Ventricular Outflow Tract Velocity Time Research Articles

Low left ventricular outflow tract velocity time integral predicts normotensive shock in patients with acute pulmonary embolism

Abstract Funding Acknowledgements None. Introduction In patients with intermediate-risk acute pulmonary embolism (PE) outcomes vary widely, with mortality rates ranging from 3-15% and rates of normotensive shock up to 30%.1-3 Current risk models don't fully capture those at higher risk and identify patients who may benefit from advanced therapies. The left ventricular outflow tract (LVOT) velocity time integral (VTI), a surrogate marker of cardiac output, has been associated with increased mortality in acute PE.4 Our objective was to determine the association between LVOT VTI and its predictive value in identifying normotensive shock in this patient population. Methods Patients who underwent percutaneous mechanical thrombectomy (MT) between August 2020 and March 2023 at a large academic public hospital were considered for the study. Inclusion criteria comprised of normotensive patients (SBP ≥ 90 mmHg) with invasive measures of cardiac index (CI). VTI was obtained by pulsed wave doppler at the LVOT in either the apical 3 or apical 5 chamber view. The primary outcome was the association between LVOT VTI and normotensive shock and a cut off of 15 cm was used to examine this association based on prior studies.4 Results A total of 49 patients with intermediate-risk PE underwent MT, 16 patients had incomplete data, resulting in a final cohort of 33 patients (mean age: 57 ± 13yrs; 38% female). Patients with LVOT VTI of <15 cm were younger (53 vs 62 years p=0.02), had lower systolic blood pressure at presentation (122 vs 134 mmHg, p=0.047), higher heart rate (112.6 vs 96.2 beats/min, p=0.008), a higher composite shock score (CPES) (5 vs 3, p=0.012), lower cardiac index (1.9 vs 3.1 L/min/m2, p<0.001), a higher PASP (61.4 vs 48.9 mmHg, p=0.018), and higher rates of elevated lactate (90% vs 42%, p=0.027). LVOT VTI threshold of <15cm effectively identified patients with normotensive shock (90% vs 8% p<0.001). There was no statistically significant difference in the rates of saddle emboli, left ventricular ejection fraction, sPESI and BOVA scores in patients with VTI above or below 15cm. In patients with normotensive shock, 19/20 (95%) had LVOT VTI ≤ 15cm with a median of 13 cm (IQR 12, 14) (Figure). In patients without normotensive shock, 11/13 (84%) had LVOT VTI >15 with a median of 18 (IQR 17, 21). The area under the curve for LVOT VTI ≤ 15 cm in predicting normotensive shock was 0.89. The sensitivity and specificity of LVOT VTI ≤ 15 cm in predicting normotensive shock was 91.6% and 90.4% respectively. Conclusion Our study suggests that LVOT VTI is a reliable surrogate for cardiac output in patients with acute PE and can effectively identify those in the intermediate-risk group who are at risk for normotensive shock. A LVOT VTI <15cm may identify intermediate-risk patients at higher risk for hemodynamic decompensation and further studies are needed to evaluate whether these patients would benefit from upfront catheter-based therapies.

Risk assessment by acute bedside echocardiography prior to acute coronary angiography in patients with ST-elevation myocardial infarction: a feasibility study

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Novo Nordisk Foundation. Background Early risk assessment by hemodynamic measurements in patients with ST-elevation myocardial infarction (STEMI) could be useful for early detection of patients at risk of developing hemodynamic instability after primary percutaneous coronary intervention (pPCI). Anterior STEMI patients have larger infarct size and may be of particular interest. Transthoracic echocardiography (TTE) is a quick, non-invasive, and available tool, however, evidence regarding the use of acute TTE prior to acute coronary angiography (CAG) is limited. Purpose To assess the feasibility of acute bedside hemodynamic assessment in the cath. lab. by TTE in addition to clinical examination, and blood samples in STEMI patients without CS at arrival in the cath. lab. Methods STEMI patients without CS at hospital arrival and treated with pPCI were included in the study during a five week period. Clinical examination (Killip class), blood sampling (lactate, troponin T (TNT), proB-type natriuretic peptide (proBNP), and focused bedside 2D TTE with Doppler were performed prior to the acute CAG. The TTE protocol was focused (approx. 5 minutes) on hemodynamic measurements, infarction related complications, and differential diagnoses e.g. aortic dissection. The TTE was performed during preparation for the acute CAG. Patients were stratified in anterior- vs. non-anterior STEMI based on the culprit artery and prehospital ECG. Feasibility was estimated by all of the following echocardiographic parameters; left ventricular ejection fraction (LVEF), left ventricular outflow tract (LVOT) velocity time integral (VTI), and right ventricular function (tricuspid annular plane systolic excursion (TAPSE)). Results A total of 60 STEMI patients (aged mean 63 years, 18% female) were included, and 47% had an anterior STEMI. No differences in baseline characteristics between the two groups were found including comorbidities, clinical parameters, and time from cath. lab. arrival to first wire over the culprit lesion (median (IQR) 28 (23; 38) vs 32 (24; 40) minutes). Admission biomarkers of blood glucose, lactate, and proBNP plasma concentrations were similar between the two groups. Whereas admission TNT were higher for patients with anterior STEMI (median (IQR) 110 (37; 449) vs. 37 (20; 94) ng/L, p=0.01). The feasibility of TTE-study protocol was 93%. Patients with anterior STEMI had lower LVEF (mean: 36±11 vs. 48±9%, p=0.0003; missing: n=0), and a trend to lower LVOT VTI (19 (6.4) vs. 22 (5.0) cm, p=0.06; missing: n=4). No difference in parameters of diastolic function or TAPSE (missing: n=0) were found. None of the included patients had echocardiographic visible complications related to the infarction. Conclusion Acute TTE is to a high degree feasible and does not delay time to acute revascularization in STEMI patients. Patients with anterior STEMI have significantly higher admission TNT levels, lower LVEF, and a trend to lower LVOT VTI compared with non-anterior STEMI patients.

