Practices surrounding pulmonary hypertension and bronchopulmonary dysplasia amongst neonatologists caring for premature infants

Inhaled Nitric Oxide Utilization in Congenital Diaphragmatic Hernia Treated With Extracorporeal Life Support: A Propensity Score Analysis

Although used commonly, ability of inhaled nitric oxide (iNO) to improve outcomes in infants with congenital diaphragmatic hernia (CDH) who receive extracorporeal life support (ECLS) remains controversial. We sought to determine the association between pre-ECLS use of iNO and mortality in infants with CDH from the Extracorporeal Life Support Organization (ELSO) Registry. Neonates who underwent ECLS for CDH were identified from the ELSO Registry from 2009 to 2019. Patients were categorized into those treated with iNO versus not prior to initiating ECLS. Patients were then matched 1:1 for case-mix based on pre-ECLS covariates using the propensity score (PS) for iNO treatment. The matched groups were compared for mortality. The matched cohorts were also compared for ELSO-defined systems-based complications as secondary outcomes. There were a total of 3,041 infants with an overall mortality of 52.2% and a pre-ECLS iNO use rate of 84.8%. With 1:1 matching, there were 461 infants with iNO use and 461 without iNO use. Following matching, use of iNO was not associated with a difference in mortality (odds ratio [OR] = 0.805; 95% confidence interval [CI], 0.621-1.042; p = 0.114). Results were similar in unadjusted analyses, and after controlling for covariates in the full cohort of patients and in the 1:1 matched data. Patients receiving iNO had significantly higher odds of renal complications (OR = 1.516; 95% CI, 1.141-2.014; p = 0.004), but no other significant differences were observed among secondary outcomes. ECLS use of iNO in CDH patients was not associated with a difference in mortality. Future randomized controlled studies are needed to delineate the utility of iNO in CDH patients.

Screening Echocardiography Identifies Risk Factors for Pulmonary Hypertension at Discharge in Premature Infants with Bronchopulmonary Dysplasia

HYPOTHESIS

Premature infants with bronchopulmonary dysplasia (BPD) are at increased risk of secondary pulmonary hypertension (BPD-PH). Prior studies yielded mixed results on the utility of echocardiographic screening at 36 weeks post-menstrual age (PMA). We present our experience using echocardiographic screening at the time of BPD diagnosis to identify infants at highest risk of BPD-PH at discharge.

MATERIALS AND METHODS

Retrospective cohort analysis of clinical/ demographic data and screening echocardiograms in patients with BPD. Discharge echocardiograms identified infants with or without BPD-PH at discharge. 36 weeks PMA screening echocardiograms and clinical data were then reviewed to identify which factors were associated with increased odds of BPD-PH at discharge. Associations between echocardiographic findings were evaluated with 2- and 3-variable models to predict increased risk of BPD-PH at discharge.

RESULTS

In our cohort of 64 infants with severe BPD, BPD-PH was present in 22/64 (34%) infants at discharge. There were no clinical differences at time of 36 weeks PMA screening evaluation (mean PMA 36.6 ± 2.9 weeks). PH at screening was poorly predictive of PH at discharge as PH at screening resolved in 49% of patients. However, having an ASD, RV dilation, hypertrophy, or reduced function on screening, especially in combination, were associated with BPD-PH at discharge.

CONCLUSION

In our cohort of premature infants with BPD, 36 weeks PMA screening echocardiogram identified patients at increased risk for BPD-PH at discharge when ASD, RVH, or impaired RV function were present. Larger prospective studies are indicated to validate these findings.

Diagnosis and management of pulmonary hypertension in infants with bronchopulmonary dysplasia: a guide for paediatric respiratory specialists

Pulmonary hypertension (PH) can develop in babies with bronchopulmonary dysplasia (BPD). PH is common in those with severe BPD and is associated with a high mortality rate. However, in babies surviving beyond 6 months, resolution of PH is likely. There is currently no standardised screening protocol for PH in BPD patients. Diagnosis in this group relies heavily on transthoracic echocardiography. Management of BPD-PH should be led by a multidisciplinary team and focus on optimal medical management of the BPD and associated conditions that may contribute to PH. PH-targeted pharmacotherapies have been used in BPD-PH. To date, these have not been investigated in clinical trials and evidence of their efficacy and safety is absent.

