Reference values of aortic flow velocity integral in 1193 healthy infants, children, and adolescents to quickly estimate cardiac stroke volume

Altered biventricular function in neonatal hypoxic-ischaemic encephalopathy: a case-control echocardiographic study

BACKGROUND

In newborns with hypoxic-ischaemic encephalopathy, more profound altered right and left ventricular function has been associated with mortality or brain injury. Mechanisms underlying cardiac dysfunction in this population are thought to be related to the persistence of increased pulmonary vascular resistance and myocardial ischaemia. We sought to compare cardiac function in newborns with hypoxic-ischaemic encephalopathy to controls using echocardiography.

METHODS

We did a retrospective case-control study with moderate or severe hypoxic-ischaemic encephalopathy between 2008 and 2017. Conventional and speckle-tracking echocardiography measures were extracted to quantify right and left ventricular systolic and diastolic function. Fifty-five newborns with hypoxic-ischaemic encephalopathy were compared to 28 controls.

RESULTS

Hypoxic-ischaemic encephalopathy newborns had higher estimated systolic pulmonary pressure (62.5 ± 15.0 versus 43.8 ± 17.3 mmHg, p < 0.0001) and higher systolic pulmonary artery pressure/systolic blood pressure ratio [101 ± 16 (iso-systemic) versus 71 ± 27 (2/3 systemic range) %, p < 0.0001]. Tricuspid annular plane systolic excursion was decreased (7.5 ± 2.2 versus 9.0 ± 1.4 mm, p = 0.002), E/e' increased (7.9 ± 3.3 versus 5.8 ± 2.0, p = 0.01), and right ventricle-myocardial performance index increased (68.1 ± 21.5 versus 47.8 ± 9.5, p = 0.0001) in hypoxic-ischaemic encephalopathy. Conventional markers of left ventricle systolic function were similar, but e' velocity (0.059 ± 0.019 versus 0.070 ± 0.01, p = 0.03) and left ventricle-myocardial performance index were statistically different (77.9 ± 26.2 versus 57.9 ± 11.2, p = 0.001). The hypoxic-ischaemic encephalopathy group had significantly altered right and left ventricular deformation parameters by speckle-tracking echocardiography. Those with decreased right ventricle-peak longitudinal strain were more likely to have depressed left ventricle-peak longitudinal strain.

CONCLUSION

Newborns with hypoxic-ischaemic encephalopathy have signs of increased pulmonary pressures and altered biventricular systolic and diastolic function.

Contemporary Use of Ultrasonography in Acute Care Pediatrics

Use of ultrasonography by clinicians at the point of care has expanded widely and rapidly. Pediatric acute care providers now leverage this valuable tool to guide procedures, diagnose pathophysiologic processes, and inform time-sensitive decisions in sick and unstable children. However, the deployment of any new technology must be packaged with training, protocols, and safeguards to optimize safety for patients, providers, and institutions. As ultrasonography is increasingly incorporated into residency, fellowship, and even medical student curricula, it is important that educators and trainees are aware of the diversity of its clinical applications. This article aims to review the current state of point-of-care ultrasonography in acute care pediatrics, with an emphasis on the literature supporting the use of this important clinical tool.

Tricuspid Annular Plane Systolic Excursion (TAPSE) correlates with mean pulmonary artery pressure especially 10 years after pediatric heart transplantation

Tricuspid annular plane systolic excursion (TAPSE) is important in the noninvasive echocardiographic assessment of right heart function. This retrospective observational study shows correlations of TAPSE with invasive right heart catheterization parameters after pediatric heart transplantation (HTx). The study included patients after pediatric HTx with cardiac catheterizations in 2018/2019 and measurement of TAPSE (n = 52 patients with 57 examinations; 50.9% adults, 52.6% female, median age: 18.54 years). TAPSE was compared with normal values. Stepwise, linear and multiple regression were used to show influencing variables on TAPSE. Mean TAPSE z-score was -3.48 (SD: 2.25) and 68.4% of HTx-recipients showed abnormally reduced TAPSE (z-score ←2) compared to normal values. Multiple regression (p-value <0.001; corrected R² = 0.338) showed significant correlations of time since HTx (p-value <0.001) and mPAP (p-value: 0.008) with TAPSE z-scores. Divided into subgroups (time since HTx <10 and ≥10 years), TAPSE and mPAP correlated only ≥10 years after HTx (p-value = 0.002). This study provides data of TAPSE even ≥10 years after pediatric HTx. Most patients showed a decreased TAPSE early after HTx, which improved over time. TAPSE z-scores correlated significantly with time since HTx and mPAP, especially ≥10 years post-HTx. Therefore, TAPSE must be used carefully in the early follow-up.

