Assessment of myocardial function in neonates using tissue Doppler imaging

Normative echocardiography data of myocardial adaptation to extrauterine life: a review of prospective studies

Recent research has increased focus and interest in characterizing the physiology of the transition circulation using echocardiography. Critique of published normative neonatal echocardiography data among healthy term neonates has not been performed. We have performed a comprehensive literature review using the key terms: cardiac adaptation, hemodynamics, neonatal transition, term newborns. Studies were included if they had reported echocardiography indices of cardiovascular function in the presence of maternal diabetes, intrauterine growth restricted newborns and prematurity and had a comparison group of healthy term newborns within first seven postnatal days. Sixteen published studies evaluating transitional circulation in healthy newborns were included. There was marked heterogeneity in the methodologies used; specifically, inconsistency in time of evaluation and imaging techniques used makes it challenging to determine specific trends of expected physiologic changes. Some studies revealed nomograms for echocardiography indices, though limitations persist in terms of sample size, number of reported parameters and consistency of measurement technique. A comprehensive standardized echocardiography framework which includes consistent techniques for assessment dimensions, function, blood flow, pulmonary/systemic vascular resistance, and shunts pattern is warranted to ensure consistency in the use of echocardiography to guide care of healthy and sick newborns.

Umbilical cord serum insulin-like growth factor-1 levels of infants of diabetic mothers are correlated with diastolic dysfunction detected by tissue Doppler echocardiography

Tissue Doppler echocardiography (TDI) is a convenient method to detect cardiac dysfunction in the infants of diabetic mothers (IDMs). Umbilical cord serum insulin-like growth factor-1 (IGF-1) is known to be higher in IDMs. We aimed to determine whether there is a relation between diastolic functions examined by TDI and cord serum IGF-1 levels of IDMs. Cord serum IGF-1 levels of 32 IDMs and 22 healthy infants were measured. The cardiac functions of the infants were evaluated by M-Mode and TDI. For statistical analysis, Mann-Whitney U and Spearman correlation tests were used for continuous variables, and the chi-square test was used for categorical variables. The cord serum IGF-1 levels of the IDMs were higher (p = 0.000). The left ventricle (LV) e', LVa', LV e'/a', and LV Tei index, indicating left ventricular diastolic dysfunction in IDMs, were detected (LV e' p = 0.016; LV a' p = 0.003; LV e'/ a' p = 0.000; LV Tei index p = 0.023). IDMs' cord serum IGF-1 levels were found weakly correlated with the interventricular septum (IVS) and left ventricle posterior wall (LVPW) thicknesses in M-Mode and LV e' and LV e'/a' in TDI (IVS r = 0.357, p = 0.008; LVPW r = 0.289, p = 0.034; LV e' r = 0.297, p = 0.029; LV e'/ a' r = 0.031, p = 0.014).

CONCLUSION

To our knowledge, this is the first study to examine the relationship between cord serum IGF-1 levels and diastolic functions of IDMs assessed by TDI. A weak correlation was found between IGF-1 levels and IVS and LVPW thicknesses in M-Mode and LV e' and LV e'/a' parameters in TDI, revealing diastolic dysfunction in IDMs.

WHAT IS KNOWN

• The umbilical cord blood serum IGF-1 level of IDMs is higher than in infants of healthy mothers. • Diastolic dysfunction is a well-studied and frequently observed consequence in IDMs.

WHAT IS NEW

• This is the first study to examine the relationship between cord serum IGF-1 levels and diastolic functions of IDMs assessed by TDI. • A weak correlation was detected between the median cord serum IGF-1 level of IDMs and the median values of IVS, LVPW, LV e', LV a', LV e'/a' ratio.

Clinical and haemodynamic characteristics of preterm infants with early onset sepsis

AIM

Early onset sepsis (EOS) in preterm infants is associated with high morbidity and mortality. Improved characterisation of the haemodynamic presentation of EOS could lead to more effective and targeted treatments.

METHODS

We performed a retrospective observational study of preterm infants ≤32 week' gestation with EOS between 2010 and 2020 and gathered clinical, haemodynamic and echocardiographic data.

RESULTS

Of the 2198 admitted infants, 27 infants (median gestational age 28 weeks, median birthweight 1174 g) developed EOS with predominantly gram-negative pathogens and the overall mortality rate was 33.3%. Besides hypotension, clinical signs were non-specific, and over half of infants were normotensive in the first 72 h of life. Those with hypotension received more fluid resuscitation, inotropic support and had a higher mortality compared to the normotensive infants. Cardiac ultrasound was available in 18 infants and commonly revealed higher as expected cardiac output, pulmonary hypertension and diastolic dysfunction.

CONCLUSION

Preterm infants with EOS had a high mortality rate, especially when they progressed from sepsis to septic shock. Echocardiography revealed a normal haemodynamic pattern, or one suggestive of vasodilatation and warm shock physiology. Targeting this pathophysiology earlier might improve outcomes.

Assessment of Indicators of Left Ventricular Performance Obtained by Tissue Doppler Imaging in Prematurely Born Neonates

Introduction: Tissue Doppler imaging techniques (pulsed-wave TDI (pwTDI) and color-coded TDI (cTDI)) allow for the assessment of myocardial performance during the cardiac cycle. The application of such techniques in neonatology is sporadic and poorly studied. Objective: The objective of the present study was to determine average values of pwTDI indicators of left ventricular performance (maximum systolic velocity of the mitral annulus (s’), maximum velocity in early diastole (e’) and maximum velocity in late diastole (a’)) and to examine their dynamics in prematurely born newborns in the first week of life. Methods: Prematurely born newborns of postnatal age up to 7 days were divided by gestational age into Group1 (<28 weeks) and Group 2 (≥28 weeks). Standard pwTDI parameters (s’, e’ and a’) were measured, compared between the groups and correlated with gestational and postnatal age, as well as application of respiratory support. Results: Fifty subjects were included (Group 1: 24; Group 2: 26). Average values of parameters s’, e’ and a’ were: Group 1: 4.06 ± 0.78 cm/s, 3.71 ± 0.40 cm/s and 3.98 ± 1.06 cm/s, respectively; Group 2: 4.18 ± 1.22 cm/s, 4.68 ± 1.04 cm/s and 4.12 ± 0.94 cm/s, respectively. Values of parameter e’ differed significantly between groups (p = 0.001) and strongly correlated with gestational age (p = 0, Pearson’s R = 0.88). There was no significant difference between groups for parameters s’ and a’ (p = 0.42 and 0.31, respectively). The values of s’, e’ and a’ did not differ between patients with an without respiratory support. Conclusion: Parameter e’ depends on gestational age, whereas parameters s’ and a’ are independent of gestational age. pwTDI indicators do not change during the first week of life, nor are all robust to hemodynamic circumstances caused by invasive/non-invasive respiratory support.

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.

Normative Echocardiographic Values for Right and Left Ventricular Function in Extremely Premature Neonates

OBJECTIVE

To identify the measures of biventricular function and surrogates of pulmonary vascular resistance that can be expected in relatively stable extremely premature neonates, and evaluate maturational changes in myocardial performance in this patient population.

STUDY DESIGN

This was a prospective observational study. Clinically stable extremely preterm newborns were divided into 3 cohorts based on gestational age: cohort 1 (24^0/7-25^6/7 weeks), cohort 2 (26^0/7-27^6/7 weeks), and cohort 3 (28^0/7-29^6/7 weeks). Serial echocardiograms were obtained on day of life 3-5, 7-10, and just prior to discharge.

RESULTS

In total, 46 subjects met the criteria aimed at capturing only the most clinically healthy and stable newborns less than 29^6/7 weeks of gestational age. Myocardial performance was reliably assessed by echocardiography with high inter-reader correlation. Normative values were identified for right ventricular function, left ventricular function, and surrogates of pulmonary vascular resistance.

CONCLUSIONS

Biventricular systolic performance is significantly different in the clinically stable extremely premature neonate when compared with healthy full-term newborns. All participants had evidence of poor biventricular compliance at birth which improved with maturation. Extreme prematurity does not appear to adversely affect myocardial functional maturation at the time of term corrected age and/or discharge.

