Inhaled nitric oxide versus aerosolized iloprost in secondary pulmonary hypertension in children with congenital heart disease: vasodilator capacity and cellular mechanisms

Safety and tolerability of continuous inhaled iloprost in critically ill pediatric pulmonary hypertension patients: A retrospective case series

Inhaled iloprost (iILO) has shown efficacy in treating patients with hypoxic lung disease and pulmonary hypertension, inducing selective pulmonary vasodilation and improvement in oxygenation. However, its short elimination half-life of 20-30 min necessitates frequent intermittent dosing (6-9 times per day). Thus, the administration of iILO via continuous nebulization represents an appealing method of drug delivery in the hospital setting. The objectives are: (1) describe our continuous iILO delivery methodology and safety profile in mechanically ventilated pediatric pulmonary hypertension patients; and (2) characterize the initial response of iILO in these pediatric patients currently receiving iNO. Continuous iILO was delivered and well tolerated (median 6 days; range 1-94) via tracheostomy or endotracheal tube using the Aerogen® mesh nebulizer system coupled with a Medfusion® 400 syringe pump. No adverse events or delivery malfunctions were reported. Initiation of iILO resulted in an increase in oxygen saturation from 81.4 ± 8.6 to 90.8 ± 4.1%, p < 0.05. Interestingly, prior iNO therapy for >1 day resulted in a higher response rate to iILO (as defined as a ≥ 4% increase in saturations) compared to those receiving iNO <1 day (85% vs. 50%, p = 0.06). When the use of iILO is considered, continuous delivery represents a safe, less laborious alternative and concurrent treatment with iNO should not be considered a contraindication. However, given the retrospective design and small sample size, this study does not allow the evaluation of the efficacy of continuous iILO on outcomes beyond the initial response. Thus, a prospective study designed to evaluate the efficacy of continuous iILO is necessary.

Long-term prognostic value of cardiac catheterization and acute vasodilator testing with inhaled iloprost in pediatric idiopathic pulmonary arterial hypertension

To assess the long-term prognostic value of cardiac catheterization and acute vasodilator testing (AVT) with inhaled iloprost in children with idiopathic pulmonary arterial hypertension (IPAH). Data on 81 consecutive children with IPAH referred to our center who underwent cardiac catheterization and AVT between June 2008 and August 2019 were collected. The correlation between the invasive hemodynamic data and transplant-free survival was analyzed. Twenty-four patients died and 1 underwent lung transplantation during a median follow-up of 3.8 years, with a 5-year transplant-free survival rate of 64.9%. Univariate analysis showed that predictors associated with improved survival included a lower pulmonary vascular resistance index (PVRI), PVRI/systemic vascular resistance index (SVRI), mean pulmonary arterial pressure (mPAP)/mean systemic arterial pressure, mean right atrial pressure, and a higher cardiac index (CI), mixed systemic venous oxygen saturations (SvO₂), and acute vasodilator response (AVR) according to the Barst criteria (decrease in mPAP and PVRI/SVRI ratio of >20% without a decrease in CI). In multivariate Cox regression analysis, Barst AVR and SvO₂ were independently related to transplant-free survival. Multiple hemodynamic variables from cardiac catheterization and AVT with inhaled iloprost have important prognostic value for long-term survival in children with IPAH, of which pulmonary vasoreactivity defined by the Barst criteria and SvO₂ are independent prognostic factors.

Dead space ratio as a tool in nitric oxide weaning: a study in pulmonary hypertensive disease

OBJECTIVES

To describe the association between successful weaning of inhaled nitric oxide and trends in dead space ratio during such weans in patients empirically initiated on nitric oxide therapy out of concern of pulmonary hypertensive crisis.

PATIENTS

Children in a cardiac intensive care unit initiated on inhaled nitric oxide out of clinical concern for pulmonary hypertensive crisis retrospectively over 2 years.

MEASUREMENTS AND MAIN RESULTS

Twenty-seven patients were included, and nitric oxide was successfully discontinued in 23/27. These patients exhibited decreases in dead space ratio (0.18 versus 0.11, p = 0.047) during nitric oxide weaning, and with no changes in dead space ratio between pre- and post-nitric oxide initiation (p = 0.88) and discontinuation (p = 0.63) phases. These successful patients had a median age of 10 months [4.0, 57.0] and had a pre-existent diagnosis of CHD in 6/23 and pulmonary hypertension in 2/23. Those who failed nitric oxide discontinuation trended with a higher dead space ratio at presentation (0.24 versus 0.10), were more likely to carry a prior diagnosis of pulmonary hypertension (50% versus 8.7%), and had longer mechanical ventilation days (5 versus 12).

CONCLUSIONS

Patients empirically placed on nitric oxide out of concern of pulmonary hypertensive crisis and successfully weaned off showed unchanged or decreased dead space ratio throughout the initiation to discontinuation phases of nitric oxide therapy. Trends in dead space ratio may aid in determining true need for nitric oxide and facilitate effective weaning. Further studies are needed to directly compare trends between success and failure groups.

Effect of postoperative administration of inhaled nitric oxide combined with high-frequency oscillatory ventilation in infants with acute hypoxemic respiratory failure and pulmonary hypertension after congenital heart surgery: A retrospective cohort study

OBJECTIVE

To evaluate the effect of inhaled nitric oxide (iNO) combined with high-frequency oscillatory ventilation (HFOV) in the treatment of infants with acute hypoxemic respiratory failure (AHRF) and pulmonary hypertension (PH) after congenital heart surgery.

METHODS

A retrospective study was conducted on 63 infants with AHRF and PH after congenital heart surgery in our cardiac intensive care unit (CICU) from January 2020 to March 2021. A total of 24 infants in the A group were treated with HFOV combined with iNO, and 39 infants in the B group were treated with HFOV. Relevant clinical data were collected.

