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.

Hemodynamic evaluation in preterm infants using ultrasonic cardiac output monitor (USCOM).

We aimed to establish reference ranges for USCOM parameters in preterm infants, determine factors that affect cardiac output, and evaluate the measurement repeatability. This retro-prospective study was performed at Fondazione IRCCS San Gerardo dei Tintori, Monza, Italy. We included infants below 32 weeks of gestational age (GA) and/or 1500 g of birth weight (BW). We excluded infants with congenital heart diseases or hemodynamic instability. Measurements were performed at 3 ± 1, 7 ± 2, and 14 ± 2 postnatal days. We analyzed 204 measurements from 92 patients (median GA = 30.57 weeks, BW = 1360 g). The mean (SD) cardiac output (CO) was 278 (55) ml/min/kg, cardiac index (CI) was 3.1 (0.5) L/min/m2, and systemic vascular resistance (SVRI) was 1292 (294) d*s*cm-5/m2. CO presented a negative correlation with postmenstrual age (PMA), while SVRI presented a positive correlation with PMA. The repeatability coefficient was 31 ml/kg/min (12%).  Conclusion: This is the first study describing reference values for USCOM parameters in hemodynamically stable preterm infants and factors affecting their variability. Further studies to investigate the usefulness of USCOM for the longitudinal assessment of patients at risk for cardiovascular instability or monitoring the response to therapies are warranted. What is Known: • The ultrasonic cardiac output monitoring (USCOM) has been widely used on adult and pediatric patients and reference ranges for cardiac output (CO) by USCOM have been established in term infants. What is New: • We established reference values for USCOM parameters in very preterm and very-low-birth-weight infants; the reference ranges for CO by USCOM in the study population were 198-405 ml/kg/min. • CO normalized by body weight presented a significant negative correlation with postmenstrual age (PMA); systemic vascular resistance index presented a significant positive correlation with PMA.

Prenatal use of indomethacin for preterm labor and renal function among very low birth weight infants.

BACKGROUND: Indomethacin is administered as a tocolytic agent for threatening preterm labor <28weeks of gestation. Only a few, not conclusive, studies have investigated its nephrotoxicity in very low birth weight (VLBW) infants. We investigated whether indomethacin increases the incidence of acute kidney injury (AKI) among VLBW infants. METHODS: This is a retrospective study including all VLBW infants born at our center between January 1, 2005, and December 31, 2013. Indomethacin was administered to women with preterm labor and intact membranes. Neonatal AKI was defined according to KDIGO classification. Univariate analyses were performed comparing VLBW infants exposed to and not exposed to indomethacin. In the multivariable model, the association of indomethacin and AKI was adjusted for patent ductus arteriosus, use of nephrotoxic medications, birth weight, and gestational age. RESULTS: Five hundred seventy-five VLBW infants were included, 49 (8.5%) of whom were exposed to indomethacin in utero. The univariate analysis showed that infants exposed to indomethacin had lower birth weight, lower gestational age, and higher incidence of AKI than infants not exposed. The multivariable model adjusted for confounding factors confirmed an increased risk of AKI in relation to gestational age at birth <27 weeks, but not to indomethacin. CONCLUSIONS: Our data suggest that extreme prematurity, but not the use of indomethacin, is associated with AKI.

Transcatheter closure in preterm infants with patent ductus arteriosus: feasibility, results, hemodynamic monitoring and future prospectives.

Ductal patency of preterm infants is potentially associated with long term morbidities related to either pulmonary overflow or systemic steal. When an interventional closure is needed, it can be achieved with either surgical ligation or a catheter-based approach.Transcatheter PDA closure is among the safest of interventional cardiac procedures and it is the first choice for ductal closure in adults, children, and infants weighing more than 6 kg. In preterm and very low birth weight infants, it is increasingly becoming a valid and safe alternative to ligation, especially for the high success rate and the minor invasiveness and side effects. Nevertheless, being it performed at increasingly lower weights and gestational ages, hemodynamic complications are possible events to be foreseen.Procedural steps, timing, results, possible complications and available monitoring systems, as well as future outlooks are here discussed.

Association of intrauterine growth restriction and low birth weight with acute kidney injury in preterm neonates.

