Ventricular Outflow Tract Velocity-time Integral Research Articles

Correlation between corrected carotid flow time and left ventricular outflow tract velocity-time integral using a novel technique.

Transthoracic echocardiography (TTE) is widely used for assessing patients in the intensive care unit, with cardiac output measurement being crucial for hemodynamic monitoring. This is achieved by measuring the velocity-time integral (VTI) of the left ventricular outflow tract (LVOT), which serves as a surrogate of stroke volume. However, conducting TTE in the critical care setting presents several challenges. Our primary objective was to investigate the relationship between carotid corrected flow time (cCFT) and LVOT VTI. Additionally, we aimed to determine the threshold cCFT value that reliably predicts a normal LVOT VTI. This proof-of-concept study involves a post-hoc analysis from a diagnostic accuracy investigation conducted in a medical-surgical intensive care unit. We included patients admitted to the ICU from December 2021 to January 2022. We used a phased array transducer to measure the cCFT at the left supraclavicular fossa and the LVOT VTI in an apical 5-chamber view. We included 22 patients. The Spearman coefficient between LVOT VTI and cCFT was 0.82 (p < 0.0001). The area under the ROC curve for cCFT to predict LVOT VTI equal to or greater than 17 cm was 0.871 (95% CI 0.660-0.974). A cCFT exceeding 283 ms predicted LVOT VTI equal to or greater than 17 cm with a sensitivity of 93.3% (95% CI 68.1% to 99.8%) and specificity of 85.7% (95% CI 42.1% to 99.6%). The cCFT, measured using a novel technique with a phased array transducer, shows a strong correlation with LVOT VTI. Additionally, cCFT predicts a normal LVOT VTI with good sensitivity and specificity in critically ill patients. Larger studies are warranted to validate these findings.

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.

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.

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.

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.

Velocity-Time Integral: A Bedside Echocardiography Technique Finding a Place in the Emergency Department

BackgroundPoint-of-care ultrasound is a fundamental tool in the emergency department when managing the critically ill patient. Determining a patient's hemodynamic status at the bedside can better guide resuscitation efforts. The left ventricular outflow tract velocity–time integral (VTI) is a validated, noninvasive, and rapidly acquired echocardiographic measurement that is analogous to stroke volume. DiscussionVTI can be used to determine fluid responsiveness and to risk stratify patients, particularly in pulmonary embolism, heart failure, and sepsis. Emergency physicians with limited experience can successfully measure VTI in a timely and accurate manner. However, VTI measurement is not commonly taught in emergency medicine residency and, as a result, it is an underused tool. ConclusionsVTI is an objective tool for clinicians to assess the hemodynamic status of critically ill patients. Understanding the acquisition of VTI and proper application in the context of the patient's history, clinical examination, and other bedside ultrasound findings, should be reviewed within the emergency medicine residency ultrasound curriculum. This article provides a simple four-step protocol, as well as bedside applications and potential limitations for VTI in the ED.

Echocardiographic recovery changes in patients supported with veno-arterial extracorporeal membrane oxygenator and weaning success

Abstract Introduction The weaning from veno-arterial extracorporeal membrane oxygenation (VA-ECMO) decision involves a meticulous evaluation of different factors, among which echocardiography is a decisive factor. Purpose Evaluate echocardiographic changes from the beginning of the support to the weaning test. Methods Analysis of VA-ECMO cases in a referral hospital which completed a weaning test. We evaluated the changes of echocardiographic parameters during the VA-ECMO support (initial and during weaning test) and successful weaning (survival &amp;gt;24h after explant and no mortality from cardiogenic shock/heart failure or cardiac arrest during admission). Results 85 out of 134 VA-ECMO patients were included from 2013 to Oct-2020 (table 1.1). Successful weaning was achieved in 61.2% and final survival at discharge 49.4%. We observed a significant increase in left ventricular ejection fraction (LVEF), left ventricular outflow tract time–velocity integral (LVOT VTI), tricuspid annular plane systolic excursion (TAPSE) and the percentage of patients with normal qualitative right ventricular function and 1:1 aortic valve opening from the initial to the weaning echocardiography (table 1.2), without significant changes in ventricular diameters. Among these changes, the increase in LVOT VTI was the only parameter that was related to weaning success (p=0.037, table 1.2). A higher LVEF increase from the initial value showed a trend to greater successful VA-ECMO disconnection (p=0.053 table 1.2). Conclusion Left and right ventricular function parameters improved significantly from baseline to weaning test echocardiography in VA-ECMO supported patients. Of these changes, the increase in LVOT VTI was related to successful disconnection from VA-ECMO and the LVEF improvement showed a trend to weaning success. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): Instituto de Salud Carlos III in Spain (Co-funded by European Social Fund “Investing in your future”). Characteristics ECMO-VA patients

