Future perspectives on the use of deformation analysis to identify the underlying pathophysiological basis for cardiovascular compromise in neonates

Increasing region of interest width reduces neonatal circumferential strain

OBJECTIVE

There is growing interest in speckle tracking echocardiography-derived strain as a measure of left ventricular function in neonates. However, knowledge gaps remain regarding the effect of image acquisition and processing parameters on circumferential strain measurements. The aim of this study was to evaluate the effect of using different region of interest (ROI) widths on speckle tracking derived circumferential strain in healthy neonates.

METHODS

Thirty healthy-term-born neonates were examined with speckle-tracking echocardiography in the short-axis view. Circumferential strain values were acquired and compared using two different ROI widths. Furthermore, strain values in the different vendor-defined wall layers were also compared.

RESULTS

Increasing ROI width led to a decrease in global circumferential strain (GCS) in the midwall and epicardial layers, the respective decreases in strain being -23.4 ± .6% to -22.0 ± 1.1%, p < .0001 and 18.5 ± 1.7% to -15.6 ± 2.0%, p < .0001. Segmental analyses were consistent with these results, apart from two segments in the midwall. There was no statistically significant effect on strain for the endocardial layer. A gradient was seen where strain increased from the epicardial to endocardial layers.

CONCLUSION

Increasing ROI width led to a decrease in GCS in the midwall and epicardium. There is an increase in circumferential strain when moving from the epicardial toward the endocardial layer. Clinicians wishing to implement circumferential strain into their practice should consider ROI width variation as a potential confounder in their measurements.

Haemodynamic assessment and management of hypotension in the preterm

The management of low blood flow states in premature neonates is fraught with many challenges. We remain over-reliant on regimented stepwise protocols that use mean blood pressure as a threshold for intervention to guide treatment, without giving due consideration to the underlying pathophysiology. The current available evidence does not reflect the need to concentrate on the unique pathophysiology of the preterm infant and thus leads to widespread misuse of vasoactive agents that often do not provide the desired clinical effect. Therefore, understanding the underlying pathophysiological underpinnings of haemodynamic compromise may better guide choice of agent and assess physiological response to the selected intervention.

Prenatal prediction of Shone's complex. The role of the degree of ventricular disproportion and speckle-tracking analysis

OBJECTIVES

Shone's complex (SC) is characterized by sequential obstructions of left ventricular (LV) inflow and outflow. It can be associated with poor long-term prognosis when compared to Simple-Aortic Coarctation (S-CoA). We aimed to assess whether the degree of ventricular disproportion and 2D-speckle-tracking echocardiography (2D-STE) could improve the accuracy of prenatal prediction of SC.

METHODS

75 consecutive fetuses were retrospectively enrolled from January 2010 to June 2021. Fetuses were divided into 4 groups (Group 1: SC; Group 2: S-CoA; Group 3: False Positive-Coarctation of the Aorta [FP-CoA]; group 4: controls). Comparisons for echocardiographic measures and myocardial deformation indices were performed. A receiver operating characteristic (ROC) analysis was performed on the MV/TV (mitral valve/tricuspid valve ratio) and LV GLS (global longitudinal strain) values to identify cut-offs to separate group 1 and 2 fetuses.

RESULTS

SC fetuses showed a significant reduction in MV/TV when compared to S-CoA and FP-CoA fetuses (p<0.001). LV GLS in SC fetuses was significantly reduced compared to S-CoA fetuses (-13.3 ± 2.1% vs. -17.0 ± 2.2%, p=0.001). A cut-off value of 0.59 for MV/TV and -15.35% for LV GLS yielded a sensitivity of 76 and 82% and a specificity of 71 and 83% respectively in separating SC vs. S-CoA fetuses.

CONCLUSIONS

SC fetuses showed a more severe degree of ventricular disproportion and a lower LV GLS compared to S-CoA, FP-CoA and control fetuses. MV/TV and GLS are both predictors of SC. These findings may improve the quality of prenatal parental counselling.

Left ventricular function before and after percutaneous patent ductus arteriosus closure in preterm infants

BACKGROUND

Definitive closure of the patent ductus arteriosus (PDA) is associated with significant changes in the loading conditions of the left ventricle (LV), which may lead to cardiovascular and respiratory instability. The objective of the study was to evaluate targeted neonatal echocardiography (TnECHO) characteristics and the clinical course of preterm infants ≤2 kg undergoing percutaneous PDA closure.