RESULTS

Comparing the two groups, the improvement of the oxygenation index, PaO₂ and PaO₂ /FiO₂ was more obvious for patients in the A group than for those in the B group after intervention (p < .05). Reexamination on the third day after the initiation of HFOV treatment indicated that the systolic pulmonary artery pressure in the A group was significantly lower than that in the B group (p < .05). In addition, the duration of mechanical ventilation and the length of CICU stay in the A group were shorter than those in the B group (p < .05). However, complications between the two groups were not statistically significant. No important adverse effects arose.

CONCLUSIONS

For infants with AHRF and PH after congenital heart surgery, iNO combined with HFOV is superior to HFOV alone to improve oxygenation, decrease pulmonary pressure, and shorten the duration of mechanical ventilation and the length of CICU stay, with no adverse effects.

Life-threatening PPHN refractory to nitric oxide: proposal for a rational therapeutic algorithm

Persistent pulmonary hypertension of the neonate (PPHN) refractory to inhaled nitric oxide still represents a frequent clinical challenge with negative outcomes in neonatal critical care. Several pulmonary vasodilators have become available thanks to improved understanding of pulmonary hypertension pathobiology. These drugs are commonly used in adults and there are numerous case series and small studies describing their potential usefulness in neonates, as well. New vasodilators act on different pathways, some of them can have additive effects and all have different pharmacology features. This information has never been summarized so far and no comprehensive pathobiology-driven algorithm is available to guide the treatment of refractory PPHN.Conclusion: We offer a rational clinical algorithm to guide the treatment of refractory PPHN based on expert advice and the more recent pathobiology and pharmacology knowledge. What is Known: • Refractory PPHN occurs in 30-40% of iNO-treated neonates and represents a significant clinical problem. Several pulmonary vasodilators have become available thanks to a better understanding of pulmonary hypertension pathobiology. What is New: • Available vasodilators have different pharmacology, mechanisms of action and may provide additive effect. We provide a rational clinical algorithm to guide the treatment of refractory PPHN based on expert advice and the more recent pathobiology and pharmacology knowledge.

Comparison of inhaled nitric oxide with aerosolized prostacyclin or analogues for the postoperative management of pulmonary hypertension: a systematic review and meta-analysis

Background: This study aims to compare the effectiveness of inhaled prostacyclin or its analoguesversus nitric oxide (NO) in treating pulmonary hypertension (PH) after cardiac or pulmonary surgery remains unclear.Methods: PubMed, Cochrane, and Embase databases were searched for literature published prior to December 2019 using the following keywords: inhaled, nitric oxide, prostacyclin, iloprost, treprostinil, epoprostenol, Tyvaso, flolan, and pulmonary hypertension. Randomized controlled trials and multiple-armed prospective studies that evaluated inhaled NO versus prostacyclin (or analogues) in patients for perioperative and/or postoperative PH after either cardiac or pulmonary surgery were included. Retrospective studies, reviews, letters, comments, editorials, and case reports were excluded.Results: Seven studies with a total of 195 patients were included. No difference in the improvement of mean pulmonary arterial pressure (pooled difference in mean change= -0.10, 95% CI: -3.98 to 3.78, p = .959) or pulmonary vascular resistance (pooled standardized difference in mean change= -0.27, 95% CI: -0.60 to 0.05, p = .099) were found between the two treatments. Similarly, no difference was found in other outcomes between the two treatments or subgroup analysis.Conclusions: Inhaled prostacyclin (or analogues) was comparable to inhaled NO in treating PH after cardiac or pulmonary surgery.Key messagesThis study compared the efficacy of inhaled prostacyclin or its analogues versus inhaled NO to treat PH after surgery. The two types of agent exhibited similar efficacy in managing MPAP, PVR, heart rate, and cardiac output was observed.Inhaled prostacyclin may serve as an alternative treatment option for PH after cardiac or pulmonary surgery.

Drug Treatment of Pulmonary Hypertension in Children

Pulmonary arterial hypertension (PAH) is a rare disease in infants and children that is associated with significant morbidity and mortality. The disease is characterized by progressive pulmonary vascular functional and structural changes resulting in increased pulmonary vascular resistance and eventual right heart failure and death. In many pediatric patients, PAH is idiopathic or associated with congenital heart disease and rarely is associated with other conditions such as connective tissue or thromboembolic disease. PAH associated with developmental lung diseases such as bronchopulmonary dysplasia or congenital diaphragmatic hernia is increasingly more recognized in infants and children. Although treatment of the underlying disease and reversal of advanced structural changes have not yet been achieved with current therapy, quality of life and survival have improved significantly. Targeted pulmonary vasodilator therapies, including endothelin receptor antagonists, prostacyclin analogs, and phosphodiesterase type 5 inhibitors have resulted in hemodynamic and functional improvement in children. The management of pediatric PAH remains challenging as treatment decisions depend largely on results from evidence-based adult studies and the clinical experience of pediatric experts. This article reviews the current drug therapies and their use in the management of PAH in children.

