Assessment and treatment of post patent ductus arteriosus ligation syndrome

Cardiorespiratory Instability after Percutaneous Patent Ductus Arteriosus Closure: A Multicenter Cohort Study

OBJECTIVE

To evaluate postprocedural clinical characteristics of preterm infants undergoing transcatheter patent ductus arteriosus (PDA) closure, including oxygenation/ventilation failure and cardiovascular compromise.

STUDY DESIGN

Multicenter retrospective cohort study of preterm infants who were ≤2 kg at the time of percutaneous PDA closure between August 2018 and July 2021. Indices of cardiorespiratory stability were collected pre-closure, immediately post-closure, and subsequently averaged every 4 hours for the first 24 hours post-procedure. The primary outcome was incidence of post-transcatheter cardiorespiratory syndrome: composite of hemodynamic instability (defined by systemic hypotension, systemic hypertension, or use of new inotropes/vasopressors in the first 24 hours after catheterization) and at least one of the following: (i) ventilation failure or (ii) oxygenation failure.

RESULTS

A total of 197 patients were included with a median [IQR] age and weight at catheterization of 34 [25, 43] days and 1090 [900, 1367] grams, respectively. The primary composite outcome of post-transcatheter cardiorespiratory syndrome was reported in 46 (23.3%).

CONCLUSION

Post-transcatheter cardiorespiratory syndrome is characterized primarily by systemic hypertension and oxygenation failure, with a very low incidence of hypotension and need for inotropes.

An Update on Pharmacologic Management of Neonatal Hypotension: When, Why, and Which Medication

Anti-hypotensive treatment, which includes dopamine, dobutamine, epinephrine, norepinephrine, milrinone, vasopressin, terlipressin, levosimendan, and glucocorticoids, is a long-established intervention in neonates with arterial hypotension (AH). However, there are still gaps in knowledge and issues that need clarification. The main questions and challenges that neonatologists face relate to the reference ranges of arterial blood pressure in presumably healthy neonates in relation to gestational and postnatal age; the arterial blood pressure level that potentially affects perfusion of critical organs; the incorporation of targeted echocardiography and near-infrared spectroscopy for assessing heart function and cerebral perfusion in clinical practice; the indication, timing, and choice of medication for each individual patient; the limited randomized clinical trials in neonates with sometimes conflicting results; and the sparse data regarding the potential effect of early hypotension or anti-hypotensive medications on long-term neurodevelopment. In this review, after a short review of AH definitions used in neonates and existing data on pathophysiology of AH, we discuss currently available data on pharmacokinetic and hemodynamic effects, as well as the effectiveness and safety of anti-hypotensive medications in neonates. In addition, data on the comparisons between anti-hypotensive medications and current suggestions for the main indications of each medication are discussed.

Reassessing the role of milrinone in the treatment of heart failure and pulmonary hypertension in neonates and children: a systematic review and meta-analysis

To evaluate milrinone's impact on pediatric cardiac function, focusing on its specific role as an inotrope and lusitrope, while considering its systemic and pulmonary vasodilatory effects. Search of PubMed, EMBASE, and the Cochrane Library up to August 2023. We included all studies that evaluated milrinone in children under 18 years old in neonatal, pediatric, or cardiac intensive care units. We excluded case reports, studies that did not provide tabular information on milrinone's outcomes, and studies focused on non-intensive care populations. We extracted data on the research design, objectives, study sample, and results of each study, including the impact of milrinone and any associated factors. We screened a total of 9423 abstracts and 41 studies were ultimately included. Milrinone significantly improved left ventricular ejection fraction (WMD 3.41 [95% CI 0.61 - 6.21]), left ventricle shortening fraction (WMD 4.25 [95% CI 3.43 - 5.08]), cardiac index (WMD 0.50 [95% CI 0.32 to 0.68]), left ventricle output (WMD 55.81 [95% CI 4.91 to 106.72]), serum lactate (WMD -0.59 [95% CI -1.15 to -0.02]), and stroke volume index (WMD 2.95 [95% CI 0.09 - 5.82]). However, milrinone was not associated with improvements in ventricular myocardial performance index (WMD -0.01 [95% CI -0.06 to 0.04]) and ventricular longitudinal strain (WMD -2.14 [95% CI -4.56 to 0.28]). Furthermore, milrinone was not associated with isovolumetric relaxation time reduction (WMD -8.87 [95% CI -21.40 to 3.66]).

CONCLUSION

Our meta-analysis suggests potential clinical benefits of milrinone by improving cardiac function, likely driven by its systemic vasodilatory effects. However, questions arise about its inotropic influence and the presence of a lusitropic effect. Moreover, milrinone's pulmonary vasodilatory effect appears relatively weaker compared to its systemic actions. Further research is needed to elucidate milrinone's precise mechanisms and refine its clinical applications in pediatric practice.

WHAT IS KNOWN

• Milrinone is a phosphodiesterase III inhibitor that has been used to treat a variety of pediatric and neonatal conditions. • Milrinone is believed to exert its therapeutic effects by enhancing cardiac contractility and promoting vascular relaxation.

WHAT IS NEW

• Milrinone may not have a significant inotropic effect. • Milrinone's pulmonary vasodilatory effect is less robust than its systemic vasodilatory effect.

Effects of Milrinone on Neonates after Patent Ductus Arteriosus Ligation: A Retrospective Nationwide Database Study

INTRODUCTION

Milrinone is administered after patent ductus arteriosus (PDA) ligation to prevent and treat postoperative hemodynamic instability (i.e., postligation cardiac syndrome). We aimed to explore the effectiveness of milrinone on in-hospital outcomes in infants who underwent PDA ligation using a nationwide inpatient database in Japan.

METHODS

Using the Japanese Diagnosis Procedure Combination database, we identified patients who received milrinone after PDA ligation (n = 428) in neonatal intensive care units between July 2010 and March 2021 and those who did not (n = 3,392). We conducted a 1:4 propensity score-matched analysis with adjustment for background characteristics (e.g., gestational age, birth weight, comorbidities, preoperative treatments, and hospital background) to compare morbidities (bronchopulmonary dysplasia, intraventricular hemorrhage, necrotizing enterocolitis, and retinopathy of prematurity), mortality, total hospitalization costs, and other outcomes. For sensitivity analysis, we performed an overlap propensity score-weighted analysis.