METHODS

Retrospective cohort study of prospectively acquired pre- and post-closure TnECHOs to assess hemodynamic changes. Cardiorespiratory parameters in the first 24 h following PDA closure were also evaluated.

RESULTS

Fifty patients were included with a mean age of 30.6 ± 9.6 days and weight of 1188 ± 280 g. LV global longitudinal strain decreased from -20.6 ± 2.6 to -14.9 ± 2.9% (p < 0.001) after 1 h. There was a decrease in LV volume loading, left ventricular output, LV systolic and diastolic parameters. Cardiorespiratory instability occurred in 24 (48%) [oxygenation failure in 44%] but systolic hypotension and/or need for cardiovascular medications was only seen in 6 (12%). Patients with instability had worse baseline respiratory severity score and lower post-closure early diastolic strain rates.

CONCLUSIONS

Percutaneous PDA closure leads to a reduction in echocardiography markers of LV systolic/diastolic function. Post-closure cardiorespiratory instability is characterized primarily by oxygenation failure and may relate to impaired diastolic performance.

IMPACT

Percutaneous patent ductus arteriosus closure leads to a reduction in echocardiography markers of left ventricular volume loading, cardiac output, and left ventricular systolic/diastolic function. Post-procedural cardiorespiratory instability is characterized primarily by oxygenation failure. Post-procedural cardiorespiratory instability may relate to impaired diastolic performance.

The association between pulmonary vascular disease and respiratory improvement in infants with type I severe bronchopulmonary dysplasia

OBJECTIVE

To describe the association between echocardiographic measures of pulmonary vascular disease and time to respiratory improvement among infants with Type I severe bronchopulmonary dysplasia (sBPD).

STUDY DESIGN

We measured the pulmonary artery acceleration time indexed to the right ventricular ejection time (PAAT/RVET) and right ventricular free wall longitudinal strain (RVFWLS) at 34-41 weeks' postmenstrual age. Cox-proportional hazards models were used to estimate the relationship between the PAAT/RVET, RVFWLS, and the outcome: days from 36 weeks' postmenstrual age to room-air or discharge with oxygen (≤0.5 L/min).

RESULT

For 102 infants, the mean PAAT/RVET and RVFWLS were 0.27 ± 0.06 and -22.63 ± 4.23%. An abnormal measurement was associated with an increased time to achieve the outcome (PAAT/RVET: 51v24, p < 0.0001; RVFWLS; 62v38, p = 0.0006). A normal PAAT/RVET was independently associated with a shorter time to outcome (aHR = 2.04, 1.11-3.76, p = 0.02).

CONCLUSION

The PAAT/RVET may aid in anticipating timing of discharge in patients with type I severe BPD.

Neonatologist Performed Echocardiography for Evaluating the Newborn Infant

The interest in the use of cardiac ultrasound for hemodynamic evaluation in neonates has increased in the last decades. Several overlapping terms exists, and a non-comprehensive list includes point-of-care ultrasound, clinician-performed ultrasound, focused cardiac ultrasound, targeted neonatal echocardiography, and neonatologist performed echocardiography. This review will use the term neonatologist performed echocardiography. Neonatologist performed echocardiography is primarily echocardiography to obtain snapshots of hemodynamics and heart function, usually as repeated exams during intensive care. It provides the neonatologist with in-depth information on the hemodynamics not available by blood pressure, pulse oximetry, capillary refill time, and various blood tests. The review provides a brief overview of some relevant methods for assessment of hemodynamics and heart function. It does not discuss training, implementation, accreditation, and certification nor in-depth technical aspects and detailed use of neonatologist performed echocardiography. If the information obtainable by neonatologist performed echocardiography had been accessible easily (e.g., via a sensor put on the neonate similarly to a pulse oximeter), neonatologist performed echocardiography would have been more widely used. Acquiring skills for neonatologist performed echocardiography take time and resources. Future developments probably include a stronger focus on education, training, and certification. It is likely that echocardiographic methods will evolve further, probably involving establishing new indexes and methods and implementing artificial intelligence in the analyses procedure to improve accuracy and workflow. It is important to acknowledge that neonatologist performed echocardiography is not a therapeutic intervention; it is a diagnostic tool providing additional information.

Real-time shear wave elastography evaluation of the correlation between brain tissue stiffness and body mass index in premature neonates

BACKGROUND

Real-time shear wave elastography (SWE) is non-invasive and reliable for quantitatively evaluate stiffness of tissues and organs. Until now, little researches have applied SWE to evaluate brain tissue of premature neonates. This study sought to compare differences in the average brain tissue elasticity modulus (Emean) values of neonates, and explore the factors affecting these differences.