Practice Variation, Costs and Outcomes Associated with the Use of Inhaled Nitric Oxide in Pediatric Heart Transplant Recipients

Right ventricular (RV) failure is a potentially fatal complication following heart transplantation (HTx). Inhaled nitric oxide (iNO) is a selective pulmonary vasodilator that is used to decrease pulmonary vascular resistance immediately post-HTx to reduce the risk of RV failure. The aim of this study was to describe utilization patterns, costs, and outcomes associated with post-transplant iNO use in children. All pediatric HTx recipients (2002-2016) were identified from a unique linked PHIS/SRTR dataset. Post-HTx iNO use was determined based on hospital billing data. Utilization patterns and associated costs were described. The association of iNO support with post-HTx survival was assessed using the Kaplan-Meier method and a multivariable Cox proportional hazards model was used to adjust for risk factors. A total of 2833 pediatric HTx recipients from 28 centers were identified with 1057 (36.5%) receiving iNO post-HTx. Post-HTx iNO use showed significant increase overall (17.2-54.7%, p < 0.001) and wide variation among centers (9-100%, p < 0.001). Patients with congenital heart disease (aOR 1.4, 95% CI 1.2, 1.6), requiring mechanical ventilation at HTx (aOR 1.3, 95% CI 1.1, 1.6), and pre-transplant iNO (aOR 9.3, 95% CI 5.4, 16) were more likely to receive iNO post-HTx. The median daily cost of iNO was $2617 (IQR $1843-$3646). Patients who required > 5 days of iNO post-HTx demonstrated inferior 1-year post-HTx survival (p < 0.001) and iNO use > 5 days was independently associated with worse post-HTx survival (AHR 1.6, 95% CI 1.2, 2.1; p < 0.001). There is wide variation in iNO use among centers following pediatric HTx with use increasing over time despite significant incremental cost. Prolonged iNO use post-HTx is associated with worse survival, likely serving as a marker of residual illness severity. Further research is needed to define the populations that derive the greatest benefit from this costly therapy.

Diagnosis and treatment of pediatric pulmonary arterial hypertension

INTRODUCTION

Pediatric pulmonary arterial hypertension (PAH) remains a rare and severe disease with a poor prognosis. PAH may be idiopathic, heritable or associated with systemic conditions in particular associated with congenital heart disease. Areas covered: A thorough and extensive diagnostic approach is required for a correct diagnosis. The outcome has improved over the last decade with a better diagnostic approach and with the initiation of new targeted therapies. However, there is still significant progress to achieve as there is still no cure for this devastating disease. Expert opinion: Adapted clinical studies to define the best therapeutic approach are needed. Even if the treatment approach is still mainly derived from adult data and expert consensus, several studies and registries are currently underway and should deliver important information in the next future. This review aims to give an overview of the current diagnosis and treatment strategies of PAH.

Acute Effect of Inhaled Iloprost in Children with Pulmonary Arterial Hypertension Associated with Simple Congenital Heart Defects

Inhaled prostacyclin analogue iloprost is currently utilized in adult patients with pulmonary arterial hypertension (PAH), but little information is available on its use in the pediatric population. This study evaluated the safety and acute haemodynamic effects of inhaled iloprost in children with PAH associated with congenital heart disease (CHD). Children with PAH-CHD who underwent cardiac catheterization and iloprost administration in our catheter laboratory between June 2007 and October 2015 were included. Iloprost was administered by atomization inhalation and changes in hemodynamic parameters were recorded. In total, 100 children with PAH-CHD were enrolled. Median age was 13 [1.5-18.0] years and 34% were male. A ventricular septal defect was present in 84%, a patent duct in 12%, a complete atrioventricular septal defect in 2%, and an isolated atrial septal defect in 2%. Pulmonary vascular resistance indexed (PVRI) was above 8 WU m² in 96% and was above a third systemic (R_p/R_s > 0.33) in 97%. Iloprost was well tolerated in all patients. Following iloprost inhalation, mean pulmonary arterial pressure decreased from 78.4 ± 9.2 to 72.8 ± 10.8 mmHg (p < 0.01) and pulmonary-to-systemic blood flow ratio (Q_p/Q_s) increased from 1.12 ± 0.48 to 1.37 ± 0.63 (p < 0.01), with no change in cardiac index (Q_s). PVRI decreased from 21.0 ± 9.0 to 16.9 ± 8.0 WU m² (p < 0.01) following inhalation but 92% patients still had a PVRI > 8 WU m² and 93% an R_p/R_s > 0.33. Acute inhalation of iloprost in children with PAH associated with CHD resulted in a significant improvement in hemodynamic parameters. Despite this, few patients achieve strict criteria of operability, underscoring the importance of early screening and timely repair of CHD.

Successful Surgical Repair and Perioperative Management of 6-Month-Old With Total Anomalous Pulmonary Venous Return in a Developing Country: Considerations for the Treatment of Pulmonary Hypertension

Total anomalous pulmonary venous return (TAPVR) is a rare congenital cardiac defect, accounting for 1.5-3% of cases of congenital heart disease. With prenatal ultrasonography, the majority of these patients are diagnosed in utero with definitive surgery performed during the neonatal period. However, as prenatal screening may not be available in developing countries, patients may present in later infancy. We present successful surgical repair of a 6-month-old infant with TAPVR who presented for medical care at 5 months of age in Lima, Peru. The late presentation of such infants and the limited resources available for the treatment of elevated pulmonary vascular resistance may impact successful surgical correction of such defects. The perioperative care of such infants in developing countries is discussed and strategies for managing postoperative pulmonary hypertension is reviewed.