BACKGROUND: Preterm birth alters nephrogenesis and reduces the total nephron number. Intrauterine growth restriction (IUGR) seems to worsen nephron loss, but only a few studies have investigated its role in neonatal kidney impairment. We investigated whether IUGR, defined as reduced estimated fetal growth and/or placental flow alterations and low birth weight z-score, increases the risk of developing acute kidney injury (AKI) in very preterm infants. METHODS: We performed a retrospective study including infants born with a birth weight (BW) ≤ 1500 g and/or gestational age (GA) ≤ 32 weeks admitted to our center between January 2016 and December 2021. Neonatal AKI was defined according to the neonatal KDIGO classification based on the decline of urine output and/or creatinine elevation. We used multivariable linear regressions to verify the association between AKI and GA, BW z-score, IUGR definition, and hemodynamically significant patent ductus arteriosus (PDA). RESULTS: We included 282 infants in the analysis, with a median (IQR) GA = 29.4 (27.4, 31.3) weeks, BW = 1150 (870, 1360) g, and BW z-score = - 0.57 (- 1.64, 0.25). AKI was diagnosed in 36 (13%) patients, and 58 (21%) had PDA. AKI was significantly associated with BW z-score (beta (std. error) = - 0.08 (0.03), p = 0.008) and severe IUGR (beta (std. error) = 0.21 (0.08), p = 0.009), after adjusting for GA and PDA. CONCLUSIONS: Our data suggest that low BW z-score and IUGR could represent adjunctive risk factors for kidney impairment in preterm babies. A higher resolution version of the Graphical abstract is available as Supplementary information.

Reply to the comment on "Fluid restriction in management of patent ductus arteriosus in Italy: a nationwide survey".

The Authors Chang Liu B.S and Yuan Shi commented our paper on Fluid restriction in management of patent ductus arteriosus (PDA) in Italy. With our study, we conducted a prospective cross-sectional survey among all Italian Neonatal Intensive Care Units (NICUs) to address conservative management of patent ductus arteriosus (PDA) in preterm infants below 29 weeks' gestational age (GA), with specific regard to fluid restriction (FR). The Authors wondered if the heterogeneity of use of fluid restriction both as a prophylactic tool and as a conservative tool when a hemodynamically significant PDA is diagnosed, was due to economic disparities among areas of the included centers. Conducting a secondary analysis of our data, we observed that if we separately consider the responses of two areas, northern and central-southern Italy, FR is slightly more frequently applied in Central and Southern regions (82%) as compared to Northern regions (78%), although this finding does not reach statistical significance. No correlation between the likelihood to adopt conservative measures and the amount of allowed fluid intake was found. The hypothesis that "less fluid intake resulted in milder clinical and echocardiographic presentations of PDA, and thus a lower rate of pharmacological treatment" cannot be supported by our current study design and might deserve future investigations.

Left ventricular diastolic function and respiratory outcomes in preterm infants: a retrospective study.

BACKGROUND: The role of left ventricular (LV) diastolic pressure in the pathophysiology of bronchopulmonary dysplasia (BPD) is unclear. We evaluated the trajectory of echocardiographic parameters of LV diastolic function and the association with respiratory outcomes in preterm infants. METHODS: We retrospectively analysed measurements of LV diastolic function (E, e', A, Ee' and E/A ratios) in infants below 32 weeks' gestation (GA). We compared infants with and without BPD by two-way RM ANOVA. We considered Ee' ratio as a proxy of LV filling pressure and identified a cut-off value using ROC analysis. We divided infants using such threshold and compared respiratory outcomes between groups by Mann-Whitney or Chi-square tests. RESULTS: We included 72 infants. Ee' ratio at 28 days was significantly associated with the duration of respiratory support (beta (std. error) = 5.32 (1.82), p = 0.005) and BPD (beta = 0.27 (0.10), p = 0.008). Infants with Ee' ratio > 12 at 28 days had longer respiratory support, oxygen requirement, and higher BPD rates than infants with Ee' ratio ≤ 12. CONCLUSION: LV diastolic function associated with elevated LV filling pressure may contribute to the pathophysiology of BPD. Serial echocardiographic measurements could identify infants at risk of worse respiratory outcomes. IMPACT: In very preterm infants, we assessed the trajectory of left ventricular diastolic function by serial echocardiographic evaluations and evaluated its association with respiratory outcomes. On average, infants who developed bronchopulmonary dysplasia had higher Ee' at 28 postnatal days and 36 weeks postmentrual age than infants who did not develop the disease. Infants with elevated Ee' at 28 postnatal days, suggestive of elevated left atrial pressure, required longer respiratory support.