Educational aims

To identify those BPD patients most at risk of developing PH.To be aware of detection, multidisciplinary management, pharmacological treatment and monitoring strategies for BPD-PH patients.To understand the potential clinical course for patients with BPD-PH and that evidence on efficacy and safety of PH-targeted pharmacotherapy in BPD-PH is limited.

Cardiopulmonary Function Abnormalities in Cohort of Adults following Bronchopulmonary Dysplasia as Preterm Infants

OBJECTIVE

This study was aimed to describe the cardiopulmonary profiles of adult patients with bronchopulmonary dysplasia (BPD), comparing them to normative adult values.

STUDY DESIGN

This study presents a retrospective chart review of all BPD patients followed in the adult BPD clinic, identified from institutional and archive databases, born preterm at ≤33 weeks of estimated gestational age (EGA) between January 1980 and December 2000.

RESULTS

Forty-four patients with BPD (26.4 ± 2.7 weeks of EGA) were included. Average age at follow-up was 19 years. Majority (61.4%) of the patients had a diagnosis of asthma. Mean spirometry values were: first second of forced expiration (FEV1) 74.1%, forced vital capacity (FVC) 80.7%, and FEV1/FVC 82.5%. Echocardiography (ECHO) images were reviewed, left ventricular (LV) structure and performance did not differ between obstructive and nonobstructive pulmonary function test (PFT) groups, but values of LV longitudinal strain were 4.8% lower than expected normal for adults. Patients with obstructive PFT had additional decreased right ventricular (RV) function by ECHO.

CONCLUSION

BPD patients in this study were found to have a burden of cardiorespiratory alterations that persisted into adulthood, with RV performance abnormalities found among patients with obstructive PFT.

KEY POINTS

· BPD patients born at extremes of prematurity have cardiorespiratory alterations in adulthood.. · Among patients with obstructive lung function, subtle cardiac performance abnormalities were found.. · Future directions should include systematic follow-up of premature newborns with BPD..

Pulmonary hypertension with bronchopulmonary dysplasia: Aichi cohort study

BACKGROUND

The incidence of pulmonary hypertension (PH) associated with bronchopulmonary dysplasia (BPD) has not been investigated in regional cohorts. The aim of this study was to clarify the incidence of PH associated with BPD in all very low birthweight infants (VLBWIs) born during the study period in Aichi Prefecture, Japan.

METHODS

We conducted a retrospective observational cohort study of all VLBWIs born in Aichi Prefecture. The inclusion criteria were VLB, birth between 1 January 2015 and 31 December 2015, and admission to any neonatal intensive care unit in Aichi Prefecture. BPD28d and BPD36w were defined as the need for supplemental oxygen or any respiratory support at 28 days of age or 36 weeks of postmenstrual age (PMA). The primary outcome was the incidence of PH after 36 weeks' PMA (PH36w) in VLBWIs with BPD28d and BPD36w. The secondary outcomes were the clinical factors related to PH36w in BPD36w patients. Mann-Whitney U-test and Fisher's exact test were used for univariate analysis. Differences were considered statistically significant at P < 0.05. Risk ratio (RR) and 95% confidence interval (CI) were also evaluated.

RESULTS

A total of 441 patients were analyzed. A total of 217 and 131 patients met the definition of BPD28d and BPD36w, respectively. Nine patients were diagnosed with PH36w (4.2% and 6.9% of the BPD28d and BPD36w patients, respectively). The presence of oligohydramnios (RR, 2.71; 95% CI: 1.55-4.73, P = 0.014) and sepsis (RR, 3.62; 95% CI: 1.51-8.63, P = 0.025) was significant in the PH36w patients.