METHODS

In total, 159 neonates admitted from December 2019 to February 2021 were taken as the study subjects and divided into 2 groups based on their time of birth. Premature neonates, full-term neonates, and neonates with neonatal pneumonia were included in this study. Of the 159 neonates, 76 were premature and 83 were full-term. SWE was used to quantitatively evaluate the Emean of bilateral paraventricular white matter, thalamus, and choroid, and to analyze the relationship between body mass index (BMI) and Emeans in both groups of neonates.

RESULTS

The Emeans of the paraventricular white matter, thalamus, and choroid of the premature neonates were lower than those of the full-term neonates (P<0.001). The BMI of the premature and full-term neonates was positively correlated to the bilateral paraventricular white matter, thalamus, and choroid Emean.

CONCLUSIONS

SWE can be used to quantitatively evaluate the brain tissue stiffness of neonates, and as a reference for neonatal brain-related diseases.

Short-term ventriculo-arterial coupling and myocardial work efficiency in preterm infants undergoing percutaneous patent ductus arteriosus closure

Definitive closure of a patent ductus arteriosus (PDA) causes significant changes in loading conditions of the left ventricle (LV) which can lead to cardiorespiratory instability including hypotension, low cardiac output, oxygenation, and ventilation impairment. Physiological insights of the adaptation of the LV can be gained by looking at ventriculo-arterial coupling (VAC) and myocardial work-energetics. We conducted a retrospective cohort study of preterm infants with echocardiographic assessment of VAC parameters, including end-systolic and arterial elastance (EES , EA ), and myocardial work indices derived from longitudinal strain analysis before and 1-h after percutaneous PDA closure. A total of 35 patients were included with mean [±SD] age at intervention of 30.8 ± 9.9 days and median [IQR] weight of 1130 [995, 1318] grams. There was a reduction in preload and stroke volume, an increase in EA (38.6 ± 11.4 vs. 60 ± 15.1 mmHg/ml/kg, p < 0.001) and in EES (72 [61.5, 109.8] vs. 91.6 [72.2, 125.2] mmHg/ml/kg, p = 0.003) post-closure. Myocardial work indices reduced after PDA closure, including global work efficiency (93.9 ± 2.3 vs. 91.1 ± 3.6%, p < 0.001). A total of 17 (48.6%) patients developed post-closure instability which was associated with younger age, lower preload, and higher EA and EES . Percutaneous PDA closure is associated with major short-term changes in VAC and myocardium energetics, which may provide novel insights on the physiology of PDA closure and on the differential vulnerability to changes in loading conditions.

The Immediate and Long-Term Impact of Preeclampsia on Offspring Vascular and Cardiac Physiology in the Preterm Infant

Hypertensive disorders of pregnancy, including preeclampsia, affect nearly 10% of all pregnancies and are associated with significant long-term detrimental effects on both maternal and offspring cardiovascular health. Current management of preeclampsia involves timely delivery with the more severe form of disease requiring iatrogenic preterm birth. The effects on the maternal cardiovascular system have been studied extensively; however, less is known about the short- and long-term impacts on offspring cardiovascular health. There is a growing body of evidence suggesting that the offspring of pre-eclamptic pregnancies have an altered cardiac structure and function, along with a unique vascular physiology driven by lower endothelial function. Many of these changes can also be seen in those born preterm even in the absence of pregnancy hypertension. It is difficult to determine the relative contribution of pre-maturity and preeclampsia to the cardiovascular phenotype of those exposed to these pregnancy complications as they are, in many cases, inextricably linked. This review, therefore, focuses specifically on the evidence from clinical studies showing a negative cardiovascular impact of preeclampsia in preterm-born offspring, investigating phenotypic similarities and differences between offspring born preterm to normotensive vs. pre-eclamptic pregnancies. We explore the unique cardiac and vascular alterations in pre-eclamptic offspring born preterm, highlighting knowledge gaps, and potential areas of further research in the field.

The impact preload on left ventricular three-plane deformation measurements in extremely premature infants

BACKGROUND

Left Ventricular (LV) deformation analysis using two-dimensional speckle tracking echocardiography (STE) is an emerging modality in premature infants.

AIMS

To assess the impact of increased preload on LV deformation in three planes: longitudinal, circumferential and radial in premature infants.

