Patent ductus arteriosus: The physiology of transition

[Predictive factors for hemodynamically significant patent ductus arteriosus in preterm infants and the construction of a nomogram prediction model]

OBJECTIVES

To explore the predictive factors for hemodynamically significant patent ductus arteriosus (hsPDA) in preterm infants and to construct a nomogram prediction model for hsPDA occurrence in this population.

METHODS

A retrospective analysis was conducted on the clinical data of preterm infants with gestational age <32 weeks diagnosed with patent ductus arteriosus (PDA) who were delivered at Nanjing Women and Children's Healthcare Hospital from January 2020 to December 2022. The subjects were divided into an hsPDA group (52 cases) and a non-hsPDA group (176 cases) based on the presence of hsPDA. Univariate analysis and multivariate logistic regression analysis were performed to screen predictive variables regarding the general information of the infants at birth, maternal pregnancy and delivery conditions, and relevant indicators during hospitalization. A nomogram prediction model for hsPDA occurrence was constructed using R software in preterm infants. Internal validation was performed using the Bootstrap method. Finally, the predictive model was evaluated for calibration, discrimination ability, and clinical utility.

RESULTS

Multivariate regression analysis showed that the ratio of the left atrium to aorta diameter (LA/AO), mode of delivery (vaginal), and duration of mechanical ventilation were independent predictive factors for hsPDA in preterm infants (P<0.05). Based on the results of univariate analysis and multivariate logistic regression analysis, variables used to construct the nomogram prediction model for hsPDA risk included: LA/AO ratio, mode of delivery (vaginal), duration of mechanical ventilation, 5-minute Apgar score, and the presence of neonatal respiratory distress syndrome requiring surfactant therapy. The area under the receiver operating characteristic curve for this model was 0.876 (95%CI: 0.824-0.927), and the calibrated curve was close to the ideal reference line, indicating good calibration. The Hosmer-Lemeshow test demonstrated that the model fit well, and the clinical decision curve was above the extreme curves.

CONCLUSIONS

The nomogram prediction model, constructed using five variables (LA/AO ratio, vaginal delivery, duration of mechanical ventilation, 5-minute Apgar score, and the presence of neonatal respiratory distress syndrome requiring surfactant therapy), has reference significance for predicting the occurrence of hsPDA in preterm infants and provides valuable guidance for the early clinical identification of hsPDA.

Experience of patent ductus arteriosus ligation during extracorporeal membrane oxygenation treatment in newborns with severe respiratory failure due to persistent pulmonary hypertension: a single-center retrospective study

BACKGROUND

The aim of this study is to summarize our center's experience with patent ductus arteriosus (PDA) ligation during extracorporeal membrane oxygenation (ECMO) treatment in newborns with severe respiratory failure due to persistent pulmonary hypertension of the newborn (PPHN).

METHODS

We retrospectively collected and analyzed clinical data from five newborns with severe respiratory failure due to PPHN who underwent PDA ligation during ECMO treatment at our hospital between January 2021 and August 2023.

RESULTS

All five patients had large PDAs, measuring 10 mm, 6 mm, 6 mm, 7 mm, and 6 mm, respectively. Significant left-to-right shunting through the PDA was observed after 29 h, 14 h, 3 h, 7 h, and 5 h of ECMO treatment, respectively, at which point successful PDA ligation was performed. The surgical durations were 52 min, 45 min, 55 min, 50 min, and 40 min, respectively. Post-ligation, blood lactate levels significantly decreased compared to preoperative values. Four patients were successfully weaned off ECMO, with ECMO support durations of 64 h, 92 h, 70 h, and 87 h, respectively. After ECMO removal, mechanical ventilation was discontinued after 5.2 days, 7.2 days, 9.5 days, and 5.5 days, respectively. None of the four surviving patients experienced complications such as residual shunting, bleeding, chylothorax, neurologic injury, pneumothorax, poor wound healing, or sepsis.

CONCLUSION

During ECMO treatment for PPHN in newborns with large PDAs, the direction of blood flow through the PDA should be closely monitored. PDA ligation is a feasible and reasonable intervention when pulmonary artery pressure decreases and left-to-right shunting through the PDA becomes evident.

Monitoring and evaluation of hypotension in the extremely preterm

With the development of neonatal medicine, more and more extremely preterm infants have been treated. How to deal with hypotension is a big challenge for neonatologist in the process of diagnosis and treatment. The lack of uniformity in the definition of hypotension, challenges in measuring blood pressure accurately, and insufficient consistency between digital hypotension and hypoperfusion are the primary causes. How to check for hypotension and monitor blood pressure is thoroughly explained in the article. To give neonatologists a resource for the clinical management of hypotension in extremely preterm.

Cardiac Development and Related Clinical Considerations

The anatomy, physiology, and hemodynamics of the premature heart vary along the range of gestational ages cared for in neonatal intensive care units, from 22 weeks to term gestation. Clinical management of the preterm neonate should account for this heterogenous development. This requires an understanding of the impact of ex utero stressors on immature and disorganized cardiac tissue, the different state of hemodynamics across intracardiac shunts impacting the natural transition from fetal to neonatal life, and the effects of intensive pharmacologic and non-pharmacologic interventions that have systemic consequences influencing cardiac function. This article provides a review of the increasing but still limited body of literature on the anatomy, hemodynamics, and electrophysiology of the preterm heart with relevant clinical considerations.

Reduced morbidity with early surgical ligation of patent ductus arteriosus in extremely low birth weight infants: a retrospective single-centre study

INTRODUCTION

Failure of the patent ductus arteriosus to close is common among extremely low birth weight neonates and has been associated with increased morbidities. The objective of this study was to compare outcomes between early and late surgical ligation in extremely low birth weight patients.

METHODS

This was a single-centre retrospective cohort study of infants who required surgical closure of patent ductus arteriosus between January 2017 and August 2022.

RESULTS

A total of 43 neonates were identified with birth weight less than 1 kg that underwent surgical patent ductus arteriosus ligation. Compared to the late ligation group, the early ligation group experienced fewer total days of mechanical ventilation (43.9 days vs. 97.2 days, p < 0.05) and a shorter length of hospital stay (114.2 days vs. 169.0 days, p < 0.05).

CONCLUSION

Early surgical ligation of haemodynamically significant patent ductus arteriosus in extremely low birth weight neonates may improve hospital morbidity, including improved ventilatory outcomes and a shorter length of stay.

Ductus Arteriosus in Fetal and Perinatal Life

The ductus arteriosus represents an essential vascular structure connecting the pulmonary artery and the aorta. Over the past decades, there has been substantial advancement in our understanding of both the fundamental and clinical aspects of the ductus arteriosus. In particular, the clarification of the regulatory mechanisms governing ductal patency in critical stages such as the fetal and the perinatal period has enabled optimal management of both physiological and pathological conditions in which the ductus arteriosus plays a crucial role. Furthermore, a more in-depth understanding of the regulatory mechanisms controlling this fundamental structure has facilitated the development of advanced therapeutic strategies and personalized interventions. In the present review, we provide a comprehensive overview of the ductus arteriosus during fetal and perinatal life, encompassing its physiological functions, pathological conditions, and clinical implications. Through this examination, we aim to contribute to a broader understanding of the ductus arteriosus' role in these critical developmental stages and its significance in clinical practice.

Gastrointestinal perforation in extremely low birth weight infants: A single center retrospective study in China

BACKGROUND

Gastrointestinal perforation in extremely low birth weight infants, characterized by its rapid onset, multiple complications, and critical condition, poses a significant risk of infant mortality. The aim of this study was to investigate the clinical characteristics of pneumoperitoneum in extremely low birth weight infants (ELBWI) and explore the risk factors associated with gastrointestinal perforation in very low birth weight preterm infants. Additionally, we shared our surgical experiences in managing gastrointestinal perforation among extremely low birth weight infants.