Clinical usefulness of left ventricular outflow tract velocity time integral for heart failure with reduced ejection fraction with rapid atrial fibrillation during landiolol treatment

BackgroundLandiolol enables us to treat the patients with rapid atrial fibrillation (AF) with acute decompensated heart failure (ADHF) efficiently. We sought to determine the role of echocardiography in predicting the prognosis. MethodsAmong 314 patients, a total 115 ADHF patients with reduced ejection fraction and rapid AF were enrolled. They received landiolol treatment to decrease the heart rate (HR) to <110 bpm and change HR (ΔHR) of >20% within 24 h. The dose of landiolol was increased every 2 h; then, we performed echocardiography repeatedly, at baseline, 2 h, and 24h. We followed the patients after discharge for 180 days, and checked cardiac death and HF hospitalization as major adverse cardiac events (MACE). ResultsDuring initial hospitalization, 5 patients (4%) died. During 180 days after discharge, 19 (16%) out of 115 patients experienced MACE (2 cardiac death, 17 HF rehospitalization, 5 in-hospital death). Multivariate analysis showed that the change in left ventricular outflow tract-velocity time integral (LVOT-VTI) at 2 h was the most significant predictor for MACE (hazard ratio =1.21, 95% confidence interval: 1.10-1.83, p=0.0001). Kaplan-Meier curves demonstrated the patients with deteriorated LVOT-VTI at minimum dose landiolol suggested the high-risk patients for MACE (χ2=30.9, p<0.0001). ConclusionsDuring landiolol treatment, the patients with deteriorated LVOT-VTI predicted the poor prognosis. We may detect the high-risk patients by two-point echocardiography.UMIN000020084. Registered 1 November 2013 – prospective studyhttps://upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&action=brows&type=summary&language=J&recptno=R000023203

Prognostic Implication of RV Coupling to Pulmonary Circulation for Successful Weaning From Extracorporeal Membrane Oxygenation

ObjectivesThe aim of this study was to explore if right ventricular (RV) contractile function and its coupling to pulmonary circulation (PC) were associated with successful weaning from venoarterial−extracorporeal membrane oxygenation (VA-ECMO) at maintenance of pump flow. BackgroundLimited data are available on predictors of successful weaning from VA-ECMO. MethodsA total of 79 patients with cardiogenic shock underwent transthoracic echocardiography to evaluate weaning from ECMO and were prospectively enrolled between 2016 and 2019. The noninvasively measured RV-PC coupling index was acquired by indexing tricuspid annular S' velocity, tricuspid annular plane systolic excursion (TAPSE), fractional area change (FAC), and RV free-wall longitudinal strain (FWLS) to right ventricular systolic pressure (RVSP). ResultsTransthoracic echocardiography was performed at a median 3.0 days (range 1 to 6 days) after ECMO initiation at a median ECMO flow of 3.2 l/min (range 3.0 to 3.6 l/min). The RV-PC coupling matrix, tricuspid annular S'/RVSP, TAPSE/RVSP, and RV FWLS/RVSP exhibited satisfactory predictive performances for predicting successful weaning from ECMO. Using the best cutoff values derived from the area under the receiver-operator characteristic curve, tricuspid annular S'/RVSP demonstrated a significantly better predictive performance than conventional echocardiographic parameters (left ventricular ejection fraction >20%, left ventricular outflow tract time-velocity integral ≥10 cm, and mitral annular S' ≥6 cm/s). ConclusionsEchocardiographic RV-PC coupling metrics exhibited a significantly better performance for predicting successful weaning from VA ECMO compared with conventional echocardiographic criteria at maintenance of pump flow.