Effect of Preterm Birth on Cardiac and Cardiomyocyte Growth and the Consequences of Antenatal and Postnatal Glucocorticoid Treatment

Preterm birth coincides with a key developmental window of cardiac growth and maturation, and thus has the potential to influence long-term cardiac function. Individuals born preterm have structural cardiac remodelling and altered cardiac growth and function by early adulthood. The evidence linking preterm birth and cardiovascular disease in later life is mounting. Advances in the perinatal care of preterm infants, such as glucocorticoid therapy, have improved survival rates, but at what cost? This review highlights the short-term and long-term impact of preterm birth on the structure and function of the heart and focuses on the impact of antenatal and postnatal glucocorticoid treatment on the immature preterm heart.

Pulmonary hypertension in a neonatologist-performed echocardiographic follow-up of bronchopulmonary dysplasia

Neonatologist-performed echocardiography (NPE) is an established tool for bedside hemodynamic evaluation, including pulmonary hypertension (PH). PH may complicate bronchopulmonary dysplasia (BPD) course. Aims of this retrospective study were to assess the feasibility of NPE follow-up of infants with BPD and to describe the course of PH of infants with moderate/severe BPD. Preterm infants <32 gestational weeks or birthweight ≤1500 g with moderate/severe BPD underwent NPE follow-up, from 36 weeks postmenstrual age up to 8 months postnatal age. Twenty-three preemies were included (birth weight 840 (213) g, gestational age 26.8 (2.3) weeks); 12/23 developed mild PH, 2/12 after discharge. PH resolved at 8.9 (3.9) months. Clinical and echocardiographic variables did not differ between infants with and without PH, except pulmonary artery acceleration time (PAAT) and PAAT/right ventricle ejection time (RVET) ratio (PAAT: 36 weeks, 68.9 (11.9) vs 52.0 (19.1), p = 0.0443; 6 months: 83.9 (38.9) vs 74.8 (16.9), p = 0.0372). No deaths or admissions for PH were reported. Neonatologist's Image Quality Assessment score attributed by the cardiologist assumed as gold standard was adequate or optimal (9.5/14 total score); inter-rater agreement was excellent (ICC 0.974).Conclusions: NPE follow-up seems to be feasible and safe in both intensive care and outpatient clinic. Mild PH is frequently detected in moderate/severe BPD, with good prognosis. What is Known: • Preterm infants with bronchopulmonary dysplasia (BPD) may develop pulmonary hypertension (PH) and have a late diagnosis. • Neonatologist-performed echocardiography (NPE) is an established tool for bedside hemodynamic evaluation of the neonate. What is New: • To our knowledge this is the first study of NPE follow-up of moderate/severe BPD, describing the course of mild PH from diagnosis to its resolution. • NPE follow-up of BPD seems to be safe and practicable, in both intensive care and outpatient clinic, as long as neonatologists maintain a sound collaboration with pediatric cardiologists.

Myocardial performance index in term appropriate and small for gestational age neonates - a cross sectional study

BACKGROUND

It is known that small for gestational age (SGA) babies may be at an increased risk of cardiovascular diseases during adulthood. There is paucity of literature regarding comparative cardiac functions of SGA and appropriate for gestational age (AGA) babies in neonatal period. The present study was conceived to compare the cardiac function of term small and appropriate for gestational age (AGA) babies through a relatively novel echocardiographic index in early neonatal period.

OBJECTIVES

To compare values of myocardial performance index (MPI) index (MPI = IVCT + IVRT/ET) at 48-72 hours of age among AGA and SGA babies.

METHODS

Morphological and anthropometric assessment of serially born term babies was done at time of birth to recruit hundred each of AGA and SGA babies. Tissue Doppler Imaging (TDI) was done between 48-72 hours for each enrolled baby to assess both right and left ventricle MPI in each group.

RESULTS

Mean±SD values for right ventricular MPI in AGA and SGA groups were 0.268 + 0.007 and 0.30 + 0.026 respectively (p < 0.001). Mean±SD values for left ventricular MPI in AGA and SGA groups were 0.25 + 0.012 and 0.30 + 0.017 respectively (p < 0.001). There was significant negative correlation between MPI values for either ventricles and the birth weight (spearmen's rho of -0.66) (p < 0.001). Mean±SD values for LVET in AGA and SGA group were 0.304 + 0.026 and 0.266 + 0.032 respectively (p < 0.001).

CONCLUSION

MPI had a higher absolute value in the SGA babies as compared to AGA babies. These observations point towards suboptimal cardiac performance among SGA babies as compared to AGA babies on the basis of myocardial performance index.

Chronological echocardiographic evaluation of left ventricular systolic and diastolic function in term and premature neonatal calves

Echocardiographic studies in human neonatology has demonstrated that prematurity can lead to cardiovascular dysfunction and especially compromises the left ventricular (LV) systolic and diastolic functions. As echocardiographic studies have not been performed on cardiovascular dysfunction in premature calves, we echocardiographically evaluated and compared the LV systolic and diastolic function in full-term and premature calves. We followed the hemodynamical changes of LV during first 3 days of life. Twenty premature calves and 10 healthy term calves were enrolled in the study. 2D, M-mode and Doppler echocardiographic examinations were performed at days 1, 2 and 3 after birth to evaluate LV systolic and diastolic functions. Our findings demonstrated that not only was there LV diastolic dysfunction (55% premature calves, 10% term calf at day 1; 65% premature calves, 10% term calf at day 2 and, 75% premature calves, 20% term calf at day 3), but also LV systolic dysfunction (55% premature calves, 60% term calf at day 1; 55% premature calves, 50% term calf at day 2, and 45% premature calves, 40% term calf at day 3) deteriorated in both term and premature calves. In conclusion, the present study, which was the first comparative echocardiographic assessment of LV systolic and diastolic functions in term and premature newborn calves, showed that both systolic and diastolic dysfunctions might occur in term and premature calves.

Changes in the Preterm Heart From Birth to Young Adulthood: A Meta-analysis

CONTEXT

Preterm birth is associated with incident heart failure in children and young adults.

OBJECTIVE

To determine the effect size of preterm birth on cardiac remodeling from birth to young adulthood.

DATA SOURCES

Data sources include Medline, Embase, Scopus, Cochrane databases, and clinical trial registries (inception to March 25, 2020).

STUDY SELECTION

Studies in which cardiac phenotype was compared between preterm individuals born at <37 weeks' gestation and age-matched term controls were included.

DATA EXTRACTION

Random-effects models were used to calculate weighted mean differences with corresponding 95% confidence intervals.

RESULTS

Thirty-two observational studies were included (preterm = 1471; term = 1665). All measures of left ventricular (LV) and right ventricular (RV) systolic function were lower in preterm neonates, including LV ejection fraction (P = .01). Preterm LV ejection fraction was similar from infancy, although LV stroke volume index was lower in young adulthood. Preterm LV peak early diastolic tissue velocity was lower throughout development, although preterm diastolic function worsened with higher estimated filling pressures from infancy. RV longitudinal strain was lower in preterm-born individuals of all ages, proportional to the degree of prematurity (R ² = 0.64; P = .002). Preterm-born individuals had persistently smaller LV internal dimensions, lower indexed LV end-diastolic volume in young adulthood, and an increase in indexed LV mass, compared with controls, of 0.71 g/m² per year from childhood (P = .007).

LIMITATIONS

The influence of preterm-related complications on cardiac phenotype could not be fully explored.

CONCLUSIONS

Preterm-born individuals have morphologic and functional cardiac impairments across developmental stages. These changes may make the preterm heart more vulnerable to secondary insults, potentially underlying their increased risk of early heart failure.