Right Heart Function of Fetuses and Infants with Large Ventricular Septal Defect: A Longitudinal Case-Control Study

The objective of this study was to detect the effect of a large ventricular septal defect (VSD) on right ventricular function before and after birth. All consecutive children with large VSD who were born in our hospital between January 2013-February 2016 and followed up throughout early infancy, and who lacked malformations or chromosomal abnormalities, were identified by a retrospective review of the medical records and included in this retrospective longitudinal case-control study (n = 30). Thirty normal control cases with an equivalent gestational age and gender served as controls. Tricuspid annular plane systolic excursion (TAPSE), right ventricle (RV) Tei index, and tricuspid E/E _m were measured in the fetal, neonatal (day 1-28), and infant (day 29-70) periods. In all periods, the VSD and control groups did not differ in TAPSE values, but VSD associated with higher Tei indices and tricuspid E/E _m values (in the fetal period: VSD group RV Tei was 0.48 ± 0.12 and E/E _m was 11.84 ± 1.53, control group RV Tei was 0.42 ± 0.16 and E/E _m was 10.16 ± 1.61; in neonatal period: VSD group RV Tei was 0.41 ± 0.17 and E/E _m was 12.21 ± 1.59, control group RV Tei was 0.30 ± 0.13 and E/E _m was 7.20 ± 1.28; in the infant period: VSD group RV Tei was 0.39 ± 0.09 and E/E _m was 11.89 ± 2.80, control group RV Tei was 0.28 ± 0.12 and E/E _m was 5.26 ± 1.90, all p < 0.05). In the fetal and neonatal periods, TAPSE correlated negatively with Tei index and tricuspid E/E _m in both groups. However, in the infant period, only the control group exhibited correlations between TAPSE and Tei index or tricuspid E/E _m. Tei index correlated positively with tricuspid E/E _m in both groups in all three periods. The VSD group had smaller correlation coefficients than the control group. Large VSD may already start to impair RV diastolic and global function before birth. This impairment continued and increased after birth. These changes did not associate with obvious RV longitudinal systolic function impairment. Large VSD mainly affected RV function by decreasing diastolic function and myocardial performance.

Pulmonary Hypertension

OBJECTIVES

To review the clinical classification, diagnosis, and pathophysiology of pulmonary hypertension in children, emphasizing the role of right ventricular function, ventricular interaction, and congenital heart disease in the evolution and progression of disease, as well as management strategies and therapeutic options.

DATA SOURCE

MEDLINE, PubMed.

CONCLUSIONS

Critically ill children with pulmonary hypertension associated with congenital heart disease are a high-risk population. Congenital cardiac defects resulting in either increased pulmonary blood flow or impaired pulmonary venous drainage predispose patients to developing structural and functional aberrations of the pulmonary vasculature. Mortality from pulmonary hypertension is most directly related to right ventricular failure.

Cardiac catheterization in children with pulmonary hypertensive vascular disease: consensus statement from the Pulmonary Vascular Research Institute, Pediatric and Congenital Heart Disease Task Forces

Cardiac catheterization is important in the diagnosis and risk stratification of pulmonary hypertensive vascular disease (PHVD) in children. Acute vasoreactivity testing provides key information about management, prognosis, therapeutic strategies, and efficacy. Data obtained at cardiac catheterization continue to play an important role in determining the surgical options for children with congenital heart disease and clinical evidence of increased pulmonary vascular resistance. The Pediatric and Congenital Heart Disease Task Forces of the Pulmonary Vascular Research Institute met to develop a consensus statement regarding indications for, conduct of, acute vasoreactivity testing with, and pitfalls and risks of cardiac catheterization in children with PHVD. This document contains the essentials of those discussions to provide a rationale for the hemodynamic assessment by cardiac catheterization of children with PHVD.

Pediatric Cardiac Intensive Care Society 2014 Consensus Statement: Pharmacotherapies in Cardiac Critical Care Pulmonary Hypertension

OBJECTIVE

To review the pharmacologic treatment options for pulmonary arterial hypertension in the cardiac intensive care setting and summarize the most-recent literature supporting these therapies.

DATA SOURCES AND STUDY SELECTION

Literature search for prospective studies, retrospective analyses, and case reports evaluating the safety and efficacy of pulmonary arterial hypertension therapies.

DATA EXTRACTION

Mechanisms of action and pharmacokinetics, treatment recommendations, safety considerations, and outcomes for specific medical therapies.

DATA SYNTHESIS

Specific targeted therapies developed for the treatment of adult patients with pulmonary arterial hypertension have been applied for the benefit of children with pulmonary arterial hypertension. With the exception of inhaled nitric oxide, there are no pulmonary arterial hypertension medications approved for children in the United States by the Food and Drug Administration. Unfortunately, data on treatment strategies in children with pulmonary arterial hypertension are limited by the small number of randomized controlled clinical trials evaluating the safety and efficacy of specific treatments. The treatment options for pulmonary arterial hypertension in children focus on endothelial-based pathways. Calcium channel blockers are recommended for use in a very small, select group of children who are responsive to vasoreactivity testing at cardiac catheterization. Phosphodiesterase type 5 inhibitor therapy is the most-commonly recommended oral treatment option in children with pulmonary arterial hypertension. Prostacyclins provide adjunctive therapy for the treatment of pulmonary arterial hypertension as infusions (IV and subcutaneous) and inhalation agents. Inhaled nitric oxide is the first-line vasodilator therapy in persistent pulmonary hypertension of the newborn and is commonly used in the treatment of pulmonary arterial hypertension in the ICU. Endothelin receptor antagonists have been shown to improve exercise tolerance and survival in adult patients with pulmonary arterial hypertension. Soluble guanylate cyclase stimulators are the first drug class to be Food and Drug Administration approved for the treatment of chronic thromboembolic pulmonary hypertension.

CONCLUSIONS

Literature and data supporting the safe and effective use of pulmonary arterial hypertension therapies in children in the cardiac intensive care are limited. Extrapolation of adult data has afforded safe medical treatment of pulmonary hypertension in children. Large multicenter trials are needed in the search for safe and effective therapy of pulmonary hypertension in children.

