Left ventricular systolic function of newborns with asphyxia evaluated by tissue Doppler imaging

Asphyxia, Therapeutic Hypothermia, and Pulmonary Hypertension

Neonates with a perinatal hypoxic insult and subsequent neonatal encephalopathy are at risk of acute pulmonary hypertension (aPH) in the transitional period. The phenotypic contributors to aPH following perinatal asphyxia include a combination of hypoxic vasoconstriction of the pulmonary vascular bed, right heart dysfunction, and left heart dysfunction. Therapeutic hypothermia is the standard of care for neonates with moderate-to-severe hypoxic ischemic encephalopathy. This review summarizes the underlying risk factors, causes of aPH in neonates with perinatal asphyxia, discusses the unique phenotypical contributors to disease, and explores the impact of the initial insult and subsequent therapeutic hypothermia on aPH.

Myocardial Work for Dynamic Monitoring of Myocardial Injury in Neonatal Asphyxia

To assess the value of parameters of myocardial work for dynamic monitoring of myocardial injury after neonatal asphyxia. Fifty-three neonates with asphyxia admitted within 24 h after delivery were divided into a mild asphyxia group (n = 40) and severe asphyxia group (n = 13). Echocardiography was performed within 24 h post-birth, within 72 h post-birth (48 h after first echo), and during recovery. The left ventricular ejection fraction on M-mode echocardiography and by Simpson's biplane method (LVEF and Bi-EF, respectively), stroke volume (SV), cardiac output (CO), cardiac index (CI), global longitudinal strain (GLS), global work index (GWI), global constructive work (GCW), and other parameters were measured. Echocardiographic indicators were compared between groups and over time. GWI was significantly increased at 72 h in the mild asphyxia group (P < 0.05) but showed no significant change over time in the severe asphyxia group (P > 0.05). While GCW increased significantly over time in both groups (P < 0.05), it increased earlier in the mild asphyxia group. Time and grouping factors had independent effects on GWI and GCW (P > 0.05). The characteristics of differences in GWI and GCW between the two groups were different from those for LVEF, Bi-EF, SV, CO, CI, and GLS and their change characteristics with improvement from treatment. GWI and GCW changed significantly during recovery from neonatal asphyxia, and their change characteristics differed between mild and severe asphyxia cases. Myocardial work parameters can be used as valuable supplements to traditional indicators of left ventricular function to dynamically monitor the recovery from myocardial injury after neonatal asphyxia.

A detailed echocardiographic evaluation of ventricular functions in stable full term small for gestational age babies

PURPOSE

SGA infants with fetal growth restriction have reduced ability to adapt themselves to the postnatal life because of certain epigenetic changes in cardiac function. The aim of the present study is to assess and compare the cardiac functions of fetal growth restricted SGA newborns to the term stable AGA newborns, and evaluate any differences in the cardiac functions during the postnatal transitional circulation.

METHOD

This observational study was conducted at a multispecialty tertiary care hospital in Western India from June to November 2021. The newborns were evaluated using bedside echocardiography at 24-48 h and repeat screening after 48 h. The echocardiographic assessment of the systolic function was done using EF, FS, FAC and TAPSE; diastolic function using E/A wave ratio and global functioning using LV MPI.

RESULT

Twnety-four babies were included in cases and 30 in the control arm of the study. Maternal and newborn characteristics were comparable between the two groups. FS, EF for left ventricle and TAPSE, FAC for right ventricular systolic function were significantly lower in SGA group (p = 0.02, 0.02, 0.00 and 0.01; respectively). The current study revealed a lower tricuspid E/A ratio and higher mitral E/A ratio with a significant difference beyond 48 h in the first week of life (p value 0.00). Left ventricular MPI was significantly higher in SGA infants compared to AGA infants during two subsequent readings in immediate newborn period with p values 0.01 and 0.02 respectively. The subgroup analysis revealed that fetal growth-restricted neonates with absent end-diastolic flow had a greater impact on ventricular functions.

CONCLUSION

Present study showed a significant systolic and diastolic dysfunction during initial newborn period in growth restricted SGA infants.

Hemodynamic changes and evaluation during hypoxic-ischemic encephalopathy and therapeutic hypothermia

Multiorgan damage is a hallmark of hypoxic-ischemic encephalopathy and cardiovascular and hemodynamic changes during asphyxia contribute significantly to the brain damage. The main insult to the heart is myocardial damage and associated ventricular dysfunction, which is manifested by reduced preload and afterload. The immature myocardium reacts to asphyxia by bradycardia and reduced contractile capacity. Pulmonary hypertension aggrevates cardiac dysfunction. Hypothermia is the only effective treatment for HIE but it may also affect the heart and peripheral vascular system leading to bradycardia and peripheral vasoconstriction. In fact, these effects might be cardioprotective also. Rewarming after hypothermia may increase the heart rate and cardiac metabolism, augmenting the cardiac output. Monitoring of patient with HIE during and after hypothermia is possible by using near-infrared spectroscopy, echocardiography and electrocardiography. Cerebral effects may be monitored by magnetic resonance imaging also. Management should include the physiological status of the patient and appropriate treatments, including inotropes, vasopressors or rarely fluid boluses. Dopamine should not be used unless absolutely necessary. Drugs like melatonin and magnesium are under investigation. All treatments should be evidence-based and targeted echocardiography should be used more often in these vulnerable infants.

Haemodynamic impact of chest compressions in the delivery room

Among 65 neonates with encephalopathy undergoing cooling, 30 (46.1%) received chest compressions during delivery room resuscitation. Despite differences in encephalopathy severity, early (<24 hours) biventricular function on echocardiogram (fractional area change, myocardial performance indices, systolic to diastolic duration ratios, tricuspid annular plane systolic excursion) was comparable between groups with and without chest compressions. Epinephrine receipt was associated with abnormal tricuspid annular plane systolic excursion.