CONCLUSIONS

The incidence of PH36w was 4.2% and 6.9% in the BPD28d and BPD36w patients, respectively. Oligohydramnios and sepsis were significantly associated with PH36w in VLBWIs.

Role of functional echocardiographic parameters in the diagnosis of bronchopulmonary dysplasia-associated pulmonary hypertension

Echocardiogram (echo) is a commonly used noninvasive modality for the diagnosis of bronchopulmonary dysplasia associated pulmonary hypertension (BPD-PH). Though not considered the gold standard for the diagnosis of BPD-PH, it is an extremely valuable tool in the neonatal and pediatric population, especially when cardiac catheterization is not feasible. In addition to the traditional echo parameters that are used to assess the presence of BPD-PH, much attention has been recently placed on newer bedside echo measures, the so-called functional echo parameters, to aid and assist in the diagnosis. This review article provides a brief introduction to BPD-PH, describes the pitfalls of traditional echo parameters and details the newer echo modalities currently available for the diagnosis of neonatal PH.

Short and long-term outcomes of chronic pulmonary hypertension in preterm infants managed using a standardized algorithm

BACKGROUND

There is limited data on management strategies for chronic pulmonary hypertension (cPH) in chronic lung disease (CLD) of prematurity. Our objective was to evaluate clinical outcomes following a standardized policy, wherein only cPH with right-ventricular (RV) dilatation was treated and diuretics were employed as first-line therapy; cPH without RV-dilatation was managed expectantly.

METHOD

In this retrospective cohort study, all infants with CLD were categorized as "CLD-only" or "CLD-cPH," using echocardiography at ≥36 weeks postmenstrual age. Intergroup comparison was performed. Regression analysis examined the association between cPH and primary outcome of death or disability at 18-24 months.

RESULTS

Of 128 CLD infants, 48 (38%) had cPH, of which 29 (60%) received diuretics. Symptomatic improvement within 1-week was recorded in 90%. Although CLD-cPH had worse in-hospital respiratory course than CLD-only, all post-discharge respiratory and neurodevelopmental outcomes were similar. cPH was not associated with death or disability (adjusted odds ratio, 1.02; 95% confidence interval, 0.32-3.27). Disease progression treated with sildenafil occurred in 2 (4%) cases. There was no death from respiratory or RV failure.

CONCLUSION

Primary treatment of CLD-cPH with diuretics using RV-dilatation as therapeutic threshold, may result in symptomatic improvement, disease stabilization and post-discharge outcomes comparable to infants without cPH.

Primary Pulmonary Vein Stenosis: A New Look at a Rare but Challenging Disease

Primary pulmonary vein stenosis (PPVS) represents a rare but emerging, often progressive heterogeneous disease with high morbidity and mortality in the pediatric population. Although our understanding of PPVS disease has improved markedly in recent years, much remains unknown regarding disease pathogenesis, distinct disease phenotypes, and patient- and disease-related risk factors driving the unrelenting disease progression characteristic of PPVS. In the pediatric population, risk factors identified in the development of PPVS include an underlying congenital heart disease, prematurity and associated conditions, and an underlying genetic or congenital syndrome. Continued improvement in the survival of high-risk populations, coupled with ongoing advances in general PPVS awareness and diagnostic imaging technologies suggest that PPVS will be an increasingly prevalent disease affecting pediatric populations in the years to come. However, significant challenges persist in both the diagnosis and management of PPVS. Standardized definitions and risk stratification for PPVS are lacking. Furthermore, evidence-based guidelines for screening, monitoring, and treatment remain to be established. Given these limitations, significant practice variation in management approaches has emerged across centers, and contemporary outcomes for patients affected by PPVS remain guarded. To improve care and outcomes for PPVS patients, the development and implementation of universal definitions for disease and severity, as well as evidence-based guidelines for screening, monitoring, cardiorespiratory care, and indications for surgical intervention will be critical. In addition, collaboration across institutions will be paramount in the creation of regionalized referral centers as well as a comprehensive patient registry for those requiring pulmonary vein stenosis.

