Exercise-Induced Pulmonary Hypertension in Long-Term Survivors of Congenital Diaphragmatic Hernia

OBJECTIVE

To determine the prevalence of exercise-induced pulmonary hypertension (PH) among long-survivors of congenital diaphragmatic hernia repair.

STUDY DESIGN

This is a single-center, retrospective cohort study of CDH survivors who underwent exercise stress echocardiography (ESE) at Boston Children's Hospital from January 2006 to June 2020. PH severity was assessed by echocardiogram at baseline and after exercise. Patients were categorized by right ventricular systolic pressure (RVSP) after exercise: Group 1 - no or mild PH; and Group 2 - moderate or severe PH (RVSP ≥ 60 mmHg or ≥ ½ systemic blood pressure).

RESULTS

Eighty-four patients with CDH underwent 173 ESE with median age 8.1 (4.8 - 19.1) years at first ESE. Sixty-four patients were classified as Group 1, 11 as Group 2, and 9 had indeterminate RVSP with ESE. Moderate to severe PH after exercise was found in 8 (10%) patients with no or mild PH at rest. Exercise-induced PH was associated with larger CDH defect size, patch repair, use of ECMO, supplemental oxygen at discharge, and higher WHO functional class. Higher VE/VCO2 slope, lower peak oxygen saturation, and lower percent predicted FEV1, and FEV1/FVC ratio were associated with Group 2 classification. ESE changed management in 9/11 Group 2 patients. PH was confirmed in all 5 Group 2 patients undergoing cardiac catheterization after ESE.

CONCLUSIONS

Among long-term CDH survivors, 10% had moderate-severe exercise-induced PH on ESE, indicating ongoing pulmonary vascular abnormalities. Further studies are needed to optimally define PH screening and treatment for patients with repaired CDH.

Actigraphy methodology in the Kids Mod PAH trial: Physical activity as a functional endpoint in pediatric clinical trials

Pulmonary vasodilator treatment can improve hemodynamics, right ventricular function, symptoms, and survival in pediatric pulmonary hypertension (PH). However, clinical trial data are lacking due to many constraints. One major limitation is the lack of relevant trial endpoints reflective of hemodynamics or functional status in patients in whom standard exercise testing is impractical, unreliable, or not reproducible. The Kids Mod PAH trial (Mono- vs. Duo Therapy for Pediatric Pulmonary Arterial Hypertension) is an ongoing multicenter, Phase III, randomized, open-label, pragmatic trial to compare the safety and efficacy of first-line combination therapy (sildenafil and bosentan) to first-line monotherapy (sildenafil alone) in 100 pediatric patients with PH across North America. Investigators will measure participants' physical activity with a research-grade, wrist-worn actigraphy device at multiple time points as an exploratory secondary outcome. Vector magnitude counts per minute and activity intensity will be compared between the treatment arms. By directly and noninvasively measuring physical activity in the ambulatory setting, we aim to identify a novel, simple, inexpensive, and highly reproducible approach for quantitative assessment of exercise tolerance in pediatric PH. These data will increase the field's understanding of the effect of pulmonary vasodilator treatment on daily activity - a quantitative measure of functional status and wellbeing in pediatric PH and a potential primary outcome for future clinical trials in children with cardiopulmonary disorders.

Measurement of Physical Activity by Actigraphy in Infants and Young Children with Pulmonary Arterial Hypertension

OBJECTIVE

To evaluate the feasibility, tolerability, and adherence with wearable actigraphy devices among infants and children with pulmonary arterial hypertension (PAH).

STUDY DESIGN

This multicenter, prospective, observational study included children ages 0-6 years with and without PAH. Participants wore the ActiGraph wGT3X-BT on the hip and FitBit Inspire on the wrist during waking hours for 14 days. Steps, vector magnitude counts per minute, activity intensity, heart rate, and heart rate variability were compared between groups.

RESULTS

Forty-seven participants (18 PAH, 29 control) were enrolled from 10 North American sites. PAH patients were mostly functional class II (n = 16, 89%) and treated with oral medications at the time of enrollment. The number of wear days was not significantly different between the groups (ActiGraph: 10 [95% CI: 5.5, 12.2] in PAH vs 8 [4, 12] in control, P = .20; FitBit 13 [10, 13.8] in PAH vs 12 [8, 14] in control, P = .87). Complete data were obtained in 81% of eligible ActiGraph participants and 72% of FitBit participants. PAH participants demonstrated fewer steps, lower vector magnitude counts per minute, more sedentary activity, and less intense physical activity at all levels compared with control participants. No statistically significant differences in heart rate variability were demonstrated between the 2 groups.