Diastolic Dysfunction in Neonates With Hypoxic-Ischemic Encephalopathy During Therapeutic Hypothermia: A Tissue Doppler Study

Diastolic dysfunction often complicates myocardial ischemia with increased mortality rates. However, less is known about diastolic function after perinatal asphyxia in neonates with hypoxic-ischemic encephalopathy (HIE) during therapeutic hypothermia (TH) and rewarming.

AIM

The aim of this study was to assess diastolic function with tissue Doppler imaging (TDI) in neonates with moderate-severe HIE during TH and rewarming.

METHOD

Newborns at >36 weeks' gestation with moderate-severe HIE treated with TH were evaluated with targeted neonatal echocardiography (TNE), including TDI, within 24 h of TH initiation (T1), at 48-72 h of treatment (T2), and after rewarming (T3). These retrospective data were collected and compared with a control group of healthy babies at >36 weeks' gestation that was prospectively evaluated following the same protocol.

RESULTS

A total of 21 patients with HIE + TH and 15 controls were included in the study. Myocardial relaxation before the onset of biventricular filling was prolonged in the HIE + TH group during TH with significantly longer isovolumic relaxation time (IVRT') in the left ventricle (LV), the septum, and the right ventricle (RV). This was associated with slower RV early diastolic velocity (e') and prolonged filling on T1. Total isovolumic time (t-IVT; isovolumic contraction time [IVCT'] + IVRT') and myocardial performance index (MPI') were globally increased in asphyxiated neonates. All these differences persisted after correction for heart rate (HR) and normalized after rewarming. TDI parameters assessing late diastole (a' velocity or e'/a' and E/e' ratios) did not differ between groups.

CONCLUSION

TDI evaluation in our study demonstrated a pattern of early diastolic dysfunction during TH that normalized after rewarming, whereas late diastole seemed to be preserved. Our data also suggest a possible involvement of impaired twist/untwist motion and dyssynchrony. More studies are needed to investigate the impact and therapeutic implication of diastolic dysfunction in these babies, as well as to clarify the role of TH in these findings.

Left Ventricular Dysfunction Persists in the First Week after Re-Warming following Therapeutic Hypothermia for Hypoxic-Ischaemic Encephalopathy

OBJECTIVES

The aim of this study was to assess serial myocardial function in newborn infants receiving therapeutic hypothermia (TH) as treatment for moderate to severe hypoxic-ischaemic encephalopathy (HIE).

METHODS

Serial echocardiography was performed in 20 term infants receiving TH on days 1-3 and again after re-warming. Left ventricular (LV) fractional shortening, LV cardiac output, and tissue Doppler imaging-derived myocardial velocities and myocardial performance index were measured. Similar assessments were obtained from 20 well term infants within 48 h of birth.

RESULTS

LV fractional shortening (LVFS) was similar between cases and controls during all measurements (25.3% vs. 27.4%). The mean LV cardiac output on day 1 was significantly lower in cases (109 mL/kg/min) than in controls (162 mL/kg/min) but increased after re-warming (145 mL/kg/min). All myocardial velocities were significantly lower in cases on day 1, increased during TH, but LV indices remained consistently lower compared to controls even after re-warming. LV myocardial performance index was higher in cases compared to controls on day 1, improved during TH but remained abnormal after re-warming. The right ventricular myocardial performance index was similar between cases and controls.

CONCLUSION

Among infants affected by moderate to severe HIE, LV function appears to be more affected than right ventricular function with LV dysfunction persisting after completion of TH. LVFS was not useful to determine dysfunction in this cohort.

Non-invasive continuous cardiac output monitoring in infants with hypoxic ischaemic encephalopathy

OBJECTIVE

To describe early, continuous, non-invasive measures of cardiac output (CO) and evolution over time in infants with hypoxic-ischaemic encephalopathy (HIE).

STUDY DESIGN

Prospective observational study of 44 infants with HIE (23 mild, 17 moderate, 4 severe) and 17 term controls. Infants with HIE had non-invasive CO monitoring (NICOM) continuously in the neonatal unit. Term controls had NICOM recorded at 6 and 24 h. A mixed-modelling approach was used to assess change in CO over time by group.

RESULTS

Infants with moderate HIE have significantly lower CO than the mild group at all timepoints (10.7 mls/kg/min lower, 95% CI:1.0,20.4, p = 0.03) which increases over time, driven by a gradual increase in stroke volume (SV). CO increased further during rewarming predominantly due to an increase in HR.

CONCLUSION

TH has a significant impact on HR but SV appears largely unaffected. NICOM may provide a non-invasive, continuous, low-cost alternative to monitoring CO in infants with HIE however further research is warranted.

Hemodynamic optimization for neonates with neonatal encephalopathy caused by a hypoxic ischemic event: Physiological and therapeutic considerations

Neonatal encephalopathy due to a hypoxic-ischemic event is commonly associated with cardiac dysfunction and acute pulmonary hypertension; both therapeutic hypothermia and rewarming modify loading conditions and blood flow. The pathophysiological contributors to disease are complex with a high degree of clinical overlap and traditional bedside measures used to assess circulatory adequacy have multiple confounders. Comprehensive, quantitative echocardiography may be used to delineate the relative contribution of lung parenchymal, pulmonary vascular, and cardiac disease to hypotension and/or hypoxemic respiratory failure. In this review, we provide a detailed overview of the contributors to hemodynamic instability following perinatal hypoxic-ischemic injury. Our proposed approach to therapy focuses on physiopathological considerations with interventions individualized to this potentially complex condition and considers the pharmacological idiosyncrasies, which may occur among neonates with NE presenting with multiorgan dysfunction while undergoing therapeutic hypothermia.

