Comparison of Left Ventricular Stroke Volume in 2nd- and 3rd Trimester Fetuses Measured by the Product of VTI and Aortic Annular Area With That Assessed by Simpson's Single-Plane Rule Using the STE Technique

OBJECTIVES

The aim of the study was to compare left ventricle stroke volume in healthy, eutrophic fetuses in the 2nd and 3rd trimesters evaluated using the velocity time integral and aortic annulus area with left ventricular stroke volume measured using Simpson's single-plane rule and to determine the discrepancy equation.

METHODS

The study included 354 fetuses. In each fetus, during the same examination, simultaneous assessment of stroke volume was performed by pulsed-wave Doppler using the product of the velocity time integral and aortic annulus area and by the fetalHQ® software using Simpson's single-plane rule. The Mann-Whitney U test was used to compare the "product-derived" stroke volume and stroke volume using fetalHQ® software values in the 2nd and 3rd trimesters separately. The agreement between the two methods were verified using Bland-Altman analysis. A linear regression model was used to obtain the discrepancy equation.

RESULTS

In the 2nd trimester, the mean percentage difference between both the techniques showed that the stroke volume values determined using pulsed-wave Doppler were, on average, 88% higher than the stroke volume values determined using fetalHQ®. The upper limit of agreement between the compared techniques was approximately 146% and the lower limit of agreement was equal to 29.6%. In the 3rd trimester, the results indicated that the stroke volume values determined using pulsed-wave Doppler were, on average, 76% higher than the stroke volume values determined using fetalHQ®. The upper limit of agreement between the compared techniques was approximately 129% and the lower limit of agreement was 23%. Based on the results of the linear regression models, discrepancy formulas of the stroke volume values were obtained. The equations to calculate the predicted mean and standard deviations were used to compute the reference intervals for the mean, 5th and 95th centiles.

CONCLUSION

The calculation of left ventricular stroke volume using pulsed Doppler has higher result in relation to stroke volume determined using Simpson's rule significantly. The aortic annulus area showed a higher correlation regarding stroke volume than the velocity time integral in both the 2nd and 3rd trimesters. Stroke volume increased with the increase in aortic annulus area, whereas the velocity time integral remained relatively constant. The retrospective analysis of the collected material enabled the determination of the discrepancy equation.

Echocardiographic measured shunt velocity does not predict pulmonary blood flow in patients with Blalock-Thomas-Taussig shunt

INTRODUCTION

Catheterisation is the gold standard used to evaluate pulmonary blood flow in patients with a Blalock-Thomas-Taussig shunt. It involves risk and cannot be performed frequently. This study aimed to evaluate if echocardiographic measurements obtained in a clinical setting correlate with catheterisation-derived pulmonary blood flow in patients with a Blalock-Thomas-Taussig shunt as the sole source of pulmonary blood flow.

METHODS

Chart review was performed retrospectively on consecutive patients referred to the catheterisation lab with a Blalock-Thomas-Taussig shunt. Echocardiographic parameters included peak, mean, and diastolic gradients across the Blalock-Thomas-Taussig shunt and forward and reverse velocity time integral across the distal transverse aorta. In addition to direct correlations, we tested a previously published formula for pulmonary blood flow calculated as velocity time integral across the shunt × heart rate × Blalock-Thomas-Taussig shunt area. Catheterisation parameters included pulmonary and systemic blood flow as calculated by the Fick principle.

RESULTS

18 patients were included. The echocardiography parameters and oxygen saturation did not correlate with catheterisation-derived pulmonary blood flow, systemic blood flow, or the ratio of pulmonary to systemic blood flow. As the ratio of reverse to forward velocity time integral across the transverse aorta increased, the probability of shunt stenosis decreased.

CONCLUSION

Echocardiographic measurements obtained outside the catheterisation lab do not correlate with catheterisation-derived pulmonary blood flow. The ratio of reverse to forward velocity time integral across the transverse aortic arch may be predictive of Blalock-Thomas-Taussig shunt narrowing; this finding should be investigated further.

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.