CONCLUSIONS

Measurement of physical activity and other end points using wearable actigraphy devices was feasible in young children with PAH. Larger studies should determine associations between physical activity and disease severity in young patients with PAH to identify relevant end points for pediatric clinical trials.

Kids Mod PAH trial: A multicenter trial comparing mono- versus duo-therapy for initial treatment of pediatric pulmonary hypertension

Pulmonary hypertension (PH) is a significant health problem that contributes to high morbidity and mortality in diverse cardiac, pulmonary, and systemic diseases in children. Evidence-based advances in PH care have been challenged by a paucity of quality endpoints for assessing clinical course and the lack of robust clinical trial data to guide pharmacologic therapies in children. While the landmark adult AMBITION trial demonstrated the benefit of up-front combination PH therapy with ambrisentan and tadalafil, it remains unknown whether upfront combination therapy leads to more rapid and sustained clinical benefits in children with various categories of PH. In this article, we describe the inception of the Kids Mod PAH Trial, a multicenter Phase III trial, to address whether upfront combination therapy (sildenafil and bosentan vs. sildenafil alone) improves PH outcomes in children, recognizing that marked differences between the etiology and therapeutic response between adults and children exist. The primary endpoint of this study is WHO functional class (FC) 12 months after initiation of study drug therapy. In addition to the primary outcome, secondary endpoints are being assessed, including a composite measure of time to clinical worsening, WHO FC at 24 months, echocardiographic assessment of PH and quantitative assessment of right ventricular function, 6-min walk distance, and NT-proBNP levels. Exploratory endpoints include selected biomarkers, actigraphy, and assessments of quality of life. This study is designed to pave the way for additional clinical trials by establishing a robust infrastructure through the development of a PPHNet Clinical Trials Network.

Exercise Pathophysiology in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Postacute Sequelae of SARS-CoV-2: More in Common Than Not?

TOPIC IMPORTANCE

Postacute sequelae of SARS-CoV-2 (PASC) is a long-term consequence of acute infection from COVID-19. Clinical overlap between PASC and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) has been observed, with shared symptoms including intractable fatigue, postexertional malaise, and orthostatic intolerance. The mechanistic underpinnings of such symptoms are poorly understood.

REVIEW FINDINGS

Early studies suggest deconditioning as the primary explanation for exertional intolerance in PASC. Cardiopulmonary exercise testing reveals perturbations related to systemic blood flow and ventilatory control associated with acute exercise intolerance in PASC, which are not typical of simple detraining. Hemodynamic and gas exchange derangements in PASC have substantial overlap with those observed with ME/CFS, suggestive of shared mechanisms.

SUMMARY

This review illustrates exercise pathophysiologic commonalities between PASC and ME/CFS that will help guide future diagnostics and treatment.

Transcatheter Ductus Arteriosus Stenting for Acute Pediatric Pulmonary Arterial Hypertension is Associated with Improved Right Ventricular Echocardiography Strain

BACKGROUND

Interventional therapies for severe pulmonary arterial hypertension (PAH) can provide right ventricular (RV) decompression and preserve cardiac output. Transcatheter stent placement in a residual ductus arteriosus (PDA) is one potentially effective option in critically ill infants and young children with PAH. We sought to assess recovery of RV function by echocardiographic strain in infants and young children following PDA stenting for acute PAH.

METHODS

Retrospective review of patients < 2 years old who underwent PDA stenting for acute PAH. Clinical data were abstracted from the electronic medical record. RV strain (both total and free wall components) was assessed from echocardiographic images at baseline and 3, 6, and 12 months post-intervention, as well as at last echocardiogram.

RESULTS

Nine patients underwent attempted ductal stenting for PAH. The median age at intervention was 38 days and median weight 3.7 kg. One-third (3of 9) of patients had PAH associated with a congenital diaphragmatic hernia. PDA stents were successfully deployed in eight patients. Mean RV total strain was - 14.9 ± 5.6% at baseline and improved to - 23.8 ± 2.2% at 6 months post-procedure (p < 0.001). Mean free wall RV strain was - 19.5 ± 5.4% at baseline and improved to - 27.7 ± 4.1% at 6 months (p = 0.002). Five patients survived to discharge, and four patients survived 1 year post-discharge.

CONCLUSION

PDA stenting for severe, acute PAH can improve RV function as assessed by strain echocardiography. The quantitative improvement is more prominent in the first 6 months post-procedure and stabilizes thereafter.