RESULTS

In-hospital morbidity, bronchopulmonary dysplasia, intraventricular hemorrhage, and necrotizing enterocolitis occurred in 58%, 48%, 9.5%, and 7.1% of patients, respectively; the in-hospital mortality was 5.4%. After 1:4 propensity score matching, no significant difference was observed regarding mortality (7.1 vs. 5.7%), in-hospital morbidity (55 vs. 50%), bronchopulmonary dysplasia (44 vs. 41%), intraventricular hemorrhage (7.8 vs. 9.1%), necrotizing enterocolitis (8.5 vs. 8.9%), retinopathy of prematurity (21 vs. 22%), or total hospitalization costs (median: approximately 86,000 vs. 82,000 US dollars) between milrinone users (n = 425) and nonusers (n = 1,698). Sensitivity analyses yielded consistent results.

CONCLUSIONS

Milrinone use after PDA ligation was not associated with improved in-hospital outcomes, such as mortality and morbidity.

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.

Percutaneous Closure of Patent Ductus Arteriosus

Percutaneous-based patent ductus arteriosus closure is technically feasible among infants less than 1.5 kg. However, marked heterogeneity in the type and nature of adverse events obscures current safety profile assessments. Although data on the risks of postdevice closure syndrome remain promising, a lack of comparative trials of surgical ductal ligation and inconsistent surveillance across published studies obscure confidence in present estimates of safety and efficacy. To minimize risk and yield the greatest benefits, clinical studies of patent ductus arteriosus treatment should consider incorporating more robust assessments to ensure that infants at greatest risk for adverse ductal consequences are included.

High-sensitivity cardiac troponins in pediatric population

Apparently healthy children often complain of chest pain, especially after physical exercise. Cardiac biomarker levels are often measured, but the clinical relevance of these assays in children is still debated, even when a cardiac disease is present. Coronary artery disease is exceedingly rare in children, but elevated circulating levels of cardiac troponin I (cTnI) and T (cTnT) in an acute setting may help detect heart failure due to an unknown cardiac disorder, or worsening heart failure, particularly in combination with other biomarkers such as B-type natriuretic peptides. However, the interpretation of biomarkers is often challenging, especially when institutions transition from conventional cTn assays to high-sensitivity (hs-cTn) methods, as well demonstrated in the emergency setting for adult patients. From a clinical perspective, the lack of established reference values in the pediatric age is the main problem limiting the use of hs-cTn methods for the diagnosis and managements of cardiac diseases in infants, children and adolescents. This review aims to discuss the possibility to use hs-cTnI and hs-cTnT to detect cardiac disease and to explore age-related differences in biomarker levels in the pediatric age. We start from some analytical and pathophysiological considerations related to hs-cTn assays. Then, after a systematic literature search, we discuss the current evidence and possible limitations of hs-cTn assay as indicators of cardiac disease in the most frequently cardiac disease in pediatric setting.

Which Inotropic Drug, Dobutamine or Milrinone, Is Clinically More Effective in the Treatment of Postligation Cardiac Syndrome in Preterm Infants?

OBJECTIVE

This study aimed to detect which of the two main medicines suggested in the treatment of postligation cardiac syndrome (PLCS)-dobutamine or mirinone-possesses a more therapeutic effect. While doing this, clinicians are provided with a broader perspective on the treatment and follow-up of cases. The desire was to increase the treatability and monitor ability of the cases in question and hence their survivability.

STUDY DESIGN

A retrospective review of a cohort of infants with PLCS was conducted between March 2012 and December 2018. In the treatment of infants with PLCS, dobutamine (dobutamine study group-DSG) or milrinone (milrinone study group-MSG) was used. The respiration, cardiac, echocardiography, and perfusion parameters of the cases were assessed both before and after ligation. Based on the data obtained, both the effects of the medicines on PLCS and the difference between their therapeutic effects were studied. The accuracy of prognostication was assessed with receiver operating characteristic analyses.

RESULTS

PLCS was detected in 29 (34.1%) of 85 patent ductus arteriosus ligation cases in total. Of all the PLCS cases, 13 (44.8%) were treated with dobutamine and 16 (55.2%) with milrinone. It was observed that the effects of the medicines on the respiratory system and cardiovascular system manifested in the third and 6th hour, respectively. It was detected that both medicines had more effect on the systolic blood pressure (SBP) (area under the curve [AUC]: 0.997/0.996, p = 0.001/0.002) than on the diastolic blood pressure (AUC: 0.911/0.843, p = 0.032/0.046).

CONCLUSION

Dobutamine and milrinone, two primary medicines that can be used in the treatment of cases with PLCS, possess similar therapeutic effects on this pathology. In addition, their postoperative therapeutic effects on the SBP are more in the foreground.

Anesthesia protocols for "bedside" preterm patent ductus arteriosus ligation: A single-institutional experience

Background :

Hemodynamically significant patent ductus arteriosus (PDA) is frequently encountered in preterm infants sometimes requiring surgical attention. Although PDA ligation is regularly performed in the operating room, conducting it at the bedside in a neonatal intensive care unit (NICU) and its anesthetic management remains challenging.

Aim :

We aim to discuss the anesthetic considerations in patients undergoing bedside PDA ligation and describe our experience highlighting the feasibility and safety of this procedure.

Setting and Design :

The study was conducted in the NICU in a tertiary care hospital; This was a retrospective, observational study.

Methods :

Preterm infants scheduled for bedside PDA ligation using a predefined anesthesia protocol between August 2005 and October 2020 were included.

Statistical Analysis Used:

Quantitative data were presented as median with interquartile range and categorical data were presented as numbers and percentage thereof.

Results :

Sixty-six premature infants underwent bedside PDA ligation. Thirty-day mortality was 4.5% (3 infants), but there were no procedural deaths. One (1.5%) patient had intraoperative endotracheal tube dislodgement. Three (4.5%) infants had postoperative pneumothorax requiring an additional chest tube insertion. Twenty-one (32%) patients required initiation of postoperative inotrope/vasodilator therapy within 6 h. Three postligation cardiac syndromes (≥ Grade-III mitral regurgitation with left ventricular dysfunction and hypotension) occurred.

Conclusions :

Although anesthesia for preterm neonates undergoing bedside PDA ligation poses unique challenges, it can be safely conducted by following a predetermined standardized anesthesia protocol. Its successful conduct requires utmost vigilance and pristine understanding of the principles of neonatal and cardiac care.