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

Background

Cardiac output (CO) perturbations are common and cause significant morbidity and mortality. Accurate CO assessment is crucial for guiding treatment in anaesthesia and critical care, but measurement is difficult, even for experts. Artificial intelligence methods show promise as alternatives for accurate, rapid CO assessment.

Methods

We reviewed paediatric echocardiograms with normal CO and a dilated cardiomyopathy patient group with reduced CO. Experts measured the left ventricular outflow tract diameter, velocity time integral, CO, and cardiac index (CI). EchoNet-Dynamic is a deep learning model for estimation of ejection fraction in adults. We modified this model to predict the left ventricular outflow tract diameter and retrained it on paediatric data. We developed a novel deep learning approach for velocity time integral estimation. The combined models enable automatic prediction of CO. We evaluated the models against expert measurements. Primary outcomes were root-mean-squared error, mean absolute error, mean average percentage error, and coefficient of determination (R2).

Results

In a test set unused during training, CI was estimated with the root-mean-squared error of 0.389 L/min/m2, mean absolute error of 0.321 L/min/m2, mean average percentage error of 10.8%, and R2 of 0.755. The Bland-Altman analysis showed that the models estimated CI with a bias of +0.14 L/min/m2 and 95% limits of agreement -0.58 to 0.86 L/min/m2.

Conclusions

Our model estimated CO with strong correlation to ground truth and a bias of 0.17 L/min, better than many CO measurements in paediatrics. Model pretraining enabled accurate estimation despite a small dataset. Potential uses include supporting clinicians in real-time bedside calculation of CO, identification of low-CO states, and treatment responses.

Targeted Neonatal Echocardiography in Patients With Hemodynamic Instability

Targeted neonatal echocardiography (TNE) has been increasingly used at the bedside in neonatal care to provide an enhanced understanding of physiology, affecting management in hemodynamically unstable patients. Traditional methods of bedside assessment, including blood pressure, heart rate monitoring, and capillary refill are unable to provide a complete picture of tissue perfusion and oxygenation. TNE allows for precision medicine, providing a tool for identifying pathophysiology and to continually reassess rapid changes in hemodynamics. A relationship with cardiology is integral both in training as well as quality assurance. It is imperative that congenital heart disease is ruled out when utilizing TNE for hemodynamic management, as pathophysiology varies substantially in the assessment and management of patients with congenital heart disease. Utilizing TNE for longitudinal hemodynamic assessment requires extensive training. As the field continues to grow, guidelines and protocols for training and indications are essential for ensuring optimal use and providing a platform for quality assurance.

Reference Values and Repeatability of Pulsed Wave Doppler Echocardiography Parameters in Normal Donkeys

Simple Summary

Cardiovascular disease is underreported in donkeys, possibly related to their limited athletic posture and frequent poor performance-related examinations. Reports on treatments for cardiovascular disease are anecdotal in donkey. Normal echocardiographic parameters have been reported in healthy donkeys. The aim of the present study was to establish the reference values and repeatability for Pulsed Wave Doppler echocardiographic variables of the mitral valve, aortic valve and myocardial performance. Two-dimensional Color flow mapping and spectral Doppler modes were performed. For the mitral valve, the mean velocity, pressure gradient and duration of E-wave were 57.7 ± 12.5 cm/s, 1.4 ± 0.7 mmHg and 0.4 ± 0.13 s, respectively. The results of the present study provide the reference values of PW echocardiographic parameters measurements in normal adult donkeys. Such reference values are helpful, especially when confronted with clinical cases with cardiovascular disorders.