Fluid restriction in management of patent ductus arteriosus in Italy: a nationwide survey.

We aimed at establishing the state of the art in fluid restriction practice in our national setting and providing a foundation for future research efforts. A prospective cross-sectional survey was conducted among all 114 Italian Neonatal Units in order to address conservative management of patent ductus arteriosus (PDA) in preterm infants below 29 weeks' gestational age (GA), with specific regard to fluid restriction. Response rate was 80%. Conservative measures for PDA management are provided in the majority of NICUs and 80% of centers reduce fluid intake in neonates with PDA. No relationship can be found among pharmacologically or surgically treated patients per year and the approach to fluid restriction. The minimum intake administered at regimen when fluid restriction is applied is associated to the ratio between the maximum number of neonates managed pharmacologically and number of admitted < 29 weeks' GA newborns. CONCLUSION: Our survey shows an extreme variability among centers in terms of use of fluid restriction as a prophylactic tool but also in terms of its use (both opportunity and modality) when a hemodynamically significant PDA is diagnosed. This variability, that can be also found in randomized trials and observational studies, suggests that further evidence is needed to better understand its potential beneficial effects and its potential harms such as dehydration, hypotension, decreased end-organ perfusion, and reduced caloric intake. WHAT IS KNOWN: • The lack of demonstrable improvement following the treatment of patent ductus arteriosus has recently paved the way to a more conservative approach. • Fluid restriction is the most commonly applied conservative treatment of PDA. WHAT IS NEW: • Among Italian NICUs an extreme variability in terms of indications, timing and modalities of application of Fluid restriction can be found. • This variability reflects the lack of standardization of this practice and the contrasting evidence on its efficacy.

Exaggerated mini-puberty in a preterm girl: a case report and review of literature.

OBJECTIVES: Mini-puberty is the physiological and transient activation of the hypothalamic-pituitary-gonadal axis occurring during the first months after birth. In preterm infants, the hormonal surge is more pronounced and longer-lasting than in at-term-peers. To date, only few cases of vaginal bleeding in the setting of an exaggerated mini-puberty have been reported. CASE PRESENTATION: At the corrected age of 3 months, an ex-very-preterm girl presented with breast enlargement and recurrent vaginal bleeding. A remarkable increase in gonadotropins and estradiol levels was detected, while pelvic ultrasound highlighted a large right ovarian cyst. As brain and pituitary MRI showed negative findings, an exaggerated mini-puberty was suspected and no additional investigations were undertaken. The subsequent progressive regression of clinical, biochemical and sonographic findings confirmed the diagnosis. CONCLUSIONS: Although exaggerated mini-puberty of infancy in ex-preterm girls is a rare event, it is important to raise knowledge of this para-physiological condition in order to avoid unnecessary investigations and treatment.

Evaluation of hemodynamics in healthy term neonates using ultrasonic cardiac output monitor.

BACKGROUND: Transition from intrauterine to extrauterine life is a critical phase during which several changes occur in cardiovascular system. In clinical practice, it is important to have a method that allows an easy, rapid and precise evaluation of hemodynamic status of a newborn for clinical management. We here propose a rapid, broadly applicable method to monitor cardiovascular function using ultrasonic cardiac output monitoring (USCOM). METHODS: We here present data obtained from a cohort of healthy term newborns (n = 43) born by programmed cesarean section at Fondazione MBBM, Ospedale San Gerardo. Measurements were performed during the first hour of life, then at 6 + 2, at 12-24, and 48 h of life. We performed a screening echocardiography to identify a patent duct at 24 h and, if patent, it was repeated at 48 h of life. RESULTS: We show that physiologically, during the first 48 h of life, blood pressure and systemic vascular resistance gradually increase, while there is a concomitant reduction in stroke volume, cardiac output, and cardiac index. The presence of patent ductus arteriosus significantly reduces cardiac output (p = 0.006) and stroke volume (p = 0.023). Furthermore, newborns born at 37 weeks of gestational age display significantly lower cardiac output (p < 0.001), cardiac index (p = 0.045) and stroke volume (p < 0.001) compared to newborns born at 38 and ≥ 39 weeks. Finally, birth-weight (whether adequate, small or large for gestational age) significantly affects blood pressure (p = 0.0349), stroke volume (p < 0.0001), cardiac output (p < 0.0001) and cardiac index (p = 0.0004). In particular, LGA infants display a transient increase in cardiac index, cardiac output and stroke volume up to 24 h of life; showing a different behavior from AGA and SGA infants. CONCLUSIONS: Compared to previous studies, we expanded measurements to longer time-points and we analyzed the impact of commonly used clinical variables on hemodynamics during transition phase thus making our data clinically applicable in daily routine. We calculate reference values for each population, which can be of clinical relevance for quick bedside evaluation in neonatal intensive care unit.