Longitudinal assessment of cardiac function in infants with Down's syndrome using novel echocardiography techniques - project protocol

Background: Down’s syndrome (DS) is the most common chromosomal abnormality globally. Ireland has one of the highest rates of DS in the western world with an incidence of 1:444 live births. Congenital heart disease (CHD) and pulmonary hypertension (PH) are the commonest morbidities affecting the cardiovascular system in DS. PH is associated with significant morbidity and an increase risk of mortality. The impact of the diagnosis of DS, the presence of CHD and the associated PH on myocardial function during transition and over the first 2 years of age in this population is not well defined and warrants further study. In particular, serial measurements of pulmonary pressures in this population over the first week of age are lacking. This study aims to characterise myocardial function and pulmonary haemodynamics in infants with Down syndrome during the transitional period (over the first week of age) and throughout the first two years of age.

Methods: A prospective, observational study utilising novel echocardiography techniques to assess myocardial function and pulmonary haemodynamics over the first two years of age in infants with Down Syndrome. A population of healthy infants without CHD or a diagnosis of DS will be recruited as controls. This study will be conducted across the three Dublin maternity units.

Discussion: In total, 70 babies with DS have been enrolled into this study with 292 echocardiograms performed to date. Further evaluation of cardiac performance in DS infants with and without CHD may yield more insight into the pathophysiology of cardiac dysfunction and pulmonary hypertension that are recognised features in these patients. This could aid in our ability to monitor and treat patients, as well as improve our ability to predict outcomes.

Patent Ductus Arteriosus-Time for a Definitive Trial

More than 70 randomized controlled trials have been conducted on the management of patent ductus arteriosus (PDA) in preterm infants. Yet, clinicians are unsure if treating a PDA improves clinically important outcomes. Earlier clinical trials have primarily explored which pharmacotherapeutic agent effectively closes the PDA. Because many of these trials included older infants, had widely varying PDA definitions, and provided open-label treatment, it is difficult to draw inferences on clinical outcomes based on the results of these trials. These flaws in trial design might have contributed to the growing notion that "no treatment" is a feasible option irrespective of the clinical characteristics of the infant and the PDA shunt volume.

Left ventricular dysfunction postsurgical patent ductus arteriosus ligation in children: predictor factors analysis

Objective

To identify the predictor factors of left ventricular (LV) dysfunction following patent ductus arteriosus (PDA) surgical ligation.

Background

PDA is viewed as a noticeable amongst the most widely recognized congenital heart defects in children and its closure is responsible for many hemodynamic changes that require intervention and care.

Methods

A retrospective study included fifty children with isolated PDA treated by surgical ligation from June 2015 to June 2018. The LV dimensions and systolic function were assessed by two-dimensional echocardiography pre and post PDA ligation. All cases were followed-up on the first-day, 1 month and 6 months post ligation.

Results

The mean age of cases was 15.78 ± 7.58 months and 72% were females. The mean duct size was 4.08 ± 1.25 mm. There was a marked decrease in LVEDd, LA/Ao, EF and FS in the first-day post ligation contrasted with pre ligation values. Moreover, an amazing decline in LVEDd and LA/Ao ratio was observed 1 month post ligation contrasted with the early post ligation status with asynchronous improvement of FS and EF at one and 6 months postoperatively.

Conclusion

PDA ligation is associated with a noteworthy LV systolic dysfunction within the first day post ligation; that in a significant number of patients may require anti-failure measures, prolong the hospital stay and necessitate a regular follow up and monitoring of LV function. PDA size, age, preoperative LVEDd and FS can be considered as predictor factors for suspicion of acute decrease in the LV systolic function early post PDA ligation.

Trial registration

ClinTrial.Gov NCT04018079.

Follow-up after Percutaneous Patent Ductus Arteriosus Occlusion in Lower Weight Infants

OBJECTIVES

To describe longer term outcomes for infants <6 kg undergoing percutaneous occlusion of the patent ductus arteriosus (PDA).

STUDY DESIGN

This was a retrospective cohort study of infants <6 kg who underwent isolated percutaneous closure of the PDA at a single, tertiary center (2003-2017). Cardiopulmonary outcomes and device-related complications (eg, left pulmonary artery obstruction) were examined for differences across weight thresholds (very low weight, <3 kg; low weight, 3-<6 kg). We assessed composite measures of respiratory status during and beyond the initial hospitalization using linear mixed effects models.

RESULTS

In this cohort of lower weight infants, 92 of 106 percutaneous occlusion procedures were successful. Median age and weight at procedure were 3.0 months (range, 0.5-11.1 months) and 3.7 kg (range, 1.4-5.9 kg), respectively. Among infants with pulmonary artery obstruction on initial postprocedural echocardiograms (n = 20 [22%]), obstruction persisted through hospital discharge in 3 infants. No measured variables were associated with device-related complications. Rates of oxygenation failure (28% vs 8%; P < .01) and decreased left ventricular systolic function (29% vs 5%; P < .01) were higher among very low weight than low weight infants. Pulmonary scores decreased (indicating improved respiratory status) following percutaneous PDA closure.

CONCLUSIONS

Percutaneous PDA occlusion among lower weight infants is associated with potential longer term improvements in respiratory health. Risks of device-related complications and adverse cardiopulmonary outcomes, particularly among very low weight infants, underscore the need for continued device modification. Before widespread use, clinical trials comparing percutaneous occlusion vs alternative treatments are needed.

Population Pharmacokinetics and Dosing of Milrinone After Patent Ductus Arteriosus Ligation in Preterm Infants

OBJECTIVES

The postoperative course of patent ductus arteriosus ligation is often complicated by postligation cardiac syndrome, occurring in 10-45% of operated infants. Milrinone might prevent profound hemodynamic instability and improve the recovery of cardiac function in this setting. The present study aimed to describe the population pharmacokinetics of milrinone in premature neonates at risk of postligation cardiac syndrome and give dosing recommendations.

DESIGN

A prospective single group open-label pharmacokinetics study.

SETTINGS

Two tertiary care neonatal ICUs: Tallinn Children's Hospital and Tartu University Hospital, Estonia.

PATIENTS

Ten neonates with postmenstrual age of 24.6-30.1 weeks and postnatal age of 5-27 days undergoing patent ductus arteriosus ligation and at risk of postligation cardiac syndrome, based on echocardiographic assessment of left ventricular output of less than 200 mL/kg/min 1 hour after the surgery.

INTERVENTIONS

Milrinone at a dose of 0.73 μg/kg/min for 3 hours followed by 0.16 μg/kg/min for 21 hours. Four blood samples from each patient for milrinone plasma concentration measurements were collected.