Measurement of inotropy and systemic oxygen delivery in term, low- and very-low-birth-weight neonates using the Ultrasonic Cardiac Output Monitor (USCOM)

Background The aim of this study was to assess the normal values of the Smith-Madigan inotropy index (SMII) and oxygen delivery index (DO2I) in low-birth-weight (LBW) and very-low-birth-weight (VLBW) newborns on the first 3 days of life, and to identify how different degrees of maturity influence cardiovascular alterations during the transitional period compared with term neonates. Methods Twenty-eight VLBW newborns, 46 LBW newborns and 50 normal full-term newborns admitted to our department were studied. Hemodynamics of the left heart were measured in all neonates over the first 3 days using the Ultrasonic Cardiac Output Monitor (USCOM). This was combined with hemoglobin concentration and pulse oximetry to calculate DO2I. Blood pressure was combined with the hemodynamic measures and hemoglobin concentration to calculate SMII. Results SMII showed statistically significant differences among the three groups (VLBW 0.48 ± 0.11; LBW 0.54 ± 0.13; term 0.69 ± 0.17 W/m2 P < 0.001), which was in line with the following myocardial parameters: stroke volume index (SVI) and cardiac index (CI) (P < 0.001 and <0.001). For systemic oxygen delivery (DO2) parameters, significant differences were found for DO2I (P < 0.001) while hemoglobin concentration and pulse oximetry demonstrated no significant differences. In the VLBW group, SMII and DO2I showed no significant change over the 3 days. Conclusion Normal inotropy and systemic DO2I values in VLBW neonates over the first 3 days of life were assessed. SMII and DO2I were significantly lower in VLBW neonates during the first 72 h of life. With increasing birth weight, higher myocardial inotropy and DO2 were found. The addition of USCOM examination to standard neonatal echocardiography may provide further important information regarding cardiac function.

Evaluation of myocardial function in neonatal sepsis using tissue Doppler imaging

Background: Neonatal sepsis is an important cause of neonatal morbidity and mortality especially in developing countries. Cardiac dysfunction is a major complication of severe sepsis and occurs as a part of multiple organ failure.Objective: To asses right and left ventricular functions in neonates with sepsis using tissue Doppler imaging (TDI).Methods: A total of 50 neonates fulfilling the diagnostic criteria for sepsis and 25 healthy neonates were enrolled in our study. Myocardial function and pulmonary systolic pressure were assessed using conventional echocardiography and tissue Doppler imaging techniques.Results: Septic neonates had a lower E/A ratio of the mitral valve when compared to healthy neonates (p = .048), indicating left ventricular diastolic dysfunction. Pulmonary systolic pressure was significantly higher in septic neonates compared to control group (p < .001). Left ventricular systolic function (left ventricular fractional shortening and S wave mitral annulus) was not significantly different between septic and healthy neonates. Left ventricular fractional shortening (LVFS) was found to be significantly higher in the survived than the nonsurvived septic neonates (p = .0387).Conclusions: Neonates with sepsis have evidence of left ventricular diastolic dysfunction and elevated pulmonary systolic pressure. Reduced left ventricular fractional shortening is associated with poor prognosis.

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.

Effects of foetal growth restriction and preterm birth on cardiac morphology and function during infancy

AIM

To investigate the effects of foetal growth restriction (FGR) and prematurity on cardiac morphology and function in infancy. We hypothesised that FGR and prematurity would both alter cardiac development.

METHODS

Cardiac morphology and function were evaluated in 24 preterm FGR infants (p-FGR) and 23 preterm and 19 term appropriately grown for gestational age infants (p-AGA and t-AGA, respectively) by conventional echocardiography and Tissue Doppler Imaging. p-FGR and p-AGA infants were studied on postnatal day 1 and all groups were studied at one-and six-months post-term age.

RESULTS

p-FGR infants demonstrated increased cardiac sphericity compared to AGA peers on postnatal day 1 (p = 0.004) and at one-month post-term age (p = 0.004). Posterior and relative wall thickness increased overtime in the p-FGR group only (p < 0.05). Systolic function was not different between groups. E/e' ratio was higher in both preterm groups compared to the term group at one-month post-term age (p = 0.01). No statistically significant group differences were found at six-months post-term age.

CONCLUSION

Foetal growth restriction was associated with subtle cardiac morphological changes, whereas both prematurity and FGR were associated with subclinical alterations in diastolic function.

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.

Vascular aging and cardiac maladaptation in growth-restricted preterm infants

OBJECTIVE

To assess arterial morphology and mechanics in preterm infants with fetal growth restriction (FGR) compared with those appropriate for gestational age (AGA) in the early neonatal period.

STUDY DESIGN

This observational study involved 20 preterm FGR infants (28 to 32 weeks) of gestational age (GA) and birth weight (BW) <10th centile and 20 preterm AGA infants. Vascular ultrasound was performed to measure aortic properties.

RESULTS

GA and BW of FGR and AGA infants were 29.8±1.3 vs 30±0.9 weeks (P=0.78) and 923.4±168 vs 1403±237 g (P<0.001), respectively. At 10.5±1.3 (s.d.) days after birth, blood pressure (systolic 51±3 vs 46±4 mm Hg, P<0.001) and maximum aorta intima-media thickness (621±76 vs 479±54 μm; P<0.001) were significantly higher in FGR infants. Arterial wall stiffness and peripheral resistance were also increased in the FGR infants (2.36±0.24 vs 2.14±0.24, P=0.008 and 22.2±5 vs 13.7±2.3 mm Hg min ml^-1, P<0.001), respectively. Significant correlations between vascular mechanics and cardiac function were observed (resistance vs E/E', r=0.7 and Tei index, r=0.79).

CONCLUSION

Maladaptive arterial-ventricular coupling was noted. Early detection may aid in early therapeutic strategies such as afterload reduction.

Cardiac Morphology and Function in Preterm Growth Restricted Infants: Relevance for Clinical Sequelae

OBJECTIVES

To assess cardiac morphology and function in preterm infants with fetal growth restriction (FGR) compared with an appropriate for gestational age cohort, and to ascertain clinical correlation with neonatal sequelae.

STUDY DESIGN

With informed consent, 20 infants born between 28 and 32 weeks of gestational age and birthweight (BW) <10th percentile were compared using conventional and tissue Doppler echocardiography with 20 preterm appropriate for gestational age infants. Total duration of respiratory support was recorded.

RESULTS

The gestational age and BW of the infants with FGR and appropriate for gestational age infants were 29.8 ± 1.3 weeks vs 30 ± 0.9 weeks (P = .78) and 923.4 ± 168 g vs 1403 ± 237 g (P < .001), respectively. Preterm infants with FGR had significantly greater interventricular septal hypertrophy, greater free wall thickening, and lower sphericity indices (1.53 ± 0.15 vs 1.88 ± 0.2; P < .001), signifying globular and hypertrophied hearts. The transmitral E/A ratio and isovolumic relaxation time, markers of diastolic function, were significantly increased in the FGR cohort (0.84 ± 0.05 vs 0.78 ± 0.03 [P < .001] and 61.4 ± 4.1 ms vs 53.2 ± 3.2 ms [P < .001], respectively). Ejection fraction, as measured by the rate corrected mean velocity of circumferential fiber shortening was reduced (1.93 ± 0.4 circ/second vs 2.77 ± 0.5 circ/second; P < .001) in the FGR cohort. On follow-up, the total duration of respiratory support was significantly longer in the FGR cohort, and correlated with tissue Doppler E/E' (r = 0.65; P = .001), mean velocity of circumferential fiber shortening (r = -0.64; P = .001) and mitral annular peak systolic excursion (r = -0.57; P = .008).

CONCLUSIONS

Preterm infants with FGR have altered cardiac function evident within days after birth, which is associated with respiratory sequelae.

Pathophysiology, screening and diagnosis of pulmonary hypertension in infants with bronchopulmonary dysplasia - A review of the literature

Bronchopulmonary dysplasia (BPD) is a common complication of extreme prematurity, which has increased over the last 20 years. BPD is associated with increased morbidities and mortality. It has been increasingly recognized that BPD affects overall lung development including the pulmonary vasculature. More recent studies have demonstrated an increased awareness of pulmonary arterial hypertension (PH) in BPD patients and recent international guidelines have advocated for better screening. This review will describe the current understanding of the pathophysiology of PH in infants with BPD, the in-depth assessment of the available literature linking PH and BPD, and propose an approach of screening and diagnosis of PH in infants with BPD.

Serial measures of cardiac performance using tissue Doppler imaging velocity in preterm infants <29weeks gestations

INTRODUCTION

Tissue Doppler imaging (TDI) is a useful marker of myocardial performance in preterm infants. We aimed to demonstrate serial changes in TDI velocity in preterm infants <29weeks gestation, to assess the impact of inotropes and a haemodynamically significant patent ductus arteriosus (hsPDA).

METHODS

This was a prospective observational study of preterm infants <29weeks gestation. Echocardiography was performed at days 1, 2, 5-7 and at 36weeks, or before hospital discharge. Infants with hsPDA's on day 5-7 and those who received inotropes in the first week of life were not included in the Reference Cohort. Systolic (s`) and diastolic (e` and a`) velocity waves were assessed at the mitral and tricuspid annulus and basal septum.