Abstract

In the present study, thirty clinically healthy donkeys were used to establish the reference values and repeatability for Pulsed Wave Doppler echocardiographic variables of the mitral valve, aortic valve and myocardial performance. 2-dimensional Color flow mapping and spectral Doppler modes were performed. For the mitral valve, the mean velocity, pressure gradient and duration of E-wave were 57.7 ± 12.5 cm/s, 1.4 ± 0.7 mmHg and 0.4 ± 0.13 s, respectively. The velocity, pressure gradient and duration of the A-wave were 32.3 ± 9.1 cm/s, 0.3 ± 0.04 mmHg and 0.3 ± 0.1 s, respectively. The mitral valve area, pressure half time, pulsatility index (PI), resistance index (RI) and velocity time integral (VTI) were 1.8 ± 0.5 cm², 66 ± 17 ms, 2.8 ± 1.4, 0.9 ± 0.03 and 19.1 ± 5.7 cm, respectively. For the aortic valve, the mean velocity was 64.9 ± 10.4 cm/s, pressure gradient was 1.8 ± 0.4 mmHg, pulsatility index was 1.4 ± 0.3, resistance index was 0.9 ± 0.02, VTI was 25.02 ± 6.2 cm, systolic/diastolic was 19 ± 4.7 and heart rate was 95.7 ± 28.9 per minute. For Myocardial Performance Index (LV)–Tei Index, the mean ejection, isovolumic relaxation, isovolumic contraction time and myocardial performance index were 0.24 ± 0.01, 0.14 ± 0.01, 0.14 ± 0.02 and 1.2 ± 0.1 s, respectively. The results of the present study provide the reference values of PW echocardiographic parameter measurements in normal adult donkeys. Such reference values are helpful, especially when confronted with clinical cases with cardiovascular disorders.

Advanced Imaging and New Cardiac Biomarkers in Long-term Follow-up After Childhood Cancer

OBJECTIVES

Pathologic ejection fraction (EF), shortening fraction (FS), and standard heart failure biomarkers (high sensitive troponin T and N-terminal brain natriuretic peptide) during follow-up after childhood cancer have been associated with irreversible cardiac damage. We aimed to evaluate strain imaging values by echocardiography and new biomarkers for heart failure with preserved ejection fraction (HFpEF) as potential more sensitive parameters for cardiac deterioration in childhood cancer survivors (CCS).

MATERIALS AND METHODS

Prospective study with 50 CCS (median 16.2 y) at a median follow-up of 13 years. In addition to standard echo and laboratory parameters for heart failure, strain measurements and new biomarkers, including myocardial inflammation (interleukin 6), extracellular matrix (ECM) remodeling (C-telopeptide for type I collagen, intact N-terminal propeptide of type III procollagen), and other heart failure biomarkers (galectin 3, solutable ST2, growth differentiation factor 15), were obtained and compared with 50 healthy controls.

RESULTS

No significant differences in EF, FS, high sensitive troponin T, N-terminal brain natriuretic peptide, interleukin 6, solutable ST2, and galectin 3 were found between study and control groups. In contrast, strain imaging showed significant differences between both groups (global longitudinal strainGLS -16.1% vs. -20.4%, P<0.0001; global circumferential strain -14.3 vs. -21.4%, P<0.0001), detecting 66% (global longitudinal strain) and 76% (global circumferential strain) of patients with pathologic values in contrast to 6% (EF) and 16% (FS) for standard parameters. Markers for disturbances of ECM remodeling (C-telopeptide for type I collagen, intact N-terminal propeptide of type III procollagen, each P<0.0001) and growth differentiation factor 15 (P<0.0001) were significantly different between the groups.

CONCLUSION

Strain imaging and new cardiac biomarkers used in HFpEF focusing on ECM remodeling appear to be more sensitive in detecting early remodeling processes in CCS than standard echo and laboratory parameters.

Fetal and Neonatal Modified Myocardial Performance Indices in Preeclamptic versus Normotensive Pregnancies: A Prospective Cohort Study

Objective

To compare fetal and neonatal cardiac functions in terms of global, systolic, and diastolic function between the preeclampsia and normotensive blood pressure of pregnancies.

Methods

A prospective cohort study was conducted at a university hospital in Northeast Thailand. Twenty-nine pregnancies diagnosed as preeclampsia with or without severe features were compared with 29 normotensive pregnancies. Global cardiac, systolic, and diastolic function were assessed at prenatal and postnatal periods, by a professionally trained obstetrician and pediatric cardiologist, respectively.