MEASUREMENTS AND MAIN RESULTS

Concentration-time data of milrinone were analyzed with nonlinear mixed-effects modeling software (NONMEM Version 7.3 [ICON Development Solutions, Ellicott City, MD]). Probability of target attainment simulations gave a dosing schedule that maximally attains concentration targets of 150-250 μg/L. Milrinone pharmacokinetics was described by a one-compartmental linear model with allometric scaling to bodyweight and an age maturation function of glomerular filtration rate. Parameter estimates for a patient with the median weight were 0.350 (L/hr) for clearance and 0.329 (L) for volume of distribution. The best probability of target attainment was achieved with a loading dose of 0.50 μg/kg/min for 3 hours followed by 0.15 μg/kg/min (postmenstrual age < 27 wk) or 0.20 μg/kg/min (postmenstrual age ≥ 27 wk).

CONCLUSIONS

Population pharmacokinetic modeling and simulations suggest a slow loading dose followed by maintenance infusion to reach therapeutic milrinone plasma concentrations within the timeframe of the postligation cardiac syndrome.

Childhood Neurodevelopmental Outcome in Low Birth Weight Infants With Post-ligation Cardiac Syndrome After Ductus Arteriosus Closure

Background

Post-ligation cardiac syndrome (PLCS) is a common complication of patent ductus arteriosus (PDA) surgical closure in low birth weight infants. It has been associated with mortality, but there is a lack of information about the neurodevelopmental outcome of the survivors. We aimed to explore the prevalence of PLCS and to assess whether this clinical condition is a risk factor for adverse outcome, (moderate or severe neurodevelopmental disabilities).

Methods

We retrospectively reviewed the medical charts of all the infants < 30 weeks of gestation who underwent ductus arteriosus ligation at our unit between 2005 and 2009.

Results

During the study period, 39 preterm infants [mean gestational age 26.4 (2) weeks] underwent surgical closure of the PDA at a mean postnatal age of 25.3 (2.3) days. Twenty six percent of the study population developed PLCS. Five infants died and the follow-up was accomplished in 24 infants (70% of the survivors) at a mean age of 5.3 (1.5) years (range 2–9 years). Neurodevelopmental impairment was observed in 6 in the PLCS group (75%) and in 6 infants in the no PLCS group (37%), p = 0.08]. Multiple regression analyses showed that the best fitting model for predicting adverse outcome included PLCS and low birth weight, p = 0.018.

Conclusion

Preterm infants undergoing surgical closure of PDA who fulfill the criteria of PLCS according to this study seem to have a tendency toward higher risk of long-term neurodevelopmental impairment. Prospective clinical trials reporting long-term follow-up data should be designed to confirm the hypotheses generated in this pilot study.

The Use of Cardiotonic Drugs in Neonates

There is a distinct lack of age-appropriate cardiotonic drugs, and adult derived formulations continue to be administered, without evidence-based knowledge on their dosing, safety, efficacy, and long-term effects. Dopamine remains the most commonly studied and prescribed cardiotonic drug in the neonatal intensive care unit (NICU), but evidence of its effect on endorgan perfusion still remains. Unlike adult and pediatric critical care, there are significant gaps in our knowledge on the use of various cardiotonic drugs in various forms of circulatory failure in the NICU.

Management strategies for the preemie ductus

PURPOSE OF REVIEW

Patent ductus arteriosus (PDA) remains the most common cardiovascular condition afflicting neonates. Despite 5 decades of scientific inquiry pediatric cardiologists and neonatologists still cannot answer the simple question of which PDAs should be treated.

RECENT FINDINGS

Although the volume of the shunt is difficult to calculate, echocardiography, biochemical markers, and clinical exam can provide clues to the magnitude and physiologic consequences of the shunt. Epidemiologic data exists showing a positive relationship between a PDA and numerous morbidities. As a result, for most of the 20th and early 21st century, nearly all PDAs where indiscriminately considered to be hemodynamically significant and attempts to close it where initiated shortly after birth. However, no randomized trials of PDA closure have been able to show significant differences between affected and unaffected groups. In fact, surgical ligation has repeatedly been associated with increased morbidities and worse long-term neurodevelopmental outcomes. As a result, most clinicians favor a strategy of watchful waiting.

SUMMARY

In this review, we aim to summarize the scientific literature, along with some of the contemporary biases, that exist with regards to the pathophysiology, genetics, and treatment strategies for the neonatal PDA.

Surgical management of a patent ductus arteriosus: Is this still an option?

The evolution of neonatal intensive care over the past decade has seen the role of surgical patent ductus arteriosus (PDA) ligation in preterm infants both decrease in scope and become laden with uncertainty. Associations of ligation with adverse neonatal and neurodevelopmental outcomes have rendered the ligation decision more challenging for clinicians and have been associated with a decline in surgical treatment, but these findings may be due to bias from confounding by indication in observational studies rather than a causal detrimental effect of ligation. Accordingly, ligation may still be indicated for infants with large ductal shunts and moderate-severe respiratory insufficiency in whom the prospect of timely spontaneous closure appears low. Ultimately a randomized trial of surgical ligation versus conservative management is necessary to assess the efficacy of this invasive intervention in a population of extremely preterm infants with large ductal shunts. Simultaneously, the transcatheter approach to ductal closure in the very immature infant represents an exciting therapeutic alternative but which is still in its infancy. Insights into the pathophysiology of postoperative cardiorespiratory deterioration, including the importance of left ventricular afterload, may help clinicians avoid instability and mitigate a potentially injurious aspect of surgical treatment. This review examines the evidence regarding the benefits and risks of PDA surgery in preterm neonates and provides a pathophysiology-based management paradigm to guide perioperative care in high-risk infants.