What Inotrope and Why?

Primary function of cardiovascular system is to meet body's metabolic demands. The aim of inotrope therapy is to minimise adverse impact of cardiovascular compromise. Current use of inotropes is primarily guided by the pathophysiology of cardiovascular compromise and anticipated actions of inotropes. Lack of significant reduction in morbidity and mortality associated with cardiovascular compromise despite inotrope use, highlights major gaps in our understanding of circulatory targets, thresholds and choices of inotrope therapy. Thus far, prevention of cardiovascular compromise remains the most effective strategy to optimize outcomes. Studies of alternative design are needed for further advancement in cardiovascular therapy in neonates.

Cardiac adaptation in asphyxiated infants treated with therapeutic hypothermia

BACKGROUND

Hypoxic ischemic encephalopathy (HIE) affects  one to two newborns per 1,000 live births and oftentimes involves multi-organ insult. The objectives were to assess the evolution of cardiac function in infants with HIE treated with therapeutic hypothermia using echocardiography (ECHO).

METHODS

Archived data during the period 2010-2016 was assessed. Amongst the infants with baseline ECHO assessments, a sub-cohort which had assessments in all the three phases (baseline/pre-active cooling [T1], cooling [T2] and rewarming [T3]) was analyzed separately.

RESULTS

Thirty three infants formed part of the overall cohort, the gestation and birthweight were 39.6 ± 1.6 weeks and 3306 ± 583 g, respectively. Baseline (T1) information noted impaired cardiac performance (right ventricle stroke volume 1.08 ± 0.04 ml/kg, fractional area change [FAC] 24 ± 0.5% and tricuspid annular peak systolic excursion [TAPSE] 7.46 ± 0.11mm). Serial information was available for 24 of 33 infants. Cardiac function improved significantly between the cooling and the re-warming kphases. This included changes in right ventricular output (127 ± 34 vs 164 ± 47 ml/kg/min, p <0.01) and FAC (20 ± 3 vs 28 ± 2%, p<0.01). Pairwise comparisons for fractional shortening did not show significant changes. From the cooling to the rewarming phase, maximum change was noted in FAC (26.3 ± 9.8%) while minimum change was noted in fractional shortening (median, interquartile range) of 4.6% (1.4, 9.1). Significant correlation between TAPSE and time to peak velocity as a proportion of right ventricular ejection time was noted (r2 = 0.68, p <0.001).

CONCLUSIONS

In infants with moderate to severe HIE, cardiac function evolves during various phases of therapeutic hypothermia. Low output state during cooling may be due to a combination of the disease state (HIE) and cooling therapy.

Tissue Doppler imaging versus conventional echocardiography in assessment of cardiac diastolic function in full term neonates with perinatal asphyxia

Background and objective: Limited number of studies evaluated cardiac diastolic function in neonates with perinatal asphyxia using tissue Doppler imaging. The aim of this study was to evaluate the echocardiographic parameters in full-term neonates with perinatal asphyxia compared to healthy full-term neonates. Diagnostic value of echocardiographic parameters of diastolic dysfunction in predicting mortality in asphyxiated neonates was assessed.Setting: Neonatal intensive care unit at the Obstetric and Gynecology Hospital, Cairo University, Egypt (a tertiary care center).Patients and methods: This study included 20 neonates with perinatal asphyxia (cases) and 20 healthy full-term nonasphyxiated neonates (as controls). The studied groups were assessed by conventional pulsed wave Doppler and tissue Doppler imaging.Results: Among pulsed wave Doppler parameters, cases had statistically significant lower values (denoting more diastolic dysfunction) than controls as regards mitral E velocity (p = .04) and mitral E/A ratio (p = .04). Similarly, among tissue Doppler parameters, cases had statistically significant lower values (denoting more diastolic dysfunction) than controls as regards septal E'/A' ratio (p = .019), left ventricular E' velocity (p = .001), and E'/A' ratio (p < .001). Septal E'/A' ratio and right ventricular E'/A' ratio were significantly lower (p = .012 and p = .025, respectively) among nonsurvivors (denoting more diastolic dysfunction) compared to survivors. Moreover, cases had statistically significant higher values (denoting more diastolic dysfunction) than controls as regards septal (p < .001), left ventricular (p < .001), and right ventricular (p < .001) tissue Doppler-based myocardial performance indices. Asphyxiated neonates showed statistically significant higher evidence of left ventricular diastolic dysfunction than controls in both pulsed wave Doppler and tissue Doppler with p < .001 and p = .001, respectively; while there was no difference as regards right ventricular diastolic dysfunction. Tissue Doppler was able to detect higher number of neonates with left ventricular diastolic dysfunction than conventional pulsed wave Doppler.Conclusions: Tissue Doppler imaging was found to be able to detect diastolic dysfunction early in neonates with perinatal asphyxia specifically as regards the left ventricle. Assessment of myocardial function is important in asphyxiated neonates. Tissue Doppler imaging should be considered an integral part of assessment of cardiac function in asphyxiated neonates.

Non-invasive Cardiac Output Monitoring in Neonates

Circulatory monitoring is currently limited to heart rate and blood pressure assessment in the majority of neonatal units globally. Non-invasive cardiac output monitoring (NiCO) in term and preterm neonates is increasing, where it has the potential to enhance our understanding and management of overall circulatory status. In this narrative review, we summarized 33 studies including almost 2,000 term and preterm neonates. The majority of studies evaluated interchangeability with echocardiography. Studies were performed in various clinical settings including the delivery room, patent ductus arteriosus assessment, patient positioning, red blood cell transfusion, and therapeutic hypothermia for hypoxic ischemic encephalopathy. This review presents an overview of NiCO in neonatal care, focusing on technical and practical aspects as well as current available evidence. We discuss potential goals for future research.