Results

The fetal left modified myocardium performance index (Mod-MPI) in preeclampsia and normotensive blood pressure were 0.60±0.08 and 0.59±0.08 (p-value=0.341), respectively, while fetal right Mod-MPI were 0.57±0.16 and 0.54±0.21 (p-value=0.861), respectively. There were no statistically significant differences in terms of fetal isovolumic contraction time (ICT), isovolumic relaxation time (IRT), ejection time (ET), aortic peak systolic velocity (Ao PSV), pulmonary artery peak systolic velocity (PA PSV), mitral valve (MV) E:A ratio, or tricuspid valve (TV) E:A ratios between the two groups. Neonatal mitral valve E peak systolic velocity (MV-E PV) in preeclamptic and normotensive blood pressure groups were significantly different at 51.1±8.02 cm/s and 43.56±5.21cm/s (p-value=0.036), respectively, whereas neonatal left Mod-MPI, mitral valve A peak systolic velocity (MV-A PV), MV E:A ratio, and Ao PSV were not significantly different (p-value=0.436, 0.119, 0.379, and 0.709), respectively.

Conclusion

Neonatal MV-E PV of the preeclampsia group was significantly higher than the normotensive blood pressure group, while there were no statistically significant differences in terms of global cardiac and diastolic functions during the fetal period between two groups.

End-organ saturations correlate with aortic blood flow estimates by echocardiography in the extremely premature newborn - an observational cohort study

BACKGROUND

Near-infrared spectroscopy (NIRS) measures of cerebral saturation (Csat) and renal saturation (Rsat) in extreme premature newborns may be affected by systemic blood flow fluctuations. Despite increasing clinical use of NIRS to monitor tissue saturation in the premature infant, validation of NIRS measures as a correlate of blood flow is still needed. We compared echocardiography (ECHO) derived markers of ascending aorta (AscAo) and descending aorta (DesAo) blood flow with NIRS measurements obtained during the ECHO.

METHODS

Newborns < 29 weeks' gestation (2013-2017) underwent routine NIRS monitoring. Csat, Rsat and systemic saturation at the time of ECHO were retrospectively analyzed and compared with Doppler markers of aortic flow. Renal and cerebral fractional tissue oxygen extraction (rFTOE and cFTOE, respectively) were calculated. Mixed effects models evaluated the association between NIRS and Doppler markers.

RESULTS

Forty-nine neonates with 75 Csat-ECHO and 62 Rsat-ECHO observations were studied. Mean post-menstrual age was 28.3 ± 3.8 weeks during the ECHO. Preductal measures including AscAo velocity time integral (VTI) and AscAo output were correlated with Csat or cFTOE, while postductal measures including DesAo VTI, DesAo peak systolic velocity, and estimated DesAo output were more closely correlated with Rsat or rFTOE.

CONCLUSIONS

NIRS measures are associated with aortic blood flow measurements by ECHO in the extremely premature population. NIRS is a tool to consider when following end organ perfusion in the preterm infant.

International evidence-based guidelines on Point of Care Ultrasound (POCUS) for critically ill neonates and children issued by the POCUS Working Group of the European Society of Paediatric and Neonatal Intensive Care (ESPNIC)

BACKGROUND

Point-of-care ultrasound (POCUS) is nowadays an essential tool in critical care. Its role seems more important in neonates and children where other monitoring techniques may be unavailable. POCUS Working Group of the European Society of Paediatric and Neonatal Intensive Care (ESPNIC) aimed to provide evidence-based clinical guidelines for the use of POCUS in critically ill neonates and children.

METHODS

Creation of an international Euro-American panel of paediatric and neonatal intensivists expert in POCUS and systematic review of relevant literature. A literature search was performed, and the level of evidence was assessed according to a GRADE method. Recommendations were developed through discussions managed following a Quaker-based consensus technique and evaluating appropriateness using a modified blind RAND/UCLA voting method. AGREE statement was followed to prepare this document.

RESULTS

Panellists agreed on 39 out of 41 recommendations for the use of cardiac, lung, vascular, cerebral and abdominal POCUS in critically ill neonates and children. Recommendations were mostly (28 out of 39) based on moderate quality of evidence (B and C).

CONCLUSIONS

Evidence-based guidelines for the use of POCUS in critically ill neonates and children are now available. They will be useful to optimise the use of POCUS, training programs and further research, which are urgently needed given the weak quality of evidence available.

Does a two-minute mini-fluid challenge predict fluid responsiveness in pediatric patients under general anesthesia?

BACKGROUND

Very little evidence for predictive markers of fluid responsiveness has been reported in children as compared to adults. The impact of hypovolemia or hypervolemia on morbidity has driven interest in the fluid challenge titration strategy.