Electrical velocimetry for non-invasive monitoring of the closure of the ductus arteriosus in preterm infants

Closure of a patent ductus arteriosus (PDA) in preterm infants modifies cardiac output and induces adaptive changes in the hemodynamic situation. The present study aims to analyze those changes, through a non-invasive cardiac output monitor based on blood electrical velocimetry, in preterm babies. A prospective observational study of preterm infants with a gestational age of less than 28 weeks, and a hemodynamic significant PDA, requires intravenous ibuprofen or surgical closure. All patients were monitored with electrical velocimetry before treatment and through the following 72 h. Two groups were defined, ibuprofen and surgical closure. Variations of cardiac output were analyzed from the basal situation and at 1, 8, 24, 48, and 72 h on each group. During a 12-month period, 18 patients were studied. The median gestational age in the ibuprofen group (12/18) was 26⁺⁵ weeks (25⁺⁵-27⁺³) with a median birth weight of 875 (670-1010) g. The cardiac output index (CI) value was 0.29 l/kg/min (0.24-0.34). Among the patients with confirmed ductus closure (50%), a significant CI decrease was shown (0.24 vs 0.29 l/kg/min; P 0.03) after 72 h (three ibuprofen doses). A statistically significant decrease in systolic volume (SVI) was found: 1.62 vs 1.88 ml/kg, P 0.03 with a decrease in contractility (ICON), 85 vs 140, P 0.02. The gestational age in the surgical group (6/18) was 25⁺² weeks (24-26⁺³) with a median weight of 745 (660-820) g. All patients in this group showed a decrease in the immediate postoperative CI (1 h after surgery) 0.24 vs 0.30 l/kg/min, P 0.05, and a significant decrease in contractility (ICON 77 vs 147, P 0.03). In addition, a no statistically significant decrease in SVI (1.54 vs 1.83 ml/kg, P 0.06), as well as an increase in systemic vascular resistance (10,615 vs 8797 dyn/cm², P 0.08), were detected. This deterioration was transient without significant differences in the remaining periods of time evaluated.

CONCLUSION

The surgical closure of the PDA in preterm infants causes a transient deterioration of cardiac function linked to a documented decrease in the left ventricular output. The hemodynamic changes detected after pharmacological PDA closure are similar but those patients present a better clinical tolerance to changes in the cardiac output. What is Known: • Surgical ductus closure generates acute hemodynamic changes in cardiac output and left ventricular function. What is New: • The hemodynamic changes detected after pharmacological ductus closure are similar to those found in the surgical closure. Electrical velocimetry can detect those changes.

The Impact of Maternal Gestational Hypertension and the Use of Anti-Hypertensives on Neonatal Myocardial Performance

BACKGROUND

Assessment of myocardial performance in neonates using advanced techniques such as deformation imaging and rotational mechanics has gained considerable interest. The applicability of these techniques for elucidating abnormal myocardial performance in various clinical scenarios is becoming established. We hypothesise that term infants born to mothers with gestational hypertension (GH) may experience impaired performance of the left and right ventricles during the early neonatal period.

OBJECTIVES

We aimed to assess left and right ventricular (LV and RV) function using echocardiography in infants born to mothers with GH and compare them to a control group.

METHODS

Term infants (>36+6 weeks) born to mothers with GH underwent assessment to measure biventricular function using ejection fraction (EF), deformation imaging, left-ventricle rotational mechanics (apical rotation, basal rotation, twist, twist rate, and untwist rate), and right ventricle-specific functional parameters (tricuspid annular plane systolic excursion and fractional area change) in the first 48 h after birth. A control group comprising infants born to healthy mothers was used for comparison.

RESULTS

Fifteen infants with maternal GH and 30 age-matched controls were enrolled. The GH infants exhibited no differences in birthweight or LV or RV length, but they had lower EF (54 vs. 61%; p < 0.01), LV global longitudinal strain (-20 vs. -25%; p < 0.01), and LV twist (11 vs. 16°; p = 0.04). There were no differences in any of the RV functional parameters.

CONCLUSION

Infants born to mothers with GH exhibited lower LV function than healthy controls, while RV function appeared to be preserved. This relationship warrants further exploration in a larger cohort.

Cardiac Output Monitoring in Preterm Infants

Maintaining optimal circulatory status is a key component of preterm neonatal care. Low-cardiac output (CO) in the preterm neonate leads to inadequate perfusion of vital organs and has been linked to a variety of adverse outcomes with heightened acute morbidity and mortality and adverse neurodevelopmental outcomes. Having technology available to monitor CO allows us to detect low-output states and potentially intervene to mitigate the unwanted effects of reduced organ perfusion. There are many technologies available for the monitoring of CO in the preterm neonatal population and while many act as useful adjuncts to aid clinical decision-making no technique is perfect. In this review, we discuss the relative merits and limitations of various common methodologies available for monitoring CO in the preterm neonatal population. We will discuss the ongoing challenges in monitoring CO in the preterm neonate along with current gaps in our knowledge. We conclude by discussing emerging technologies and areas that warrant further study.

Application of NPE in the assessment of a patent ductus arteriosus

In many preterm infants, the ductus arteriosus remains patent beyond the first few days of life. This prolonged patency is associated with numerous adverse outcomes, but the extent to which these adverse outcomes are attributable to the hemodynamic consequences of ductal patency, if at all, has not been established. Different treatment strategies have failed to improve short-term outcomes, with a paucity of data on the correct diagnostic and pathophysiological assessment of the patent ductus arteriosus (PDA) in association with long-term outcomes. Echocardiography is the selected method of choice for detecting a PDA, assessing the impact on the preterm circulation and monitoring treatment response. PDA in a preterm infant can result in pulmonary overcirculation and systemic hypoperfusion, Therefore, echocardiographic assessment should include evaluation of PDA characteristics, indices of pulmonary overcirculation with left heart loading conditions, and indices of systemic hypoperfusion. In this review, we provide an evidence-based overview of the current and emerging ultrasound measurements available to identify and monitor a PDA in the preterm infant. We offer indications and limitations for using Neonatologist Performed Echocardiography to optimize the management of a neonate with a PDA.

Management of Neonatal Hypotension

Hypotension is a common problem in neonates with complex underlying pathophysiology. Although treatment of low blood pressure is common, clinicians must use all available information to target neonates with compromised perfusion. Pharmacotherapy should be tailored to the specific physiologic perturbations of the individual neonate. Dopamine is the most commonly utilized agent and may be the most appropriate agent for septic shock with low diastolic blood pressure. However, alternative therapies should be considered for other etiologies of hypotension, including milrinone and vasopressin for persistent pulmonary hypertension of the newborn and dobutamine for patent ductus arteriosus. Additional studies are required to refine the approach to neonatal hypotension and document the long-term outcomes of treated neonates.

Hemodynamic Assessment and Monitoring of Premature Infants

The management of the hemodynamic status of critically ill preterm infants, particularly around the periviable period, remains a significant challenge in the neonatal intensive care unit for a multitude of reasons. The causes of hemodynamic compromise in this population are heterogeneous and usually superimposed on the complex physiologic processes that occur during transition from fetal to neonatal life. This review outlines the unique nature of low blood flow states in this population and present an overview of the current methods for identification and assessment of hemodynamic compromise.

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.