Practice patterns of pulmonary hypertension secondary to left heart disease among pediatric pulmonary hypertension providers

Development of pulmonary hypertension (PH) in patients with left side heart disease (LHD) is a predictor of poor prognosis. The use of pulmonary vasodilators in PH associated with LHD (PH-LHD) is controversial. In this study, we describe the practice patterns regarding the use of pulmonary vasodilators in PH-LHD among a group of international pediatric PH specialists. A survey was distributed to the members of three pediatric PH networks: PPHNet, PVRI, and REHIPED. The survey queried participants on the rationale, indications, and contraindications of the use of pulmonary vasodilators in children with PH-LHD. Forty-seven PH specialists from 39 PH centers completed the survey. Participants included PH specialists from North America (57%), South America (15%), and Europe (19%). The majority of participants (74%) recommended the use of pulmonary vasodilators only in patients with combined pre-capillary and post-capillary pulmonary hypertension. Participants required the presence of clinical symptoms or signs of heart failure (68%) or right ventricular dysfunction by echocardiography (51%) in order to recommend pulmonary vasodilator therapy. There was no agreement regarding hemodynamic criteria used to recommend pulmonary vasodilators or the etiologies of LHD considered contraindications for using pulmonary vasodilators to manage PH-LHD. Of the available PH-targeted drugs, most participants preferred the use of phosphodiesterase-5-inhibitors for this indication. In conclusion, the practice of recommending pulmonary vasodilators in PH-LHD is highly variable among international pediatric PH specialists. Most specialists of those surveyed (57% in North America) would consider the use of pulmonary vasodilators in PH-LHD only if pre-capillary pulmonary hypertension and right ventricular dysfunction are present.

Lung disease and pulmonary hypertension in the premature infant

The premature infant is born into the world unprepared to naturally thrive in a foreign environment. Lung development entails immense growth, structural remodeling and differentiation of specialized cells during the normal term perinatal and postnatal periods. Thus, the premature infant presents with a lung deficient for appropriate respiration. Disruption of lung development seen in bronchopulmonary dysplasia (BPD) and chronic lung disease (CLD) results in not only impaired airway growth but also a deficiency in the accompanying vasculature including the capillary system required for gas exchange. Deficient vascular area can lead to elevated pulmonary vascular resistance and the development of pulmonary hypertension (PH). Unlike PH seen in children and adults with pulmonary arterial hypertension (PAH), treatment with conventional pulmonary vasodilators can be limited in developmental lung disease-associated PH because there are fewer blood vessels to dilate. In this brief review, we highlight some of the knowledge on PH in the premature infant presented at the Proceedings of the 22^nd Annual Update on Pediatric and Congenital Cardiovascular Disease.

Survey of practices in relation to chronic pulmonary hypertension in neonates in the Canadian Neonatal Network and the National Institute of Child Health and Human Development Neonatal Research Network

Current knowledge gaps pertaining to diagnosis and management of neonatal chronic pulmonary hypertension (cPH) may result in significant variability in clinical practice. The objective of the study is to understand cPH management practices in neonatal intensive care units affiliated with the Canadian Neonatal Network (CNN) and National Institute of Child Health and Human Development Neonatal Research Network (NRN). A 32-question survey seeking practice details for cPH evaluation, diagnostic criteria, conservative measures, pharmacotherapeutics, and follow-up was e-mailed to a designated physician at each center. Responses were described as frequency (percentage) and compared between CNN and NRN, where appropriate. Overall response rate was 67% (CNN 20/28 (71%), NRN 9/15 (60%)). While 8 (28%) centers had standardized management protocols, 17 (59%) routinely evaluate high-risk patients; moderate-severe chronic lung disease being the commonest indication. While interventricular septal flattening on echocardiography was the commonest listed diagnostic criterion, several adjunctive indices were also identified. Asymptomatic neonates with cPH were managed expectantly (routine care) in 50% of sites, and using various conservative measures in others. Pulmonary vasodilators were prescribed for symptomatic cases, with 60% of sites using them early (86% reporting any use). Seventy-five percent of sites use inhaled nitric oxide and sildenafil citrate as first- and second-line agents, respectively. Use of standard protocols, cardiac catheterization, and conservative measures for asymptomatic cases was more common in NRN units (p < 0.05). While there is relative homogeneity in patient identification and diagnostic criteria used for neonatal cPH, significant interunit inconsistencies still exists in routine evaluation, use of additional investigations, management of asymptomatic cases, frequency and type of conservative measures, and choice of pulmonary vasodilators.