RESULTS

One hundred and thirty nine infants with a mean (SD) gestation and birthweight of 26.7 (1.5) weeks and 946 (247) grams were enrolled. The 66 infants (47%) in the Reference Cohort demonstrated an increase in functional parameters with increasing age [LV s`, Septal s`, and RV s`, Day 1-36weeks: 2.8 (0.6) to 4.7 (1.0), 2.4 (0.6) to 4.6 (0.8), 3.6 (0.6) to 6.9 (1.0) cm/s respectively; all p<0.05). The 24 infants who received inotropes had lower LV e` [2.9 vs. 3.6cm/s], Septal e` [2.3 vs. 2.8cm/s] and a` [3.2 vs. 3.9cm/s], and lower RV a` [3.3 vs. 3.9cm/s] on Day 1 (all p<0.05). Fifty five infants had a hsPDA on Day 5-7, demonstrating higher LV [4.7 vs. 4.0cm/s] and Septal e` [3.9 vs. 3.3cm/s], and a higher LV E/e` [13 vs. 10] (all p<0.05).

CONCLUSION

Extremely preterm infants display a gradual increase in tissue Doppler velocities from birth until 36weeks corrected age. The presence of a hsPDA increases diastolic TDI velocities. Infants requiring inotropes have lower diastolic myocardial velocities on Day 1.

Left Ventricular Function in Healthy Term Neonates During the Transitional Period

OBJECTIVES

To evaluate whether incorporating conventional, tissue Doppler imaging and speckle tracking echocardiography are reliable and can characterize changes in left ventricular (LV) function properly in healthy neonates in the early transitional newborn period.

STUDY DESIGN

A prospective observational study was conducted in 50 healthy term neonates with a mean ± SD gestational age and birth weight of 39.3 ± 1.2 weeks and 3.5 ± 0.44 kg, respectively. All infants underwent serial echocardiograms at 15 ± 2 (day 1) and 35 ± 2 hours (day 2) of age. The LV dimensions and various functional indices including tissue Doppler imaging velocities and speckle tracking echocardiography-derived peak longitudinal strain, and systolic and diastolic strain rate were acquired and compared between time points.

RESULTS

All measurements were feasible from each scan except speckle tracking echocardiography in 10% and 20% of images on days 1 and 2 of age, respectively. LV dimensions, but not functional measures, demonstrated a small to moderate positive correlation with birth weight. On day 2, a small reduction was observed in LV basal diameter, mitral valve inflow velocity time integral, and systolic velocity of the lateral wall and septum. Other indices remained unchanged. Tissue Doppler imaging-derived functional and flow-derived hemodynamic measures demonstrated the least measurement bias, and strain measurements demonstrated better reliability than strain rate, fractional shortening, and ejection fraction.

CONCLUSION

The relative reliability of various echocardiographic indices to quantify LV function in neonates establish a normative dataset and provide evidence for their validity during the first 2 days of life.

Right ventricular performance using myocardial deformation imaging in infants with bronchopulmonary dysplasia

OBJECTIVE

Right ventricular (RV) performance among infants with bronchopulmonary dysplasia (BPD) remains poorly understood. We tested the hypothesis that myocardial deformation imaging (MDI) strain and strain rate would allow for differentiation between infants with severe and milder forms of BPD, independent of tissue Doppler imaging (TDI) and superior to conventional echocardiographic measurements.

STUDY DESIGN

Infants with various severities of BPD (11 with none or mild, 13 with moderate and 10 with severe) underwent conventional echocardiography, TDI and MDI assessments at >36 weeks of corrected gestational age. BPD severity grading was determined according to the National Institutes of Child Health and Disease workshop rating scale by physicians blinded to the echocardiogram results. Group data were compared with one-way analysis of variance or Kruskal-Wallis tests, with post hoc multiple comparisons.

RESULTS

No differences in traditional echocardiographic parameters or TDI among the three BPD severity groups were observed; none of the infants had evidence of pulmonary hypertension. Using MDI, infants with severe BPD had lower peak global systolic strain than did infants with moderate BPD (P<0.01) or mild/none BPD (P<0.01). Early and late diastolic strain rate measurements were similar across the three groups.

CONCLUSIONS

Among infants with severe forms of BPD, evidence of abnormal RV systolic function was detected with MDI, but not traditional echocardiographic or TDI measurements. Infants with severe forms of BPD may represent a particularly high-risk subgroup for decreased RV performance warranting cardiac surveillance. MDI should be considered as a method to quantitate RV function in this population.

Assessment of myocardial function in preterm infants with chronic lung disease using tissue Doppler imaging

OBJECTIVES

To assess myocardial function and presence of pulmonary hypertension (PH) using both tissue Doppler imaging (TDI) and conventional echocardiography in preterm infants of <32 weeks gestation with chronic lung disease (CLD).

DESIGN

Prospective observational study.

SETTING

Tertiary neonatal intensive care unit.

PATIENTS

Three groups of preterm infants were recruited. Group 1-CLD receiving positive pressure airway support including high-flow humidified nasal cannula oxygen (n=25), group 2-CLD receiving low-flow nasal oxygen (n=25) and group 3-no CLD (n=22).

METHODS

Echocardiography was performed around 36 weeks corrected gestational age. Myocardial function and PH were assessed using both conventional (left ventricular fractional shortening (LVFS) and left ventricular output (LVO), tricuspid regurgitation and ventricular septal flattening) and TDI techniques (myocardial velocities, myocardial performance index (MPI) and right ventricular isovolumetric relaxation time (RV-IVRT)).

RESULTS

The MPI of right ventricle (RV) and left ventricle (LV) was significantly higher in CLD infants: mean RV MPI group 1-0.79, group 2-0.65 and group3-0.52. LV MPI: group 1-0.77, group 2-0.70 and group 3-0.45. There was a trend towards higher MPIs in group 1 compared with group 2. LVFS and LVO were similar across all three groups. RV-IVRT was also significantly higher in infants with CLD infants (group 1-64 milliseconds, group 2-62 milliseconds and group 3-52 milliseconds). PH was not detected by conventional echocardiography.

CONCLUSIONS

Infants with CLD have evidence of relative biventricular dysfunction and higher pulmonary arterial blood pressure as demonstrated by TDI, which were not detected by conventional echocardiography.

Cardiac Function After the Immediate Transitional Period in Very Preterm Infants Using Speckle Tracking Analysis

BACKGROUND

The postnatal period in preterm infants involves multiple physiologic changes starting directly after birth and continuing for days or weeks. To recognize and treat compromise, it is important to measure cardiovascular function. We used a novel technique (speckle tracking echocardiography, STE) to measure cardiac function in this period.

METHODS

We obtained cardiac ultrasound images at day 3, 7, 14, 21 and 28 in preterm infants <30-week gestation. Conventional measures included cardiac size, left ventricular stroke volume, atrial volume and the patent ductus arteriosus (PDA). Four chamber images were analyzed with STE, which provided parameters of left ventricular volume, longitudinal deformation and myocardial velocities.

RESULTS

Images of 54 infants (gestational age 23-29 weeks) were analyzed. STE-derived stroke volume correlated well with conventional echocardiography-derived stroke volume, but agreement was suboptimal. Most STE parameters showed good reliability. All volume parameters and systolic and atrial velocities increased over time. Cardiac deformation and early diastolic velocity did not change. A PDA was associated with 33 % increased stroke volume at day 3 up to 98 % at day 28 with a spherically enlarged heart and increased filling pressure.

CONCLUSION

Speckle tracking echocardiography analysis is a feasible and reliable technique that can simultaneously obtain systolic and diastolic volumes, longitudinal deformation and myocardial velocities from one ultrasound window. Preterm hearts maintain cardiac function well during the first weeks of life, even with increased preload as a consequence of a PDA.

Right Ventricular Function in Infants with Bronchopulmonary Dysplasia: Association with Respiratory Sequelae

BACKGROUND

While cor pulmonale has been noted in infants with bronchopulmonary dysplasia (BPD), information on right ventricular (RV) function is limited.

OBJECTIVE

To assess RV function in infants with severe BPD and ascertain correlation with respiratory outcomes.