The Role of LVOT-VTI Measurement in the Evaluation of Systolic Heart Function in Pulmonary ICU Patients

Introduction: The detection of cardiac systolic dysfunction is very important for well management of pulmonary critical care patients (PCCPs). However, there is a poor correlation between echocardiographic cardiac systolic function (CSF) parameters and it is not easy to obtain these parameters in PCCPs. Therefore, this cross-sectional observational study was planned for the detection of a more easily obtainable echocardiographic CSF parameter that is well correlated with other CSF parameters in PCCPs. Materials and Methods: Total 88 PCCPs were included. Demographic and clinical information and laboratory tests of all patients were recorded. The CSF parameters of the heart were obtained by transthoracic echocardiography with appropriate technique. LVOT-VTI (Left ventricular outflow tract velocity time integral), CO (cardiac output), EPSS (e point septal separation), Left ventricular EF (ejection fraction) and TAPSE (Tricuspid Annular Plane Systolic Excursion) as an indicator of CSF were tried to obtain from all patients. We also calculated sensitivity, specificity, positive and negative predictive values of LVOT-VTI&lt;20 parameters to diagnose heart failure. Results: The mean age of the patients was 73±12, 40% were female, 38% were intubated and 52% had COPD. LVOT-VTI, EF, CO, EPSS parameters were obtained in 54(61%), 24(27%), 48(54%), 48(54%) patients, respectively. Decreased LVOT-VTI (&lt;20 cm) was well correlated with decreased EF (&lt;45%) (p=0.001, r=0.77), decreased CO (&lt;5 L/dk) (p=0.03, r=0.64) and decreased TAPSE (&lt;17 mm) (p=0.001, r=0.71). Also, there was good agreement between the EF and LVOTVTI measurements (Kappa:0.78, p:0.001). Sensitivity, specificity, positive and negative predictive values of LVOT-VTI&lt;20 for heart failure were 58, 78, 84, 49, repectively. Conclusion: LVOT-VTI is a more easily obtainable and well correlated parameter, which can be used as an indicator of CSF in PCCPs. Clinical Significances: The authors believe that LVOT-VTI measurement has good correlation with other echocardiographic systolic function parameters, and its easy measurement in intensive care patients makes it a very useful test for cardiac systolic function evaluation.

Usefullness of peak mitral regurgitation velocity to left ventricular outflow tract time velocity integral ratio as a new prognostic marker for one year and long term mortality in failing heart

Abstract Background and aim Systemic vascular resistance (SVR) is useful for risk estimation and therapy guidance in HF. It has been showed that the ratio of peak mitral regurgitation velocity (MRV) to left ventricular outflow tract velocity-time integral (LVOT VTI) correlated positively with SVR. We aimed to assess the association of MRV/LVOT VTI ratio with established prognostic markers and its prognostic role for predicting one year and long term composite end-points in patients with HF and reduced ejection fraction (HFrEF). Material and methods We prospectively enrolled a total of 72 patients with HFrEF and 10 control subjects. Patients were followed up patients for median 40.5 months. Primary composite endpoint (CEP) was defined as any of these outcomes including requiring mechanical circulatory support, cardiac transplantation and all-cause mortality. Results CEP(+) patients had higher MRV/LVOT VTI ratio than others (0.48±0.15 vs. 0.39±0.18 p=0.012). MRV/LVOT VTI ratio was positively correlated with functional status (β=0.539, p=0&amp;lt;001), serum BNP level (β=0.479, p&amp;lt;0.001),troponin I (β=0.415, p&amp;lt;0.001), and Uric acid level (β=0.235 p=0.018) and negatively correlated with SEATTLE score derived life expectancy (β=−0.248, p=0.032). Adjusted with other parameters, every 0.1 increase in MRV/LVOT VTI ratio increased the one-year CEP risk by 27% and long-term CEP risk by 24.6%. In Kaplan Meier analysis, patients with MRV/LVOTVTI ratio ≥0.39 had more long-term CEP compared to others. Conclusion MRV/LVOT VTI ratio seemed to be useful predictor of poor prognosis associated with other established HF prognostic markers. Figure 1 Funding Acknowledgement Type of funding source: None