Oxygen therapy in preterm infants with pulmonary hypertension

Premature neonates <34 weeks gestation can present with early-onset, late-onset and bronchopulmonary dysplasia (BPD) associated pulmonary hypertension (PHT), with clinical, echocardiographic, and histological features similar to term infants with PHT. Changes in pulmonary vascular resistance (PVR) in response to oxygen are diminished in preterm infants compared to term. Studies from preterm lambs and human infants with BPD have shown that PaO₂ > 30-55 mm Hg promotes pulmonary vasodilation. Targeting saturations of 80-85% by 5 min, 85-95% by 10 min during resuscitation and 90-95% during the postnatal course are appropriate targets for routine management of preterm infants. Among preterm infants with PHT, avoiding hypoxia/hyperoxia by titrating supplemental oxygen to maintain saturations in low to mid 90s with alarm limits at 90 and 97% seems to be a reasonable approach pending further studies. Further high-quality evidence generated from randomized trials is required to guide oxygen therapy in preterm PHT.

Utility of echocardiography in predicting mortality in infants with severe bronchopulmonary dysplasia

OBJECTIVE

To determine the relationship between interventricular septal position (SP) and right ventricular systolic pressure (RVSP) and mortality in infants with severe BPD (sBPD).

STUDY DESIGN

Infants with sBPD in the Children's Hospitals Neonatal Database who had echocardiograms 34-44 weeks' postmenstrual age (PMA) were included. SP and RVSP were categorized normal, abnormal (flattened/bowed SP or RVSP > 40 mmHg) or missing.

RESULTS

Of 1157 infants, 115 infants (10%) died. Abnormal SP or RVSP increased mortality (SP 19% vs. 8% normal/missing, RVSP 20% vs. 9% normal/missing, both p < 0.01) in unadjusted and multivariable models, adjusted for significant covariates (SP OR 1.9, 95% CI 1.2-3.0; RVSP OR 2.2, 95% CI 1.1-4.7). Abnormal parameters had high specificity (SP 82%; RVSP 94%), and negative predictive value (SP 94%, NPV 91%) for mortality.

CONCLUSIONS

Abnormal SP or RVSP is independently associated with mortality in sBPD infants. Negative predictive values distinguish infants most likely to survive.

Diminished right ventricular function at diagnosis of pulmonary hypertension is associated with mortality in bronchopulmonary dysplasia

Pulmonary vascular disease and resultant pulmonary hypertension (PH) have been increasingly recognized in the preterm population, particularly among patients with bronchopulmonary dysplasia (BPD). Limited data exist on the impact of PH severity and right ventricular (RV) dysfunction at PH diagnosis on outcome. The purpose of this study was to evaluate if echocardiography measures of cardiac dysfunction and PH severity in BPD-PH were associated with mortality. The study is a retrospective analysis of the echocardiography at three months or less from time of PH diagnosis. Survival analysis using a univariate Cox proportional hazard model is presented and expressed using hazard ratios (HR). We included 52 patients with BPD and PH of which 16 (31%) died at follow-up. Average gestational age at birth was 26.3 ± 2.3 weeks. Echocardiography was performed at a median of 43.3 weeks (IQR: 39.0–54.7). The median time between PH diagnosis and death was 117 days (range: 49–262 days). Multiple measures of PH severity and RV performance were associated with mortality (sPAP/sBP: HR 1.02, eccentricity index: HR 2.02, tricuspid annular plane systolic excursion Z-score: HR 0.65, fractional area change: HR 0.88, peak longitudinal strain: HR 1.22). Hence, PH severity and underlying RV dysfunction at PH diagnosis were associated with mortality in BPD-PH patients. While absolute estimation of pulmonary pressures is not feasible in every screening echocardiography, thorough evaluation of RV function and other markers of PH may allow to discriminate the most at-risk population and should be considered as standard add-ons to the current screening at 36 weeks.