Maturational Patterns of Systolic Ventricular Deformation Mechanics by Two-Dimensional Speckle-Tracking Echocardiography in Preterm Infants over the First Year of Age

BACKGROUND

The aim of this study was to determine the maturational changes in systolic ventricular strain mechanics by two-dimensional speckle-tracking echocardiography in extremely preterm neonates from birth to 1 year of age and discern the impact of common cardiopulmonary abnormalities on the deformation measures.

METHODS

In a prospective multicenter study of 239 extremely preterm infants (<29 weeks gestation at birth), left ventricular (LV) global longitudinal strain (GLS) and global longitudinal systolic strain rate (GLSRs), interventricular septal wall (IVS) GLS and GLSRs, right ventricular (RV) free wall longitudinal strain and strain rate, and segmental longitudinal strain in the RV free wall, LV free wall, and IVS were serially measured on days 1, 2, and 5 to 7, at 32 and 36 weeks postmenstrual age, and at 1 year corrected age (CA). Premature infants who developed bronchopulmonary dysplasia or had echocardiographic findings of pulmonary hypertension were analyzed separately.

RESULTS

In uncomplicated preterm infants (n = 103 [48%]), LV GLS and GLSRs remained unchanged from days 5 to 7 to 1 year CA (P = .60 and P = .59). RV free wall longitudinal strain, RV free wall longitudinal strain rate, and IVS GLS and GLSRs significantly increased over the same time period (P < .01 for all measures). A significant base-to-apex (highest to lowest) segmental longitudinal strain gradient (P < .01) was seen in the RV free wall and a reverse apex-to-base gradient (P < .01) in the LV free wall. In infants with bronchopulmonary dysplasia and/or pulmonary hypertension (n = 119 [51%]), RV free wall longitudinal strain and IVS GLS were significantly lower (P < .01), LV GLS and GLSRs were similar (P = .56), and IVS segmental longitudinal strain persisted as an RV-dominant base-to-apex gradient from 32 weeks postmenstrual age to 1 year CA.

CONCLUSIONS

This study tracks the maturational patterns of global and regional deformation by two-dimensional speckle-tracking echocardiography in extremely preterm infants from birth to 1 year CA. The maturational patterns are ventricular specific. Bronchopulmonary dysplasia and pulmonary hypertension leave a negative impact on RV and IVS strain, while LV strain remains stable.

[Vasopressors and inotropes: use in paediatrics]

The cardiovascular system is a dynamic system, which is required to ensure adequate delivery of oxygen, nutrients, and hormones to the tissues that are necessary for cell metabolism. It also synthesises and modifies the vasoactive components that regulate vascular tone and myocardial function. These vasoactive components have demonstrated their beneficial effects in the management of paediatric patients in a critical condition with heart failure and shock. However, their use and abuse brings harmful effects, increases mortality, and is associated with arrhythmias. An increase in myocardial oxygen consumption favours the presence of ischaemia, therefore it is necessary to know the mechanism of action and indications of these drugs to minimise their harmful effects. The purpose of this review is to describe the pharmacology and clinical applications of inotropic and vasopressor agents in the paediatric patient in acritical condition.

Echocardiographic Evaluation of Hemodynamics in Neonates and Children

Hemodynamic instability and inadequate cardiac performance are common in critically ill children. The clinical assessment of hemodynamic status is reliant upon physical examination supported by the clinical signs such as heart rate, blood pressure, capillary refill time, and measurement of the urine output and serum lactate. Unfortunately, all of these parameters are surrogate markers of cardiovascular well-being and they provide limited direct information regarding the adequacy of blood flow and tissue perfusion. A bedside point-of-care echocardiography can provide real-time hemodynamic information by assessing cardiac function, loading conditions (preload and afterload) and cardiac output. The echocardiography has the ability to provide longitudinal functional assessment in real time, which makes it an ideal tool for monitoring hemodynamic assessment in neonates and children. It is indispensable in the management of patients with shock, pulmonary hypertension, and patent ductus arteriosus. The echocardiography is the gold standard diagnostic tool to assess hemodynamic stability in patients with pericardial effusion, cardiac tamponade, and cardiac abnormalities such as congenital heart defects or valvar disorders. The information from echocardiography can be used to provide targeted treatment in intensive care settings such as need of fluid resuscitation versus inotropic support, choosing appropriate inotrope or vasopressor, and in providing specific interventions such as selective pulmonary vasodilators in pulmonary hypertension. The physiological information gathered from echocardiography may help in making timely, accurate, and appropriate diagnosis and providing specific treatment in sick patients. There is no surprise that use of bedside point-of-care echocardiography is rapidly gaining interest among neonatologists and intensivists, and it is now being used in clinical decision making for patients with hemodynamic instability. Like any other investigation, it has certain limitations and the most important limitation is its intermittent nature. Sometimes acquiring high quality images for precise functional assessment in a ventilated child can be challenging. Therefore, it should be used in conjunction with the existing tools (physical examination and clinical parameters) for hemodynamic assessment while making clinical decisions.

Dosing of Milrinone in Preterm Neonates to Prevent Postligation Cardiac Syndrome: Simulation Study Suggests Need for Bolus Infusion

BACKGROUND

Milrinone has been suggested as a possible first-line therapy for preterm neonates to prevent postligation cardiac syndrome (PLCS) through decreasing systemic vascular resistance and increasing cardiac contractility. The optimal dosing regimen, however, is not known.

OBJECTIVE

To model the dosing of milrinone in preterm infants for prevention of PLCS after surgical closure of patent ductus arteriosus (PDA).

METHODS

Milrinone time-concentration profiles were simulated for 1,000 subjects using the volume of distribution and clearance estimates based on one compartmental population pharmacokinetic model by Paradisis et al. [Arch Dis Child Fetal Neonatal Ed 2007;92:F204-F209]. Dose optimization was based on retrospectively collected demographic data from neonates undergoing PDA ligation in Estonian PICUs between 2012 and 2014 and existing pharmacodynamic data. The target plasma concentration was set at 150-200 ng/ml.

RESULTS

The simulation study used demographic data from 31 neonates who underwent PDA ligation. The median postnatal age was 13 days (range: 3-29) and weight was 760 g (range: 500-2,351). With continuous infusion of milrinone 0.33 μg/kg/min, the proportion of subjects within the desired concentration range was 0% by 3 h, 36% by 6 h, and 61% by 8 h; 99% of subjects exceeded the range by 18 h. The maximum proportion of total simulated concentrations in the target range was attained with a bolus infusion of 0.73 μg/kg/min for 3 h followed by a 0.16-μg/kg/min maintenance infusion.