METHODS

We prospectively assessed RV function using tissue Doppler imaging (TDI), 2D fractional area change (FAC), M-mode tricuspid annular plane systolic excursion (TAPSE) and myocardial performance index (MPI) using echocardiography. Additionally, we compared RV function with preterm infants with no BPD.

RESULTS

Eighteen preterm infants with severe BPD were enrolled at 36 weeks' gestation. Higher E/E' (r = 0.78, p < 0.0001) and lower FAC (r = 0.8, p < 0.0001) showed strong correlations with the subsequent duration of respiratory support. Correlations with TDI isovolumic velocity and Tei index were significant (-0.69, p = 0.002 and 0.58, p = 0.011, respectively). On comparison with infants with no BPD, TDI peak systolic velocities (0.06 ± 0.01 vs. 0.09 ± 0.01 m/s, p < 0.0001), peak isovolumic systolic velocities (0.05 ± 0.009 vs. 0.07 ± 0.008 m/s, p < 0.0001) and RV FAC (31 ± 4.7 vs. 36 ± 3.6%, p = 0.019) were significantly lower. Cardiac relaxation was impaired [higher TDI E/E' ratio (9.6 ± 1.8 vs. 5.2 ± 0.5, p < 0.0001) and higher RV MPI (0.33 ± 0.03 vs. 0.25 ± 0.03, p < 0.0001)].

CONCLUSIONS

Impaired RV performance in the infants with severe BPD at 36 weeks' corrected gestation correlated with a longer duration of subsequent respiratory support.

Novel Echocardiography Methods in the Functional Assessment of the Newborn Heart

Echocardiography in the neonatal intensive care unit has led to improvements in our ability to assess the neonatal heart in health and disease. Advances in neonatal cardiac imaging have provided the capability to obtain quantitative information that often supersedes the qualitative information provided by conventional methods. Novel quantitative measures of function include the assessment of the velocity of muscle tissue movement during systole and diastole using tissue Doppler velocity imaging, and evaluation of deformation and rotational characteristics of the myocardium utilizing speckle tracking echocardiography or tissue Doppler-derived strain imaging. A comprehensive understanding of these novel functional modalities, their predictive value, and limitations can greatly assist in managing both the normal and maladaptive responses in the newborn period. This article discusses the novel and emerging methods for assessment of left and right heart function in the neonatal population.

Maturational Changes in Diastolic Longitudinal Myocardial Velocity in Preterm Infants

BACKGROUND

Doppler tissue imaging (DTI) has been used to evaluate myocardial velocity during ventricular filling, a means of characterizing diastolic function. Previous studies in older children have shown age-related increases in early diastolic tissue velocities, but there are limited data in preterm infants. The aim of this study was to prospectively determine maturational changes in diastolic tissue velocities at two points in time: (1) 7 days of age and (2) 36 weeks' postmenstrual age (PMA). It was further determined whether DTI measures were altered in infants who developed bronchopulmonary dysplasia with or without pulmonary hypertension.

METHODS

A total of 277 preterm infants born at <34 weeks' PMA, with birth weights between 500 and 1,250 g, were prospectively enrolled. Echocardiograms were obtained at 7 days of age and repeated at 36 weeks' PMA. Measurements included DTI assessment of early (E') and late (A') annular velocities of the left ventricular free wall, septum and the right ventricular free wall. Statistical analysis included the Wilcoxon rank sum test, simple linear regression, and the χ(2) test.

RESULTS

At 7 days of age, there was a statistically significant increase in the E'/A' ratio as a function of gestational age at birth. At 36 weeks' PMA, E'/A' ratio was increased, but there was no association with gestational age. DTI measures were not different between infants who did or did not develop bronchopulmonary dysplasia or pulmonary hypertension at either time point.

CONCLUSIONS

A gestational age-related increase was found in the early diastolic tissue velocities of preterm infants. At a gestational age equivalent to near term, no difference was observed in diastolic tissue velocities, regardless of gestational age at birth. These findings suggest that maturational changes in diastolic function occur relatively independently of the timing of birth.

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.

Assessment of myocardial function in preterm infants with patent ductus arteriosus using tissue Doppler imaging

OBJECTIVE

To assess myocardial function in preterm infants with different degrees of ductal patency in the first week of life using tissue Doppler imaging.

STUDY DESIGN

Infants <30 weeks of gestation underwent echocardiography on day 3. A total of 72 infants were recruited into the study and categorised into three groups (i) haemodyamically significant ductus arteriosus, (ii) patent ductus arteriosus and (iii) no patent ductus arteriosus. Those with haemodynamically significant ductus arteriosus were treated with indometacin and echocardiography was repeated after 48-72 hours following treatment. Peak systolic and diastolic myocardial velocities were obtained using tissue Doppler imaging, and myocardial performance index was calculated.

RESULTS

Initial myocardial velocities were significantly lower and myocardial performance index significantly higher in the haemodynamically significant ductus arteriosus group compared with other groups. For the haemodynamically significant ductus arteriosus group, post-treatment myocardial velocities were higher and myocardial performance index lower than pre-treatment.

CONCLUSION

Preterm infants with haemodynamically significant ductus arteriosus had lower myocardial velocities and higher myocardial performance index, suggesting relative systolic and diastolic myocardial dysfunction. Babies whose patent ductus arteriosus remained open despite indometacin had lower pre-treatment myocardial velocities and higher myocardial performance index than those babies whose patent ductus arteriosus closed, suggesting worse myocardial function in this group. Measurement of myocardial function using tissue Doppler imaging in preterm infants is feasible and may prove to be helpful in the management of babies with patent ductus arteriosus.

Diastolic ventricular function improves during the first 48-hours-of-life in infants weighting <1250 g

AIM

Few studies have focused on cardiac ventricular diastolic function in preterm neonates in the immediate post-natal period. This study evaluated Doppler-derived parameters of diastolic ventricular function in infants with birth weights of <1250 g during the transitional period.

METHODS

This was a prospective observational study conducted in the Coombe Women and Infants University Hospital in Dublin, Ireland. Flow patterns on the mitral and tricuspid valve, isovolumic relaxation time (IVRT), left and right ventricular output and superior vena cava flow were measured in 22 infants with a birth weight of below 1250 g at six, 12, 24 and 48 h of age.

RESULTS

Early filling peak velocity of the left and right ventricle increased significantly from 30.3 to 39.5 cm/sec and 26.6 to 32.1 cm/sec, respectively. IVRT of the right ventricle decreased from 70 to 57 ms, and there was a nonsignificant decrease in IVRT of the left ventricle from 61.6 to 54 ms over the first 48 h.

CONCLUSION

We have demonstrated that parameters of diastolic ventricular function change significantly over the first 48 h of life in preterm infants <1250 g and that these changes may represent early diastolic dysfunction during the transitional period.

Heterogeneity of ventricular repolarization in newborns with intrauterine growth restriction

BACKGROUND

Intrauterine growth restriction (IUGR) is associated with structural and functional cardiac alterations but the electrophysiological consequences of these disturbances remain unknown.

AIMS

To explore the distribution of ventricular repolarization and its relation to myocardial mechanics in newborns with IUGR. STUDY DESIGN, SUBJECTS AND OUTCOME MEASUREMENTS: Conventional and tissue Doppler echocardiographic data, and electrocardiographic parameters used to describe the distribution of ventricular repolarization (dispersion of QT [QTd] and JT [JTd]), were obtained on the second (D2) and fifth (D5) postnatal day and compared between 25 IUGR newborns and 25 matched-for-gestational age controls.

RESULTS

IUGR was associated with relative interventricular septum hypertrophy, increased left ventricular (LV) E/E' ratio and higher LV myocardial performance index (MPI). On both study days, the IUGR infants presented higher QTd and JTd compared to controls (QTd-D2: 66±20 ms vs. 36±12 ms, P<0.001; JTd-D2: 54±13 ms vs. 34±9 ms, P<0.001; QTd-D5: 61±14 ms vs. 27±12 ms, P<0.001; JTd-D5: 54±13 ms vs. 27±9 ms, P<0.001). The association between QTd and LV E/E' (D2: regression coefficient beta 0.747, R(2) 0.585; D5: beta 0.843, R(2) 0.646) and QTd and MPI (D2: beta 0.680, R(2) 0.576; D5: beta 0.698, R(2) 0.650) was also significant (P<0.001 for all analyses).