The Correlation between Carotid Artery Corrected Flow Time and Velocity Time Integral during Central Blood Volume Loss and Resuscitation

Background

Doppler ultrasound of the common carotid artery is used to infer central hemodynamics. For example, change in the common carotid artery corrected flow time (ccFT) and velocity time integral (VTI) are proposed surrogates of changing stroke volume. However, conflicting data exist which may be due to inadequate beat sample size and measurement variability - both intrinsic to handheld systems. In this brief communication, we determined the correlation between changing ccFT and carotid VTI during progressively severe central blood volume loss and resuscitation.

Methods

Measurements were obtained through a novel, wireless, wearable Doppler ultrasound system. Sixteen participants (ages of 18-40 years with no previous medical history) were studied across 25 lower body-negative pressure protocols. Relationships were assessed using repeated-measures correlation regression models.

Results

In total, 33,110 cardiac cycles comprise this analysis; repeated-measures correlation showed a strong, linear relationship between ccFT and VTI. The strength of the ccFT-VTI relationship was dependent on the number of consecutively averaged cardiac cycles (R1 cycle = 0.70, R2 cycles = 0.74, and R10 cycles = 0.81).

Conclusions

These results positively support future clinical investigations employing common carotid artery Doppler as a surrogate for central hemodynamics.

Velocity Time Integral: A Novel Method for Assessing Fetal Anemia

The velocity time integral (VTI) is a clinical Doppler ultrasound measurement of blood flow, measured by the area under the wave curve and equivalent to the distance traveled by the blood. This retrospective study assessed the middle cerebral artery (MCA) VTI of fetuses in pregnancies complicated by maternal alloimmunization. Doppler indices of the MCA were retrieved from electronic medical records. Systolic deceleration-diastolic time, systolic acceleration time, VTI, and peak systolic velocity (PSV) were measured at 16-40 weeks gestation. Cases with PSV indicating fetal anemia (cutoff 1.5 MoM) and normal PSV were compared. The study included 255 Doppler ultrasound examinations. Of these, 41 were at 16-24 weeks (group A), 100 were at 25-32 weeks (group B), and 114 were at 33-40 weeks (group C). VTI increased throughout gestation (5.5 cm, 8.6 cm, and 12.1 cm in groups A, B, and C, respectively, p = 0.003). VTI was higher in waveforms calculated to have MCA-PSV ≥ 1.5 MoM compared to those with MCA-PSV < 1.5 MoM (9.1 cm vs. 14.1 cm, respectively, p < 0.001), as was VTI/s (22.04 cm/s vs. 33.75 cm/s, respectively; p < 0.001). The results indicate that the MCA VTI increases significantly among fetuses with suspected anemia, indicating higher perfusion of hemodiluted blood to the brain. This feasible measurement might provide a novel additional marker for the development of fetal anemia.

Right heart echocardiographic variables and prediction of clinical severity in dogs with pulmonary stenosis

BACKGROUND

Pulmonary stenosis (PS) usually is evaluated using echocardiography. A multiparametric approach, in addition to the maximum pressure gradient (PG), might be indicated to better characterize PS severity and address its management.

HYPOTHESIS/OBJECTIVES

Our hypothesis was that right heart size and function are associated with echocardiographic and clinical severity of pulmonary stenosis in dogs.

ANIMALS

Client-owned dogs with PS.

METHODS

Prospective, multicenter, observational study. Enrolled dogs underwent complete echocardiographic examination. Associations among right heart echocardiographic variables, PS transvalvular PG >80 mm Hg and presence of clinical signs (exercise intolerance, syncope, right-sided congestive failure, or some combination of these) were assessed using logistic regression analysis.

RESULTS

Eighty-eight dogs with PS. Twenty-eight dogs were symptomatic. Increased right ventricular end-diastolic free wall thickness (odds ratio [OR] > 100; 95% confidence interval [95%CI], 50- > 100; P = .01) and decreased aorta-to-pulmonary artery velocity time integral ratio (OR, < 0.001; 95%CI, 0.0-0.001; P = .005) were independently associated with PS PG >80 mm Hg. Decreased tricuspid annular plane systolic excursion (OR, 0.35; 95%CI, 0.15-0.77; P = .01) and increased right ventricular end-diastolic area (OR, 1.4; 95%CI, 1.08-2.02; P = .01) were independently associated with clinical severity.