Study on Image Acquisition of Transthoracic Echocardiography in Mechanically Ventilated ICU Patients

Objective This study aimed to determine which parameters in transthoracic echocardiography (TTE) are more likely to be affected when applied in a critical care setting with mechanical ventilation.Methods Ninety mechanically ventilated ICU patients were enrolled into the study group. The control group consisted of 90 patients who underwent interventional therapy. All patients had bedside TTE for parametric measurements including the right ventricular size, septal kinetics and left ventricular ejection fraction (LVEF) by eyeballing (visual assessment), the tricuspid annular plane systolic excursion (TAPSE), mitral annular plane systolic excursion (MAPSE) by M-mode sonography, the right ventricular outflow tract velocity-time integral (RVOT VTI) and left ventricular outflow tract velocity-time integral (LVOT VTI) by pulse-Doppler, the right ventricular fraction of area change (FAC) and left ventricular ejection fraction (LVEF Simpson) by endocardium tracing. We compared the differences in the frequency of optimal image acquisition in assessments of these parameters between the two groups, as well as the differences in acquisition rates of parameter measurements in ventilated ICU patients.Results There were significantly fewer patients in the study group than in the control group who had optimal images acquisitions for parameter assessments with M-mode method, pulse Doppler method and endocardium-tracing method (P<0.05); no significant difference was obsered in the number of patients with optimal images for RV eyeballing and LVEF eyeballing between the two groups. In the study group, significantly fewer optimal images were acquired for FAC than for TAPSE (22.2% vs. 72.2%, χ2=45.139, P<0.001) and RVOT VTI (22.2% vs. 71.1%, χ2=43.214, P<0.001); there were also fewer optimal images acquired for LVEF Simpson than for MAPSE (37.8% vs. 84.4%, χ2=41.236, P<0.001) and LVOT VTI (37.8% vs. 85.6%, χ2=43.455, P<0.001).Conclusions Images acquisition of optimal TTE images tend to be difficult in mechanically ventilated ICU patients, but eyeballing method for functional evaluation could be an alternative method. For quantitative parameters measurements, M-mode based longitudinal function evaluation and pulse Doppler-based VTI were superior to the endocardium-tracing based parameter assessments.

End Tidal Carbon dioxide can track cardiac output changes during fluid challenge in Shocked Mechanically Ventilated Patients

Background: In this study, we investigated the ability of end tidal carbon dioxide pressure (PETCO2) to monitor the changes in cardiac output (CO) induced by fluid challenge and to predict fluid responsiveness. Patients and Methods: We conducted our study upon 38 shocked patients requiring fluid challenge (FC). Hemodynamic variables, central venous pressure (CVP), End-tidal CO2, arterial and venous blood gas analysis and cardiac output were recorded before and after fluid challenges. Fluid responders were identified when cardiac output increased more than 15% after fluid challenge, cardiac output (CO) was estimated by measuring left ventricular outflow tract velocity-time integral (LVOT VTI) by transthoracic doppler echocardiography. Results: Twenty-one (55.3%) patients were fluid responders. Fluid challenge induced increase in CO and PETCO2 was moderately correlated (r = 0.5; P 0.002). The area under receiver operating characteristic (ROC) curve of Δ PETCO2 was 0.89±0.05 CI (81- 98) with an increase ≥ 3.13% in PETCO2 can predict fluid responsiveness with 85.7% sensitivity and 88.3% specificity. No other clinical or hemodynamic variables can predict fluid responsiveness. The area under ROC curve of ΔCVP was 0.48±0.1 CI (32- 64) with an increase ≥ 2cmH2O in CVP can predict fluid responsiveness with 38% sensitivity and 76.5% specificity. Conclusions: Our findings indicate that induced changes in PETCO2 during fluid challenge could be used to monitor changes in cardiac output (CO) for prediction of fluid responsiveness in mechanically ventilated shocked patients, under stationary minute ventilation and steady CO2 production