Hemodynamic management in chronically ventilated infants

Positive pressure ventilation can significantly alter hemodynamics. The reduction in systemic venous return and increase in right ventricular afterload in response to an inappropriately high mean airway pressure can decrease pulmonary blood flow and compromise systemic perfusion as a result. In addition to ventilator parameters, the degree of hemodynamic effects depends on the baseline cardiac function and lung compliance. Furthermore, the chronically ventilated infants often have a multitude of comorbidities which may also impact hemodynamics. These include pulmonary and systemic hypertension which can lead to myocardial dysfunction as a result of the increase in the right and left ventricular afterload, respectively. In this section, we aim to outline the hemodynamic changes associated with chronic lung disease and mechanical ventilation and discuss management options.

Oxygen Therapy and Pulmonary Hypertension in Preterm Infants

The goal of oxygen therapy and oxygen saturation targeting in extremely preterm infants is to improve outcomes and balance the risks associated with both hypoxemia and hyperoxemia. Although the NeOProM trials addressed whether low or high oxygen saturation targets affect the most important outcomes of extreme prematurity including death and other co-morbidities, the trials did not evaluate infants for pulmonary hypertension. There is limited evidence for the optimal oxygen saturation targets in extremely preterm infants that can be used to prevent the development of pulmonary hypertension and manage pulmonary hypertension once developed.

Agreement of an echocardiogram-based diagnosis of pulmonary hypertension in infants at risk for bronchopulmonary dysplasia among masked reviewers

OBJECTIVE

To evaluate the agreement of an echocardiogram-based pulmonary hypertension diagnosis in premature infants at risk for bronchopulmonary dysplasia (BPD).

STUDY DESIGN

Echocardiograms from infants born ≤28 weeks post menstrual age were retrospectively reviewed with a standardized reading protocol by three pediatric cardiologists masked to patient's clinical history to determine the presence of pulmonary hypertension.

RESULTS

A total of 483 echocardiograms from 49 unique patients were each reviewed by three pediatric cardiologists. Overall there was an 82.9% agreement on the presence of pulmonary hypertension among the three readers (95% CI: 78.4%, 85.4%) with a modified Fleiss' kappa of 0.759 (95% CI: 0.711, 0.801). Percent agreement between rereads was 92.4%, and modified Fleiss' kappa was 0.847 (95% CI: 0.750, 0.931).

CONCLUSIONS

Using a standardized reading protocol and echocardiogram-based definition of pulmonary hypertension, there is high inter- and intra-rater agreement for the diagnosis of pulmonary hypertension in at-risk premature infants, suggesting echocardiography can be successfully used for clinical and research monitoring of pulmonary hypertension in infants.

Factors influencing decision making in neonatology: inhaled nitric oxide in preterm infants

OBJECTIVE

We studied decision making regarding inhaled nitric oxide (iNO) in preterm infants with Pulmonary Hypertension (PH).

STUDY DESIGN

We asked members of the AAP-Society of Neonatal-Perinatal Medicine and Division-Chiefs to select from three management options- initiate iNO, engage parents in shared decision making or not consider iNO in an extremely preterm with PH followed by rating of factors influencing their decision.