CONCLUSION AND CLINICAL IMPORTANCE

Structural and functional right heart echocardiographic variables are associated with echocardiographic and clinical severity in dogs with PS. A multiparametric approach is advised to better assess PS severity.

Left Ventricle Outflow Tract Velocity-Time Index and Right Ventricle to Left Ventricle Ratio as Predictors for in Hospital Outcome in Intermediate-Risk Pulmonary Embolism

Accurate estimation of risk with both imaging and biochemical parameters in intermediate risk pulmonary embolism (PE) remains challenging. The aim of the study was to evaluate echocardiographic parameters that reflect right and left heart hemodynamic as predictors of adverse events in intermediate risk PE. This was a retrospective observational study on patients with computed tomography pulmonary angiography diagnosis of PE admitted at Cardiology department of the Clinical Emergency Hospital of Oradea, Romania between January 2018—December 2021. Echocardiographic parameters obtained at admission were studied as predictors of in hospital adverse events. The following adverse outcomes were registered: death, resuscitated cardiac arrest, hemodynamic deterioration and need of rescue thrombolysis. An adverse outcome was present in 50 patients (12.62%). PE related death was registered in 17 patients (4.3%), resuscitated cardiac arrest occurred in 6 patients (1.51%). Another 20 patients (5.05%) required escalation of therapy with thrombolysis and 7 (1.76%) patients developed haemodynamic instability. Echocardiographic independent predictors for in hospital adverse outcome were RV/LV ≥ 1 (HR = 3.599, 95% CI 1.378−9.400, p = 0.009) and VTI ≤ 15 mm (HR = 11.711, 95% CI 4.336−31.633, p < 0.001). The receiver operator curve renders an area under curve for LVOT VTI ≤ 15 mm of 0.792 (95% CI 0.719−0.864, p < 0.001) and for a RV/LV ≥ 1 of 0.746 (95% CI 0.671−0.821, p < 0.001). A combined criterion (LVOT VTI ≤ 15 and RV/LV ≥ 1) showed a positive predictive value of 75% and a negative predictive value of 95% regarding in hospital adverse outcomes. Low LVOT VTI and increased RV/LV are useful for identifying normotensive patients with PE at risk for short term adverse outcomes. Combining an LVOT VTI ≤ 15 cm with a RV/LV ≥ 1 can identify with increased accuracy PE patients with impending risk of clinical deterioration.

Inferring the Frank-Starling Curve From Simultaneous Venous and Arterial Doppler: Measurements From a Wireless, Wearable Ultrasound Patch

The Frank–Starling relationship is a fundamental concept in cardiovascular physiology, relating change in cardiac filling to its output. Historically, this relationship has been measured by physiologists and clinicians using invasive monitoring tools, relating right atrial pressure (P_ra) to stroke volume (SV) because the P_ra-SV slope has therapeutic implications. For example, a critically ill patient with a flattened P_ra-SV slope may have low P_ra yet fail to increase SV following additional cardiac filling (e.g., intravenous fluids). Provocative maneuvers such as the passive leg raise (PLR) have been proposed to identify these “fluid non-responders”; however, simultaneously measuring cardiac filling and output via non-invasive methods like ultrasound is cumbersome during a PLR. In this Hypothesis and Theory submission, we suggest that a wearable Doppler ultrasound can infer the P_ra-SV relationship by simultaneously capturing jugular venous and carotid arterial Doppler in real time. We propose that this method would confirm that low cardiac filling may associate with poor response to additional volume. Additionally, simultaneous assessment of venous filling and arterial output could help interpret and compare provocative maneuvers like the PLR because change in cardiac filling can be confirmed. If our hypothesis is confirmed with future investigation, wearable monitors capable of monitoring both variables of the Frank–Starling relation could be helpful in the ICU and other less acute patient settings.