Tissue damage in the heart after cardiac arrest induced by asphyxia and hemorrhage in newborn pigs

BACKGROUND

Asphyxia of newborns is a severe and frequent challenge of the peri- and postnatal period.

METHODS

Forty-four neonatal piglets underwent asphyxia and hemorrhage (AH), followed by resuscitation with blood or crystalloid transfusion. In this study, 15 piglets (blood n = 9, NaCl n = 6, mean age 31 h) were randomly chosen. Four hours after return of spontaneous circulation, heart tissue and blood were collected. Analyses of heart fatty acid binding protein (HFABP), cardiac troponin I (TnI) levels, and activation of the complement system were performed. Histological staining for connexin 43 (Cx43) and complement C5a receptor 1 (C5aR1) was performed.

RESULTS

Following AH, systemic elevation of cardiac TnI and HFABP revealed cardiac damage in both groups. Systemic activation of the complement system and the appearance of extracellular histones in plasma of the blood transfusion group were observed. The Cx43 was translocated from the intercalated discs to the cytosol after AH. Cardiac glycogen concentration was reduced in both groups. A significant reduction of C5aR1 in the left ventricle and a significant elevation of the heart injury score were investigated after blood transfusion.

CONCLUSION

AH leads to alteration of the heart, particularly in Cx43 and glycogen reserves, as well as local inflammation.

Use of high-sensitivity cardiac troponin I levels for early diagnosis of myocardial injury after neonatal asphyxia

Objective

Low-cost diagnostic and prognostic biomarkers could help guide clinical management of neonates with myocardial injury after asphyxia. This study aimed to assess the utility of creatine kinase (CK)-MB, high-sensitivity cardiac troponin I (hs-cTnI), brain natriuretic peptide (BNP), and myoglobin in the early diagnosis of myocardial injury following neonatal asphyxia.

Methods

Eighteen neonates with asphyxia and myocardial injury, 22 neonates with asphyxia and no myocardial injury, and 19 neonates without asphyxia (controls) were enrolled consecutively at the Neonatology Department, First Hospital of Lanzhou University (August 2013 to December 2014). Serum CK-MB, hs-cTnI, BNP, and myoglobin levels were evaluated at 12 hours and 7 days after birth. Their diagnostic value for myocardial injury was assessed by receiver operating characteristic (ROC) curve analysis.

Results

Levels of all four markers were higher in neonates with asphyxia and myocardial injury than in neonates with asphyxia and no myocardial injury or controls 12 hours after birth. The marker hs-cTnI had the highest diagnostic value. Using a cutoff value of 0.087 µg/L for hs-cTnI, the sensitivity, specificity, and diagnostic accuracy for asphyxia-induced myocardial injury were 55.6%, 95.5%, and 77.5%, respectively.

Conclusions

Serum hs-cTnI levels can predict myocardial injury caused by neonatal asphyxia at an early stage.

Lactate acidosis and cardiac output during initial therapeutic cooling in asphyxiated newborn infants

Aim

We hypothesized that compromised cardiac output in asphyxiated infants may influence on the rate of disappearance of lactate due to insufficient perfusion.

Methods

The study was a prospective, observational study, where infants with perinatal asphyxia who met the criteria for therapeutic hypothermia were included. Cardiac output, stroke volume and heart rate were measured by electrical velocimetry in 15 newborn infants with perinatal asphyxia during the first six hours of active therapeutic hypothermia. Results from routine blood samples were collected retrospectively. Cardiac parameters were also measured in 10 healthy, term infants after caesarian section. Cardiac parameters were compared between the asphyxiated group and the control group prior to and during hypothermia. Rate of disappearance of lactate was correlated to cardiac output in the asphyxiated infants.

Results

Cardiac output was stable in the healthy infants from 0.5 to 6 hours postnatally. The infants with perinatal asphyxia had lower cardiac output prior to and during therapeutic hypothermia compared to the control group. Rate of disappearance of lactate was not related to cardiac output.

Conclusion

An association between disappearance of lactate acidosis and low cardiac output was not confirmed. A low rate of disappearance of lactate may rather be an indicator of organ injury due to asphyxia.

Birth Injury: Birth Asphyxia and Birth Trauma

Injury to a fetus or neonate during delivery can be due to several factors involving the fetus, placenta, mother, and/or instrumentation. Birth asphyxia results in hypoxia and ischemia, with global damage to organ systems. Birth trauma, that is mechanical trauma, can also cause asphyxia and/or morbidity and mortality based on the degree and anatomic location of the trauma. Some of these injuries resolve spontaneously with little or no consequence while others result in permanent damage and severe morbidity. Unfortunately, some birth injuries are fatal. To understand the range of birth injuries, one must know the risk factors, clinical presentations, pathology and pathophysiology, and postmortem autopsy findings. It is imperative for clinicians and pathologists to understand the causes of birth injury; recognize the radiographic, gross, and microscopic appearances of these injuries; differentiate them from inflicted postpartum trauma; and work to prevent future cases.

Cardiac injury biomarkers in paediatric age: Are we there yet?