STUDY DESIGN AND SUBJECTS

Infants recruited to the PDA RCT (ISRCTN 13281214) and survived to discharge were included with the cohort divided into infants who closed their patent ductus arteriosus (PDA) by Day 8 (Low preload, PDA Closed) and those who maintained ductal patency (high preload, PDA Open).

OUTCOME MEASURES

Longitudinal, circumferential and radial strain and systolic strain rate (SRs) were measured at 36 h, Days 4 & 8 and 36 weeks.

RESULTS

61 infants were included. The PDA open Group had a lower gestation (26.4 vs. 27.4 weeks, p < 0.01) with a median PDA exposure of 30 days (vs. 2 days, p < 0.01), and demonstrated echocardiography evidence of pulmonary overcirculation. There was higher LV longitudinal strain and SRs over the first 3 scans in the PDA Open Group. Circumferential strain was higher over the first 2 scans while circumferential SRs was higher at 36 h. Radial Strain and SRs were only higher on Day 4.

CONCLUSION

Increased preload is associated with higher strain and systolic strain rate values in the premature population indicating that preload has a significant effect on deformation measurements in this population across all three planes.

Updates on Management for Acute and Chronic Phenotypes of Neonatal Pulmonary Hypertension

Neonatal pulmonary hypertension is a heterogeneous disease in term and preterm neonates. It is characterized by persistent increase of pulmonary artery pressures after birth (acute) or an increase in pulmonary artery pressures after approximately 4 weeks of age (chronic); both phenotypes result in exposure of the right ventricle to sustained high afterload. In-depth clinical assessment plus echocardiographic measures evaluating pulmonary blood flow, pulmonary vascular resistance, pulmonary capillary wedge pressure, and myocardial contractility are needed to determine the cause and provide individualized targeted therapies. This article summarizes the causes, risk factors, hemodynamic assessment, and management of neonatal pulmonary hypertension.

Hypothermia and Cardiovascular Instability

Severely asphyxiated neonates have acute heart failure as part of their multiorgan dysfunction syndrome during the first days of life. Supporting the cardiovascular system during this phase is part of contemporary treatment and regarded as vital for limiting the neurodevelopmental injury. The decision to treat cardiovascular instability should be based on evaluation of end-organ function. Neonatologist-performed echocardiography in combination with other diagnostic modalities enables comprehensive real-time assessment. This review discusses associations between hemodynamics and adverse outcome, modalities for evaluating the hemodynamic state of the infant, and therapeutic approaches during intensive care.

Clinical Trials in Hemodynamic Support: Past, Present, and Future

Managing low blood flow states in the preterm population remains a challenge in neonatal clinical care. The heterogeneity of the trials to date and the relatively low number of infants enrolled, in addition to a desire to oversimplify the underlying pathophysiology, have contributed to an inability to draw meaningful conclusions to direct clinical care. This article reviews the current literature on this topic in the preterm population and outlines the challenges that have been encountered in performing such trials. Alternative studies are proposed, based on the lessons learned over the past number of years.

Myocardial function in late preterm infants during the transitional period: comprehensive appraisal with deformation mechanics and non-invasive cardiac output monitoring

BACKGROUND

There is a paucity of functional data on mid-to-late preterm infants between 30+0 and 34+6 weeks gestation. We aimed to characterise transitional cardiopulmonary and haemodynamic changes during the first 48 hours in asymptomatic mid-to-late preterm infants.

METHODS

Forty-five healthy preterm newborns (mean ± standard deviation) gestation of 32.7 ± 1.2 weeks) underwent echocardiography on Days 1 and 2. Ventricular mechanics were assessed by speckle tracking-derived deformation, rotational mechanics, tissue Doppler imaging, and right ventricle-focused measures (tricuspid annular plane systolic excursion, fractional area change). Continuous haemodynamics were assessed using the NICOM™ system to obtain left ventricular output, stroke volume, heart rate, and total peripheral resistance by non-invasive cardiac output monitoring.

RESULTS

Right ventricular function increased (all measures p < 0.005) with mostly stable left ventricular performance between Day 1 and Day 2. NICOM-derived left ventricular output [mean 34%, 95% confidence interval 21-47%] and stroke volume [29%, 16-42%] increased with no change in heart rate [5%, -2 to 12%]. There was a rise in mean blood pressure [11%, 1-21%], but a decline in total peripheral resistance [-14%, -25 to -3%].

CONCLUSION

Left ventricular mechanics remained persevered in mid-to-late premature infants, but right ventricular function increased. Non-invasive cardiac output monitoring is feasible in preterm infants with an increase in left ventricular output driven by an improvement in stroke volume during the transitional period.