR 6 95% CI 1.3-27.8, Group 3 HR 12, 95% CI 1.7-86). Further studies are needed to assess the exact pathophysiological link between fibrinolytic status and poor outcome after acute PE and to ascertain the impact of anti-inhibitors of the fibrinolytic system on response to therapy and outcomes after acute PE.

End-expiratory Occlusion Test and Mini-fluid Challenge Test for Predicting Fluid Responsiveness in Acute Circulatory Failure.

Predicting which patients with acute circulatory failure will respond to the fluid by an increase in cardiac output is a daily challenge. End-expiratory occlusion test (EEOT) and mini-fluid challenge (MFC) can be used for assessing fluid responsiveness in patients with spontaneous breathing activity, cardiac arrhythmias, low-tidal volume and/or low lung compliance. The objective of the study is to evaluate the value of EEOT and MFC-induced rise in left ventricular outflow tract (LVOT) velocity time integral (VTI) in predicting fluid responsiveness in acute circulatory failure in comparison to the passive leg-raising (PLR) test. Hundred critically ill ventilated and sedated patients with acute circulatory failure were studied. LVOT VTI was measured by transthoracic echocardiography before and after EEOT (interrupting the ventilator at end-expiration over 15 s), and before and after MFC (100 ml of Ringer lactate was infused over 1 min). The variation of LVOT VTI after EEOT and the MFC was calculated from the baseline. Sensitivity, specificity, and area under the receiver-operating characteristic (AUROC) curve of LVOT VTI after EEOT and MFC to predict fluid responsiveness were determined. After PLR, stroke volume (SV) increased by ≥12% in 49 patients, who were defined as responders and 34 patients in whom the increase in SV <12% were defined as nonresponders. A cutoff of 9.1% Change in VTI after MFC (ΔVTIMFC) predicted fluid responsiveness with an AUROC of 0.96 (P < 0.001) with sensitivity and specificity of 91.5% and 88.9%, respectively. Change in VTI after EEOT (ΔVTIEEOT) >4.3% predicted fluid responsiveness with sensitivity and specificity 89.4% and 88.9%, respectively, with an AUROC of 0.97 (P < 0.001), but in 17 patients, EEOT was not possible because triggering of the ventilator by the patient's inspiratory effort. In conclusion, in mechanically ventilated patients with acute circulatory failure Δ VTIMFC and Δ VTI EEOT accurately predicts fluid responsiveness.