METHODS

The Department of Neonatology at Chengdu Women and Children's Central Hospital conducted a retrospective study on gastrointestinal perforation in extremely low birth weight infants (birth weight <1000 g) who were admitted between 2014 and 2021. After baseline analysis and comparing it with the control group, we identified the risk factors associated with gastrointestinal perforation in ELBWI by multiple logistic regression analysis. The Kaplan-Meier analysis was performed to assess the adverse effect of gastrointestinal perforation for survival in ELBW infants. Cox multivariate regression analysis was used to evaluate hazard level of different variables for ELBW infants survival.

RESULTS

Hemodynamically significant patent ductus arteriosus (hsPDA)(p = 0.043, OR = 2.779) and sepsis (p = 0.014, OR = 2.265) were significant risk factors for gastrointestinal perforation in extremely low birth weight infants. The Cox proportional hazard model revealed that intraventricular hemorrhage (HR = 2.854, p＜0.001) Sepsis (HR = 1.645, p = 0.015) and gastrointestinal perforation (HR = 1.876, p = 0.008) had detrimental effects on the survival of extremely low birth weight infants; conversely, ibuprofen (HR = 0.304, p＜0.001) and blood transfusion (HR = 0.372, p＜0.001) are beneficial factors for their survival. The preoperative indicators of infection in infants with spontaneous intestinal perforation (SIP) were significantly better than those in the necrotizing enterocolitis (NEC) group (p < 0.05).

CONCLUSIONS

Gastrointestinal perforation poses a significant threat the survival of extremely low birth weight (ELBW) infants, with hsPDA and sepsis serving as predisposing factors for gastrointestinal perforation. The gastrointestinal perforation caused by various diseases exhibits distinct clinical characteristics, necessitating tailored surgical approaches based on operative conditions.

Predicting the effectiveness of drugs used for treating cardiovascular conditions in newborn infants

BACKGROUND

Cardiovascular support (CVS) treatment failure (TF) is associated with a poor prognosis in preterm infants.

METHODS

Medical charts of infants with a birth weight <1500 g who received either dopamine (Dp) or dobutamine (Db), were reviewed. Treatment response (TR) occurred if blood pressure increased >3rd centile for gestational age or superior vena cava flow was maintained >55 ml/kg/min, with decreased lactate or less negative base excess, without additional CVS. A predictive model of Dp and Db on TR was designed and the impact of TR on survival was analyzed.

RESULTS

Sixty-six infants (median gestational age 27.3 weeks, median birth weight 864 g) received Dp (n = 44) or Db (n = 22). TR occurred in 59% of the cases treated with Dp and 31% with Db, p = 0.04. Machine learning identified a model that correctly labeled Db response in 90% of the cases and Dp response in 61.4%. Sixteen infants died (9% of the TR group, 39% of the TF group; p = 0.004). Brain or gut morbidity-free survival was observed in 52% vs 30% in the TR and TF groups, respectively (p = 0.08).

CONCLUSIONS

New predictive models can anticipate Db but not Dp effectiveness in preterm infants. These algorithms may help the clinicians in the decision-making process.

IMPACT

Failure of cardiovascular support treatment increases the risk of mortality in very low birth weight infants. A predictive model built with machine learning techniques can help anticipate treatment response to dobutamine with high accuracy. Predictive models based on artificial intelligence may guide the clinicians in the decision-making process.

Pulmonary Vascular Regulation in the Fetal and Transitional Lung

Fetal lungs have fewer and smaller arteries with higher pulmonary vascular resistance (PVR) than a newborn. As gestation advances, the pulmonary circulation becomes more sensitive to changes in pulmonary arterial oxygen tension, which prepares them for the dramatic drop in PVR and increase in pulmonary blood flow (PBF) that occur when the baby takes its first few breaths of air, thus driving the transition from fetal to postnatal circulation. Dynamic and intricate regulatory mechanisms control PBF throughout development and are essential in supporting gas exchange after birth. Understanding these concepts is crucial given the role the pulmonary vasculature plays in the development of complications with transition, such as in the setting of persistent pulmonary hypertension of the newborn and congenital heart disease. An improved understanding of pulmonary vascular regulation may reveal opportunities for better clinical management.

Transcatheter closure of patent ductus arteriosus in preterm infants: results from a single-center cohort

Objective

To assess the success rate of patent ductus arteriosus (PDA) transcatheter closure in preterm infants and to describe the nature of procedural adverse events and short-term clinical status.

Study design

All the preterm infants with PDA transcatheter closure were evaluated retrospectively between July 2019 and March 2023 in a single level III neonatal intensive care unit in France. The procedure was performed in the catheterization laboratory using venous canulation. We retrospectively collected data about the patients' characteristics, procedural outcomes and complications.

Results

Twenty-five infants born between 23.4 and 32.0 weeks of gestational age (mean ± SD 26.3 ± 1.9 weeks) underwent transcatheter PDA closure. Their mean age and weight at the time of the procedure were 52 days (range 22-146 days) and 1,620 g (range 890-3,700 g), respectively. Successful closure was achieved in all but one patient. Procedure related complications were reported in 10 infants (40%), including 6 left pulmonary artery stenosis one of which required a balloon dilatation, two cardiac tamponades and two inferior vena cava thrombosis. Only two post-ligature syndromes occurred after the procedure. Two infants died one of which was related to the procedure.

Conclusion

Transcatheter closure of a PDA is a valid alternative to surgical ligation due to its high success rate and low incidence of post-ligature syndrome. Nevertheless, we also report rare, although serious complications.

[Risk factors and prognosis of hypotension within 72 hours after birth in extremely preterm infants]

OBJECTIVES

To investigate the risk factors and prognosis of hypotension within 72 hours after birth in extremely preterm infants.

METHODS

A retrospective analysis was conducted on clinical data of extremely preterm infants admitted to the Children's Hospital of Zhejiang University School of Medicine from January 2019 to April 2022. Based on the presence of hypotension within 72 hours after birth, the eligible infants were divided into a hypotension group (41 cases) and a normotension group (82 cases). The clinical characteristics, echocardiographic parameters within 72 hours after birth, and early complications were compared between the two groups. Multivariate logistic regression analysis was used to explore the risk factors for hypotension within 72 hours after birth, and receiver operating characteristic curve analysis was performed to evaluate the predictive value of relevant indicators for the occurrence of hypotension within 72 hours after birth in the preterm infants.

RESULTS

The proportion of infants who required medication or surgical closure of patent ductus arteriosus (PDA), the proportions of infants with intraventricular hemorrhage ≥ grade III and severe pulmonary hemorrhage, and the mortality rate within 7 days in the hypotension group were significantly higher than those in the normotension group (P<0.05). Multivariate logistic regression analysis showed that lower birth weight, larger PDA diameter, and hemodynamically significant PDA were risk factors for the occurrence of hypotension within 72 hours after birth in extremely preterm infants (P<0.05). The receiver operating characteristic curve analysis showed that the combination of birth weight, PDA diameter, and hemodynamically significant PDA had an area under the curve of 0.873 (95%CI: 0.802-0.944, P<0.05) for predicting hypotension within 72 hours after birth, with a sensitivity of 73.2% and specificity of 91.5%.

CONCLUSIONS

Hypotension within 72 hours after birth is closely related to birth weight and PDA, and increases the risk of early severe complications and mortality in extremely preterm infants.

The association between patterns of early respiratory disease and diastolic dysfunction in preterm infants

BACKGROUND

This study aims to determine the association between clinical patterns of early respiratory disease and diastolic dysfunction in preterm infants.

METHODS

Preterm infants <29 weeks' gestation underwent cardiac ultrasounds around day 7 and 14-21. Respiratory dysfunction patterns were classified as stable (ST), respiratory deterioration (RD) or early persistent respiratory dysfunction (EPRD) according to oxygen need. Diastolic dysfunction was diagnosed using a multi-parameter approach including left atrial strain (LASR) to help differentiate between cardiac or pulmonary pathophysiology.

RESULTS

98 infants (mean 27 weeks) were included. The prevalence of ST, RD and EPRD was 53%, 21% and 26% respectively. Diastolic dysfunction was more prevalent in the RD and EPRD groups with patent ductus arteriosus and significant growth restriction as risk factors. Not all infants with a PDA developed diastolic dysfunction. LASR was lower in the EPDR group.