Correlation of Carotid Doppler Blood Flow With Invasive Cardiac Output Measurements in Cardiac Surgery Patients

OBJECTIVE

Carotid Doppler ultrasound has been a topic of recent interest, as it may be a promising noninvasive hemodynamic monitoring tool. In this study, the relation between carotid artery blood flow and invasive cardiac output (CO) was evaluated.

DESIGN

A prospective, observational study.

SETTING

A single-institution, tertiary referral hospital.

PARTICIPANTS

Eighteen elective cardiac surgery patients.

INTERVENTIONS

CO was measured by calibrated pulse contour analysis. Simultaneously, carotid artery pulsed-wave Doppler measurements were obtained in the operating room in three clinical settings: after induction of anesthesia (T1), after a passive leg raise maneuverer (T2), and at the end of surgery (T3).

MEASUREMENTS AND MAIN RESULTS

Correlation and trending between carotid artery blood flow and invasive CO were evaluated. Furthermore, two Bland-Altman plots were constructed to evaluate the level of agreement between carotid artery-derived CO and invasive CO measurements. Carotid artery blood flow correlated moderately with invasive CO (ρ = 0.67, 95% confidence interval 0.56-0.76, p < 0.05). Concordance between the percentage change of carotid artery blood flow and invasive CO from T1 to T3 was 72%. The level of agreement between carotid artery-derived CO and invasive CO was ±2.29; ±2.57 L/min, with a bias of 0.1; -0.54 L/min, and mean error of 50% and 48%, for the two Bland-Altman analyses, respectively. Intraexamination precision was acceptable.

CONCLUSIONS

In cardiac surgery patients, carotid artery blood flow correlated moderately with invasive CO measurements. However, the trending ability of carotid artery blood flow was poor, and carotid artery-derived CO tended not to be interchangeable with invasive CO.

The Doppler shock index measured by a wearable ultrasound patch accurately detects moderate-to-severe central hypovolemia during lower body negative pressure

OBJECTIVE

Moderate-to-severe hemorrhage is a life-threatening condition, which is challenging to detect in a timely fashion using traditional vital signs because of the human body's robust physiologic compensatory mechanisms. Measuring and trending blood flow could improve diagnosis of clinically significant exsanguination. A lightweight, wireless, wearable Doppler ultrasound patch that captures and trends blood flow velocity could enhance hemorrhage detection.

METHODS

In 11 healthy volunteers undergoing simulated hemorrhage and resuscitation during graded lower body negative pressure (LBNP) and release, we studied the relationship between stroke volume (SV) and common carotid artery velocity time integral (VTI) and corrected flow time (FTc). We assessed the diagnostic accuracy of 2 variations of a novel metric, the Doppler shock index (ie, the DSIVTI and DSIFTc), at capturing moderate-to-severe central hypovolemia defined as a 30% reduction in SV. The DSIVTI and DSIFTc are calculated as the heart rate divided by either the VTI or FTc, respectively.

RESULTS

A total of 17,822 cardiac cycles were analyzed across 22 LBNP protocols. The average SV reduction to the lowest tolerated LBNP stage was 40%; there was no clinically significant fall in the mean arterial pressure. Correlations between changing SV and the common carotid artery VTI and FTc were strong (R 2 of 0.87, respectively) and concordant. The DSIVTI and DSIFTc accurately detected moderate-to-severe central hypovolemia with values for the area under the receiver operator curves of 0.96 and 0.97, respectively.

CONCLUSION

In a human model of hemorrhage and resuscitation, measures from a wearable Doppler ultrasound patch correlated strongly with SV and identified moderate-to-severe central hypovolemia with excellent diagnostic accuracy.

Carotid Doppler Measurement Variability in Functional Hemodynamic Monitoring: An Analysis of 17,822 Cardiac Cycles

Carotid Doppler ultrasound is used as a measure of fluid responsiveness, however, assessing change with statistical confidence requires an adequate beat sample size. The coefficient of variation helps quantify the number of cardiac cycles needed to adequately detect change during functional hemodynamic monitoring.