CONCLUSION

Mathematical simulations suggest that in preterm neonates the plasma time-concentration profile of milrinone can be optimized with a slow loading dose followed by maintenance infusion.

Surgical ligation of patent ductus arteriosus in premature infants: trends and practice variation

OBJECTIVE

We sought to analyse the variation in the incidence of patent ductus arteriosus over three recent time points and characterise ductal ligation practices in preterm infants in the United States, adjusting for demographic and morbidity factors.

METHODS

Using the Kids' Inpatient Database from 2003, 2006, and 2009, we identified infants born at ⩽32 weeks of gestation with International Classification of Diseases, Ninth Revision diagnosis of patent ductus arteriosus and ligation code. We examined patient and hospital characteristics and identified patient and hospital variables associated with ligation.

RESULTS

Of 182,610 preterm births, 30,714 discharges included a patent ductus arteriosus diagnosis. The rate of patent ductus arteriosus diagnosis increased from 14% in 2003 to 21% in 2009 (p<0.001). A total of 4181 ligations were performed, with an overall ligation rate of 14%. Ligation rate in infants born at ⩽28 weeks of gestation was 20% overall, increasing from 18% in 2003 to 21% in 2009 (p<0.001). The ligation rate varied by state (4-28%), and ligation was associated with earlier gestational age, associated diagnoses, hospital type, teaching hospital status, and region (p<0.001).

CONCLUSION

The rates of patent ductus arteriosus diagnosis and ligation have increased in the recent years. Variation exists in the practice of patent ductus arteriosus ligation and is influenced by patient and non-patient factors.

Optimal Acquisition Settings for Speckle Tracking Echocardiography-Derived Strains in Infants: An In Vitro Study

The purpose of this study was to investigate the effect of frame rate and probe frequency on the accuracy of speckle tracking echocardiography-derived strain measurements in infants. An infant-sized left ventricle phantom with sonomicrometer crystals was made from polyvinyl alcohol. The examined stroke rates were 60, 120 and 180 strokes per min (SPM). Longitudinal strain and circumferential strain measurements were analyzed from a total of 1860 cine loops. These cine loops were acquired using two pediatric probes of different frequencies at both fundamental and harmonic imaging modes. Both probes were examined at different settings (in total, 30 different frame rate-frequency combinations). At optimal settings, both longitudinal and circumferential strain displayed high accuracy. Frequency settings did not have a consistent effect on accuracy, while low frame rates led to less accurate measurements. We recommend a frame rate/heart ratio >1 frame per second/beats per min, especially for circumferential strain.

The impact of a dedicated patent ductus arteriosus ligation team on neonatal health-care outcomes

OBJECTIVE

The decision to perform patent ductus arteriosus (PDA) ligation is controversial. Patient selection is oftentimes poorly standardized, leading to delays in referral and inappropriate intervention. A system for PDA ligation categorization and triaging process was introduced in 2006 at a quaternary hospital in Canada to streamline referrals and enhance perioperative care. We aimed to evaluate the impact of this dedicated PDA ligation triaging system comparing pre- and postimplementation of this system.

STUDY DESIGN

We performed a retrospective chart review. Demographic and cardiorespiratory data of neonates ⩽30 weeks gestation age at birth, who were referred for and/or had a PDA ligation performed during two distinct epochs (EPOCH 1 (2003 to 2005) and EPOCH 2 (2010 to 2012)), were analyzed. All surgeries were performed at The Hospital for Sick Children, the regional referral center for PDA ligation. The primary outcome was incidence of PDA ligation and procedural cancellations. Secondary outcomes included postoperative need for cardiovascular or respiratory support. Subgroup analysis was performed in neonates <1000 vs >1000 g at the time of surgery during both epochs.

RESULT

A total of 198 neonates underwent surgery with no difference in baseline demographics between epochs. The incidence of PDA ligation as a proportion of total live births under 30 weeks in Central East Region of Ontario was lower in the second epoch (EPOCH 1: 117/1092 (10.7%) vs EPOCH 2: 81/1520 (5.3%)). During the second epoch, 24% of referrals for surgery were canceled after review by our PDA ligation team. There were no overall differences in the proportion of neonates with oxygenation failure, ventilation failure or Post-Ligation Cardiac Syndrome (PLCS), after surgery, between epochs. The proportion of neonates who developed systemic hypotension was higher in patients <1000 g (n=34 (34%) vs n=17 (17.4%), P=0.01) at the time of surgery. In addition, we identified a reduction in the proportion of neonates <1000 g who developed PLCS in EPOCH 2. On the contrary, there was an increase in the proportion of neonates >1000 g who developed ventilation failure in EPOCH 2.

CONCLUSION

The presence of dedicated triaging and management system enhances efficiency of referral process through careful selection of patients for PDA ligation and optimizes perioperative management. We demonstrated a reduction in the incidence of PDA ligation without any negative impact on short-term neonatal morbidity. The use of targeted neonatal echocardiography in the assessment of PDA shunt volume and guiding postoperative decision making is likely to have contributed to these findings.

The effect of milrinone on right and left ventricular function when used as a rescue therapy for term infants with pulmonary hypertension

INTRODUCTION

Milrinone may be an appropriate adjuvant therapy for infants with persistent pulmonary hypertension of the newborn. We aimed to describe the effect of milrinone administration on right and left ventricular function in infants with persistent pulmonary hypertension not responding to inhaled nitric oxide after 4 hours of administration.

MATERIALS AND METHODS

This is a retrospective review of infants born after or at 34 weeks of gestation with persistent pulmonary hypertension who received milrinone treatment. The primary endpoint was the effect of milrinone on myocardial performance and haemodynamics, including right and left ventricular outputs, tissue Doppler velocities, right ventricle and septal strain, and strain rate. Secondary endpoints examined included duration of inhaled nitric oxide and oxygen support.

RESULTS

A total of 17 infants with a mean (standard deviation) gestation and birth weight of 39.8 (2.0) weeks and 3.45 (0.39) kilograms, respectively, were included in the study. The first echocardiogram was performed 15 hours after the commencement of nitric oxide inhalation. Milrinone treatment was started at a median time of 1 hour after the echocardiogram and was associated with an increase in left ventricular output (p=0.04), right ventricular output (p=0.004), right ventricle strain (p=0.01) and strain rate (p=0.002), and left ventricle s` (p<0.001) and a` (p=0.02) waves. There was a reduction in nitric oxide dose and oxygen requirement over the subsequent 72 hours (all p<0.05).