The aim of this article is to evaluate the clinical utility of cardiac injury biomarkers in paediatric age. In December 2015, a literature search was performed (PubMed access to MEDLINE citations; http://www.ncbi.nlm.nih.gov/PubMed/ ). The search strategy included the following medical subject headings and text terms for the key words: "cardiac injury biomarkers", "creatine kinase-MB", "myoglobin", "troponin", "children", "neonate/s", "newborn/s", "infant/s" and echocardiography. In the paediatric population, troponins show a good correlation with the extent of myocardial damage following cardiac surgery and cardiotoxic medication and can be used as predictors of subsequent cardiac recovery and mortality. Elevation of cardiac injury biomarkers may also have diagnostic value in cases when cardiac contusion or pericarditis is suspected. Cardiac injury biomarkers are very sensitive markers for the detection of myocardial injury and have been studied in healthy newborns, after tocolysis, intrauterine growth restriction, respiratory distress and asphyxia. The proportion of newborns with elevated troponin was higher than that in ill infants, children, and adolescents and in healthy adults, suggesting that myocardial injury, although clinically occult, is common in this young age group. Results suggest that significant elevation of cord troponin is an excellent early predictor of severity of hypoxic-ischaemic encephalopathy and mortality in term infants. Cardiac biomarkers may also benefit centres without on-site echocardiography with evidence showing good correlation with echo-derived markers of myocardial function. Further studies are needed to better clarify the role of cardiac biomarkers in paediatric age and their correlation with echocardiographic parameters.

Tissue Doppler velocity imaging and event timings in neonates: a guide to image acquisition, measurement, interpretation, and reference values

Neonatologists can use echocardiography for real-time assessment of the hemodynamic state of neonates to support clinical decision-making. There is a large body of evidence showing the shortcomings of conventional echocardiographic indices in neonates. Newer imaging modalities have evolved. Tissue Doppler imaging is a new technique that can provide measurements of myocardial movement and timing of myocardial events and may overcome some of the shortcomings of conventional techniques. The high time resolution and its ability to assess left and right cardiac function make tissue Doppler a favorable technique for assessing heart function in neonates. The aim of this review is to provide an up-to-date overview of tissue Doppler techniques for the assessment of cardiac function in the neonatal context, with focus on measurements from the atrioventricular (AV) plane. We discuss basic concepts, protocol for assessment, feasibility, and limitations, and we report reference values and give examples of its use in neonates.

Application of Neonatologist Performed Echocardiography in the Assessment and Management of Neonatal Heart Failure unrelated to Congenital Heart Disease

Neonatal heart failure (HF) is a progressive disease caused by cardiovascular and non-cardiovascular abnormalities. The most common cause of neonatal HF is structural congenital heart disease, while neonatal cardiomyopathy represents the most common cause of HF in infants with a structurally normal heart. Neonatal cardiomyopathy is a group of diseases manifesting with various morphological and functional phenotypes that affect the heart muscle and alter cardiac performance at, or soon after birth. The clinical presentation of neonates with cardiomyopathy is varied, as are the possible causes of the condition and the severity of disease presentation. Echocardiography is the selected method of choice for diagnostic evaluation, follow-up and analysis of treatment results for cardiomyopathies in neonates. Advances in neonatal echocardiography now permit a more comprehensive assessment of cardiac performance that could not be previously achieved with conventional imaging. In this review, we discuss the current and emerging echocardiographic techniques that aid in the correct diagnostic and pathophysiological assessment of some of the most common etiologies of HF that occur in neonates with a structurally normal heart and acquired cardiomyopathy and we provide recommendations for using these techniques to optimize the management of neonate with HF.

Cardiovascular Alterations and Multiorgan Dysfunction After Birth Asphyxia

The cardiovascular response to asphyxia involves redistribution of cardiac output to maintain oxygen delivery to critical organs such as the adrenal gland, heart, and brain, at the expense of other organs such as the gut, kidneys and skin. This redistribution results in reduced perfusion and localized hypoxia/ischemia in these organs, which, if severe, can result in multiorgan failure. Liver injury, coagulopathy, bleeding, thrombocytopenia, renal dysfunction, and pulmonary and gastrointestinal injury all result from hypoxia, underperfusion, or both. Current clinical therapies need to be considered together with therapeutic hypothermia and cardiovascular recovery.

Evidence-based versus pathophysiology-based approach to diagnosis and treatment of neonatal cardiovascular compromise

With the advances in biomedical research and neonatal intensive care, our understanding of cardiovascular developmental physiology and pathophysiology has significantly improved during the last few decades. Despite this progress, the current management of circulatory compromise depends primarily on experts' opinions rather than high level of evidence. The lack of reliable, accurate, continuous and preferably non-invasive monitoring techniques has further limited our ability to collect the information needed for the design and execution of more sophisticated clinical trials with a better chance to provide the evidence we need. Given the lack of randomized, placebo-controlled trials investigating clinically relevant outcomes of novel treatments of neonatal cardiovascular compromise, we must now use the available lower level of evidence and our present understanding of developmental physiology and pathophysiology when providing cardiovascular supportive care to critically ill neonates. However, with recent advances in cardiovascular monitoring capabilities, direct and more objective assessment of the changes in cardiovascular function, organ blood flow, and tissue oxygenation have become possible. These advances have helped in our clinical assessment and enabled us to start designing more sophisticated interventional clinical trials using clinically relevant endpoints.

Serial assessment of right ventricular function using tissue Doppler imaging in preterm infants within 7 days of life

BACKGROUND

We aimed to evaluate right ventricular (RV) function longitudinally using tissue Doppler imaging (TDI) echocardiography in preterm infants.

METHODS

We selected 101 very-low-birth-weight (VLBW) infants for the study. Echocardiographic examinations including TDI were performed serially within 7days of life. Pulsed-Doppler TDI waveforms were recorded at the tricuspid valve annulus, and peak systolic velocities (Sa), early diastolic velocities (Ea), and late diastolic velocities (Aa) were measured.

RESULTS

Sa, Ea and Aa were all reduced significantly from 3h to 12h, and then increased gradually thereafter. These three velocities also increased with gestational age in the early neonatal period. The ratio of Ea to Aa (Ea/Aa) did not change significantly within the first week of life. The ratio of E to Ea (E/Ea) in VLBW infants also seemed to remain stable from birth to day 7. The values of Sa appeared to be associated with cardiac output in the early neonatal period. Both Sa and Aa in intubated infants were significantly higher than in non-intubated infants.