DESIGN

Prospective, observational, human model of hemorrhage and resuscitation.

SETTING

Human physiology laboratory at Mayo Clinic.

SUBJECTS

Healthy volunteers.

INTERVENTIONS

Lower body negative pressure.

MEASUREMENTS AND MAIN RESULTS

We measured the coefficient of variation of the carotid artery velocity time integral and corrected flow time during significant cardiac preload changes. Seventeen-thousand eight-hundred twenty-two cardiac cycles were analyzed. The median coefficient of variation of the carotid velocity time integral was 8.7% at baseline and 11.9% during lowest-tolerated lower body negative pressure stage. These values were 3.6% and 4.6%, respectively, for the corrected flow time.

CONCLUSIONS

The median coefficient of variation values measured in this large dataset indicates that at least 6 cardiac cycles should be averaged before and after an intervention when using the carotid artery as a functional hemodynamic measure.

Functional Hemodynamic Monitoring With a Wireless Ultrasound Patch

In this Emerging Technology Review, a novel, wireless, wearable Doppler ultrasound patch is described as a tool for resuscitation. The device is designed, foremost, as a functional hemodynamic monitor-a simple, fast, and consistent method for measuring hemodynamic change with preload variation. More generally, functional hemodynamic monitoring is a paradigm that helps predict stroke volume response to additional intravenous volume. Because Doppler ultrasound of the left ventricular outflow tract noninvasively measures stroke volume in realtime, it increasingly is deployed for this purpose. Nevertheless, Doppler ultrasound in this manner is cumbersome, especially when repeat assessments are needed. Accordingly, peripheral arteries have been studied and various measures from the common carotid artery Doppler signal act as windows to the left ventricle. Yet, handheld Doppler ultrasound of a peripheral artery is susceptible to human measurement error and statistical limitations from inadequate beat sample size. Therefore, a wearable Doppler ultrasound capable of continuous assessment minimizes measurement inconsistencies and smooths inherent physiologic variation by sampling many more cardiac cycles. Reaffirming clinical studies, the ultrasound patch tracks immediate SV change with excellent accuracy in healthy volunteers when cardiac preload is altered by various maneuvers. The wearable ultrasound also follows jugular venous Doppler, which qualitatively trends right atrial pressure. With further clinical research and the application of artificial intelligence, the monitoring modalities with this new technology are manifold.

Use of aortic flow indexes derived from transthoracic echocardiography to evaluate response to a fluid challenge in anesthetized dogs

OBJECTIVE

To evaluate the ability of transthoracic echocardiographic aortic flow measurements to discriminate response to a fluid challenge (FC) in healthy anesthetized dogs.

STUDY DESIGN

Prospective experimental study.

ANIMALS

A total of 48 isoflurane-anesthetized dogs (14.2-35.0 kg) undergoing elective surgery.

METHODS

Fluid responsiveness was evaluated before surgery by FC (lactated Ringer's 10 mL kg^-1 intravenously over 5 minutes). Percentage increases in transpulmonary thermodilution stroke volume (ΔSV_TPTD) >15% from values recorded before FC defined responders to volume expansion. A group of 24 animals were assigned as nonresponders (ΔSV_TPTD ≤15%). When ΔSV_TPTD was >15% after the first FC, additional FC were administered until ΔSV_TPTD was ≤15%. Final fluid responsiveness status was based on the response to the last FC. Percentage increases after FC in aortic flow indexes [velocity time integral (ΔVTI_FC) and maximum acceleration (ΔVmax_FC)] and in mean arterial pressure (ΔMAP_FC) were compared with ΔSV_TPTD.