CONCLUSIONS

Our findings suggest that IUGR is associated with electrophysiological remodeling of the neonatal heart, a process which is closely related to the underlying alterations in ventricular mechanics and might predispose to adverse electrophysiological events.

A comprehensive echocardiographic protocol for assessing neonatal right ventricular dimensions and function in the transitional period: normative data and z scores

BACKGROUND

There is a paucity of echocardiographic data describing right ventricular (RV) dimensions and function in the early transitional newborn period.

METHODS

Fifty healthy term newborns underwent serial echocardiography at a mean of 15 ± 2 and 35 ± 2 hours of age. RV dimensions and functional indices were measured as recommended in the American Society of Echocardiography's recent guidelines. Additional novel parameters included RV anteroinferior basal diameter, fractional area change (FAC) from the apical three-chamber view, and speckle-tracking echocardiography-derived peak longitudinal strain in the RV lateral (apical four-chamber view) and inferior (apical three-chamber view) walls. Results obtained at both time points were compared.

RESULTS

Linear dimensions and tissue Doppler velocities were highly reproducible, while time intervals and FAC measurements were more variable. Three-chamber FAC was higher than four-chamber FAC (36 ± 5% vs. 24 ± 7%, P < .001). Lateral wall peak longitudinal strain was similar to the value for the inferior wall (22 ± 4% vs 18 ± 5%, P > .05). A small increase in RV dimensions was noted on day 2 of life (midcavity diameter, 1.71 ± 0.19 vs 1.55 ± 0.19 cm, P < .01; RV anteroinferior basal diameter, 2.24 ± 0.29 vs 2.06 ± 0.24 cm, P < .01; end-diastolic-area in the apical four-chamber view, 4.32 ± 0.64 vs 4.10 ± 0.69 cm(2), P = .04), while no changes occurred in functional indices. RV dimensions and FAC showed moderate linear correlations with birth weight. Z scores could be computed for the majority of measured indices.

CONCLUSIONS

Using conventional and novel indices, the investigators describe a comprehensive echocardiographic protocol for neonatal RV imaging, establish reference ranges, and describe the effect of physiologic postnatal transition on RV dimensions and function. This will facilitate future investigations of RV dysfunction in neonatal cardiopulmonary disorders.

Myocardial function in term and preterm infants. Influence of heart size, gestational age and postnatal maturation

BACKGROUND

Sparse knowledge exists on the differences in cardiac function between term and preterm infants. This study examines the impact of heart size, gestational age and postnatal maturation on myocardial function.

AIM

To assess and compare serial echocardiographic indices of myocardial function in term and moderately preterm infants.

METHODS

Longitudinal, prospective, observational echocardiographic cohort study of 45 healthy term infants examined at day three and at 12-20weeks postnatal age and 53 moderately preterm infants (gestational age 31-35weeks) examined at day three and at term equivalent (4-10weeks postnatal age).

OUTCOMES

Primary: Systolic mitral and tricuspid annular plane excursions and annular peak systolic pulsed wave tissue Doppler (pwTDI) velocities. Secondary: Indices normalized for heart size.

RESULTS

On day three, all indices were higher in the term than in the preterm infants whereas normalized systolic pwTDI velocities were lower in the term infants and normalized excursions showed no difference. All indices increased with advanced postnatal age. The indices in term infants on day three were lower than in preterm infants at term equivalent, with and without normalization. After postnatal maturation in both groups, all indices were higher in the term group (except left pwTDI), whereas normalized indices showed no consistent pattern.

CONCLUSIONS

Myocardial function indices increased with gestational age at birth and more profoundly with postnatal maturation. Serial examinations of non-normalized and normalized myocardial function indices showed no sustained differences between the preterm and the term infants. Normalization by heart size may be of value when assessing myocardial function in infants.

Serial changes in myocardial function in preterm infants over a four week period: the effect of gestational age at birth

BACKGROUND

Myocardial performance is impaired in the first days of life in preterm infants but improves by day 5. Tissue Doppler imaging (TDI) is a novel and reliable means of assessing myocardial performance.

OBJECTIVE

To investigate myocardial performance using TDI and shortening fraction (SF) in preterm infants of different gestational age groups and serial changes in these parameters in first four weeks of life. Study design Infants less than 36 weeks of gestation were divided into group 1 (24-27 weeks, n=8), group 2 (28-31 weeks, n=12) and group 3 (32-35 weeks, n=13). Infants with severe congenital malformations, a hypoxic insult at birth, and those on inotropic support were excluded. Echocardiograms were performed at 36-48 hours, 2 weeks and 4 weeks of life. Left ventricular (LV) SF, systolic (S'), early diastolic (E') and late diastolic (A') TDI velocities were assessed. We analyzed the data using a repeated-measures ANOVA.

RESULTS

Thirty three infants underwent serial TDI and SF measurements. There was an increase in LV S' (p=.02) and E' (.01) velocities in group 2 , and in group 3 (p=.03 for S' and p=.04 for E'), but no significant increase in group 1 (p=.48 for S' and .32 for E'). At each study point, there was significant difference in myocardial performance between group 1 and 3 for each of the parameters (p<.05). There was no significant increase in SF over time in any of the groups.

CONCLUSION

We describe a serial increase in myocardial performance in infants of 28 weeks gestation and above. While there was no change in myocardial performance among the most extremely preterm infants, this may have been the result of small sample size of the group.

Assessment and treatment of post patent ductus arteriosus ligation syndrome

OBJECTIVE

To compare differences in tissue Doppler imaging, global longitudinal strain (GLS), and cardiac troponin T (cTnT) between infants with low (<200 mL/kg/min) and high (>200 mL/kg/min) left ventricular (LV) output 1 hour after duct ligation and assess the impact of milrinone treatment on cardiac output and myocardial performance.

STUDY DESIGN

LV function was assessed preoperatively and 1 and 18 hours postoperatively. Infants were categorized into a low-output or a normal-output group based on the echocardiographic assessment of LV output at 1 hour.

RESULTS

Thirty infants with a mean gestation of 25.3 weeks were enrolled. LV basal lateral S', basal septal S', and basal right ventricular S' were lower in the low-output group (n = 19) at 1 hour postoperatively, with no significant difference in GLS (low-output -10.3% vs high-output -14.4%, P >.05) or cTnT between the groups. Patients in the low-output group were treated with milrinone, and by 18 hours LV performance recovered to levels comparable with the high output group. cTnT values increased at 18 hours in the whole cohort with no significant difference between the groups.

CONCLUSION

Tissue Doppler imaging and GLS provide novel insights and further characterization of myocardial performance immediately after patent ductus arteriosus ligation. A reduction in tissue Doppler-derived LV systolic velocity may further help in monitoring cardiac performance after patent ductus arteriosus ligation and for monitoring the effects of treatment.

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.

Neonatal cardiac dysfunction in intrauterine growth restriction

BACKGROUND

The early postnatal cardiovascular consequences of intrauterine growth restriction (IUGR) have not been completely elucidated. This study aimed to evaluate the effect of IUGR on neonatal myocardial function and cardiovascular adaptation to extrauterine life.

METHODS

Conventional and tissue Doppler echocardiographic parameters were compared on the second and fifth postnatal day between 30 IUGR and 30 appropriate-for-gestational age (AGA) neonates.

RESULTS

IUGR neonates presented relative interventricular septum (IVS) hypertrophy (IVS to left ventricular (LV) posterior wall diastolic ratio: median IUGR-AGA difference of 0.05 (interquartile range: 0.04-0.06); P = 0.020), relative LV dilatation (wall thickness to end-diastolic LV dimension difference of 0.12 (0.06-0.16); P = 0.012), and increased left myocardial performance index (MPI difference of 0.19 (0.05-0.28); P = 0.012). Repeated measurements ANOVA revealed a different pattern of change in LV stroke volume (LVSV; P < 0.001), LV cardiac output (LVCO; P < 0.001), MPI (P < 0.001), and heart rate (HR; P = 0.025) between AGA and IUGR infants. From the second to the fifth postnatal day, AGA neonates presented a decrease in MPI and HR with an increase in LVSV and LVCO. IUGR neonates failed to achieve similar changes in MPI, HR, and LVSV, whereas their LVCO decreased.