CONCLUSION

RV TDI velocities of preterm infants in the early neonatal period are influenced by gestational age, postnatal age, and respiratory status, although the RV E/Ea ratio appears to be almost stable throughout the neonatal period. Our findings may provide some basis for assessment of RV function in critically ill preterm infants.

Longitudinal systolic left ventricular function in preterm and term neonates: reference values of the mitral annular plane systolic excursion (MAPSE) and calculation of z-scores

The mitral annular plane systolic excursion (MAPSE) is a quick and reliable echocardiographic tool for assessing longitudinal left ventricular (LV) systolic function in children and adults. Because this parameter is affected by the LV longitudinal dimension, pediatric and adult normal values are not suitable for preterm and term neonates. A prospective study investigated a large group of preterm and term neonates [gestational age (GA), 26/0-6 to 40/0-6; birth weight (BW), 670-4,140 g]. The growth- and BW-related changes in MAPSE were determined to establish normal z-score values for preterm and term neonates. The MAPSE ranged from a mean of 0.36 ± 0.05 cm in preterm neonates with a GA of 26/0-6 to 0.56 ± 0.08 cm in term neonates with a GA of 40/0-6. The findings showed MAPSE, GA, and BW to be moderately correlated. Pearson's correlation coefficient was 0.56 for GA (MAPSE; p < 0.001) and 0.58 for BW (MAPSE; p < 0.001). The normal MAPSE values did not differ significantly between females and males (p = 0.946). The absolute values and z-scores of normal MAPSE values in healthy preterm and term neonates within the first 48 h of life were calculated, and percentile charts were established. Determination of LV function using MAPSE might be useful for vulnerable infants for whom a prolonged examination is inappropriate and for neonates with suboptimal visualization of the endocardium.

The myocardial function during and after whole-body therapeutic hypothermia for hypoxic-ischemic encephalopathy, a cohort study

BACKGROUND

Therapeutic hypothermia has become standard treatment for moderate and severe neonatal hypoxic-ischemic encephalopathy (HIE) to reduce cerebral morbidity and mortality. The effect on the heart is incompletely explored.

AIM

To assess the myocardial function during and after whole-body therapeutic hypothermia for HIE.

STUDY DESIGN

Observational cohort study.

SUBJECTS

Forty-four infants with HIE cooled for 72hours were compared with 48 healthy term infants and 20 normothermic infants with HIE.

OUTCOME MEASURES

Tissue Doppler deformation indices of myocardial function (peak systolic strain, peak systolic strain-rate, early diastole strain-rate and strain-rate in atrial systole) during (days 1 and 3) and after (day 4) therapeutic hypothermia.

RESULTS

On days one and three all indices in both HIE groups were lower than the corresponding indices in the healthy infants. The two HIE groups had similar indices, except peak systolic strain-rate on days 1 and 3 and strain-rate in atrial systole on day 1. All strain-rate indices improved from day 3 to 4 (after rewarming) in the cooled group and achieved similar values to those in healthy infants on day 3. All indices were higher in the cooling-group after rewarming than in the normothermic infants with HIE on day 3, except early diastolic strain-rate.

CONCLUSIONS

Infants with HIE had similarly impaired myocardial function during days 1-3 whether normothermic or hypothermic. The myocardial function improved significantly at day 4 (after rewarming), approaching the day 3 levels in the healthy neonates.

Cardiac troponin I concentrations as a marker of neurodevelopmental outcome at 18 months in newborns with perinatal asphyxia

OBJECTIVE

To investigate whether creatine kinase-MB (CK-MB) and cardiac troponin I (cTnI) can be used to predict neurodevelopmental outcome at 18 months in infants with perinatal asphyxia (PA). The diagnostic value of cTnI to assess myocardial dysfunction was considered as well.

STUDY DESIGN

Retrospective study of 178 neonates admitted with PA. cTnI concentrations measured within 12 h of birth were compared with medium-term outcome assessed with the Bayley Scales of Infant Development. cTnI concentrations measured within 12 h of birth were compared with clinical grade of hypoxic-ischemic encephalopathy (HIE) and with duration of inotropic support. Two-dimensional Doppler and color Doppler findings were recorded. Fractional shortening, tricuspid and mitral regurgitation were evaluated.

RESULT

A statistically significant correlation between cTnI concentration and BSID-II score was found (mental development index r -0.69, P<0.05 and psychomotor development index r -0.39, P<0.05). There was no statistically significant correlation between CK-MB and BSID-II score (P>0.05).Serum cTnI concentrations and duration of inotropic support were significantly greater with increasing severity of PA. cTnI was negatively correlated with fraction shortening (r -0.64; P<0.05). The severity of tricuspid regurgitation was correlated with the cTnI concentration (r 0.61; P<0.05).

CONCLUSION

In asphyxiated neonates, cTnI concentrations within 12 h of birth correlate with medium-term outcome. Early cTnI concentration correlates with severity of HIE, myocardial dysfunction and with Bayley II scores at 18 months.

Effect of birth asphyxia on p wave dispersion

OBJECTIVES

To evaluate the cardiac conduction system using P wave dispersion on electrocardiogram and its relationship with the short term mortality and development of arrhythmia in asphyxiated neonates.

METHODS

Thirty term babies with evidence of asphyxia and without any congenital abnormalities were consecutively evaluated as cases. They were compared with thirty healthy term babies without asphyxia. Twelve-lead surface electrocardiography was obtained from all the patients and the controls, and P wave dispersion was calculated according to its definition as the difference between P maximum duration and P minimum duration in 12-lead electrocardiogram.