RESULTS

After one FC, 24 animals were responders. For nonresponders, ΔSV_TPTD was ≤15% after one, two and three FCs in eight/24, 15/24 and one/24 animals, respectively. The FC that defined responsiveness increased ΔSV_TPTD by 29 (18-53)% in responders and by 8 (-3 to 15)% in nonresponders [mean (range)]. The area under the receiver operating characteristics curve (AUROC) of ΔVTI_FC (0.901) was larger than the AUROCs of ΔVmax_FC (0.774, p = 0.041) and ΔMAP_FC (0.519, p < 0.0001). ΔMAP_FC did not predict responsiveness (p = 0.826). Best cut-off thresholds for discriminating responders, with respective zones of diagnostic uncertainty (gray zones) were >14.7 (10.8-17.6)% for ΔVTI_FC and >8.6 (-0.3 to 14.7)% for ΔVmax_FC. Animals within the gray zone were 17% (ΔVTI_FC) and 50% (ΔVmax_FC).

CONCLUSIONS AND CLINICAL RELEVANCE

Changes in VTI induced by FC can determine responsiveness with reasonable accuracy in dogs and could play an important role in goal-directed fluid therapy.

A wearable carotid Doppler tracks changes in the descending aorta and stroke volume induced by end-inspiratory and end-expiratory occlusion: A pilot study

BACKGROUND AND AIMS

To test the feasibility of a novel, wearable carotid Doppler ultrasound to track changes in cardiac output induced by end-inspiratory and end-expiratory occlusion tests.

METHODS

We observed the pattern of Doppler change of the common carotid artery during a simulated end-inspiratory and expiratory occlusion test (sEIOT/sEEOT) in 10, nonventilated, healthy subjects. Simultaneously, we measured the Doppler signal of the descending aorta using duplex ultrasound (Xario, Toshiba Medical Systems) and stroke volume (SV) using noninvasive pulse contour analysis (Clearsight, Edwards Lifesciences, Irvine, California).

RESULTS

During sEIOT, SV, maximum velocity time integral (VTI) of the descending aorta, and common carotid fell by 25.7% (P = .0131), 26.1% (P < .0001), and 18.5% (P < .0001), respectively. During sEEOT, SV, maximum VTI of the descending aorta, and common carotid rose by: 41.3% (P = .0051), 28.3% (P < .0001), and 41.6% (P < .0001), respectively. There was good correlation between change in aortic VTI and carotid VTI (r 2 = 0.79); SV and aortic VTI (r 2 = 0.82), and SV and carotid VTI (r 2 = 0.95).The coefficient of variation of the VTI measured by the Doppler patch was roughly 60% less than that of the duplex system.

CONCLUSIONS

The pattern of SV change induced by a sEIOT/sEEOT in nonmechanically ventilated volunteers is reflected in the common carotid artery and descending aorta. The VTI variability of the Doppler patch was less than that of the traditional, duplex Doppler.

Results of a Prospective Study to Evaluate the Impact of Point-of-Care Ultrasound in the Enhancement of Gastrointestinal Bleeding Risk Scores

OBJECTIVES

Gastrointestinal (GI) bleeding is a common illness seen in the emergency department. The prognosis varies from self-limited to potentially life threatening. Currently available GI bleeding risk scores have only a modest predictive value, limiting their wide implementation. The aim of this study was to assess the association and capability of point-of-care ultrasound (POCUS) used by emergency physicians to improve common GI bleeding scores for predicting complications and long-term outcomes of patients with GI bleeding, which to our knowledge have never been studied.

METHODS

Between August 2015 and April 2017, 203 hemodynamically stable patients with acute GI bleeding admitted to the emergency department were prospectively investigated. Using ultrasound, we measured the inferior vena cava diameter, cardiac output with surrogate markers such as the velocity time integral before and after the passive leg-raising test, and the presence of systolic obliteration of the left ventricle. The Rockall and Glasgow-Blatchford scores were calculated for patients with upper GI bleeding and the Velayos score for lower GI bleeding. The patients had follow-up during hospitalization and 30 days later to assess for early and late adverse events (AEs). Then we integrated the ultrasound findings of hypovolemia into the GI bleeding scores, assessing the capability to detect AEs.