CONCLUSION

Respiratory dysfunction patterns are associated with diastolic dysfunction in preterm infants.

Patent ductus arteriosus (PDA) and response to late surfactant treatment in premature infants

OBJECTIVE

To determine the clinical/echocardiography (ECHO) phenotype of patients with hypoxic respiratory failure (HRF) and response to late surfactant, according to patent ductus arteriosus (PDA) status.

STUDY DESIGN

This retrospective study included infants ≤26+6 weeks gestation who received ≥1 surfactant dose after 6 postnatal days and where PDA status was available by ECHO. Response to surfactant was appraised based on change in respiratory severity score over 48 h. The relationship between PDA status and response to surfactant was evaluated via univariate analysis.

RESULT

We studied late surfactant (n = 71 doses) administration in 35 preterm infants born at a mean weight and GA at birth were 595 g (508, 696) and 23.3 (22.7, 25) weeks, respectively of whom 16 (46%) had a diagnosis of PDA. Positive response to late surfactant treatment was independently associated with absence of PDA [OR 26 (2, 334), p = 0.01] whereas presence of PDA was independently associated with negative response [OR 12 (1.1, 126), p = 0.04].

CONCLUSIONS

In neonates ≤26+6 weeks gestation, with HRF, response to surfactant after postnatal day 6 is influenced by PDA status. Future trials should consider PDA status which may enhance diagnostic precision and refine patient selection for late surfactant treatment.

Nutrition of the preterm infant with persistent ductus arteriosus: existing evidence and practical implications

The persistence of a patent ductus arteriosus (PDA) is a common condition in preterm infants with a prevalence inversely proportional to gestational age. PDA is associated with mild-to-severe gastrointestinal complications such as feeding intolerance, gastrointestinal perforation, and necrotizing enterocolitis, which represent a major challenge for the nutritional management in preterm infants. In this context, the Section on Nutrition, Gastroenterology and Metabolism and the Circulation Section of the European Society for Pediatric Research have joined forces to review the current knowledge on nutritional issues related to PDA in preterm infants. The aim of the narrative review is to discuss the clinical implications for nutritional practice. Because there is little literature on postnatal nutrition and PDA in preterm infants, further research with well-designed studies on this topic is urgently needed. Guidelines should also be developed to clearly define the implementation and course of enteral nutrition and the target nutritional intake before, during, and after pharmacologic or surgical treatment of PDA, when indicated. IMPACT: Persistent ductus arteriosus (PDA) is associated with gastrointestinal complications such as feeding intolerance, gastrointestinal perforation, and necrotizing enterocolitis, which pose a major challenge to the nutritional management of preterm infants. In PDA infants, fluid restriction may lead to inadequate nutrient intake, which may negatively affect postnatal growth and long-term health. The presence of PDA does not appear to significantly affect mesenteric blood flow and splanchnic oxygenation after enteral feedings. Initiation or maintenance of enteral nutrition can be recommended in infants with PDA.

A Network Meta-Analysis of Intravenous Versus Oral Acetaminophen for Patent Ductus Arteriosus

The use of acetaminophen to close a PDA in preterm infants is increasing; however, the most effective route of administration is not yet known. This network meta-analysis compares the efficacy of IV versus PO routes of acetaminophen administration on clinical outcomes related to the presence of a PDA in preterm neonates. Medline, Embase, Cochrane Central Register of Controlled Trials, Embase, Web of Science, ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform were searched from inception to October 2020. A total 21 randomized controlled trials in neonates less than 37 weeks at birth, comparing oral or intravenously administered acetaminophen to close a PDA based on study criteria were included. Two authors extracted data independently and in duplicate. All outcomes were binary, and a frequentist network meta-analysis was performed. After one or two courses, both PO and IV acetaminophen were efficacious in closing a PDA with oral ranking higher than IV (low confidence). Neither medication was better than no treatment for secondary outcomes of NEC or BPD (moderate and low confidence respectively). We did not test the rectal route of acetaminophen administration and cannot make generalized statements. This study suggests oral acetaminophen increases the odds of being able to close a PDA in preterm neonates when compared to IV acetaminophen.

Delayed Surgical Closure of the Patent Ductus Arteriosus: Does the Brain Pay the Price?

OBJECTIVE

To investigate the relation between duration of hemodynamically significant patent ductus arteriosus (PDA), cerebral oxygenation, magnetic resonance imaging-determined brain growth, and 2-year neurodevelopmental outcome in a cohort of infants born preterm whose duct was closed surgically.

STUDY DESIGN

Infants born preterm at <30 weeks of gestational age who underwent surgical ductal closure between 2008 and 2018 (n = 106) were included in this observational study. Near infrared spectroscopy-monitored cerebral oxygen saturation during and up to 24 hours after ductal closure and a Bayley III developmental test at the corrected age of 2 years is the institutional standard of care for this patient group. Infants also had magnetic resonance imaging at term-equivalent age.

RESULTS

In total, 90 infants fulfilled the inclusion criteria (median [range]: 25.9 weeks [24.0-28.9]; 856 g [540-1350]. Days of a PDA ranged from 1 to 41. Multivariable linear regression analysis showed that duration of a PDA negatively influenced cerebellar growth and motor and cognitive outcome at 2 years of corrected age.

CONCLUSIONS

Prolonged duration of a PDA in this surgical cohort is associated with reduced cerebellar growth and suboptimal neurodevelopmental outcome.

Fresh Frozen Plasma Transfusion: An Independent Risk Factor for Hemodynamically Significant Patent Ductus Arteriosus in Premature Infants

OBJECTIVE

The incidence of patent ductus arteriosus (PDA), a major complication of prematurity, may be reduced by restricting fluid administration. Prophylactic fresh frozen plasma (FFP) transfusion may reduce the incidence of intraventricular hemorrhage in these infants, but risks transfusion-related volume overload. We conducted a retrospective study to investigate whether FFP transfusion is a risk factor for hemodynamically significant PDA (hsPDA) in very low birth weight (BW) premature infants.

STUDY DESIGN

From January 2009 to December 2014, 102 premature infants with gestational age (GA) less than or equal to 30 weeks were admitted to a level III neonatal intensive care unit, and 88 patients were enrolled. Patients were further divided into non-hsPDA (n = 29) and hsPDA groups (n = 59). We retrospectively reviewed demographic characteristics and various perinatal and postnatal variables. Univariate and multivariable analyses were performed to identify risk factors for hsPDA.

RESULTS

Compared with non-hsPDA patients, hsPDA patients had lower mean BW and GA, a higher incidence of severe respiratory distress symptoms, perinatal infection, use of surfactant, and need for FFP transfusion. However, multivariable logistic regression analysis showed that only FFP transfusion remained an independent risk factor for hsPDA (adjusted odds ratio = 3.880, 95% confidence interval: 1.214-12.402, p = 0.022) after adjusting for confounding factors.

CONCLUSION

FFP transfusion is a significant risk factor for the subsequent development of hsPDA in our study population. FFP transfusion may complicate the fluid management of premature infants and increase the risk of hsPDA.

KEY POINTS

· Hemodynamic significant PDA is an important complication of preterm infant.. · FFP transfusion may complicate the fluid management of premature infants.. · FFP transfusion is an independent risk factor for hsPDA in very low birth weight premature infants..