CONCLUSION

The use of milrinone as an adjunct to nitric oxide is worth further exploration, with preliminary evidence suggesting an improvement in both oxygenation and myocardial performance in this group of infants.

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.

The effect of antenatal magnesium sulfate on left ventricular afterload and myocardial function measured using deformation and rotational mechanics imaging

OBJECTIVE

Assess the effect of antenatal magnesium sulfate (MgSO4) on left ventricular function measured using deformation and rotational mechanics imaging.

STUDY DESIGN

Infants who received MgSO4 were matched for gestation, birth weight and mode of delivery with controls. Echocardiography was carried out on days 1 and 2 to measure left ventricle longitudinal strain (LV LS), twist, untwist rate, ejection fraction (EF), and systemic vascular resistance (SVR).

RESULTS

Thirty-eight infants with a median gestation and birth weight of 27.1 weeks and 923 g were included. On day 1, the MgSO4 group (n=19) had a lower SVR and higher LV LS, EF, twist and untwist rate than the Control group (n=19) (all P<0.05). There were no differences between the groups on day 2.

CONCLUSION

Antenatal MgSO4 administration is associated with a lower SVR and higher myocardial function on day 1 in preterm infants <29 weeks gestation.

Challenges in Treating Low Blood Pressure in Preterm Infants

Whilst the prevalence of low blood pressure in preterm infants seems to have fallen over the last number of years, the problem is still frequently encountered in the neonatal intensive care unit and many babies continue to receive intervention. Great variability in practice persists, with a significant number of extremely low gestational age newborns in some institutions receiving some form of intervention, and in other units substantially less. A great degree of this variability relates to the actual criteria used to define hypotension, with some using blood pressure values alone to direct therapy and others using a combination of clinical, biochemical and echocardiography findings. The choice of intervention remains unresolved with the majority of centres continuing to administer volume followed by dopamine as a first line inotrope/vasopressor agent. Despite over 40 years of use there is little evidence that dopamine is of benefit both in the short term and long-term. Long-term follow up is available in only two randomised trials, which included a total of 99 babies. An under recognized problem relates to the administration of inotrope infusions in very preterm infants. There are no pediatric specific inotrope formulations available and so risks of errors in preparation and administration remain. This manuscript outlines these challenges and proposes some potential solutions.

Treatment of premature infants with pulmonary hypertension and right ventricular dysfunction with milrinone: a case series

OBJECTIVE

Milrinone has been proposed as an effective treatment for pulmonary hypertension (PH) and right ventricular (RV) dysfunction. We aimed to determine the effect of milrinone therapy on clinical and echocardiography parameters of PH in preterm infants with elevated pulmonary pressures.

STUDY DESIGN

A retrospective case review was conducted on infants <32 weeks gestation who received milrinone for the treatment of PH and reduced RV function. Echocardiographic data were collected before and after treatment with milrinone, and serial clinical parameters were recorded over a 72h  period.

RESULT

Seven infants met the inclusion criteria with a median gestation and birth weight of 27.3 weeks and 1140 g, respectively. Four infants had a diagnosis of pulmonary hypoplasia with PH, and three infants were recipients in twin-to-twin transfusion syndrome who also developed PH. Nitric oxide was used in six infants before commencement of milrinone. Milrinone was commenced at a dose of 0.33 μg kg(-1) min(-1) to 0.5 μg kg(-1) min(-1) and continued for a median duration of 70 h. Use of milrinone was associated with a fall in oxygenation index and inhaled nitric oxide dose. Following an initial fall in blood pressure over the first 6 h, there was an increase in blood pressure over the subsequent 72 h. Echocardiographic data demonstrated an increase in indicators of myocardial performance and PH. One infant died before discharge.

CONCLUSION

This case series suggests that milrinone may be a useful therapy for premature infants with echocardiography findings of PH and/or RH dysfunction. This data support the need for a randomised control trial to confirm its efficacy.

Left Ventricular Rotational Mechanics in Preterm Infants Less Than 29 Weeks' Gestation over the First Week after Birth

BACKGROUND

There is a paucity of data on left ventricular (LV) rotational physiology, twist, and torsional mechanics in preterm infants. The principal aims of the present study were to assess the feasibility and reproducibility of measuring LV rotation, twist, and torsion in preterm infants (<29 weeks' gestation) using two-dimensional speckle-tracking echocardiography and to examine the changes in those parameters over the first week after birth.

METHODS

This was a prospective observational study involving preterm infants <29 weeks' gestation. Echocardiographic evaluations were performed on days 1, 2, and 5 to 7 after delivery. LV basal and apical rotation, LV twist, LV twist rate (LVTR), and LV untwist rate (LVUTR) were measured from the basal and apical short-axis parasternal views and calculated using two-dimensional speckle-tracking echocardiography. Torsion was also calculated by normalizing LV twist to LV end-diastolic length. One-way repeated-measures analysis of variance was used to compare values across the three time points. Intra- and interobserver reproducibility were assessed using Bland-Altman analysis and the intraclass correlation coefficient.

RESULTS

Fifty-one infants with a mean ± SD gestational age of 26.8 ± 1.5 weeks and a mean birth weight of 945 ± 233 g were included. There was high intra- and interobserver reproducibility for basal and apical rotation, LV twist, and LV torsion, with intraclass correlation coefficients ranging from 0.78 to 0.96 (P < .001 for all). Intra- and interobserver intraclass correlation coefficients for LVTR and LVUTR ranged from 0.70 to 0.88 (P < .001 for all). Apical rotation remained constant over the first week of age in a positive counterclockwise fashion (11.8 ± 5.0° vs 12.1 ± 6.1° vs 11.7 ± 8.3°, P = .92). Basal rotation changed from counterclockwise on day 1 to clockwise on day 7 (median, 5.5° [interquartile range, -0.3° to 8.3°] vs 4.0 [interquartile range, -4.7° to 7.2°] vs -4.5° [interquartile range, -5.8° to -2.3°], P < .001), with resultant net increases in twist and torsion (P < .05). There was no change in LVTR (P = .60), but LVUTR increased across the same time period (P = .01).

CONCLUSIONS

Assessment of twist, LVTR, and LVUTR is feasible in preterm infants, with acceptable reproducibility. There are increases in LV twist and torsion in addition to LVUTR, suggesting changes in LV mechanics during the first week of age.