AIM

The objective of this study was to explore the ability of a 3 mL kg^-1 mini-fluid challenge over 2 minutes to predict fluid responsiveness in children under controlled ventilation.

METHODS

Children scheduled for surgery under general anesthesia were included and received a fluid challenge of 15 mL kg^-1 of crystalloid prior to incision administered over 10 minutes in two steps: 3 mL kg^-1 over 2 minutes then 12 mL kg^-1 over 8 minutes. Fluid responsiveness was defined as a change of ≥10% in cardiac output estimated by left ventricular outflow tract velocity time integral (VTI) as measured by transthoracic ultrasound before and after the fluid challenge of 15 mL kg^-1 .

RESULTS

Of the 55 patients included in the analysis, 43 were fluid responders. The increase in the VTI after the mini-fluid challenge (ΔVTI_miniFC ) predicted fluid responsiveness with an area under the receiver operating characteristic curve of 0.77; 95% CI (0.63-0.87), P = .004. Considering the least significant change which was 7.9%; 95% CI (6-10), the threshold was 8% with a sensitivity of 53%; 95% CI (38-68); and a specificity of 77%; 95% CI (54-100).

CONCLUSION

ΔVTI_miniFC weakly predicted the effects of a fluid challenge of 15 mL kg^-1 of crystalloid in anesthetized children under controlled mechanical ventilation.

Immediate Postnatal Ventricular Performance Is Associated with Mortality in Hypoplastic Left Heart Syndrome

Right ventricular (RV) function as assessed by deformation has been evaluated prenatally and after palliation in hypoplastic left heart syndrome (HLHS). However, limited data exist about the immediate postnatal cardiac adaptation and RV function in HLHS. We compared echocardiographic measures of cardiac performance in HLHS versus controls in their first week of life. As a secondary objective, we evaluated if markers at the first echocardiogram were associated with mid- and long-term outcomes. Clinical and echocardiographic data of patients with HLHS between 2013 and 2016 were reviewed. The study population was matched with controls whose echocardiograms were obtained due to murmur or rule out coarctation. Speckle-tracking echocardiography was used to assess deformation. Thirty-four patients with HLHS and 28 controls were analyzed. Age at echocardiogram was similar between HLHS and controls. The RV of HLHS was compared to both RV and left ventricle (LV) of controls. HLHS deformation parameters [RV peak global longitudinal strain (GLS), global longitudinal strain rate (GLSR)] and tricuspid annular plane systolic excursion (TAPSE) were decreased compared to RV of controls. The LV-fractional area change, peak GLS, GLSR, circumferential strain, and strain rate of controls were higher than the RV of HLHS. Calculated cardiac output (CO) was higher in the HLHS group (592 vs. 183 mL/kg/min, p = 0.0001) but similar to the combined LV and RV output of controls. Later mortality or cardiac transplantation was associated with the RV CO and RV stroke distance at initial echocardiogram. Cox proportional hazard regression determined that restriction at atrial septum, decreased initial RV stroke distance and decreased TAPSE had a higher risk of death or cardiac transplantation. TAPSE and RV stroke distance by velocity time integral had adequate inter-reader variability by Bland-Altman plot and Pearson's correlation. Our study found that the HLHS RV deformation is decreased in the early postnatal period when compared to both LV and RV of controls, but deformation was not associated with mid- and long-term outcomes. Later mortality or cardiac transplantation was associated with decreased initial stroke distance and cardiac output. Early evaluation of patients with HLHS should include an assessment of stroke distance and future research should evaluate its implication in management strategies.

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).

Chronological Echocardiographic Changes in Healthy Term Neonates within Postnatal 72 Hours Using Doppler Studies

BACKGROUND

This study evaluated echocardiographic changes in full-term healthy neonates during early transitional period from postnatal 0-72 hours at 12-hour intervals by echocardiography.

METHODS

This was a prospective, observational, and longitudinal single-center cohort study. Morphometric, functional, systolic, diastolic, and tissue Doppler imaging (TDI) parameters (patent ductus arteriosus [PDA], aorta, superior vena cava [SVC], stroke volume [SV], cardiac output [CO], cardiac index [CI], early diastolic flow velocity [E], late diastolic flow velocity [A], early filling in TDI [E'], peak systolic annular velocity in TDI [S'], late velocity peak in TDI [A'], and myocardial performance index [MPI]) were evaluated in left ventricle (LV) and right ventricle (RV) with 56 newborns.