[Fetal and pediatric cardiovascular physiology : Things you should know as an (pediatric) anesthesiologist]

Immediately after birth the physiology of the cardiovascular system of the neonate undergoes some significant changes. The first breaths in life and the inflation of the lungs lead to a considerable drop in pulmonary arterial resistance. This results in the closure of the foramen ovale and ductus arteriosus; however, during the first weeks of life a sharp rise in pulmonary vascular resistance caused by hypoxia, hypercapnia and excessive positive pressure ventilation can lead to the reopening of the ductus arteriosus. This may result in subsequent strain of the left heart. In order to anticipate the reopening of the ductus arteriosus, it is recommended to measure the saturation of peripheral oxygen not only preductal (right hand), but also postductal (feet).An excessive volume therapy should be avoided as the neonatal myocardium is hallmarked by low cardiac compliance, reduced contractility and reduced ventricular filling.Until now there is still no uniform definition of hypotension in pediatric patients. Blood pressure values that are measured in awake children or are derived from the 50% age percentile values can thus only be used as approximate values. In all cases it is mandatory to recognize and consistently treat hypotension during pediatric anesthesia in order to prevent postoperative organ damage, particularly of the brain.The transcranial measurement of cerebral regional oxygen saturation (c‑rSO₂) by means of near-infrared spectroscopy (NIRS) provides valuable information about regional tissue oxygenation of the brain. This enables conclusions about the state of the multifactorial cerebral perfusion to be drawn. In this way monitoring of the hypoxia sensitive cerebral tissue can be accomplished and should be used in premature infants and neonates. When measuring a baseline in awake patients, a 20% drop of c‑rSO₂ from this baseline should be challenged and treated if necessary.

Management of cardiac dysfunction in neonates with pulmonary hypertension and the role of the ductus arteriosus

Pulmonary hypertension in the neonate is associated with cardiopulmonary disturbances and neurodevelopment morbidity. The patent ductus arteriosus is a persistent fetal shunt that can be pathologic vs supportive in the setting of neonatal pulmonary hypertension. Understanding the underlying pathophysiology of pulmonary hypertension and the cardiopulmonary effects of various phenotypes can guide management in this vulnerable population. In this narrative, we will summarize the physiologic principles of pulmonary hypertension, the impact of the patent ductus arteriosus on various phenotypes, and the utility of serial targeted neonatal echocardiography to individualize clinical assessment and management.

Clinical determinants of cerebrovascular reactivity in very preterm infants during the transitional period

BACKGROUND

Preterm infants are at enhanced risk of brain injury due to altered cerebral haemodynamics during postnatal transition. This observational study aimed to assess the clinical determinants of transitional cerebrovascular reactivity and its association with intraventricular haemorrhage (IVH).

METHODS

Preterm infants <32 weeks underwent continuous monitoring of cerebral oxygenation and heart rate over the first 72 h after birth. Serial cranial and cardiac ultrasound assessments were performed to evaluate the ductal status and to diagnose IVH onset. The moving correlation coefficient between cerebral oxygenation and heart rate (TOHRx) was calculated. Linear mixed-effect models were used to analyse the impact of relevant clinical variables on TOHRx. The association between TOHRx and IVH development was also assessed.

RESULTS

Seventy-seven infants were included. A haemodynamically significant patent ductus arteriosus (hsPDA) (β = 0.044, 95% CI: 0.007-0.081) and ongoing dopamine treatment (β = 0.096, 95% CI: 0.032-0.159) were associated with increasing TOHRx, indicating impaired cerebrovascular reactivity. A significant association between TOHRx, mean arterial blood pressure (β = -0.004, 95% CI: -0.007, -0.001) and CRIB-II score (β = 0.007, 95% CI: 0.001-0.015) was also observed. TOHRx was significantly higher in infants developing high-grade IVH compared to those without IVH.

CONCLUSIONS

Dopamine treatment, low blood pressure, hsPDA and high CRIB-II are associated with impaired cerebrovascular reactivity during postnatal transition, with potential implications on IVH development.

IMPACT

The correlation coefficient between cerebral oxygenation and heart rate (TOHRx) provides a non-invasive estimation of cerebrovascular reactivity, whose failure has a potential pathogenic role in the development of IVH in preterm infants. This study shows that cerebrovascular reactivity during the transitional period improves over time and is affected by specific clinical and therapeutic factors, whose knowledge could support the development of individualized neuroprotective strategies in at-risk preterm infants. The evidence of increased TOHRx in infants developing high-grade compared to low-grade or no IVH during the transitional period further supports the role of impaired cerebrovascular reactivity in IVH pathophysiology.

[Timing of surgical ligation of patent ductus arteriosus in very low birth weight infants]

OBJECTIVES

To study the effect of timing of surgical ligation of patent ductus arteriosus (PDA) on the prognosis of very low birth weight infants (VLBWI).

METHODS

The medical data of VLBWI who underwent transthoracic ligation for PDA from June 2018 to May 2021 were reviewed retrospectively. The infants were divided into early ligation group (≤21 days of age) and late ligation group (>21 days of age) based on the age of ligation. The two groups were compared in terms of perioperative clinical features, complications, and mortality. The risk factors for early surgical ligation were analyzed.

RESULTS

A total of 72 VLBWI were enrolled, with 19 infants (26%) in the early ligation group and 53 infants (74%) in the late ligation group. There were significant differences in birth weight, gestational age, weight at operation, days of age at operation, rates of preoperative invasive and noninvasive mechanical ventilation, incidence rate of pulmonary hemorrhage, incidence rate of hypotension, preoperative PDA internal diameter (mm/kg), intraoperative PDA external diameter (mm/kg), incidence rate of post-ligation cardiac syndrome, and duration of postoperative invasive mechanical ventilation between the two groups (P<0.05). A binary logistic regression analysis showed that pulmonary hemorrhage was an indication of early surgical ligation of PDA (P<0.05). There were no significant differences in the incidence rates of post-operative complications and the mortality rate between the early ligation and late ligation groups.

CONCLUSIONS

Early surgical ligation may be performed for VLBWI who are experiencing pulmonary hemorrhage and hemodynamically significant PDA confirmed by cardiac ultrasound after birth. However, post-ligation cardiac syndrome should attract enough attention. In addition, early surgical ligation of PDA does not increase the risk of surgery-related and long-term complications or death, indicating that it is a safe and feasible treatment option.

Value of bedside echocardiography in predicting persistent patency of the ductus arteriosus during the early postnatal period in very low birth weight infants

OBJECTIVES

To study the value of bedside echocardiography in predicting persistent patency of the ductus arteriosus during the early postnatal period in very low birth weight (VLBW) infants.

METHODS

A retrospective analysis was performed for 51 VLBW infants who were admitted from March 2020 to June 2021, with an age of ≤3 days and a length of hospital stay of ≥14 days. According to the diameter of patent ductus arteriosus (PDA) on days 14 and 28 after birth, the infants were divided into three groups: large PDA group (PDA diameter ≥2 mm), small PDA group (PDA diameter <2 mm), and PDA closure group (PDA diameter =0 mm). The echocardiographic parameters measured at 72 hours after birth were compared among the three groups. The receiver operating characteristic (ROC) curve was used to evaluate the value of the echocardiographic parameters in predicting persistent patency of the ductus arteriosus (PDA≥2 mm) at the ages of 14 and 28 days.

RESULTS

On day 14 after birth, there were 17 infants in the large PDA group, 11 in the small PDA group, and 23 in the PDA closure group. On day 28 after birth, there were 14 infants in the large PDA group, 9 in the small PDA group, and 26 in the PDA closure group. There were significant differences in gestational age, birth weight, rate of pulmonary surfactant use, and incidence rate of hypotension among the three groups (P<0.05). PDA diameter, end-diastolic velocity of the left pulmonary artery, left ventricular output, and left ventricular output/superior vena cava flow ratio measured at 72 hours after birth were associated with persistent patency of the ductus arteriosus at the ages of 14 and 28 days (P<0.05), and the ratio of the left atrium to aorta diameter was associated with persistent patency of the ductus arteriosus at the age of 28 days (P<0.05). The ROC curve analysis showed that the area under the curve that the PDA diameter measured at 72 hours after birth predicting the persistent patency of the ductus arteriosus at the ages of 14 and 28 days was the largest (0.841 and 0.927 respectively), followed by end-diastolic velocity of the left pulmonary artery, with the area under the curve of 0.793 and 0.833 respectively.