Survey of PDA management in very low birth weight infants across Italy.

BACKGROUND: The optimal management of PDA in very low birth weight (VLBW) infants is still controversial. Aim of our study was to investigate the management of PDA in the Italian neonatal intensive care units (NICU). METHODS: We conducted an on-line survey study from June to September 2017. A 50-items questionnaire was developed by the Italian Neonatal Cardiology Study Group and was sent to Italian NICUs. RESULTS: The overall response rate was 72%. Diagnosis of PDA was done by neonatologists, cardiologists or both (62, 12 and 28% respectively). PDA significance was assessed by a comprehensive approach in all centers, although we found a heterogeneous combination of parameters and cut-offs used. None used prophylactic treatment. 19% of centers treated PDA in the first 24 h, 60% after the first 24 h, following screening echocardiography or clinical symptoms, 18% after the first 72 h and 2% after the first week. In the first course of treatment ibuprofen, indomethacin and paracetamol were used in 87, 6 and 7% of centers respectively. Median of surgical ligation was 3% (1-6%). CONCLUSIONS: Significant variations exist in the management of PDA in Italy. Conservative strategy and targeted treatment to infants older than 24 h with echocardiographic signs of hemodynamic significance seemed to be the most adopted approach.

Effects of antenatal indomethacin on ductus arteriosus early closure and on adverse outcomes in preterm neonates.

Introduction: Premature birth is a leading cause of neonatal morbidity and mortality. Since gestational age at birth is the most important predictive factor of adverse neonatal outcomes, strategies to postpone premature labor are of major importance. Studies on tocolytic drugs show that COX inhibitors such as indomethacin are superior to others in terms of efficiency in delaying birth, but results concerning neonatal outcomes associated with prenatal exposure to these drugs show controversial results. Indomethacin is also used in the postnatal age for pharmacologic treatment of patent ductus arteriosus (PDA), but no data concerning the effects of antenatal exposure on postnatal ductal patency are available.Methods: In this study, we focused primarily on the association between antenatal indomethacin (AI) and postnatal patency of ductus arteriosus while our secondary aim was to highlight any possible influence of AI exposure on adverse neonatal outcomes. We performed a retrospective analysis of 241 medical records of newborns born before 33 weeks' gestation and exposed to antenatal tocolysis. Obstetrical data and neonatal outcomes of newborns exposed to AI were compared to those of neonates exposed to other tocolytic drugs. Early ductal closure (EDC) was defined when functional echocardiography performed within 24 hours of life showed a closed duct. Occurrence of intraventricular hemorrhage (IVH), periventricular leukomalacia (PVL), respiratory distress syndrome (RDS), chronic lung disease (CLD), necrotizing enterocolitis (NEC), sepsis, and PDA were compared between the groups and the diagnosis of at least one of III-IV grade IVH, PVL, CLD, sepsis, surgical NEC, or death was defined as a severe outcome.Results: The univariate analysis showed that infants in the AI group were at a higher risk of IVH, CLD, RDS, sepsis, and PDA. The incidence of severe outcomes also appeared to be higher in this group, while no effect of AI on PDA was observed. Since we noticed that infants exposed to AI had a lower gestational age and worse clinical conditions at birth when compared to the controls, we considered this as a confounding factor. To overcome this bias, we performed a multivariate analysis that evidenced no significant role of AI on the occurrence of severe outcomes. On the other hand, a possible association was confirmed for all degrees of IVH (OR: 3.16, 95% CI : [1.41; 7.05]) and sepsis (OR: 2.81, 95% CI: [1.24; 6,28]).Conclusions: The unexpected result shown by the multivariate analysis was the association between AI exposure and EDC (OR: 2.52, 95% CI: [1.02; 6.21]). This result, which has never been evidenced in previous studies, has great clinical importance. It is well known that PDA is more frequent at lower gestational ages, thus reducing the incidence of PDA could lead to an improvement of overall outcomes in extremely preterm newborns.