Pulmonary Hypertension in Infants and Children with Vein of Galen Malformation and Association with Clinical Outcomes

OBJECTIVE

To assess the extent and resolution of pulmonary hypertension (PH), cardiovascular factors, and echocardiographic findings associated with mortality in infants and children with vein of Galen malformation (VOGM).

STUDY DESIGN

We performed a retrospective review of 49 consecutive children with VOGM admitted to Boston Children's Hospital from 2007 to 2020. Patient characteristics, echocardiographic data, and hospital course were analyzed for 2 cohorts based on age at presentation to Boston Children's Hospital: group 1 (age ≤60 days) or group 2 (age >60 days).

RESULTS

Overall hospital survival was 35 of 49 (71.4%); 13 of 26 (50%) in group 1 and 22 of 23 (96%) in group 2 (P < .001). High-output PH (P = .01), cardiomegaly (P = .011), intubation (P = .019), and dopamine use (P = .01) were significantly more common in group 1 than group 2. Among patients in group 1, congestive heart failure (P = .015), intubation (P < .001), use of inhaled nitric oxide (P = .015) or prostaglandin E1 (P = .030), suprasystemic PH (P = .003), and right-sided dilation were significantly associated with mortality; in contrast, left ventricular volume and function, structural congenital heart disease, and supraventricular tachycardia were not associated. Inhaled nitric oxide achieved no clinical benefit in 9 of 11 treated patients. Resolution of PH was associated with overall survival (P < .001).

CONCLUSIONS

VOGM remains associated with substantial mortality among infants presenting at ≤60 days of life owing to factors associated with high output PH. Resolution of PH is an indicator associated with survival and a surrogate end point for benchmarking outcomes.

Long-Term Functional Outcomes at 1-Year After Hospital Discharge in Critically Ill Neonates With Congenital Diaphragmatic Hernia

OBJECTIVES

Congenital diaphragmatic hernia (CDH) is a birth defect associated with long-term morbidity. Our objective was to examine longitudinal change in Functional Status Scale (FSS) after hospital discharge in CDH survivors.

DESIGN

Single-center retrospective cohort study.

SETTING

Center for comprehensive CDH management at a quaternary, free-standing children's hospital.

PATIENTS

Infants with Bochdalek CDH were admitted to the ICU between January 2009 and December 2019 and survived until hospital discharge.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

One hundred forty-two infants (58% male, mean birth weight 3.08 kg, 80% left-sided defects) met inclusion criteria. Relevant clinical data were extracted from the medical record to calculate FSS (primary outcome) at hospital discharge and three subsequent outpatient follow-up time points. The median (interquartile range [IQR]) FSS score at hospital discharge was 8.0 (7.0-9.0); 39 patients (27.5%) had at least moderate impairment (FSS ≥ 9). Median (IQR) FSS at 0- to 6-month (n = 141), 6- to 12-month (n = 141), and over 12-month (n = 140) follow-up visits were 7.0 (7.0-8.0), 7.0 (6.0-8.0), and 6.0 (6.0-7.0), respectively. Twenty-one patients (15%) had at least moderate impairment at over 12-month follow-up; median composite FSS scores in the over 12-month time point decreased by 2.0 points from hospital discharge. Median feeding domain scores improved by 1.0 (1.0-2.0), whereas other domain scores remained without impairment. Multivariable analysis demonstrated right-sided, C- or D-size defects, extracorporeal membrane oxygenation use, cardiopulmonary resuscitation, and chromosomal anomalies were associated with impairment.

CONCLUSIONS

The majority of CDH survivors at our center had mild functional status impairment (FSS ≤ 8) at discharge and 1-year follow-up; however, nearly 15% of patients had moderate impairment during this time period. The feeding domain had the highest level of functional impairment. We observed unchanged or improving functional status longitudinally over 1-year follow-up after hospital discharge. Longitudinal outcomes will guide interdisciplinary management strategies in CDH survivors.

Molecular Function and Contribution of TBX4 in Development and Disease

Over the past decade, recognition of the profound impact of the TBX4 (T-box 4) gene, which encodes a member of the evolutionarily conserved family of T-box-containing transcription factors, on respiratory diseases has emerged. The developmental importance of TBX4 is emphasized by the association of TBX4 variants with congenital disorders involving respiratory and skeletal structures; however, the exact role of TBX4 in human development remains incompletely understood. Here, we discuss the developmental, tissue-specific, and pathological TBX4 functions identified through human and animal studies and review the published TBX4 variants resulting in variable disease phenotypes. We also outline future research directions to fill the gaps in our understanding of TBX4 function and of how TBX4 disruption affects development.