CONCLUSIONS

The indicators obtained by beside echocardiography at 72 hours after birth, especially PDA diameter and end-diastolic velocity of the left pulmonary artery, can predict persistent patency of the ductus arteriosus at the ages of 14 and 28 days in VLBW infants, which provides a basis for the implementation of early targeted treatment strategy for PDA.

Reference Values for Point-of-Care Echocardiographic Measurements of Preterm Infants in China

BACKGROUND

Few studies have examined the reference value of the left ventricular structure and function in preterm infants. This study was designed to establish a point-of-care echocardiographic reference range of left ventricular structure and function based on different gestational age, weight, and body surface area (BSA) for preterm infants within 7 days after birth.

METHODS

We retrospectively studied 489 patients with traditional echocardiographic data of left ventricular (LV) M-mode: LV end diastolic dimensions (LVED), LV end systolic dimension (LVES), end-diastolic interventricular septal thickness (IVSd), end diastolic LV posterior wall thickness (LVPWd), left atrial (LA) and aortic root (AO) diameters, and index of LA/AO, LV ejection fraction (LVEF), LV fractional shortening (LVFS), and pulsed wave Doppler: aortic valve flow rate (AV), peak mitral valve flow rate E(MV-E), peak mitral valve flow rate A(MV-A), and MV-E/A. The LV dimensions and the maximum blood flow velocities of the aortic valves and mitral valves according to gestational age, birth weight, and body surface area (BSA) are presented in percentiles tables. Percentile curves of aforesaid four cardiac measurements (LVED, LA diameter (LAD), MV-E, MV-E/A) using the R language Generalized Additive Models for Location, Scale and Shape (GAMLSS) method were developed according to different gestational ages and weights.

RESULTS

Measurements of all cardiac dimensions and Doppler maximum velocities of AV, MV-E, and MV-E/A showed a correlation with gestational age, weight, and BSA. LVED, LAD, MV-E, and MV-E/A showed a trend of increasing values with gestational age and weight on the percentile curves.

CONCLUSION

The percentile tables and graphs of these point-of-care echocardiographic data can provide reliable reference data for Chinese neonates. Normative values are recommended as a source of reference data for the identification of potentially abnormal echocardiography.

Impact of Carbon Dioxide on Cerebral Oxygenation and Vital Parameters in Stable Preterm and Term Infants Immediately after Birth

INTRODUCTION

Carbon dioxide (pCO2) induces changes in the tone of cerebral vessels. The aim of the present study was to evaluate the impact of pCO2 on cerebral regional tissue oxygen saturation (crSO2), cerebral fractional tissue oxygen extraction (cFTOE), and cerebral tissue oxygen extraction (cTOE), measured with near-infrared spectroscopy (NIRS), in preterm and term infants 15 min after birth.

METHODS

Post hoc analyses of secondary outcome parameters of prospective observational studies were performed. Stable preterm and term infants with cerebral NIRS monitoring (INVOS 5100C) until minute 15 after birth and a blood gas analysis, performed between minutes 14-18 after birth, were included. Heart rate (HR) and arterial oxygen saturation (SpO2) were recorded. pCO2 was correlated with crSO2, cFTOE, cTOE, SpO2, HR, and partial pressure of oxygen (pO2).

RESULTS

Eleven preterm infants with a median (IQR) gestational age of 34.8 (32.7-36.1) weeks were analyzed. Mean ± SD pCO2 was 53.5 ± 4.2 mm Hg. At minute 15 after birth, crSO2 was 82.6 (74.3-91.3)%, cFTOE 0.15 ± 0.09, cTOE 14.6 ± 8.4%, SpO2 97.4 ± 2.1%, and HR 152 (136-167) bpm. pCO2 correlated negatively with crSO2 (p = 0.012) and positively with cFTOE (p = 0.035) and cTOE (p = 0.037). Eighty-four term infants with a gestational age of 39.0 (38.5-38.9) weeks were analyzed. pCO2 was 53.5 ± 6.3 mm Hg. At minute 15 after birth, crSO2 was 84.4 (80.8-85.1)%, cFTOE 0.14 ± 0.08, cTOE 13.6 ± 7.9%, SpO2 96.5 ± 2.6%, and HR 155 (153-163) bpm. pCO2 did only negatively correlate with pO2 (p = 0.034) in term infants.

CONCLUSION

In preterm infants, higher pCO2 was associated with lower crSO2 and higher cFTOE/cTOE. In term infants, no associations were observed. The present findings suggest that the vasodilatative effect of pCO2 is less pronounced in preterm infants during immediate postnatal transition.

Correlation between arterial blood pressures and regional cerebral oxygen saturation in preterm neonates during postnatal transition-an observational study

OBJECTIVE

To assess whether blood pressure (systolic (SABP), diastolic (DABP), and mean arterial blood pressure (MABP) and cerebral-regional-oxygen-saturation (crSO2) and cerebral-fractional-tissue-oxygen-extraction (cFTOE) are associated after immediate fetal-to-neonatal transition in preterm neonates with and without respiratory support.

STUDY DESIGN

Post-hoc analyses of secondary outcome parameters of prospective observational studies were performed. We included moderate and late preterm neonates with and without respiratory support with cerebral NIRS monitoring (INVOS 5100c) and an oscillometric blood pressure measurement at minute 15 after birth. Heart rate (HR) and arterial oxygen saturation (SpO2) were monitored routinely. Blood pressure values were correlated with crSO2 and cFTOE.

RESULTS

47 preterm neonates with NIRS measurements and blood pressure measurement during immediate transition after birth were included. Twenty-five preterm neonates (gestational age: 34.4±1.6 weeks) received respiratory support. In these neonates crSO2 correlated significantly positively with systolic blood pressure (SABP; r = 0.46, p = 0.021), diastolic blood pressure (DABP; r = 0.51, p = 0.009) and, mean arterial pressure (MABP; r = 0.48, p = 0.015). cFTOE correlated significantly negatively with SABP (r = -0.44, p = 0.027), DABP (r = -0.49, p = 0.013) and mean MABP (r = -0.44, p = 0.029). Twenty-two preterm neonates (gestational age: 34.5 ± 1.5 weeks) did not receive respiratory support. In those neonates, neither crSO2 nor cFTOE correlated with blood pressure.

CONCLUSION

In compromised moderate and late preterm neonates with respiratory support, both, crSO2 and cFTOE correlated with blood pressure. These findings suggest that passive pressure-dependent cerebral perfusion was present in preterm neonates with respiratory support, indicating an impaired cerebral autoregulation in those compromised preterm neonates.

Percutaneous Closure of the Patent Ductus Arteriosus in Very-Low-Weight Infants

In view of the known complications of drug therapy and open surgical ligation, and the potential for prolonged patent ductus arteriosus (PDA) exposure to be harmful, health care practitioners have sought new approaches to achieve definitive ductal closure. Interest in percutaneous (catheter-based) PDA closure has emerged within the neonatal community as a viable treatment option, because it has been fueled by recent procedural and device modifications, as well as mounting feasibility and safety data. Herein, we provide a contemporary review of percutaneous PDA closure among infants at the crux of the medical debate-very-low-weight infants (≤1,500 g), including: 1) characterization of traditional PDA treatments (drug therapy, open surgical ligation) and conservative (nonintervention) management options; 2) a general overview of the major procedural steps of percutaneous ductal closure, including efforts to reduce thrombotic complications and the emergence of a novel US Food and Drug Administration-approved device; 3) a systematic review and meta-analysis to better understand risk profiles of percutaneous PDA closure in this population; and 4) discussion of current gaps in our understanding of optimal PDA care, including the critical need for well-designed, randomized, controlled clinical trials.

Relationship between gentamicin administration and ductal patency in very low birth weight infants

Background:

Patent ductus arteriosus (PDA) is associated with adverse clinical outcomes in very low birth weight (<1500g) infants.

Objective:

In our study, it was aimed to investigate the effect of gentamicin treatment, which is frequently used for early-onset sepsis on ductal patency.