Iloprost for children with pulmonary hypertension after surgery to correct congenital heart disease

Congenital heart disease (CHD) can cause pulmonary hypertension (PH) in children, and surgery to correct CHD may be complicated by postoperative pulmonary hypertensive crises (PHC). Clinical data regarding the use of inhaled iloprost to treat children with PH are scarce. Our aim was to determine the efficacy and safety of iloprost in children with PH following surgery to correct CHD. This was a randomized, placebo-controlled study of 22 children (median age 7 months) undergoing surgery to achieve biventricular repair. The combined clinical endpoint was a decrease of more than 20% in the ratio of systolic pulmonary arterial pressure to systolic arterial pressure or pulmonary resistance to systemic resistance, with no PHC or death. Patients were randomized to receive low-dose iloprost (30 ng/kg/min), high-dose iloprost (50 ng/kg/min), or placebo, for 10 min every 2 hr in the first 48 hr after surgery. PHC were experienced by two patients who received placebo and one patient treated with high-dose iloprost. The combined clinical endpoint was reached by six patients administered low-dose iloprost (P = 0.005) and four administered high-dose iloprost (P = 0.077), compared with none in the placebo group. Patients treated with iloprost showed a significant reduction from baseline in mean pulmonary vascular resistance index (-2.2 Wood units, P < 0.05), whereas patients who received placebo showed no significant change. This study supports the use of iloprost to treat children with PH following surgery to correct CHD.

Treating pulmonary hypertension in pediatrics

INTRODUCTION

Pulmonary hypertension is a hemodynamic condition occurring rarely in pediatrics. Nevertheless, it is associated with significant morbidity and mortality. When characterized by progressive pulmonary vascular structural changes, the disease is called pulmonary arterial hypertension (PAH). It results in increased pulmonary vascular resistance and eventual right ventricular failure. In the vast majority of cases, pediatric PAH is idiopathic or associated with congenital heart disease, and, contrary to adult PAH, is rarely associated with connective tissue, portal hypertension, HIV infection or thromboembolic disease.

AREAS COVERED

This article reviews the current drug therapies available for the management of pediatric PAH. These treatments target the recognized pathophysiological pathways of PAH with endothelin-1 receptor antagonists, prostacyclin analogs and PDE type 5 inhibitors. New treatments and explored pathways are briefly discussed.

EXPERT OPINION

Although there is still no cure for PAH, quality of life and survival have been improved significantly with specific drug therapies. Nevertheless, management of pediatric PAH remains challenging, and depends mainly on results from adult clinical trials and pediatric experts. Further research on PAH-specific treatments in the pediatric population and data from international registries are needed to identify optimal therapeutic strategies and treatment goals in the pediatric population.

Use of inhaled iloprost for the management of postoperative pulmonary hypertension in congenital heart surgery patients: review of a transition protocol

Inhaled nitric oxide (iNO) is considered standard therapy for pediatric postcardiac surgical pulmonary hypertension (PH). Limited data suggest that inhaled iloprost (inIlo), an aerosolized prostacyclin, may be a feasible and more affordable therapeutic alternative. The goal of this study was to determine if significant hemodynamic change or adverse events would occur in postoperative congenital heart surgery (CHS) patients with PH after their transition from iNO to inIlo. This retrospective review investigated CHS patients with postoperative PH (mean pulmonary artery pressure [mPAP] >25 mmHg) between January 1, 2010 and December 31, 2011 who transitioned from iNO to inIlo. By protocol, CHS patients receiving stable doses of iNO were gradually transitioned to inIlo. After full transition, the patients received inIlo every 2 h, with a final dosing range of 1.25-5 μg/dose. Both PAP and systemic arterial pressure (SAP) were invasively measured during the transition period. Seven patients ages 10 days to 1.5 years completed the protocol. Measurements of mPAP (p = 0.27) and systolic PAP (p = 0.25) did not differ between iNO and inIlo therapy alone. No serious adverse events or complications (bleeding or thrombocytopenia) occurred. The ratio of systolic PAP to SAP decreased in all patients receiving inIlo alone (p = 0.03). Pulmonary hypertension in postoperative CHS patients can be managed successfully with inIlo, and the measured hemodynamics with this agent are similar to those observed with iNO. For the management of postoperative PH, inIlo may be a reasonable alternative, thus reducing the need for costly iNO. Larger confirmatory studies would more robustly facilitate its integration into standard care.

Perioperative pharmacological management of pulmonary hypertensive crisis during congenital heart surgery

Pulmonary hypertensive crisis is an important cause of morbidity and mortality in patients with pulmonary arterial hypertension secondary to congenital heart disease (PAH-CHD) who require cardiac surgery. At present, prevention and management of perioperative pulmonary hypertensive crisis is aimed at optimizing cardiopulmonary interactions by targeting prostacyclin, endothelin, and nitric oxide signaling pathways within the pulmonary circulation with various pharmacological agents. This review is aimed at familiarizing the practitioner with the current pharmacological treatment for dealing with perioperative pulmonary hypertensive crisis in PAH-CHD patients. Given the life-threatening complications associated with pulmonary hypertensive crisis, proper perioperative planning can help anticipate cardiopulmonary complications and optimize surgical outcomes in this patient population.

The anesthetic management of children with pulmonary hypertension in the cardiac catheterization laboratory

Children need cardiac catheterization to establish the diagnosis and monitor the response to treatment when undergoing drug therapy for the treatment of pulmonary arterial hypertension (PAH). Children with PAH receiving general anesthesia for cardiac catheterization procedures are at significantly increased risk of perioperative complications in comparison with other children. The most acute life-threatening complication is a pulmonary hypertensive crisis. It is essential that the anesthesiologist caring for these children understands the pathophysiology of the disease, how anesthetic medications may affect the patient's hemodynamics, and how to manage an acute pulmonary hypertensive crisis.