RESULTS

Three hundred and four respondents (9%) completed the survey; 36.5% chose to initiate iNO, 42% to engage parents, and 21.5% did not consider iNO. Provider's prior experience, safety, and patient-centered care were rated higher by those who initiated or offered iNO; lack of effectiveness and cost considerations by participants who did not chose iNO.

CONCLUSIONS

Most neonatologists offer or initiate iNO therapy based on their individual experience. The minority who chose not to consider iNO placed higher value on lack of effectiveness and cost. These results demonstrate a tension between evidence and pathophysiology-based-therapy/personal experience.

An update on the diagnosis and management of bronchopulmonary dysplasia (BPD)-associated pulmonary hypertension

The past decade of neonatal care has been highlighted by increased survival rates in smaller and more premature infants. Despite reduction in mortality associated with extreme prematurity, long term pulmonary morbidities remain a concern, with growing recognition of the clinical burden attributable to infants with bronchopulmonary dysplasia (BPD)-associated pulmonary hypertension (PH). Recent publications shed light on the critical contributions of maternal placental pathology and compromised intrauterine growth to fetal pulmonary vascular development. A body of literature has further clarified postnatal risk factors for PH, most notably the severity of BPD but surprisingly the additional presence of non-pulmonary morbidities including necrotizing enterocolitis (NEC). Limitations of current diagnostics persist with growing consideration of novel echocardiographic approaches as well as complementary non-invasive biomarkers to better identify infants at risk. In 2015, a joint report published by the American Heart Association and American Thoracic Society provided the first guidelines for the care of children with PH with limited content to address BPD-associated PH. These guidelines were expanded upon in an expert consensus report produced by the Pediatric Pulmonary Hypertension Network (PPHNet). These recommendations encouraged the use of standardized screening protocols and emphasized the importance of evaluation and treatment of comorbidities when PH is identified. Cardiac catheterization was recommended prior to initiation of therapy for more accurate quantification of pulmonary pressures, clarification of anatomy and guidance in the use of pharmacotherapy. Despite these guidelines, significant practice variation persists and gaps remain with respect to optimal evaluation and management of BPD-associated PH.

Evidence of Echocardiographic Markers of Pulmonary Vascular Disease in Asymptomatic Infants Born Preterm at One Year of Age

OBJECTIVE

To test the hypothesis that echocardiographic markers of pulmonary vascular disease (PVD) exist in asymptomatic infants born preterm at 1-year corrected age.

STUDY DESIGN

We conducted a prospective cohort study of 80 infants born preterm (<29 weeks of gestation) and 100 age- and weight-matched infants born at term and compared broad-based conventional and quantitative echocardiographic measures of pulmonary hemodynamics at 1-year corrected age. Pulmonary artery acceleration time (PAAT), a validated index of pulmonary vascular resistance, arterial pressure, and compliance, was used to assess pulmonary hemodynamics. Lower PAAT is indicative of PVD. Subanalyses were performed in infants with bronchopulmonary dysplasia (BPD, n = 48, 59%) and/or late-onset pulmonary hypertension (n = 12, 15%).

RESULTS

At 1 year, there were no differences between conventional measures of pulmonary hypertension in the infants born at term and preterm. All infants born preterm had significantly lower values of PAAT than infants born at term (73 ± 8 milliseconds vs 98 ± 5 milliseconds, P < .001). Infants born preterm with BPD had even lower PAAT than those without BPD (69 ± 5 milliseconds vs 79 ± 4 milliseconds, P < .01). The degree of PVD at 1-year corrected age was inversely related to gestation in all infants born preterm. Data analysis included adjustment for ventricular function and other confounding factors.

CONCLUSIONS

In comparison with infants born at term, infants born preterm exhibit abnormal PAAT at 1-year corrected age irrespective of neonatal lung disease status, suggesting the existence of PVD beyond infancy. PAAT measurements offer a reliable, noninvasive tool for screening and longitudinal monitoring of pulmonary hemodynamics in infants.