RESULTS

Sizes and peak velocities of PDA before postnatal 24 hours were significantly changed than those after postnatal 24 hours. Aortic velocity time integral (VTI), systolic blood pressure (BP), LV SV/kg, LV CO/kg, LV CI, and SVC flow/LV CO before 24 hours showed significantly changes than those after 24 hours. Also, LV and RV MPI before 24 hours were significantly higher than those after 24 hours. LV E/E' was significantly higher than RV E/E'.

CONCLUSION

Postnatal 24 hours is critical time for hemodynamic closure of PDA because aortic VTI, systolic BP, LV SV, LV CO, LV CI, and SVC flow/LV CO showed simultaneously significant changes after 24 hours at the same time as 24 hours of physiological closure of PDA. Chronological and dramatic changes of systolic, diastolic, and TDI parameters during early postnatal period can be used to compile normal baseline data of healthy full-term neonates.

Centile Curves for Velocity-Time Integral Times Heart Rate as a Function of Ventricular Length: The Use of Minute Distance Is Advantageous to Enhance Clinical Reliability in Children

BACKGROUND

The generation of velocity-time integrals (VTIs) from Doppler signals is an essential component of standard echocardiographic investigations. The most effective algorithm to compensate for growth in children has, however, not yet been identified. This study was initiated to establish pediatric reference values for VTI and to enhance the interpretability of those values, considering technical and physiological factors.

METHODS

The echocardiographic data sets of healthy children and adolescents (N = 349; age range, 0-20 years) were recorded in a prospective approach and subsequently analyzed. In a pilot study, aortic and pulmonary VTIs were set in relation to the physiologic parameters of heart size as possible influencing parameters in a subgroup of children with comparable physical characteristics. The ratio with the smallest SD was taken as the base to generate centile curves using the LMS method. The clinical utility of the model was tested by examining patients (n = 80) with shunt lesions such as patent ductus arteriosus and atrial septal defect.

RESULTS

Feasibility was 94.6% for aortic VTI and 92.8% for pulmonary VTI. The pilot study identified ventricular length and heart rate as suitable parameters with the lowest relative SDs and high correlations with VTI. Gender differences were not relevant for children <7 years of age, and with increasing age, SD increased because of higher stroke volume variations. The detection of increased aortic VTI was possible with sensitivity of 73% for patients with patent ductus arteriosus with moderate or large hemodynamically significant ductus arteriosus. Patients with atrial septal defects with enlarged right ventricles could be identified as having increased pulmonary VTI with sensitivity of 84%.

CONCLUSIONS

These new reference values for VTI times heart rate as a function of ventricular length may be of specific clinical value to improve the assessment of cardiac function, therapeutic decision making, and follow-up in pediatric patients with heart disease.

Right and left ventricular function in hospitalized children with respiratory syncytial virus infection

Background

Extrapulmonary manifestations including cardiac dysfunction have been demonstrated in children with respiratory syncytial virus (RSV) infection requiring intensive care. The aim of this study was to examine cardiac function in hospitalized children with moderate RSV infection admitted to a regular pediatric ward.

Methods

We used echocardiography to determine cardiac output, and right and left ventricular function in 26 patients (aged 2 weeks to 24 months) with RSV infection. The echocardiographic results were compared with s-troponin, the need for supplementary oxygen or noninvasive respiratory support, and capillary refill time.

Results

The number of measured s-troponins (ten [38%] of the included children) was too low to assess differences between children with elevated levels and those with normal levels. There were no differences in cardiac function between patients receiving oxygen treatment or respiratory support and those who did not. Capillary refill time did not correlate with any of the echocardiographic parameters. Both left and right ventricular output (mL/kg/min) was higher than published reference values. All other echocardiographic parameters were within the reference range.

Conclusion

Children with moderate RSV infection had an increased left and right ventricular output, and cardiac function was well maintained. We conclude that routine cardiac ultrasound is not warranted in children with moderate RSV infection. The role of an elevated s-troponin in these patients remains to be determined.