Method:

We performed a single-center retrospective review of charts of preterm infants <32 weeks gestation with birth weight <1500 grams born between June 1, 2015, and December 31, 2019, at the neonatal intensive care unit. All infants underwent an echocardiogram (ECHO) at 72 hours. To determine the effect of gentamicin treatment on hemodynamically significant PDA (hsPDA), we compared the frequency and duration of gentamicin administration between infants with hsPDA and without hsPDA.

Results:

During the study period, 792 patients were evaluated. Gentamicin was given to more infants with hsPDA than to those without hsPDA (89.2 % vs. 64.6 %, p<0.001), and the duration of therapy was longer in those infants with hsPDA (7 days vs. 9 days, p<0.001). The area under the curve for duration of gentamicin was 0.772 (%95 CI: 0.742-0.804, P=0.0001), sensitivity: 59 (%95 CI: 53-65), specificity: 82 (%95 CI: 78-88), with a cut-off day for duration of gentamicin >7 days.

Conclusion:

In our study, it was found that ductal contraction decreased and hsPDA rate increased as the rate and duration of gentamicin increased.

Missed case of fever of unknown origin during COVID-19 pandemic: patent ductus arteriosus endarteritis

A 40-year-old woman presented with fever of unknown origin (FUO) for 2 months. Without a definitive diagnosis and having received multiple empirical antibiotics from outside without relief, she was referred to our centre. Cardiac auscultation was remarkable for a grade 3/6 continuous murmur in the upper left sternal border. Echocardiogram revealed a patent ductus arteriosus (PDA) and a 5×7 mm mobile vegetation at the pulmonary artery bifurcation. Blood culture grew Streptococcus mutans. Embolisation of the vegetation to the pulmonary circulation occurred after the start of intravenous antibiotics resulting in fever relapse. Antibiotics were continued for 6 weeks and the fever settled. She underwent device closure of PDA after 12 weeks and is currently doing fine. Infective endocarditis/endarteritis is an important differential in a patient of FUO. A thorough clinical examination is important in every case of FUO, gives an important lead into diagnosis and guides appropriate investigations to confirm it.

Association between intrauterine growth restriction and patent ductus arteriosus: Use of a dichorionic twin pregnancy model

OBJECTIVE

To evaluate the association between intrauterine growth restriction (IUGR) and the incidence of fetuses with patent ductus arteriosus (PDA) and Hemodynamically significant PDA (Hs-PDA) in dichorionic twins (DC) with selective IUGR.

MATERIALS AND METHODS

This is an observational cohort study and retrospective case assessment, involved twins born at Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan between 2013 and 2018. DC twins with selective IUGR (sIUGR) were defined as the presence of a birth weight discordance of >25% and a smaller twin with a birth weight below the tenth percentile. PDA was diagnosed using echocardiography between postnatal day 3 and 7. Hs-PDA was defined as PDA plus increased pulmonary circulation, poor systemic perfusion, cardiomegaly, pulmonary edema, or hypotension requiring pharmacotherapeutic intervention.

RESULT

A total of 1187 twins were delivered during the study period, and 53 DC twins with selective IUGR were included in this study. DC twins with PDA have higher rate of preterm birth, lower gestational age of delivery, and lower mean birth weight of both twins compared with DC twins without PDA. In a comparison of the sIUGR twin with the appropriate for gestational age co-twin, both the incidences of PDA (28.30% vs. 7.55%, respectively; P = 0.003) and Hs-PDA (24.53% vs. 5.66%, respectively; P = 0.002) were higher in sIUGR fetuses than in the appropriate for gestational age co-twins. Small gestational age of delivery was the only variable to predict PDA and Hs-PDA [p = 0.002, Odds ratio = 0.57 (0.39-0.82), p = 0.009, Odds ratio = 0.71 (0.55-0.92), respectively].

CONCLUSION

An analysis of dichorionic twins with sIUGR indicated that IUGR increased the risk of PDA and hemodynamically significant PDA.

Patent ductus arteriosus in preterm newborns: a tertiary hospital experience

INTRODUCTION

Patent ductus arteriosus (PDA) in preterm newborns has been associated with increased mortality and co-morbidities. This study aimed to characterize the population of preterm infants diagnosed with PDA and to identify predictive factors of response to medical treatment of PDA.

METHODS

An eight-year retrospective observational study was conducted, which included all preterm newborns (PTNB) with a gestational age between 23 and 32 weeks diagnosed with PDA, admitted to the Neonatal Unit of the Centro Hospitalar Universitário de São João. Univariate comparative analysis was performed and models for predicting the effectiveness of PDA treatment with ibuprofen were explored by multivariate logistic regression analysis.

RESULTS

115 cases were included in the study and 34 were excluded, with a final sample of 81 PTNB with PDA. The univariate analysis revealed significant differences in the closure efficacy by medical treatment with ibuprofen in several variables, and a multivariate logistic regression model was obtained (discriminative capacity 72.2%, sensitivity 98.1%, specificity 57.1%), considering the effect of gestational age, type of delivery, need for diuretics treatment and platelet transfusion.

CONCLUSION

This study enabled the characterization of the population of preterm infants diagnosed with PDA and the identification of a predictive model that can assist with predicting the effectiveness of the medical treatment and thus contribute to optimizing the medical approach to non-responders.

Management of Patent Ductus Arteriosus in Premature Infants in 2020

The patent ductus arteriosus (PDA) is the most commonly found cardiac condition in neonates. While there have been several studies and thousands of publications on the topic, the decision to treat the PDA is still strongly debated among cardiologists, surgeons, and neonatologists. This is in part due to the shortage of long-term benefits with the interventions studied. Practice variations still exist within sub-specialties and centers. This article briefly summarizes the history, embryology and histology of the PDA. It also succinctly discusses the hemodynamic significance of a PDA which builds the framework to review all the available literature on PDA closure in premature infants, though not a paradigm shift just yet; it introduces transcatheter PDA closure (TCPC) as a possible armament to the clinician for this age-old problem.

A Randomized Placebo-Controlled Pilot Trial of Early Targeted Nonsteroidal Anti-Inflammatory Drugs in Preterm Infants with a Patent Ductus Arteriosus

OBJECTIVE

To establish the feasibility of a future large randomized trial to compare early treatment with nonsteroidal anti-inflammatory drugs (NSAIDs) while awaiting spontaneous patent ductus arteriosus (PDA) closure.

STUDY DESIGN

Preterm infants at <29 weeks of gestation with a PDA diameter >1.5 mm and <72 hours after birth were randomized to NSAIDs vs placebo. No open-label NSAID treatment was allowed in either arm, but all infants with PDA volume load received supportive management, including optimization of airway pressure, careful fluid management, and diuretics as needed. The pilot outcomes were recruitment rate and incidence of open-label treatment. Secondary clinical outcomes included chronic lung disease or death, the planned primary outcome for a future large trial.

RESULTS

Overall, 54% of the approached parents consented to participate in the study. The median recruitment rate was 3 infants per month, and a total of 72 infants were randomized. One patient in each arm received open-label treatment. PDA closure rates were 74% for the NSAIDs arm vs 30% for the placebo arm, but this was not associated with significant changes in clinical outcomes.

CONCLUSIONS

This pilot trial showed that recruitment of more than one-half of eligible infants with a low incidence of open-label treatment is feasible. PDA closure rates and clinical outcomes were similar to those reported in previous PDA trials.