RESULTS

A statically significant difference of P wave dispersion was observed between the patients and the control group (0.027 ± 0.011 mm/s and 0.016 ± 0.006 mm/s, respectively; P value = 0.0001). The P wave dispersion had a statistically significant correlation with the grade of asphyxia (P = 0.004, r = 0.62), the P wave dispersion had no statistically significant correlation with Apgar scores, short term arrhythmia, and troponin I level in asphyxiated neonates (P < 0.05).

CONCLUSIONS

The P wave dispersion increased in asphyxiated neonates and correlated with grade of asphyxia; however, the increased P wave dispersion was not correlated with the short term mortality, arrhythmia and troponin I level of the asphyxiated neonates.

Serial assessment of left-ventricular function using tissue Doppler imaging in premature infants within 7 days of life

Although many echocardiographic parameters can assess cardiac function noninvasively in preterm infants, it has not been determined what indices are the best. We assessed left-ventricular performance in 101 very low-birth weight (VLBW) infants using tissue Doppler imaging (TDI) echocardiography. Echocardiographic examinations, including TDI, were performed serially within 7 days of life. Pulsed-Doppler TDI waveforms were recorded at the mitral valve annulus, and peak systolic velocities (Sa), early diastolic velocities (Ea), and late diastolic velocities (Aa) were measured. Sa and Aa velocities were both decreased significantly from 3 to 12 h and then gradually increased. Ea velocities showed no significant, longitudinal changes, but Ea values in premature groups appeared to be significantly lower than those in mature groups. The ratio of E to Ea (E/Ea) of VLBW infants seemed to be almost stable from birth to day 7, and this also showed no significant differences between different gestational age groups. E/Ea values in infants with patent ductus arteriosus (PDA) appeared to be greater than those in non-PDA infants. Our present findings suggest that TDI assessment in the early neonatal period might be useful in detecting latent systolic/diastolic failure of critically ill preterm infants.

Evaluation of cardiac functions in term small for gestational age newborns with mild growth retardation: a serial conventional and tissue Doppler imaging echocardiographic study

BACKGROUND

The aim of this study is to evaluate the cardiac functions of term small for gestational age (SGA) babies with mild growth retardation by echocardiography during the postnatal period.

METHODS AND RESULTS

Thirty term SGA (2271±207 g/38-41 weeks (mean 39.5 weeks)) and 30 term AGA (3298±338 g/38-41 weeks (mean 39 weeks)) newborns as the control group, with normal general health status and with no nutritional problems were evaluated at three time points, on the 3rd postnatal day, at the 3rd and the 6th months. In the initial analysis, heart rate, left ventricular end diastolic diameter index (LVEdDI), cardiac index (CI), all E/A, Em/Am and E/Em ratios, pulsed wave Doppler myocardial performance index (MPI), and tissue Doppler imaging MPI values were higher in SGA babies than the control group. In the last analysis, only heart rate, LVEdDI and CI values were different between SGA and control groups.

CONCLUSIONS

Systolic and diastolic cardiac dysfunctions were determined in SGA babies with mild growth retardation during the first 6 months of postnatal period. Any disease that affects the hemodynamic stability of these patients during postnatal period may lead to early progressive deterioration in cardiac functions. Furthermore, many of the cardiac functions of these babies have been improved about the 6th month period, and high levels of heart rate and LVEdDI may be suggested as an indicator of cardiac remodeling.

The assessment of time-dependent myocardial changes in infants with perinatal hypoxia

OBJECTIVE

The aim of the study was to assess myocardial damage in infants due to perinatal hypoxia.

METHODS

The findings of 29 infants with perinatal hypoxia and 20 healthy infants were compared. Blood gas analysis, serum lactate, cardiac troponin I (cTnI), troponin T (cTnT), creatine kinase-MB (CK-MB) and B-type natriuretic peptide (BNP) were evaluated. Echocardiography together with tissue Doppler imaging was performed.

RESULTS

cTnT, CK-MB and BNP were higher in patients at the first day. There were positive correlations between the left ventricular (LV) myocardial performance index (MPI) and cTnT at first day and also at first month. LV ejection fraction and fractional shortening were lower at first day and at first month in patients. Myocardial systolic (Sm) and diastolic (Em and Am) velocities at all segments were lower at first day, and interventricular septum Sm, LV Sm, LV Em, right ventricular Em and LV Am were still lower at first month in patients. Isovolumic relaxation time at all segments together with LV MPI was higher at first day, ejection time values were lower and MPI values were higher at all segments at first month in patients.

CONCLUSIONS

These findings demonstrated that the signs of myocardial damage due to perinatal hypoxia still present at first month.

Myocardial performance assessment in neonates by one-segment strain and strain rate analysis by tissue Doppler - a quality improvement cohort study

OBJECTIVES

To investigate one-segment strain and strain rate indices as measures of myocardial performance in asphyxiated term neonates.

DESIGN

Quality improvement cohort study.

SETTING

Newborns admitted to a neonatal intensive care unit at a Norwegian University Hospital for perinatal asphyxia and non-asphyxiated newborn recruited from the maternity ward at the same hospital.

PARTICIPANTS

Twenty asphyxiated and 48 non-asphyxiated term neonates.

PRIMARY OUTCOME MEASURE

Strain and strain rate indices and repeatability measures. One-segment longitudinal strain and strain rate by tissue Doppler were assessed on days 1, 2 and 3 of life in nine heart walls. Repeatability was compared against measurements from two-segment analyses previously performed in the same images.