Drug treatment of pulmonary hypertension in children

Pulmonary arterial hypertension (PAH) is a rare disease in infants and children that is associated with significant morbidity and mortality. The disease is characterized by progressive pulmonary vascular functional and structural changes resulting in increased pulmonary vascular resistance and eventual right heart failure and death. In the majority of pediatric patients, PAH is idiopathic or associated with congenital heart disease and rarely is associated with other conditions such as connective tissue or thromboembolic disease. Although treatment of the underlying disease and reversal of advanced structural changes has not yet been achieved with current therapy, quality of life and survival have been improved significantly. Targeted pulmonary vasodilator therapies, including endothelin receptor antagonists, prostacyclin analogs, and phosphodiesterase type 5 inhibitors, have demonstrated hemodynamic and functional improvement in children. The management of pediatric PAH remains challenging, as treatment decisions continue to depend largely on results from evidence-based adult studies and the clinical experience of pediatric experts. This article reviews the current drug therapies and their use in the management of PAH in children.

Current challenges in pediatric pulmonary hypertension

Pulmonary arterial hypertension (PAH) in the pediatric population is associated with a variety of underlying diseases and causes, significantly morbidity and mortality. In the majority of patients, PAH in children is idiopathic or associated with congenital heart disease (CHD), with pulmonary hypertension (PH) associated with connective tissue disease, a rare cause in children. Classification of pediatric PH has generally followed the WHO classification, but recognition of the importance of fetal origins of PH and developmental abnormalities have led to the formation of a new pediatric-specific classification. Incidence data from the Netherlands has revealed an annual incidence and point prevalence of 0.7 and 4.4 for idiopathic PAH and 2.2 and 15.6 for associated pulmonary arterial hypertension-CHD cases per million children. Although the treatment with new selective pulmonary vasodilators offers hemodynamic and functional improvement in pediatric populations, the treatments in children largely depend on results from evidence-based adult studies and experience of clinicians treating children. A recent randomized clinical trial of sildenafil and its long-term extension has led to disparate recommendations in the United States and Europe.

Acute pulmonary vasodilator testing with inhaled treprostinil in children with pulmonary arterial hypertension

Acute pulmonary vasodilator testing (AVT) is essential to determining the initial therapy for children with pulmonary arterial hypertension (PAH). This study aimed to report the initial experience with inhaled treprostinil used for AVT in children with PAH and to evaluate the hemodynamic change after inhaled treprostinil compared with inhaled nitric oxide. This prospective cohort study was designed for 13 children who underwent AVT with inhaled treprostinil or oxygen plus inhaled nitric oxide (iNO) during catheterization. Inhaled treprostinil was delivered during cardiac catheterization by adapting the Optineb ultrasonic nebulizer via either a flow-inflating bag or the manual mode of the anesthesia system. The median age of the patients was 10 years (range 4-17 years). The etiologies of PAH included idiopathic PAH and associated PAH. All the patients tolerated inhaled treprostinil without marked clinical worsening and received six or nine breaths (36 or 54 μg) of treprostinil. The median of the total treprostinil doses was 1.53 μg/kg (range 0.71-2.89 μg/kg). Inhaled treprostinil was administrated via an endotracheal tube (n = 8), anesthesia mask (n = 3), or laryngeal mask airway (n = 2). Inhaled nitric oxide (iNO) and inhaled treprostinil significantly decreased the mean pulmonary artery pressure and the pulmonary vascular resistance index compared with baseline. Three adverse events were reported after inhaled treprostinil, including cough and mild to moderate hypotension with higher doses. All adverse events resolved without any intervention. This study report is the first to describe the use of inhaled treprostinil for AVT in children with PAH. In this small pediatric cohort, inhaled treprostinil was effectively delivered and well tolerated and may be useful for AVT.

Long-term inhaled iloprost use in children with pulmonary arterial hypertension

BACKGROUND

We performed a retrospective analysis of patients with pulmonary arterial hypertension receiving inhaled iloprost in a single centre to evaluate long-term tolerability, safety, and efficacy of chronic inhaled iloprost therapy in children.

METHODS

A total of 20 patients with either idiopathic or associated pulmonary arterial hypertension were treated with iloprost between April, 2003 and January, 2010. The median age and weight of the patients were 3.8 years--ranging from 4 months to 19 years--and 12.3 kilograms--ranging from 4 to 73 kilograms-- respectively. Pulmonary arterial hypertension was idiopathic or hereditary in eight patients (40%) and associated with congenital cardiac disease in 12 patients (60%).

RESULTS

Of the 20 patients, 15 had combined therapy--12 patients with two and three patients with three different classes of drugs. In all, six patients died during follow-up. The median follow-up time was 18 months, ranging from 6 to 74 months. The 6-minute walking test was performed in 7 out of 20 patients at baseline and on follow-up. The median 6-minute walking test increased from 420 to 490 metres after iloprost therapy (p = 0.028). After initiation of iloprost therapy, one patient complained of headache and another had a rash around his mouth, none necessitating discontinuation of therapy. Overall compliance with inhaled iloprost was good.

CONCLUSION

Pulmonary hypertension is associated with significant morbidity and mortality. Careful assessment of each patient and timely combination of specific vasodilator therapy is needed to improve clinical outcomes. This study suggests that inhaled iloprost, with or without concomitant endotelin receptor antagonist and/or phosphodiesterase inhibitor, is safe and efficacious for treatment of pulmonary arterial hypertension in children.

Inhaled iloprost for the control of acute pulmonary hypertension in children: a systematic review

OBJECTIVE

Inhaled iloprost is attracting growing interest as a potential alternative and/or adjuvant to inhaled nitric oxide in the management of pediatric pulmonary hypertension in the acute and intensive care settings. However, there are currently no formal evidence-based guidelines regarding the use of inhaled iloprost in children with pulmonary hypertension. The aim of this systematic review is to assess the literature concerning the use of inhaled iloprost in children with pulmonary hypertension in the acute setting.