Neonatologist performed echocardiography (NPE) in Italian neonatal intensive care units: a national survey.

BACKGROUND: Neonatologist performed echocardiography (NPE) has increasingly been used to assess the hemodynamic status in neonates. Aim of this survey was to investigate the utilization of NPE in Italian neonatal intensive care units (NICUs). METHODS: We conducted an on-line survey from June to September 2017. A questionnaire was developed by the Italian neonatal cardiology study group and was sent to each Italian NICU. RESULTS: The response rate was 77%. In 94% of Italian NICUs functional echocardiography was used by neonatologists, cardiologists or both (57, 15 and 28% respectively). All the respondents used NPE in neonates with patent ductus arteriosus and persistent pulmonary hypertension, 93% in neonates with hypotension or shock, 85% in neonates with perinatal asphyxia, 78% in suspicion of cardiac tamponade, and 73% for line positioning. In 30% of center, there was no NPE protocol. Structural echocardiography in stable and critically ill neonates was performed exclusively by neonatologists in 46 and 36% of center respectively. CONCLUSIONS: NPE is widely used in Italian NICUs by neonatologists. Structural echocardiography is frequently performed by neonatologists. Institutional protocols for NPE are lacking. There is an urgent need of a formal training process and accreditation to standardize the use of NPE.

Relationship between Mean Airways Pressure, Lung Mechanics, and Right Ventricular Output during High-Frequency Oscillatory Ventilation in Infants.

OBJECTIVE: To characterize changes in lung mechanics and right ventricular output (RVO) during incremental/decremental continuous distending pressure (CDP) maneuvers in newborn infants receiving high-frequency oscillatory ventilation, with the aim of evaluating when open lung maneuvers are needed and whether they are beneficial. STUDY DESIGN: Thirteen infants on high-frequency oscillatory ventilation were studied with a median (IQR) gestational age of 261 (253-291) weeks and median (IQR) body weight of 810 (600-1020) g. CDP was increased stepwise from 8 cmH2O to a maximum pressure and subsequently decreased until oxygenation deteriorated or a CDP of 8 cmH2O was reached. The lowest CDP that maintained good oxygenation was considered the clinically optimal CDP. At each CDP, the following variables were evaluated: oxygenation, respiratory system reactance (Xrs), and RVO by Doppler echocardiography. RESULTS: At maximal CDP reached during the trial, 19 [1] cmH2O (mean [SEM]), oxygenation markedly improved, and Xrs and RVO decreased. During deflation, oxygenation remained stable over a wide range of CDP settings, Xrs returned to the baseline values, and RVO increased but the baseline values were not readily restored in all patients. CONCLUSION: These results suggest that Xrs and RVO are more sensitive than oxygenation to overdistension and they may be useful in clinical practice to guide open lung maneuvers.

Factors affecting survival in infants weighing 750 g or less.

OBJECTIVE: To assess which factors independently affect survival in infants weighing 750g or less. STUDY DESIGN: We reviewed the obstetric, neonatal, and placental pathology information of all non-malformed neonates with birth weight of 750g or less from January 1998 to December 2002. Logistic regression analysis was used to control for the effect of confounding variables. A P<0.05 was considered significant. RESULTS: Fifty nine neonates fulfilled the inclusion criteria; 30 (51%) survived the perinatal period. Surviving neonates were more frequently born after steroid administration (P=0.03) and from indicated delivery (P=0.01), had greater birth weight (P=0.001), gestational age at delivery (P<0.001), and 5-min Apgar scores of 7 or more (P=0.04) than those who died. There were no significant differences in placental pathology between survivors and neonates who died. Stepwise logistic regression analysis showed that gestational age (P=0.01), birth weight (P=0.004), female sex (P=0.03), 5-min Apgar score (0.026), and steroid administration (P=0.04) were independent predictors of survival. Cumulatively these five predictors explained 69% of neonatal survival. CONCLUSIONS: The predictors of survival among micropremies are the same as those reported for older preterm neonates. The type of preterm delivery (spontaneous versus indicated) and placental pathology do not independently affect survival.