RESULTS

In our cohort, patients with upper GI bleeding who showed left ventricle kissing walls had a worse evolution, with a greater presence of late AEs (odds ratio [OR], 3.8; 95% confidence interval [CI], 1.32-10.96; P = .01). Patients with lower GI bleeding who showed a collapse of the inferior vena cava (>50%) after passive leg raising had a greater presence of early AEs (OR, 3.6; 95% CI, 1.46-9.00; P = .004). The predictive performance of the Rockall score (receiver operating characteristic analysis: area under the curve [AUC], 77.6%; 95% CI, 66.3%-88.8%) increased with POCUS (AUC, 80.3%; 95% CI, 69.5%-91.1%); that of the Glasgow-Blatchford score (AUC, 72.5%; 95% CI, 59.9%-85.2%) increased with POCUS (AUC, 73.2%; 95% CI, 61.1%-85.4%); and that of Velayos score (AUC, 55.7%; 95% CI, 42.5%-69.0%) also increased with POCUS (AUC, 72.2%; 95% CI, 61.1%-83.3%).

CONCLUSIONS

The use of POCUS in GI bleeding is feasible and enhances common GI bleeding risk scores, showing better predictive performance in detecting AEs.

Bedside Echocardiography and Passive Leg Raise as a Measure of Volume Responsiveness in the Emergency Department

OBJECTIVES

The aim of this study was to investigate the value of bedside echocardiography with a passive leg raise as a noninvasive marker of volume responsiveness.

METHODS

This work was a prospective observational study of patients with end-stage renal disease presenting to the emergency department. The left ventricular outflow tract (LVOT) velocity time integral (VTI) was obtained. Measurements before and after dialysis as well as before and after the passive leg raise were recorded.

RESULTS

Fifty-four patients were enrolled, in whom the mean volume of fluid removed ± SD was 3.89 ± 0.91 L. In the predialysis cohort, the mean LVOT VTI was 28.05 cm (95% confidence interval [CI], 26.55-29.55 cm). After the passive leg raise, the mean VTI was 28.52 cm (95% CI, 26.98-30.07 cm). In the postdialysis cohort, the mean VTI was 30.31 cm (95% CI, 28.92-31.69 cm), and it increased to 34.91 cm (95% CI, 33.11-36.72 cm) after the passive leg raise. The Δ VTI values were 1.83% (95% CI, 0.12%-3.55%) in the predialysis group and 15.05% (95% CI, 12.76%-17.34%) in the postdialysis cohort. When stratified by fluid removal, the mean Δ VTI values after hemodialysis were 12.64% (95% CI, 9.79%-15.49%) and 16.84% (95% CI, 13.47%-20.22%) for patients who had less than 4 L and 4 L or greater removed, respectively. In patients without congestive heart failure, the Δ VTI was 15.28% (95% CI, 12.25%-18.32%), whereas for those with congestive heart failure, the mean change was 14.63% (95% CI, 10.91%-18.35%).

CONCLUSIONS

The LVOT VTI in conjunction with a passive leg raise seems to correlate with the volume status and volume responsiveness.

Reference intervals and percentile curve for left ventricular outflow tract (LVOT), velocity time integral (VTI), and LVOT-VTI-derived hemodynamic parameters in healthy children and adolescents: Analysis of echocardiographic methods association and agreement

BACKGROUND

Echocardiographic reference intervals (RIs) for left ventricular outflow tract (LVOT) and velocity time integral (VTI) are scarce in pediatrics.

AIMS

(a) to generate RIs and percentiles for LVOT, VTI, and hemodynamic variables in healthy children and adolescents from Argentina; (b) to analyze the equivalence between stroke volume (SV), cardiac output (CO), and cardiac index (CI) obtained from two-dimensional echocardiography (2D) and LVOT-VTI analysis with pulsed wave Doppler (PWD); and (c) to analyze the association between subjects' characteristics and VTI and LVOT-VTI-derived parameters.

METHODS

Two-dimensional and PWD studies were done in 385 subjects (5-24 years). Mean and standard deviation age-related and body surface area (BSA)-related equations were obtained for VTI and LVOT-VTI-derived parameters (parametric regression methods based on fractional polynomials). BSA- and age-specific percentiles were determined.