An intronic variant in TBX4 in a single family with variable and severe pulmonary manifestations

A male infant presented at term with neonatal respiratory failure and pulmonary hypertension. His respiratory symptoms improved initially, but he exhibited a biphasic clinical course, re-presenting at 15 months of age with tachypnea, interstitial lung disease, and progressive pulmonary hypertension. We identified an intronic TBX4 gene variant in close proximity to the canonical donor splice site of exon 3 (hg 19; chr17:59543302; c.401 + 3 A > T), also carried by his father who had a typical TBX4-associated skeletal phenotype and mild pulmonary hypertension, and by his deceased sister who died shortly after birth of acinar dysplasia. Analysis of patient-derived cells demonstrated a significant reduction in TBX4 expression resulting from this intronic variant. Our study illustrates the variable expressivity in cardiopulmonary phenotype conferred by TBX4 mutation and the utility of genetic diagnostics in enabling accurate identification and classification of more subtly affected family members.

Outcomes for Children With Pulmonary Hypertension Undergoing Tracheostomy Placement: A Multi-Institutional Analysis

OBJECTIVES

To describe epidemiology, interventions, outcomes, and the health services experience for a cohort of children with pulmonary hypertension (PH) who underwent tracheostomy placement and to identify risk factors for inhospital mortality and 30-day readmissions.

DESIGN

Retrospective cohort study of the Pediatric Health Information System database.

SETTING

Thirty-seven freestanding U.S. children's hospitals.

PATIENTS

Patients 31 days to 21 years old who were discharged from the hospital between January 1, 2009, and December 31, 2017, with a diagnosis of primary or secondary PH, and who underwent tracheostomy placement. Outcomes were examined over a 2-year period from the time of discharge from the index encounter.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

There were 793 patients with PH who underwent tracheostomy placement. The overall inhospital mortality rate was 23.7%. Secondary PH due to congenital heart disease (CHD) was significantly associated with overall inhospital mortality (adjusted odds ratio [OR], 2.36; 95% CI, 1.38-4.04). The rate of 30-day readmissions for patients over the 2-year follow-up period was 33.3%. Tracheostomy during the index encounter and the diagnosis of secondary PH due to CHD were significantly associated with lower rates of 30-day readmissions (adjusted OR, 0.34; 95% CI, 0.19-0.61; and adjusted OR, 0.43; 95% CI, 0.24-0.77, respectively).

CONCLUSIONS

In the context of expanding utilization of tracheostomy and long-term ventilation, children with PH are among the highest risk cohorts for extended and repeated hospitalization and death. Tracheostomy placement during the index encounter was associated with fewer 30-day readmissions over the 2-year follow-up period. Further understanding of which subgroups may benefit from earlier intervention and which subgroups are at highest risk may offer important clinical insight when considering optimal timing of tracheostomy and may enhance informed decision-making for all stakeholders.

Diagnosis and management of pulmonary hypertension in infants with bronchopulmonary dysplasia

Chronic pulmonary hypertension of infancy (cPHi) is a heterogeneous disease process that contributes to morbidity and mortality in preterm infants. cPHi is most commonly associated with chronic lung disease of prematurity and represents a unique phenotype of bronchopulmonary dysplasia. It is characterized by persistently elevated or newly rising pulmonary vascular resistance and pulmonary artery pressure beyond the first weeks of age. The high-pressure afterload on the right ventricle may or may not be tolerated, depending upon additional cardiovascular shunting and co-morbidities. A comprehensive clinical evaluation combined with advanced hemodynamic assessment by echocardiography and other cardiac imaging modalities help decipher the etiopathologies of disease, identify cardiopulmonary compromise earlier and guide individualized therapeutic intervention tailored by the phenotype. This review summarizes the underlying etiologies, risk factors for development, hemodynamic assessment, management, and follow-up of cPHi in preterm infants. We offer an algorithm for early detection of cPHi and outline research priorities.