DATA SOURCES

Studies were identified from PubMed and Embase. Internal literature databases and recent congress abstracts (2009 onward) were also searched for relevant publications.

STUDY SELECTION

Studies were included if they examined the use of inhaled iloprost in children with pulmonary hypertension in an acute or intensive care setting.

DATA EXTRACTION AND SYNTHESIS

Twenty-eight studies were included in the review. The majority were case studies or case series (n = 17), and in total, the 28 studies represented the treatment of 195 children with iloprost. Iloprost was most frequently studied in children undergoing cardiac surgery (as a bridge to surgery and postoperatively), in children undergoing acute pulmonary vasoreactivity testing, and in neonates with persistent pulmonary hypertension of the newborn. The results of the included studies suggested that inhaled iloprost may have a diverse role in the acute treatment of pediatric pulmonary hypertension and that its acute effects are similar to those of inhaled nitric oxide. However, the iloprost dose was not consistently reported and varied greatly between studies, and several different administration devices were used.

CONCLUSIONS

Inhaled iloprost may be useful in the acute treatment of children and neonates with pulmonary hypertension, but clinical data are scarce, and the appropriate dosing of iloprost in different scenarios is uncertain. Well-designed prospective clinical trials are needed.

Advances in pediatric pulmonary arterial hypertension

PURPOSE OF REVIEW

Pulmonary arterial hypertension (PAH) is an important cause of morbidity and mortality in children. Approved medications for the treatment of adult PAH have been used to treat children, but evidence-based treatment algorithms for children are lacking.

RECENT FINDINGS

Pediatric PAH registries have begun to define the incidence and prevalence of idiopathic PAH and PAH associated with congenital heart disease. A pediatric-specific classification of pulmonary hypertensive vascular disease has been proposed. Furthermore, the first randomized placebo-controlled trial of type-5 phosphodiesterase therapy in treatment-naïve children with PAH has been completed and reported. This trial highlights the importance of the difficulties of performing clinical trials in children with targeted PAH therapy as well as the importance of long-term follow-up of adverse events.

SUMMARY

Classification, clinical trials, and therapy for children with PAH must take into account the unique aspects of PAH in children.

Adult congenital heart disease and pulmonary arterial hypertension: the Texas Adult Congenital Heart Program experience

Congenital heart disease (CHD) is a common structural defect of the heart or major blood vessels. Patients with adult congenital heart disease (ACHD) have medical needs that are distinct from those of pediatric patients with CHD, and the transition into adult health care is important for management of the patient with ACHD. A large proportion of patients with CHD develop diseases and complications associated with the long-term stress of intracardiac shunts. Pulmonary arterial hypertension (PAH) is a significant complication of some CHD lesions. The treatment of these patients remains challenging due to their combined heart and lung disease, and multidisciplinary care is ofen necessitated for a variety of secondary conditions. A number of treatment options are available for the management of PAH associated with CHD, including prostanoids, phosphodiesterase type-5 inhibitors, and endothelin receptor antagonists. This article discusses the diagnosis and management of such ACHD patients with PAH.

Milrinone attenuates thromboxane receptor-mediated hyperresponsiveness in hypoxic pulmonary arterial myocytes

BACKGROUND AND PURPOSE

Neonatal pulmonary hypertension (PPHN) is characterized by pulmonary vasoconstriction, due in part to dysregulation of the thromboxane prostanoid (TP) receptor. Hypoxia induces TP receptor-mediated hyperresponsiveness, whereas serine phosphorylation mediates desensitization of TP receptors. We hypothesized that prostacyclin (IP) receptor activity induces TP receptor phosphorylation and decreases ligand affinity; that TP receptor sensitization in hypoxic myocytes is due to IP receptor inactivation; and that this would be reversible by the cAMP-specific phosphodiesterase inhibitor milrinone.

EXPERIMENTAL APPROACH

We examined functional regulation of TP receptors by serine phosphorylation and effects of IP receptor stimulation and protein kinase A (PKA) activity on TP receptor sensitivity in myocytes from neonatal porcine resistance pulmonary arteries after 72 h hypoxia in vitro. Ca(2+) response curves to U46619 (TP receptor agonist) were determined in hypoxic and normoxic myocytes incubated with or without iloprost (IP receptor agonist), forskolin (adenylyl cyclase activator), H8 (PKA inhibitor) or milrinone. TP and IP receptor saturation binding kinetics were measured in presence of iloprost or 8-bromo-cAMP.

KEY RESULTS

Ligand affinity for TP receptors was normalized in vitro by IP receptor signalling intermediates. However, IP receptor affinity was compromised in hypoxic myocytes, decreasing cAMP production. Milrinone normalized TP receptor sensitivity in hypoxic myocytes by restoring PKA-mediated regulatory TP receptor phosphorylation.

CONCLUSIONS AND IMPLICATIONS

TP receptor sensitivity and EC(50) for TP receptor agonists was regulated by PKA, as TP receptor serine phosphorylation by PKA down-regulated Ca(2+) mobilization. Hypoxia decreased IP receptor activity and cAMP generation, inducing TP receptor hyperresponsiveness, which was reversed by milrinone.

Perioperative management of pulmonary hypertension in children with critical heart disease

OPINION STATEMENT

Pulmonary hypertension (PHTN) is common to a variety of conditions occurring in infants and children presenting to the intensive care unit. A fundamental understanding of the response of the right ventricle to an increase in afterload and the clinical syndromes responsible for PHTN is essential for managing patients with PHTN and critical heart disease. There are important distinguishing features between PHTN syndromes, and although one form of PHTN may predominate, often more than one mechanism of PHTN is contributing to the pathophysiologic state. Thus, it is imperative to tailor therapies accordingly in order to optimize outcomes.