Low left ventricular outflow tract velocity time integral predicts normotensive shock in patients with acute pulmonary embolism

In this study, we found that a low LVOT VTI (<15 cm), a simple bedside point-of-care measurement, predicts normotensive shock in patients with acute intermediate-risk PE.

The Utility of Echocardiography in Estimating Fluid Responsiveness.

Assessing the volume status in critically ill patients is the key to maintain the stability of the hemodynamics; however, it can be challenging to view the complexity of cases and the diversity of shock etiology. Multiple noninvasive means have been used to study the effectiveness of volume resuscitation, but none of them have been used as gold standard. We aim to illustrate the most used techniques: left ventricular outflow tract velocity time integral versus inferior vena cava compressibility index, and highlight their limitations and strengths. These tools are both operator-dependent and might be affected by several factors including ventilator settings.

A Curious Case of Left Ventricular Outflow Tract Velocity Time Integral Alternans With an Intra-Aortic Balloon Pump: Physiology in Action

A Curious Case of Left Ventricular Outflow Tract Velocity Time Integral Alternans With an Intra-Aortic Balloon Pump: Physiology in Action

Diagnostic accuracy of left ventricular outflow tract velocity time integral versus inferior vena cava collapsibility index in predicting post-induction hypotension during general anesthesia: an observational study.

Point of care ultrasound (POCUS) is being explored for dynamic measurements like inferior vena cava collapsibility index (IVC-CI) and left ventricular outflow tract velocity time integral (LVOT-VTI) to guide anesthesiologists in predicting fluid responsiveness in the preoperative period and in treating post-induction hypotension (PIH) with varying accuracy. In this prospective, observational study on included 100 adult patients undergoing elective surgery under general anesthesia, the LVOT-VTI and IVC-CI measurements were performed in the preoperative room 15 minutes prior to surgery, and PIH was measured for 20 minutes in the post-induction period. The incidence of PIH was 24%. The area under the curve, sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of the two techniques at 95% confidence interval was 0.613, 30.4%, 93.3%, 58.3%, 81.4%, 73.6% for IVC-CI and 0.853, 83.3%, 80.3%, 57.1%, 93.8%, 77.4% for LVOT-VTI, respectively. In multivariate analysis, the cutoff value for IVC-CI was >51.5 and for LVOT-VTI it was ≤17.45 for predicting PIH with odd ratio [OR] of 8.491 (P=0.025) for IVCCI and OR of 17.427 (P<0.001) for LVOT. LVOT-VTI assessment was possible in all the patients, while 10% of patients were having poor window for IVC measurements. We recommend the use of POCUS using LVOT-VTI or IVC-CI to predict PIH, to decrease the morbidity of patients undergoing surgery. Out of these, we recommend LVOT-VTI measurements as it has showed a better diagnostic accuracy (77.4%) with no failure rate.

The left ventricular outflow tract and carotid artery velocity time integrals

The left ventricular outflow tract velocity time integral (LVOT VTI) is commonly used in the intensive care unit as a measure of stroke volume (SV) and how the SV changes in response to an intervention; therefore, the LVOT VTI is used to guide intravenous fluid management. Various peripheral Doppler surrogates are proposed to infer the LVOT VTI (e.g., measures from the common carotid artery). A recently-described, novel method of insonation has an excellent ability to detect change in the LVOT VTI. This approach raises important facets of Doppler flow and insonation error, as well as the general principles at play when using a peripheral artery to infer changes from the left ventricle. Relating the VTI of a peripheral artery to the LVOT VTI was recently described mathematically and may help clinicians think about the Doppler relationship between central and peripheral flow.

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 &lt;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 &lt; 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 &lt;24 and LAFI ≥24. Those with abnormal LAFI had lower EF (45.04±11.06 vs. 63.73±14.73, p&lt;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&lt;0.0001) and LAVI (37.22±5.80 vs. 16.48±5.65, p&lt;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.

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.

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.

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.

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

Echocardiography- versus intracardiac electrocardiogram-based optimization of cardiac resynchronization therapy: A systematic review.

This systematic review aimed to evaluate the performance of echocardiography-based programming in comparison with the intracardiac electrocardiogram (IEGM)-based method for the optimization of cardiac resynchronization therapy (CRT). A literature review was conducted using digital databases to systematically identify the studies reporting CRT optimization through echocardiography compared with IEGM. Detailed patient-level study characteristics including the type of study, sample size, therapy, the New York Heart Classification (NYHA) status, lead placement, and other parameters were abstracted. Finally, postprogramming outcomes were extracted for each article. In a total of 11 studies, 919 patients were recruited for the final analysis. Overall, 692 (75.29%) were males. The mean duration of the QRS complex in our study population ranged from 145.2± 21.8ms to 183 ± 19.9ms. There was an equal improvement in the NYHA class between the two methods while the left ventricular ejection fraction (LVEF) demonstrated an improvement by IEGM. Many studies supported IEGM to increase the 6-minute walk test and left ventricular outflow tract velocity time interval (LVOT VTI) when compared to echocardiography. The mean time for echocardiography-based optimization was 60.15 min while that of IEGM-based optimization was 6.65 min. IEGM is an alternative method for CRT optimization in improving the NYHA class, LVEF, and LVOT VTI, and is less time-consuming when compared to the echocardiography-based methods.