RESULTS

The 95% limits of agreement were significantly better for the one-segment than two-segment repeatability analyses, the inter-rater peak systolic strain (PSS) was (-3.1, 3.3) vs (-11.4, 18.3)%, the inter-rater peak systolic strain rate (PSSR) was (-0.38, 0.40) vs (-0.79, 1.15)/s, the intra-rater PSS was (-2.5, 2.6) vs (-8.0, 9.8)% and the intra-rater PSSR was (-0.23, 0.25) vs (-0.75, 0.80)/s (p<0.05). The myocardial performance was lower in the asphyxiated neonates (indices closer to zero) than in the non-asphyxiated neonates, PSS was -17.8 (0.6) (mean (SEM)) vs -21.2 (0.3)%, PSSR -1.43 (0.08) vs -1.61 (0.03)/s, early diastolic strain rate 1.72 (0.11) vs 2.00 (0.11)/s and strain rate during the atrial systole 1.92 (0.17) vs 2.27 (0.10)/s (p<0.05), despite no difference in fractional shortening (29.0 (0.5) vs 29.1 (1.0)%) (p>0.05).

CONCLUSIONS

One-segment strain and strain rate assessed the reduced myocardial performance in asphyxiated neonates with significantly improved reproducibility as compared with two-segment analysis and was therefore more feasible than two-segment analyses for assessment of myocardial performance after perinatal asphyxia.

Effects of post-resuscitation treatment with N-acetylcysteine on cardiac recovery in hypoxic newborn piglets

Aims

Although N-acetylcysteine (NAC) can decrease reactive oxygen species and improve myocardial recovery after ischemia/hypoxia in various acute animal models, little is known regarding its long-term effect in neonatal subjects. We investigated whether NAC provides prolonged protective effect on hemodynamics and oxidative stress using a surviving swine model of neonatal asphyxia.

Methods and Results

Newborn piglets were anesthetized and acutely instrumented for measurement of systemic hemodynamics and oxygen transport. Animals were block-randomized into a sham-operated group (without hypoxia-reoxygenation [H–R, n = 6]) and two H-R groups (2 h normocapnic alveolar hypoxia followed by 48 h reoxygenation, n = 8/group). All piglets were acidotic and in cardiogenic shock after hypoxia. At 5 min after reoxygenation, piglets were given either saline or NAC (intravenous 150 mg/kg bolus + 20 mg/kg/h infusion) via for 24 h in a blinded, randomized fashion. Both cardiac index and stroke volume of H-R controls remained lower than the pre-hypoxic values throughout recovery. Treating the piglets with NAC significantly improved cardiac index, stroke volume and systemic oxygen delivery to levels not different from those of sham-operated piglets. Accompanied with the hemodynamic improvement, NAC-treated piglets had significantly lower plasma cardiac troponin-I, myocardial lipid hydroperoxides, activated caspase-3 and lactate levels (vs. H-R controls). The change in cardiac index after H-R correlated with myocardial lipid hydroperoxides, caspase-3 and lactate levels (all p<0.05).

Conclusions

Post-resuscitation administration of NAC reduces myocardial oxidative stress and caused a prolonged improvement in cardiac function and in newborn piglets with H-R insults.

Myocardial performance in asphyxiated full-term infants assessed by Doppler tissue imaging

The aim of this study was to assess myocardial performance of full-term infants with perinatal asphyxia using Doppler tissue imaging (DTI) and to correlate it with serum cardiac troponin T (cTnT) concentrations. Twenty-five asphyxiated and 20 nonasphyxiated term infants were investigated. Serum cTnT concentrations were measured between 12 and 24 h of life. Conventional two-dimensional Doppler echocardiography and DTI were done during the first 72 h of life. Right ventricular (RV) and left ventricular (LV) Tei indexes were significantly higher in asphyxiated neonates (mean +/- SD: 0.45 +/- 0.05 vs. 0.28 +/- 0.05, P < 0.001 and 0.51 +/- 0.04 vs. 0.38 +/- 0.04, P < 0.001, respectively). Mitral and tricuspid systolic (Sm) velocities were significantly lower in asphyxiated neonates (mean +/- SD: 5.06 +/- 0.89 vs. 6.89 +/- 0.94 cm/s, P < 0.001 and 5.78 +/- 0.58 vs. 6.69 +/- 0.87 cm/s, P < 0.001, respectively). cTnT concentrations were significantly higher in asphyxiated neonates [median (range): 0.17 (0.05-0.23) vs. 0.03 (0-0.07) microg/l, P < 0.001)], and they correlated positively with the LV Tei index (r = 0.67, P < 0.001) and the RV Tei index (r = 0.68, P < 0.001) and negatively with the mitral systolic (Sm) velocity (r = -0.68, P < 0.001) and tricuspid systolic (Sm) velocity (r = -0.41, P = 0.01). A higher cTnT was a significant predictor of mortality, whereas fractional shortening (FS) and DTI measurements did not show any significant predictive value. The DTI technique appears to be more sensitive than conventional echocardiography in the early detection of myocardial dysfunction induced by perinatal asphyxia in full-term infants.

Functional echocardiography; from physiology to treatment

Functional echocardiography (fECHO) is the bedside use of ultrasound to longitudinally assess myocardial function, systemic and pulmonary blood flow, and intra and extracardiac shunts. This review will focus on fECHO as a tool for the clinician to assess the hemodynamic condition of sick neonates and describe situations where fECHO can help determine a pathophysiological choice for cardiovascular support. The very low birth weight infant with hypotension during the first 24h of life, assessment and monitoring of the ductus arteriosus, assessment and response to treatment of infants with pulmonary hypertension, the infant with perinatal asphyxia and the infant with sepsis and cardiovascular compromise are reviewed. Close cooperation with pediatric cardiology, proper logistics and training programs are mandatory to achieve a 24h a day fECHO service run by bedside clinicians.