Diagnosis and treatment of pulmonary chronic GVHD: report from the consensus conference on clinical practice in chronic GVHD

This consensus statement established under the auspices of the German working group on BM and blood stem cell transplantation (DAG-KBT), the German Society of Hematology and Oncology (DGHO), the Austrian Stem Cell Transplant Working Group, the Swiss Blood Stem Cell Transplantation Group (SBST) and the German-Austrian Pediatric Working Group on SCT (Päd-Ag-KBT) summarizes current evidence for diagnosis, immunosuppressive and supportive therapy to provide practical guidelines for the care and treatment of patients with pulmonary manifestations of chronic GVHD (cGVHD). Pulmonary cGVHD can present with obstructive and/or restrictive changes. Disease severity ranges from subclinical pulmonary function test (PFT) impairment to respiratory insufficiency with bronchiolitis obliterans being the only pulmonary complication currently considered diagnostic of cGVHD. Early diagnosis may improve clinical outcome, and regular post-transplant follow-up PFTs are recommended. Diagnostic work-up includes high-resolution computed tomography, bronchoalveolar lavage and histology. Topical treatment is based on inhalative steroids plus beta-agonists. Early addition of azithromycin is suggested. Systemic first-line treatment consists of corticosteroids plus, if any, continuation of other immunosuppressive therapy. Second-line therapy and beyond includes extracorporeal photopheresis, mammalian target of rapamycin inhibitors, mycophenolate, etanercept, imatinib and TLI, but efficacy is limited. Clinical trials are urgently needed to improve understanding and treatment of this deleterious complication.

Plasma cyclic 3',5'-adenosine monophosphate in patients with elevated pulmonary pressure due to left-to-right shunt

BACKGROUND

Increased pulmonary blood flow in patients with left-to-right shunt has been shown to be associated with alterations in prostacyclin-synthesis. There are limited data with respect to the plasma cAMP in patients with elevated pulmonary artery pressure due to left-to-right shunt. We hypothesized that plasma cAMP might be influenced by pulmonary blood flow or pressure in patients with left-to-right shunt.

METHODS

Plasma cAMP from venous blood was measured in 122 healthy controls aged 8.3 (0.2 - 14.9) years (median [range]) and in 130 patients with left-to-right shunt aged 1.4 (0.1 - 19.1) years by radioimmunoassay.

RESULTS

Plasma cAMP in controls and in patients was similar and decreased with age. Healthy infants (n = 42) showed higher plasma cAMP (46 [27-112] nmol/l) than children > 6 years of age (n = 40, 39 [19-73] nmol/l; P < 0.001).

CONCLUSIONS

These values should be taken into consideration when reporting plasma values for cAMP in patients with congenital heart disease. The values for healthy children obtained in this study should allow a better interpretation of plasma cAMP levels in various disease conditions such as chronic renal failure, liver chirrhosis, hyperthyreosis, or children with intellectual disability.

Pediatric pulmonary arterial hypertension: current and emerging therapeutic options

INTRODUCTION

Pulmonary arterial hypertension (PAH) is a rare disease in neonates, infants and children that is associated with significant morbidity and mortality. An adequate understanding of the controlling pathophysiologic mechanisms is lacking and although mortality has decreased as therapeutic options have increased over the past several decades, outcomes remain unacceptable.

AREAS COVERED

This review summarizes the currently available therapies for neonates, infants and children with PAH and describes emerging therapies in the context of what is known about the underlying pathophysiology of the disease.

EXPERT OPINION

All of the currently approved PAH therapies impact one of three endothelial-based pathways: nitric oxide-guanosine-3'-5'cyclic monophosphate, prostacyclin or endothelin-1. The beneficial effects of these agents may relate to their impact on pulmonary vascular tone, and/or their antiproliferative and antithrombotic properties. Fundamental advances in PAH therapy are likely to relate to: i) a better understanding of PAH subpopulations, allowing for therapies to be better tailored to individual patients and pathophysiologic processes; and ii) therapies that promote the regression of advanced structural remodeling.

Evaluation of drug formularies for pediatric intensive care

OBJECTIVES

To evaluate availability and reliability of pediatric drug dosing guidelines in selected formularies for intensive care patients. Most drugs used in the pediatric intensive care unit are prescribed off-label, often on the guidance of limited information from commonly used drug formularies.

DESIGN

Availability of dosing information on prescribed drugs in a Dutch intensive care unit from January 1, 2005 to December 31, 2006 was compared among four selected formularies (Micromedex, Lexi-Comp, Drug Formulary for Children, Drug Doses). Reliability of dosing guidelines was assessed by evaluating labeling status and literature data for the three most (midazolam, acetaminophen, and amoxicillin/clavulanic acid) and the three least (bosentan, ketanserin, and iloprost) prescribed drugs.

MEASUREMENTS AND MAIN RESULTS

The selected formularies covered 68% to 86% of all 257 prescribed drugs. Guidelines differ widely on daily doses per kilogram, dose description, dosing regimen, and age ranges. For the three most prescribed and one of the least prescribed drugs (bosentan), dosing guidelines adequately reflected labeling status and existing (but scarce) literature. No dosing guidelines were available for iloprost, and only one dosing guideline was available for ketanserin.

CONCLUSIONS

This study shows that four commonly used drug formularies give few and widely differing dosing guidelines for drugs prescribed in the intensive care unit. If guidelines exist, they seem to reflect labeling status (if present) and limited literature available. Findings from this study likely reflect the scarcity of drug studies in this population. Physicians should be aware of the limitations of these formularies for daily practice in this group of vulnerable patients.