Platelet Count Might Be Associated With the Closure of Hemodynamically Significant Patent Ductus Arteriosus

Background: Platelet-rich thrombosis leads to the occlusion of arteries. Whether the association between platelet count and closure of hemodynamically significant patent ductus arteriosus (hsPDA) exists remains inconclusive. Given that neonatal platelet count is significantly affected by infection, this study aims to evaluate the association of platelet parameters before ibuprofen treatment with the closure of hsPDA in very low birth weight (VLBW) infants without concurrent infection. Methods: A retrospective study was conducted at the NICU of Shenzhen Maternity and Child Healthcare Hospital from January 2016 to August 2020. VLBW infants diagnosed with hsPDA, treated with oral ibuprofen and without concurrent infection were included in this study. The platelet parameters were retrieved from the whole-blood test routinely performed within 24 h before starting treatment of oral ibuprofen. A multiple regression model was built to evaluate the association between platelet parameters before ibuprofen treatment and successful closure of hsPDA. Results: A total of 129 premature infants with hsPDA were analyzed in this study. After oral ibuprofen treatment, successful closure of hsPDA was achieved in 70 (54.3%) infants. The gestational age at birth and birth weight in infants with successful or failed closure of hsPDA after ibuprofen treatment were 28.3 vs. 27.6 weeks (p = 0.016) and 1,120 vs. 960 g (p = 0.043), respectively. The rate of mechanical ventilation in infants with successful closure of hsPDA was significantly lower compared to those with failed closure of hsPDA, 31.4 vs. 54.2%, p = 0.014. The platelet count in infants with successful closure of hsPDA after ibuprofen treatment was significantly higher compared to those with failed closure of hsPDA, 212 vs. 183 (in a unit of 10⁹/L), respectively (p = 0.024). Multivariate logistic regression analysis showed that a higher platelet count (≥181 × 10⁹/L) before ibuprofen treatment was independently associated with successful closure of hsPDA [odds ratio 2.556, 95% confidence interval (1.101-5.932), p = 0.029]. Conclusion: The findings in this study suggest that a higher platelet count before oral ibuprofen treatment may predict the probability of successful closure of hsPDA in VLBW infants.

Interventions on patent ductus arteriosus and its impact on congenital heart disease

The ductus arteriosus (DA) connects the pulmonary artery to the aorta to bypass the pulmonary circulation in utero. It normally closes within 24-72 hours after birth due to increased pulmonary resistance from an increase in oxygen partial pressure with the baby's first breath. Medical treatment can help close the DA in certain situations where closure is delayed. However, in duct-dependent cardiac defects, the presence of the DA is crucial for survival and as such medical and surgical techniques have evolved to prevent closure. This review aims to outline the two main management options for keeping a ductus arteriosus patent. This includes stenting the PDA and shunting via a modified Blalock-Taussig shunt. Whilst both techniques exist, multicentre trials have found equal mortality end points but significantly reduced morbidity with stenting than shunting. This is also reflected by shorter recovery times, reduced requirement for extracorporeal membrane oxygenation (ECMO), and improved quality of life, although stent longevity remains a limiting factor.

Patent ductus arteriosus and cerebral, cardiac, and gut hemodynamics in premature neonates

Patent ductus arteriosus is associated with multiple comorbidities in premature infants, however a causal link or strategy to decrease these morbidities has not been found. The association between the patent ductus arteriosus and morbidities has biologic plausibility as, like any cardiac mixing lesion, a significant systemic to pulmonic shunt may lead to pulmonary over-circulation and systemic hypoperfusion. Understanding the underlying pathophysiology of associated morbidities in the setting of a patent ductus arteriosus may aid in risk stratifying infants and offer a patient targeted approach to infants with a pathological ductal shunt. While the deleterious impact of increased pulmonary blood flow maybe easier to identify, the impact on end-organ perfusion is more challenging. In this review, we will discuss the pathophysiology of a hemodynamically significant patent ductus arteriosus in premature infants, impact on end-organ perfusion and associated morbidities, and novel modalities to assess shunt volume and effect on end-organ perfusion.

Molecular and Mechanical Mechanisms Regulating Ductus Arteriosus Closure in Preterm Infants

Failure of ductus arteriosus closure after preterm birth is associated with significant morbidities. Ductal closure requires and is regulated by a complex interplay of molecular and mechanical mechanisms with underlying genetic factors. In utero patency of the ductus is maintained by low oxygen tension, high levels of prostaglandins, nitric oxide and carbon monoxide. After birth, ductal closure occurs first by functional closure, followed by anatomical remodeling. High oxygen tension and decreased prostaglandin levels mediated by numerous factors including potassium channels, endothelin-1, isoprostanes lead to the contraction of the ductus. Bradykinin and corticosteroids also induce ductal constriction by attenuating the sensitivity of the ductus to PGE2. Smooth muscle cells of the ductus can sense oxygen through a mitochondrial network by the role of Rho-kinase pathway which ends up with increased intracellular calcium levels and contraction of myosin light chains. Anatomical closure of the ductus is also complex with various mechanisms such as migration and proliferation of smooth muscle cells, extracellular matrix production, endothelial cell proliferation which mediate cushion formation with the interaction of blood cells. Regulation of vessel walls is affected by retinoic acid, TGF-β1, notch signaling, hyaluronan, fibronectin, chondroitin sulfate, elastin, and vascular endothelial cell growth factor (VEGF). Formation of the platelet plug facilitates luminal remodeling by the obstruction of the constricted ductal lumen. Vasa vasorum are more pronounced in the term ductus but are less active in the preterm ductus. More than 100 genes are effective in the prostaglandin pathway or in vascular smooth muscle development and structure may affect the patency of ductus. Hemodynamic changes after birth including fluid load and flow characteristics as well as shear forces within the ductus also stimulate closure. Current pharmacological treatment for the closure of a patent ductus is based on the blockage of the prostaglandin pathway mainly through COX or POX inhibition, albeit with some limitations and side effects. Further research for new agents aiming ductal closure should focus on a clear understanding of vascular biology of the ductus.

Cardiovascular and cerebrovascular responses to cardio-respiratory events in preterm infants during the transitional period

KEY POINTS

Non-invasive simultaneous multiparametric monitoring allows the in vivo evaluation of cerebral and cardiovascular haemodynamic responses to different types of recurrent episodes of intermittent hypoxia and/or bradycardia, also defined as cardio-respiratory events (CRE), in preterm neonates during postnatal transition. By decreasing left cardiac output, bradycardia further contributes to cerebral hypoxia during CRE. The presence of a haemodynamically significant patent ductus arteriosus results in a deeper impairment of cerebral oxygen status in response to CRE, whereas the brain-sparing remodelling of the fetal circulation resulting from placental insufficiency is associated with more favourable haemodynamic responses to intermittent hypoxia. During transition, the haemodynamic impact of CRE is influenced not only by the event type, but also by specific clinical features; this highlights the importance of developing individualized approaches to reduce the hypoxic burden in this delicate phase.

ABSTRACT

The present observational prospective study aimed to investigate cerebral and cardiovascular haemodynamic responses to different types of cardio-respiratory events (CRE) in preterm infants during postnatal transition, as well as evaluate the impact of relevant clinical characteristics. Infants with gestational age (GA) <32 weeks and/or birth weight <1500 g were enrolled after birth. Cerebral oxygenation index (cTOI), fractional oxygen extraction (cFTOE), cardiac output (CO), cardiac contractility (iCON) and systemic vascular resistances (sVR) were simultaneously monitored over the first 72 h by near-infrared spectroscopy and electrical velocimetry. CRE were clustered into isolated bradycardia (IB), isolated desaturation (ID) and combined desaturation/bradycardia (DB). For each parameter, percentage changes from baseline (%Δ) were calculated. The impact of different CRE types and clinical variables on %Δ was evaluated with generalized estimating equations. In total, 1426 events were analysed. %ΔcTOI significantly differed among ID, IB and DB (P < 0.001), with the latter showing the greatest drop. %ΔcFTOE decreased significantly during DB (P < 0.001) and ID (P < 0.001) compared to IB. DB and IB were associated with more negative %ΔCO (P < 0.001) and more positive %ΔsVR (P < 0.001) compared to ID. A slight iCON reduction was observed during DB compared to ID (P = 0.043). Antenatal umbilical Doppler impairment, GA and the presence of a haemodynamically significant patent ductus arteriosus had a significant independent impact on %ΔcTOI, %ΔcFTOE and %ΔCO. During the transitional period, the haemodynamic responses to CRE are influenced by the event type and by specific neonatal characteristics, suggesting the importance of targeted individualized approaches for minimizing the risk of cerebral injury in the preterm population.