RESULTS

Pulsed wave Doppler- and 2D-derived parameters were positively correlated. However, PWD values were always lower than those from 2D. Specific RIs for PWD and 2D data were necessary. Covariance analysis showed that sex-specific RIs were required for LVOT, but not for VTI, VTI-derived CO and CI. Age-related RIs were obtained for LVOT, LVOT-VTI, and VTI-derived CO and CI. BSA-related RIs for VTI-derived CO and CI were obtained.

CONCLUSIONS

Stroke volume, CO, and CI data from 2D and PWD are not equivalent. An accurate analysis of LVOT-VTI-derived parameters requires considering age and BSA. In this study, age- and BSA-related RIs and percentiles for LVOT, VTI, and hemodynamic parameters in healthy children and adolescents were determined, discriminating data according to the methodological approach (2D or PWD).

Transcatheter aortic valve implantation in the elderly: who to refer?

In recent years, experience with transcatheter aortic valve implantation has led to improved outcomes in elderly patients with severe aortic stenosis (AS) who may not have previously been considered for intervention. These patients are often frail with significant comorbid conditions. As the prevalence of AS increases, there is a need for improved assessment parameters to determine the patients most likely to benefit from this novel procedure. This review discusses the diagnostic criteria for severe AS and the trials available to aid in the decision to refer for aortic valve procedures in the elderly.

Non-invasive estimation of pulmonary vascular resistance in patients of pulmonary hypertension in congenital heart disease with unobstructed pulmonary flow

Context:

Pulmonary vascular resistance (PVR) is a critical and essential parameter during the assessment and selection of modality of treatment in patients with congenital heart disease accompanied by pulmonary arterial hypertension.

Aim:

The present study was planned to evaluate non-invasive echocardiographic parameters to assess pulmonary vascular resistance.

Settings and Design:

This prospective observational study included 44 patients admitted in the cardiology and pediatric cardiology ward of our institution for diagnostic or pre-operative catheter based evaluation of pulmonary arterial pressure and PVR.

Materials and Methods:

Detailed echocardiographic evaluation was carried out including tricuspid regurgitation velocity (TRV) and velocity time integral of the right-ventricular outflow tract (VTI_RVOT). These parameters were correlated with catheter-based measurements of PVR.

Results:

The TRV/VTI_RVOT ratio correlated well with PVR measured at catheterization (PVRcath) (r = 0.896, 95% confidence interval [CI] 0.816 to 0.9423, P < 0.001). Using the Bland-Altman analysis, PVR measurements derived from Doppler data showed satisfactory limits of agreement with catheterization estimated PVR. For a PVR of 6 Wood units (WU), a TRV/VTI_RVOT value of 0.14 provided a sensitivity of 96.67% and a specificity of 92.86% (area under the curve 0.963, 95% confidence interval 0.858 to 0.997) and for PVR of 8 WU a TRV/VTI_RVOT value of 0.17 provided a sensitivity of 79.17% and a specificity of 95% (area under the curve 0. 0.923, 95% confidence interval 0.801 to 0.982).

Conclusions:

Doppler-derived ratio of TRV/VTI_RVOT is a simple, non-invasive index, which can be used to estimate PVR.

Myocardial ischemia in aortic stenosis: insights from arterial pulse-wave dynamics after percutaneous aortic valve replacement

Wave-intensity analysis is a technique that can qualify both the direction and magnitude of the forces accelerating and decelerating coronary blood flow and is derived from simultaneously acquired measures of coronary pressure and velocity using invasive intracoronary wires. Using this technique during TAVI, the dominant force (or 'wave') acting to increase the coronary blood flow which originates from microvascular relaxation is shown to be elevated in severe aortic stenosis and decreased post-implantation. Additionally, with increasing heart rate a progressive fall in the magnitude of this wave is noted and after TAVI this effect is reversed (returning towards the physiological norm). The potential causes of myocardial ischemia in aortic stenosis are clearly multi-factorial but this observation suggests a decoupling between the aorta and myocardium in aortic stenosis, the effects of which are magnified during increased heart rate.