CONCLUSION

IUGR neonates present changes in cardiac morphology and subclinical myocardial dysfunction, which may result in an altered pattern of cardiovascular adaptation to extrauterine life.

Tissue Doppler, strain, and strain rate measurements assessed by two-dimensional speckle-tracking echocardiography in healthy newborns and infants

OBJECTIVES

To evaluate cardiac maturational and haemodynamic alteration in healthy newborns and infants and determine reference values in this period using tissue Doppler, strain, and strain rate echocardiography.

MATERIAL AND METHODS

The study included 149 healthy subjects. Babies from 1 day to 3 months were selected from the well-baby nursery department, and infants were selected from paediatric clinics during routine visits for health maintenance. Subjects were allocated to four groups: preterm (36-37 weeks, n = 32), term (≥ 38 weeks, n = 32), 1 month of age (n = 47), and 3 months of age (n = 38). Standard echocardiographic evaluations, pulsed wave Doppler, tissue Doppler echocardiography, strain, and strain rate studies were applied by the same person using a MyLab50 echo machine. Longitudinal and circumferential systolic strain and strain rate measurements were assessed by two-dimensional speckle-tracking echocardiography in all subjects.

RESULTS

The longitudinal systolic velocity, strain, and strain rate values derived from left ventricle apical four-, three-, and two-chamber images, and circumferential systolic velocity, strain, and strain rate values derived from left ventricle short-axis images decreased from the base to the apex in all subjects (p < 0.001).

CONCLUSION

Significant cardiac haemodynamic alterations occurred during the newborn and early infancy periods and were detected by tissue Doppler, strain, and strain rate echocardiography. Although two-dimensional speckle-tracking echocardiography is useful and can produce improved, reliable results in clinical practice, it has some limitations. Therefore, more studies on this issue are required.

Pilot observational study on haemodynamic changes after surfactant administration in preterm newborns with respiratory distress syndrome

Background

Surfactant treatment reduces respiratory morbidity and mortality in preterm infants. Data on its haemodynamic consequences are conflicting. The aim was to characterise the haemodynamic effects of surfactant treatment on cardiac function in preterm newborns with respiratory distress syndrome (RDS).

Methods

Preterm infants (gestational age <34 weeks, birth weight <2000 g) with RDS, who received surfactant within 72 hours of life, were recruited.

Echocardiography was performed before surfactant, and 2 and 24 hours after. Left and right ventricular peak systolic, early diastolic and late diastolic myocardial velocities were measured using Tissue Doppler Imaging (TDI), while characteristics of the ductus arteriosus, pulmonary artery pressure, right ventricular (RVO) and left ventricular output were measured by standard echocardiography. Tricuspidal Annular Plane Systolic Excursion (TAPSE) was measured on the free wall of the tricuspid annulus.

Results

Fourteen patients were studied. Surfactant was associated with a decrease in pulmonary pressure and an increase in RVO. The improvement of right ventricular function was also confirmed by a significant increase in right peak systolic velocity and in TAPSE. Left ventricular velocities did not change significantly after surfactant.

Conclusions

Surfactant administration in preterm infants with RDS did not impair myocardial contractility and was followed by increased RVO, in agreement with other parameters of right ventricular function. TDI and TAPSE appeared to be reliable and feasible in this population. The addition of TDI and TAPSE to standard neonatal echocardiography may provide additional information about cardiac function.

Tissue Doppler imaging in very preterm infants during the first 24 h of life: an observational study

BACKGROUND

Very preterm newborn infants often need cardiovascular support. More knowledge about myocardial function and factors that influence the immature myocardium may be helpful for optimising cardiovascular support in these infants.

OBJECTIVE

Serial assessment of global myocardial function by means of colour tissue Doppler imaging (cTDI) in very and extremely preterm infants during the first 24 h of life.

STUDY DESIGN

One-centre, prospective, observational longitudinal cohort study in a third level Neonatal Intensive Care Unit. Sixty-five infants with median (range) gestational age (GA) 27 (24-31) weeks and birth weight (BW) 1049 (484-1620) g underwent echocardiographic examinations including cTDI at 5, 12 and 24 h after birth.

MAIN OUTCOME MEASURES

Peak systolic and peak diastolic annular velocity and peak annular displacement of the left and right ventricle.

RESULTS

There was a significant reduction in systolic and diastolic velocities and displacement of both ventricles from 5 to 12 h age. From 12 to 24 h, there was a non-significant increase in myocardial velocities and displacement. At 5 h, babies with haemodynamically significant patent ductus arteriosus (PDA) had significantly higher systolic and diastolic velocities in both ventricles than those with non-significant PDA.

CONCLUSIONS

Myocardial tissue velocities decrease significantly from 5 to 12 h after birth in very preterm infants. Further studies are needed to confirm these results and to determine their clinical implications.

Right ventricular diastolic function measured by tissue Doppler imaging predicts early outcome in congenital diaphragmatic hernia

OBJECTIVE

To investigate the relationship between early right ventricular function measured by tissue Doppler imaging and early outcome measures in newborn infants with congenital diaphragmatic hernia.

DESIGN

Retrospective cohort study.

SETTING

Surgical neonatal ICU within a regional pediatric center.

PATIENTS

Twenty newborn infants with congenital diaphragmatic hernia.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Analysis of serial echocardiograms in a cohort of 20 infants with congenital diaphragmatic hernia was done. Tissue Doppler early diastolic and systolic myocardial velocities were measured to assess diastolic and systolic function, respectively, in the basal right ventricle. Pulmonary:systemic peak pressure ratio was estimated using velocity of tricuspid regurgitation. Physiologic, treatment, and early outcome data (duration of respiratory support and length of stay) were recorded. For analysis, duration of respiratory support was selected as the main outcome measure, and infants were divided into two groups based on median duration of respiratory support of 21 days: duration of respiratory support more than 21 days and duration of respiratory support less than 21 days. In 16 surviving infants, mean right ventricular early diastolic myocardial velocity on days 1 and 2 of life correlated with length of stay and duration of respiratory support (r = -0.75, p = 0.002 and r = -0.84, p = 0.0001, respectively). Mean pulmonary:systemic peak pressure ratio on days 1 and 2 of life did not significantly correlate with outcome measures. At receiver-operating characteristics analysis, averaged right ventricular early diastolic myocardial velocity on days 1 and 2 of life of less than 4.6 cm/s predicted duration of respiratory support more than 21 days, with 100% sensitivity and 88% specificity (area under the curve = 0.96, p = 0.002). Right ventricular early diastolic myocardial velocity was significantly lower in the first week of life in the duration of respiratory support more than 21-day group on days 1 and 2 and days 7 and 8. After surgery, right ventricular early diastolic myocardial velocity decreased in the duration of respiratory support more than 21-day group and was significantly lower at days 3 and 4 postoperative.

CONCLUSIONS

Tissue Doppler imaging mean right ventricular early diastolic myocardial velocity on days 1 and 2 of life predicted early outcome in surviving infants with congenital diaphragmatic hernia. Right ventricular diastolic dysfunction is associated with disease severity in congenital diaphragmatic hernia. Right ventricular function may be optimized by delaying surgical repair in infants with severe congenital diaphragmatic hernia.

Feasibility and reproducibility of systolic right ventricular strain measurement by speckle-tracking echocardiography in premature infants

BACKGROUND

Right ventricular (RV) systolic function is an important prognostic determinant of cardiopulmonary pathologies in premature infants. Measurements of dominant RV longitudinal deformation are likely to provide a sensitive measure of RV function. An approach for image acquisition and postacquisition processing is needed for reliable and reproducible measurements of myocardial deformation by two-dimensional (2D) speckle-tracking echocardiography. The aims of this study were to determine the feasibility and reproducibility of 2D speckle-tracking echocardiographic measurement of RV peak global longitudinal strain (pGLS) and peak global longitudinal strain rate in premature infants and to establish methods for acquiring and analyzing strain.

METHODS

The study was designed in two phases: (1) a training phase to develop methods of image acquisition and postprocessing in a cohort of 30 premature infants (born at 28 ± 1 weeks) and (2) a study phase to prospectively test in a separate cohort of 50 premature infants (born at 27 ± 1 weeks) if the methods improved the feasibility and reproducibility of RV pGLS and peak global longitudinal strain rate measurements to a clinically significant level, assessed using Bland-Altman analysis (bias, limits of agreement, coefficient of variation, and intraclass correlation coefficient).