The Use of Transthoracic Echocardiogram to Quantify Pulmonary Vascular Resistance in Patients with Systemic Sclerosis.

To explore the accuracy of tricuspid regurgitation velocity (TRV) to right ventricular outflow tract time-velocity integral (TVIRVOT) ratio by Doppler to determine pulmonary vascular resistance (PVR) in patients with systemic sclerosis (SSc). Thirty-five consecutive adult patients with SSc, fulfilling the 2013 European League Against Rheumatism/American College of Rheumatology classification criteria, with sinus rhythm referred for right heart catheterization (RHC), were retrospectively included. All patients underwent a transthoracic echocardiogram (TTE) performed within 24 h of RHC. Patients with SSc were recruited regardless of disease activity, cardiac symptoms, and treatment regimen. Doppler measurements were compared to RHC measurements. A linear regression equation was generated to predict PVR by echocardiogram based on the TRV/TVIRVOT ratio. The accuracy of Doppler measurements for predicting PVR > 3 Wood units was assessed by computing the areas under the receiver-operating characteristic curves. There were 20 (57%) females in the study. The mean age was 65 ± 12 years. Mean and systolic pulmonary arterial pressures were 31 ± 8 and 53 ± 15 mmHg, respectively. There was a good correlation between TRV/TVIRVOT ratio assessed by Doppler and PVR measured by RHC (R = 0.743, p < 0.001). The equation generated by this analysis was the following: PVR by Doppler = 11.3 × (TRV/TVIRVOT) + 1.7. A cutoff value of 0.21 for TRV/TVIRVOT ratio provided the best sensitivity (86%) and specificity (86%) to determine PVR > 3 Wood units. Our study suggests that TTE using Doppler could be a useful and noninvasive tool for estimating PVR in patients with SSc.

Self-Appraisal of Clinical Competence in Echocardiography of Chinese Intensivists Post Basic Echocardiography Training

ObjectivesTo learn the echocardiography skills of intensivists after receiving a basic critical care echocardiography training course, and investigate factors that may influence their performance. MethodsWe completed a web-based questionnaire that assessed the skills in ultrasound scanning techniques of intensivists who took a training course on basic critical care echocardiography held in 2019 and 2020. Mann-Whitney test was used to analyze the factors which might affect their performance on image acquisition, recognizing clinical syndrome, and measuring the diameter of inferior vena cava, left ventricular ejection fraction and left ventricular outflow tract velocity-time integral. ResultsWe enrolled 554 physicians from 412 intensive care units across China. Among them, 185 (33.4%) reported that they had 10%–30% chance of being misled by critical care echocardiography when making therapeutic decision, and 34 (6.1%) reported that the chance was greater than 30%. Intensivists who performed echocardiography under the guidance of a mentor and finished ultrasound scanning more than 10 times per week reported significant higher scores in image acquisition, clinical syndrome recognition, and quantitative measurement of inferior vena cava diameter, left ventricular ejection fraction and left ventricular outflow tract velocity-time integral than those without mentor and performing echocardiography 10 times or less per week respectively (all p < 0.05). ConclusionThe skills in diagnostic medical echocardiography of Chinese intensivists after a basic echocardiographic training course remain low, and further quality assurance training program is clearly warranted.

Evaluation of volume responsiveness by pulse pressure variability and inferior vena cava dispensability index at different tidal volumes by mechanical ventilation.