LVOT-VTI is a Useful Indicator of Low Ventricular Function in Young Patients

Left ventricular outflow tract velocity time integral (LVOT-VTI), a Doppler-derived measure of stroke distance, is used as a surrogate marker of cardiac function in adults. LVOT-VTI is easily obtained, independent of ventricular geometry and wall motion abnormalities. We investigated the relationship between LVOT-VTI and conventional measures of function in young patients by comparing controls to children with dilated cardiomyopathy (DCM). Sixty-two healthy and 52 DCM patients over 1 year were studied retrospectively. The average pulsed (PW) and continuous wave (CW) LVOT-VTIs from apical views were measured from three cycles. Body surface area (BSA) and Ejection fraction (EF) were obtained. We compared LVOT-VTIs between study and control groups and assessed BSA's impact on LVOT-VTI. The entire cohort was classified into three levels of LV function which were compared. We determined LVOT-VTI cutoff values that indicated an EF <50%. The mean PW-LVOT-VTI in the DCM group was significantly lower than that of the normal group (0.15 vs. 0.18 m; p < 0.0012). The mean CW-LVOT-VTI was significantly lower in DCM (0.20 vs. 0.24 m; p < 0.0001). There was no impact of BSA on LVOT-VTI except when comparing BSA and CW-LVOT-VTI in the normal group. There was a positive relationship between LVOT-VTI and EF for PW (Rs = 0.29, p = 0.0022) and CW (Rs = 0.22, p = 0.0364) and a difference in mean LVOT-VTI between EF groups (p < 0.0001). ROC analysis demonstrated that PW-LVOT-VTI <0.17 m (AUC = 0.73; p < 0.0001) and CW-LVOT-VTI <0.22 m (AUC = 0.76; p < 0.0001) was associated with EF <50%. This study indicates that LVOT-VTI can be a useful alternative measure of LV performance in children over 1 year.

Right Ventricular Outflow Tract Velocity Time Integral Determination in 570 Healthy Children and in 52 Pediatric Atrial Septal Defect Patients

Determination of the right ventricular outflow tract velocity time integral (RVOT VTI) is an important part of the noninvasive investigation of pulmonary blood flow in adults; however, age-related pediatric reference data are lacking. We examined growth-related changes of RVOT VTI values in children and the predictive value of RVOT VTI values in identifying enhanced pulmonary blood flow in children with secundum type atrial septal defect (ASD). A prospective study was conducted in a group of 570 healthy children and 52 children with a moderate-sized to large ASD. We determined the effects of age, body length (BL), body weight (BW), and body surface area (BSA) on RVOT VTI values. The predictive value of normal values stratified for age, BW, BL, and BSA was tested in our 52 ASD children. RVOT VTI values ranged from mean 9.7 ± 1.2 cm in neonates to 23.3 ± 2.7 cm in children with 18 years of age and showed a positive correlation with age, BL, BSA, and BW. In our population, RVOT VTI z-scores showed a high specificity for detecting ASD patients (>97 %) with sensitivity up to 71 %. We provide normal ranges and calculated z-scores of pediatric RVOT VTI values. Normal RVOT VTI z-scores might be additional predictors in identifying increased pulmonary blood flow in patients with ASD.

Computational simulations of flow dynamics and blood damage through a bileaflet mechanical heart valve scaled to pediatric size and flow

Despite pressing needs, there are currently no FDA approved prosthetic valves available for use in the pediatric population. This study is performed for predictive assessment of blood damage in bileaflet mechanical heart valves (BMHVs) with pediatric sizing and flow conditions. A model of an adult-sized 23 mm St. Jude Medical (SJM) Regent(™) valve is selected for use in simulations, which is scaled in size for a 5-year old child and 6-month old infant. A previously validated lattice-Boltzmann method (LBM) is used to simulate pulsatile flow with thousands of suspended platelets for cases of adult, child, and infant BMHV flows. Adult BMHV flows demonstrate more disorganized small-scale flow features, but pediatric flows are associated with higher fluid shear stresses. Platelet damage in the pediatric cases is higher than in adult flow, highlighting thrombus complication dangers of pediatric BMHV flows. This does not necessarily suggest clinically important differences in thromboembolic potential. Highly damaged platelets in pediatric flows are primarily found far downstream of the valve, as there is less flow recirculation in pediatric flows. In addition, damage levels are well below expected thresholds for platelet activation. The extent of differences here documented between the pediatric and adult cases is of concern, demanding particular attention when pediatric valves are designed and manufactured. However, the differences between the pediatric and adult cases are not such that development of pediatric sized valves is untenable. This study may push for eventual approval of prosthetic valves resized for the pediatric population. Further studies will be necessary to determine the validity and potential thrombotic and clinical implications of these findings.