RESULTS

Strain imaging was feasible from 84% of the acquisitions using the methods developed for optimal speckle brightness and frame rate for RV-focused image acquisition. There was high intraobserver (bias, 3%; 95% limits of agreement, -1.6 to +1.6; coefficient of variation, 2.7%; intraclass correlation coefficient, 0.97; P = .02) and interobserver (bias, 7%; 95% limits of agreement, -4.8 to +4.73; coefficient of variation, 3.9%; intraclass correlation coefficient, 0.93; P < .05) reproducibility, with excellent linear correlation between the two pGLS measurements (r = 0.97 [P < .01] and r = 0.93 [P < .05], respectively).

CONCLUSIONS

This study demonstrates high clinical feasibility and reproducibility of RV pGLS and RV peak global longitudinal strain rate measurements by 2D speckle-tracking echocardiography in premature infants and offers methods for image acquisition and data analysis for systolic strain imaging that can provide a reliable assessment of global RV function.

Serial change in myocardial tissue Doppler imaging from fetus to neonate

BACKGROUND

Our goal was to evaluate the serial change in myocardial performance from fetus to neonate using tissue Doppler imaging (TDI).

METHOD AND RESULTS

There were 37 term infants in the present study. The TDI sensor was placed at the level of the lateral mitral annulus (M-TDI), inter-ventricular septum (IVS-TDI) and the lateral tricuspid annulus (T-TDI). We measured TDI parameters from fetus to neonate. On univariate analysis, E' (cm/s), A' (cm/s), and S' (cm/s) of three ventricular walls of TDI parameters excluding E' IVS-TDI significantly decreased during the transition from fetal to neonatal circulation. E'/A' ratio, E/E' ratio and myocardial performance index (MPI) of three ventricular walls of TDI parameters excluding T-TDI MPI significantly increased during the transition from fetal to neonatal circulation. When multiple linear regression analysis with a step-wise procedure during the transition from fetus to neonate for TDI parameters was applied to variables, significant differences were noted for predicting decreases in M-TDI S' (6.55 to 3.97, p < 0.001) and IVS-TDI A', (6.69 to 4.69, p < 0.001), and increases in IVS-TDI E'/A' ratio (0.77 to 1.02, p < 0.001) and IVS-TDI E/E' ratio (8.25 to 13.65, p < 0.001).

CONCLUSION

In conclusion, we found that the myocardial performances of both ventricles decreased during the transition from fetus to neonate using TDI parameters. In particular, left ventricular systolic performance was affected more than when fetal circulation changed to neonate circulation. Our findings suggest that serial change in TDI can give new information to estimate myocardial performance of the neonate.

Myocardial assessment using tissue doppler imaging in preterm very low-birth weight infants before and after red blood cell transfusion

OBJECTIVE

To investigate myocardial velocities in anemic very low-birth weight (VLBW) preterm infants, pre and post red blood cells transfusion using tissue Doppler imaging echocardiography.

STUDY DESIGN

Forty-eight VLBW preterm infants34 weeks and>2 weeks old were prospectively divided: Transfused symptomatic infants (Hematocrit (Hct)<0.30 (n=32)) and non transfused asymptomatic controls (control 1, Hct >0.30 (n=9) and control 2, Hct <0.30 (n=7)). Echocardiography was performed before and 3-5 days after transfusion in the transfused, and the controls were studied at similar intervals. Non parametric tests were used for statistical analysis.

RESULT

Left ventricular (LV) systolic velocity increased (transfused (4.6±0.70 vs 6.0±0.65, P<0.01)) as did LV diastolic velocities (P<0.01) without significant difference over time in each control. The percentage change in LV velocity following transfusion correlated negatively (ρ=0.36) with pre transfusion Hct.

CONCLUSION

There is a significant increase in myocardial performance following transfusion, which is related to the severity of the anemia.

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.

Myocardial function in premature infants: a longitudinal observational study

OBJECTIVES

Gestational and chronological age may have an impact on myocardial function. We studied the longitudinal changes of the atrioventricular tissue Doppler velocities in premature infants through the neonatal transitional period and at expected term and explored the reproducibility of the measurements.

DESIGN

Prospective, observational and longitudinal cohort study.

SETTING

Two-centre study, from a secondary and a tertiary neonatal intensive care unit.

PARTICIPANTS

55 infants (29 males) with gestational age 31-35 weeks and birth weight 1127-2836 grams.

PRIMARY AND SECONDARY OUTCOME MEASURES

Pulsed-wave atrioventricular left, septum and right ventricular annulus tissue Doppler systolic (S'), early diastolic (E') and late diastolic (A') velocities measured by repeated echocardiographic examinations days 1, 2 and 3 and at expected term.

RESULTS

All velocities increased significantly from the neonatal period to expected term (p<0.001). We found a significant correlation between gestational age and right-sided S', E' and A' on day 1 (Pearson correlation 0.32-0.46, p<0.05), for S' in all three walls and septal E' and A' on day 2 (Pearson correlation 0.27-0.49, p<0.05). There was a moderate linear correlation between left ventricle end-diastolic length and septal and right S' at term and for septal E' and A' at day 1 (Pearson correlation 0.30-0.56, p<0.05). We found no correlation between heart rate and tissue Doppler velocities when controlling for the effect of fusion. Continuous positive airway pressure showed moderate effect where as persistence of the ductus arteriosus showed no effect on the tissue Doppler velocities. The E'/A' relationship was consistently reversed throughout the study with frequently fused diastolic tissue velocity signals.

CONCLUSIONS

Pulsed-wave atrioventricular annulus tissue Doppler velocities were related to gestational age, postnatal age and ventricular size. Right ventricle velocities showed more pronounced increase with postnatal maturation than left ventricle velocities. The degree of E'/A' fusion influenced the diastolic tissue Doppler velocities and should be reported if present.

Right ventricular performance in preterm and term neonates: reference values of the tricuspid annular peak systolic velocity measured by tissue Doppler imaging

BACKGROUND

The tricuspid annular peak systolic velocity (S') is an echocardiographic measurement to assess systolic right ventricular function in adults and children.

OBJECTIVE

We determined growth and birth weight-related changes of S' to establish reference values in preterm and term neonates.

METHODS

A prospective study was conducted in a group of 290 preterm and term neonates (gestational age 26 + 0 to 40 + 6 weeks of gestation; birth weight 660-4,460 g). A correlation of S' values with established tricuspid annular plane systolic excursion (TAPSE) values was performed.

RESULTS

The S' ranged from a mean of 4.5 cm/s (Z-score ± 2 SD: 3.6-5.5 cm/s) in preterm neonates in week 26(0-6) of gestation to 7.8 cm/s (Z-score ± 2 SD: 5.5-10.1 cm/s) in term neonates in week 40(0-6) of gestation. The S' values increased from 26 to 40 weeks of gestation. S' and week of gestation are strongly correlated: Pearson's correlation coefficient was 0.66 for week of gestation - S' (p < 0.001). A significant correlation was found between S' and TAPSE values (r = 0.67; p < 0.001).

CONCLUSION

Z-scores of S' values were calculated and percentile charts were established to serve as reference data for preterm and term neonates with structurally normal hearts.

Assessment of contractility and myocardial function in small and appropriate for gestational age premature neonates using the stress-velocity relationship and tissue Doppler imaging immediately after birth

Our aim was to determine whether small for gestational age (SGA) neonates exhibit reduced left ventricular contractility and diastolic dysfunction, through the assessment of tissue by Doppler imaging and investigation of the stress-velocity relationship (SVR). The study subjects were limited to 37 neonates just after birth. These patients were grouped into 14 SGA neonates with birth weights below the 10th percentile (aged 29-36 weeks, birth weight 860-2066 g) and 23 appropriate for age (AGA) neonates with birth weights between the 10th-90th percentile (aged 20-36 weeks, birth weight 954-2945 g). Although there were no significant differences in the SVR or diastolic function between the SGA and AGA neonates, wall stress correlated significantly and inversely with birth weight in all subjects with a higher E/Ew ratio by tissue Doppler imaging. In conclusion, there were no significant differences in cardiac function between SGA and AGA neonates. By contrast, the relationship between wall stress, diastolic dysfunction, and birth weight may be due to physiological alterations in neonates, including those with low birth weights, just after birth.