Cardiorespiratory Events in Infants Born Preterm during the Transitional Period

OBJECTIVE

To investigate the features of cardiorespiratory events in infants born preterm during the transitional period, and to evaluate whether different neonatal characteristics may correlate with event type, duration, and severity.

STUDY DESIGN

Infants with gestational age (GA) <32 weeks and/or birth weight <1500 g were enrolled in this observational prospective study. Heart rate (HR) and peripheral oxygen saturation (SpO₂) were recorded continuously over the first 72 hours. Cardiorespiratory events of ≥10 seconds were clustered into isolated desaturation (SpO₂ <85%), isolated bradycardia (HR <100 bpm or <70% of baseline), or combined desaturation/bradycardia and classified as mild, moderate, or severe. The daily incidences of isolated desaturation, isolated bradycardia, and combined desaturation and bradycardia were analyzed. The effects of relevant clinical variables on cardiorespiratory event type and severity were assessed using generalized estimating equations.

RESULTS

Among the 1050 events analyzed, isolated desaturations were the most frequent (n = 625) and isolated bradycardias the least common (n = 171). The number of cardiorespiratory events increased significantly from day 1 to day 2 (P = .028). One in 5 events had severe characteristics; event severity was highest for combined desaturation and bradycardia (P < .001). Compared with other event types, the incidence of combined desaturation and bradycardia was inversely correlated with GA (P = .029) and was higher with the use of continuous positive airway pressure (P = .002). The presence of a hemodynamically significant patent ductus arteriosus was associated with the occurrence of isolated desaturations (P = .001) and with a longer duration of cardiorespiratory events (P = .003).

CONCLUSIONS

Cardiorespiratory events during transition exhibit distinct types, duration, and severity. Neonatal characteristics are associated with the clinical features of these events, indicating that a tailored clinical approach may reduce the hypoxic burden in preterm infants aged 0-72 hours.

Related Factors of Patent Ductus Arteriosus in Preterm Infants: A Systematic Review and Meta-Analysis

Background: Patent ductus arteriosus (PDA) is a dramatically harmful disease in the neonatal period, in particular common in preterm infants, and our study was to determine related factors of PDA in preterm infants. Methods: A comprehensive literature review was conducted in PubMed, EMBASE, and Web of Science. The pooled odds ratio and standard mean difference were calculated to compare dichotomous and continuous variables, respectively. In addition, we also assessed the heterogeneity and publication bias and carried out sensitivity analysis for each related factor. Results: We included 45 studies with 87,419 individuals. After the primary analysis and a series of adjustments, results showed chorioamnionitis, lower gestational age, lower birth weight, bronchopulmonary dysplasia, intraventricular hemorrhage, necrotizing enterocolitis, respiratory distress syndrome, sepsis, surfactant treatment, ventilation, and lower platelet count had a positive correlation with PDA, while small for gestational age decreased the incidence of PDA in preterm infants. Besides, premature rupture of membranes, preeclampsia, antenatal steroids, male gender, mean platelet volume, and platelet distribution width were found to have no statistically significant relationship with PDA. Conclusion: Preterm infants with more immature characteristics generally have a higher likelihood to develop PDA. The prevention, diagnosis, and management of PDA may depend on these results, and effective measures can be taken accordingly.

To Feed or Not to Feed: A Critical Overview of Enteral Feeding Management and Gastrointestinal Complications in Preterm Neonates with a Patent Ductus Arteriosus

The management of enteral feeds in preterm infants with a hemodynamically significant patent ductus arteriosus (hs-PDA) is a major challenge for neonatologists due to the fear of gastrointestinal (GI) complications. This review aims to analyze the available evidence on the complex relation between the presence and management of PDA, enteral feeding practices, and GI outcomes in the preterm population. There is limited evidence, based on small and heterogeneous trials, that hs-PDA may affect the splanchnic hemodynamic response to enteral feeds. While the presence of PDA seems a risk factor for adverse GI outcomes, the benefits of feeding withholding during pharmacological PDA treatment are controversial. The lack of robust evidence in support of or against a timely feeding introduction or feeding withholding during pharmacological PDA closure in preterm neonates does not allow to draw any related recommendation. While waiting for further data, the feeding management of this population should be carefully evaluated and possibly individualized on the basis of the infants’ hemodynamic and clinical characteristics. Large, multicentric trials would help to better clarify the physiological mechanisms underlying the development of gut hypoperfusion, and to evaluate the impact of enteral feeds on splanchnic hemodynamics in relation to PDA features and treatment.

NT-proBNP as an Early Marker of Diastolic Ventricular Dysfunction in Very-Low-Birth-Weight Infants

The objective is to examine the correlation between plasma levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) and tissue Doppler imaging (TDI) echocardiographic parameters in the first 28 days of life in very-low-birth-weight infants (VLBWI). VLBWI admitted to the Neonatal Intensive Care Unit (NICU) at Hospital Puerta del Mar, Spain, from January 2015 to January 2017 were prospectively enrolled. Weekly determination of plasma NT-proBNP (pg/mL), and echocardiograms were done during the first 28 days of life. 101 preterm infants with a mean GA of 28.85 weeks (± 1.85 SD) and mean birth weight of 1152 g (± 247.4 SD) were included. A total of 483 echocardiograms and 139 NT-proBNP determinations were performed. We found a negative correlation between plasma NT-proBNP levels and diastolic velocities: mitral A' (ρ = - 0.15, p = 0.04), mitral E' (ρ = - 0.17, p = 0.02), tricuspid A' (ρ = - 0.20, p = 0.006), tricuspid E' (ρ = - 0.24, p = 0.0009). In the first 24 h of life, NT-proBNP levels were strongly correlated with mitral A' and E' velocities in patients with no patent ductus arteriosus (PDA) (ρ = - 0.75, p = 0.04). In preterm patients, elevated NT-proBNP levels are related to worse diastolic myocardial function. In the first 24 h, this correlation is much stronger in the absence of PDA.

Intrauterine Growth Restriction and Patent Ductus Arteriosus in Very and Extremely Preterm Infants: A Systematic Review and Meta-Analysis

It is generally accepted that intrauterine growth restriction (IUGR) increases morbidity and mortality among very preterm neonates. However, evidence is hampered by the widespread practice of using the terms small for gestational age (SGA) and IUGR as synonyms. We conducted a systematic review of studies reporting on the association between IUGR/SGA and patent ductus arteriosus (PDA). PubMed/MEDLINE and EMBASE databases were searched. Of 993 studies reviewed, 47 (50,790 infants) were included. Studies were combined using a random effects model and sources of heterogeneity were determined by subgroup and meta-regression analyses. Meta-analysis of all included studies showed a significantly reduced risk of PDA in the SGA/IUGR group with an odds ratio (OR) of 0.82, and a 95% confidence interval (CI) of 0.70 to 0.96 (p = 0.015). Of the 47 studies, only 7 used a definition for growth restriction that went beyond birth weight (BW) for gestational age (GA). When pooled, meta-analysis could not demonstrate a significant effect size (OR 1.31, 95% CI 0.75 to 2.27, p = 0.343). Moreover, the significantly reduced risk of PDA was found in the 25 studies defining SGA as BW <10th percentile (OR 0.81, 95% CI 0.66 to 0.98, p = 0.032), but not in the 6 studies defining SGA as BW <3rd (OR 1.09, 95% CI 0.70 to 1.71, p = 0.694), or in the 27 studies using a more refined definition of PDA (i.e., hemodynamically significant PDA or PDA requiring treatment, OR 0.87, 95% CI 0.72 to 1.04, p = 0.133). In addition, we found that GA was significantly higher in the SGA/IUGR group (18 studies, mean difference 0.63 weeks, 95% CI 0.24 to 1.03, p = 0.002). Meta-regression analysis confirmed the correlation between this difference in GA and PDA risk. In summary, we observed marked heterogeneity across studies in the definition of growth restriction and PDA, and we found differences between the control and growth-restricted groups in relevant baseline characteristics, such as GA. Therefore, our meta-analysis could not provide conclusive evidence on the association between growth restriction and PDA.

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.