This study investigated the effects of tidal volume (TV) on the diagnostic value of pulse pressure variation (PPV) and the inferior vena cava dispensability index (IVC-DI) for volume responsiveness during mechanical ventilation. In patients undergoing elective surgery with mechanical ventilation, different TVs of 6, 9, and 12 mL/kg were given for two min. The left ventricular outflow tract velocity-time integral (VTI) was measured by transthoracic echocardiography. The IVC-DI was measured at sub-xyphoid transabdominal long axis. The PPV was measured via the radial artery and served as baseline. Index measurements were repeated after fluid challenge. VTI increased by more than 15% after fluid challenge, which was considered as volume responsive. Seventy-nine patients were enrolled, 38 of whom were considered positive volume responsive. Baseline data between the response group and the non-response group were similar. Receiver operating characteristic curve confirmed PPV accuracy in diagnosing an increase in volume responsiveness with increased TV. When TV was 12 mL/kg, the PPV area under the curve (AUC) was 0.93 and the threshold value was 15.5%. IVC-DI had the highest diagnostic accuracy at a TV of 9 mL/kg and an AUC of 0.79, with a threshold value of 15.3%. When TV increased to 12 mL/kg, the IVC-DI value decreased. When the TV was 9 and 12 mL/kg, PPV showed improved performance in diagnosing volume responsiveness than did IVC-DI. PPV diagnostic accuracy in mechanically ventilated patients was higher than IVC-DI. PPV accuracy in predicting volume responsiveness was increased by increasing TV.

Right Atrial Function Predicts Clinical Outcome in Patients with Precapillary Pulmonary Hypertension

Although the primary role of right atrial (RA) size in the diagnosis and risk stratification of precapillary pulmonary hypertension (PH) has been studied, little is known about the clinical significance of RA function. In line with studies assessing left atrial function in heart failure, the aim of this study was to introduce the RA function index (RAFi) and to explore its prognostic power in precapillary PH. RA emptying fraction was calculated as (RA end-systolic volume-RA end-diastolic volume)×100/(RA end-systolic volume). RAFi was calculated as (RA emptying fraction×right ventricular outflow tract velocity-time integral)/(RA end-systolic volume index). Patients were followed for the end point of clinical failure, which was defined as death, hospitalization because of PH, or disease progression. In total, 47 patients with precapillary PH were included. Mean RAFi was 16.1±22.3%. Over a median follow-up period of 25months (interquartile range, 9.5-41.1months), 29 patients experienced clinical failure. Univariate Cox proportional-hazard analysis showed that RAFi was a predictor of clinical failure (hazard ratio, 0.935; 95% CI, 0.890-0.981; P=.007). Addition of RAFi to established predictors of outcomes, including 6-minute walk distance, N-terminal pro-B-type natriuretic peptide, and RA area, improved their prognostic power. RAFi is an easily assessed echocardiographic parameter, which is strongly predictive of clinical outcomes in patients with precapillary PH. Further studies are needed to validate RAFi and define its role in clinical practice.

Serial echocardiographic changes with different body positions and sleeping side preference in heart failure patients.

The sleeping position plays an important role in overall health in both healthy individuals and heart failure (HF) patients, which complain of increasing dyspnea when adopting left lateral decubitus position (LLDP) that improves when turning over to the right lateral decubitus position (RLDP). Several theories have been proposed to explain this preference of HF patients; however, the underlying mechanisms remain unclear. We evaluated consecutive dilated cardiomyopathy (DCMP) patients with regard to whether they had a sleeping position preference and analyzed early and late left ventricular filling velocities, tissue Doppler recordings, tricuspid annular plane systolic excursion (TAPSE), and left ventricular outflow tract time-velocity integral (LVOT-TVI). Baseline echocardiographic parameters were obtained first by LLDP, followed by the supine position (SP) and finally RLDP in each position for 10minutes to ensure a stabilized hemodynamic milieu. A total of 26 DCMP patients were included in this study and a 78 echocardiographic examination performed. We detected that many HF patients preferred the right lateral decubitus sleeping position (RLDSP, 54%) and avoided from the left lateral decubitus sleeping position (LLDSP, 40%); the echocardiographic LVOT TVI and TAPSE parameters were statistically higher in RLDP compared to SP and LLDP. The echocardiographic LVOT TVI and TAPSE values as functional parameters of left and right ventricular function change with body position, and these hemodynamic changes may explain why HF patients willingly adopt RLDSP.

Relation of Velocity-Time Integral of the Left Ventricular Outflow Tract to that of the Descending Thoracic Aorta and Usefulness of a Fixed Ratio for Internal Validation

Measurement of left ventricular outflow tract velocity-time integral (LVOT VTI) is technician-, instrument-, and reader-dependent; variability is more common for pulsed-wave Doppler than continuous-wave Doppler. We hypothesize that in a population with normal cardiac structure and function, LVOT VTI is higher than VTI of the descending thoracic aorta (DTA) and this relation may be used clinically to validate the former. Furthermore, the DTA VTI could also be used to estimate LVOT. We retrospectively compared the LVOT VTI against VTI measured from DTA, abdominal aorta, and pulmonary artery among 108 healthy subjects. The ratio of LVOT VTI (n = 108) to DTA VTI (n = 108) was 1.27. There was a difference of 19.6% between LVOT VTI and DTA VTI with the former being higher. This percentage decrease in VTI from LVOT VTI to abdominal aortic (AA) VTI was directly proportional to the LVOT VTI. Similarly, there was a difference of 23.4% in the VTI values obtained from DTA and abdominal aorta. Moreover, there was a decrease of 40.4% when LVOT VTI was compared against AA VTI. The ratio of LVOT VTI to pulmonary VTI was 1.19. VTI values decrease in a linear fashion from the LVOT to abdominal aorta likely because of progressive decrease in circulating volume, and this change is not obscured by diminishing aortic diameter. Any deviation from this relation should be treated as abnormal and should prompt further investigation. Our findings support routine measurement of DTA VTI in clinical practice.

Noninvasive Echocardiographic Measures of Pulmonary Vascular Resistance in Children and Young Adults with Cardiomyopathy

Patients with cardiomyopathy (CM) are at increased risk for pulmonary hypertension (PH). Data are lacking on the use of noninvasive PH measures by echocardiography in patients with CM. The aim of this study was to evaluate the correlation between Doppler-derived echocardiographic indices and catheterization-based measurement of pulmonary vascular resistance (PVR) in children and young adults with CM. Imaging studies were retrospectively reviewed from pediatric patients with CM who underwent both echocardiography and cardiac catheterization within a 72-hour period. The ratio of peak tricuspid regurgitation velocity to right ventricular outflow tract velocity-time integral, the S/D ratio, and right ventricular myocardial performance index were correlated with invasive PVR. Receiver operating characteristic curves were developed to determine cutoffs for detecting PVR ≥ 6 indexed Wood units, a value associated with higher heart transplantation risk. Twenty-three patients with CM (median age, 11.7years; range, 0.5-21years) met the criteria for analysis,the majority (n=17 [74%]) of whom had dilated CM. Linear regression showed significant correlations between echocardiography-based ratio of peak tricuspid regurgitation velocity to right ventricular outflow tract velocity-time integral, S/D ratio, and right ventricular myocardial performance index versus invasive PVR (r=0.84, r=0.72, and r=0.72, respectively, P<.001). All echocardiographic measures showed high sensitivity, specificity, and predictive values to detect PVR ≥ 6 indexed Wood units, with ratio of peak tricuspid regurgitation velocity to right ventricular outflow tract velocity-time integral demonstrating the highest area under the curve (0.958; 95% CI, 0.866-1). Right-sided Doppler-derived echocardiographic indices correlate with PVR measured by cardiac catheterization in children and young adults with CM. These parameters may serve as useful adjuncts in serial assessment of right ventricular hemodynamics in this population.