Factors Determining Change in Treatment for Ambulatory Children With Pulmonary Arterial Hypertension: Implications for Monitoring

While care models adapt to the COVID‐19 pandemic with virtual and hybrid visits, clinical factors associated with treatment changes among ambulatory pediatric pulmonary arterial hypertension (PAH) patients are not well characterized. To understand which data critically altered treatment recommendations, we conducted a retrospective review among ambulatory children with Group 1 PAH to determine optimal visit and diagnostic strategies. Changes in management included: unplanned new treatments, dose modifications of vasodilators or diuretics, unscheduled hospitalizations, or changes to activity recommendations, catheterization schedule, or other testing. Factors prompting management changes were classified as symptoms, exam findings, or diagnostic tests. Across 398 ambulatory visits by 48 patients, 38 patients (79%) at 88 visits (22%) required change in management, most commonly in targeted PH medication. Changes were driven by symptoms alone (15%), diagnostic testing alone (47%), exam only (2%), symptoms and exam (2%), combination of testing and symptoms or testing and exam (25%), and other reasons (9%). Patients with World Health Organization functional Class IV (odds ratio [OR] 9.04 vs. Class I, p = 0.014) or Class III (OR 2.08 vs. Class I, p = 0.050) were more likely to undergo change in management. However, among Class I patients, 18% of visits generated changes in management because of test findings. While multiple factors affect management in ambulatory pediatric PH, neither symptoms nor exam was sufficient for identifying patients warranting clinical change in management. Testing accounted for most changes. Thus, in‐person or hybrid surveillance including history, exam, and diagnostic testing remains essential for optimal management of pediatric PAH.

Recovery of right ventricular function after bilateral lung transplantation for pediatric pulmonary hypertension

BACKGROUND

Lung transplantation is a therapeutic option for end-stage pediatric pulmonary hypertension (PH). Right ventricular (RV) recovery post-lung transplant in children with PH has not been well-described, and questions persist about the peri-operative course and post-transplant cardiac function after lung transplantation in medically refractory PH patients with baseline RV dysfunction.

METHODS

A single-center chart review identified patients with childhood PH who subsequently underwent bilateral orthotopic lung transplantation between 2000 and 2020. Twenty-six patients met criteria; three were excluded due to echocardiograms not available for digital review. RV fractional area change (FAC) and left ventricular eccentricity index (LVEI) were determined prior to transplantation, and at 1, 3, 6, and 12-month post-transplantation.

RESULTS

Fourteen of 23 patients had baseline RV dysfunction. The median age at transplantation was 16.5 years and 13.9 years for those with and without baseline RV dysfunction, respectively. Of the 14 with baseline RV dysfunction, 12 (86%) were alive 1-year post-transplantation. All patients with baseline RV dysfunction had increased RV-FAC post-transplantation with normalization of RV-FAC in 70% at 3 months and 100% of patients by 12-month post-transplantation. Duration of ventilation (p = .4), intensive care unit (p = .5), or hospital stay (p = .9) was not associated with pre-transplant RV function.

CONCLUSIONS

Among pediatric patients with PH and RV dysfunction, pre-transplantation RV function was not associated with short-term outcomes. All patients with baseline RV dysfunction had improvement in RV function, justifying consideration of lung transplantation among pediatric patients with end-stage PH and RV dysfunction.

A homozygous stop-gain variant in ARHGAP42 is associated with childhood interstitial lung disease, systemic hypertension, and immunological findings

ARHGAP42 encodes Rho GTPase activating protein 42 that belongs to a member of the GTPase Regulator Associated with Focal Adhesion Kinase (GRAF) family. ARHGAP42 is involved in blood pressure control by regulating vascular tone. Despite these findings, disorders of human variants in the coding part of ARHGAP42 have not been reported. Here, we describe an 8-year-old girl with childhood interstitial lung disease (chILD), systemic hypertension, and immunological findings who carries a homozygous stop-gain variant (c.469G>T, p.(Glu157Ter)) in the ARHGAP42 gene. The family history is notable for both parents with hypertension. Histopathological examination of the proband lung biopsy showed increased mural smooth muscle in small airways and alveolar septa, and concentric medial hypertrophy in pulmonary arteries. ARHGAP42 stop-gain variant in the proband leads to exon 5 skipping, and reduced ARHGAP42 levels, which was associated with enhanced RhoA and Cdc42 expression. This is the first report linking a homozygous stop-gain variant in ARHGAP42 with a chILD disorder, systemic hypertension, and immunological findings in human patient. Evidence of smooth muscle hypertrophy on lung biopsy and an increase in RhoA/ROCK signaling in patient cells suggests the potential mechanistic link between ARHGAP42 deficiency and the development of chILD disorder.

Characterisation of Pediatric Pulmonary Hypertensive Vascular Disease from the PPHNet Registry

BACKGROUND

There are limited data about the range of diseases, natural history, age-appropriate endpoints and optimal care for children with pulmonary hypertension (PH), including the need for developing high quality patient registries of children with diverse forms of PH to enhance care and research.

OBJECTIVE

To characterise the distribution and clinical features of diseases associated with pediatric PH, including natural history, evaluation, therapeutic interventions and outcomes, as defined by the WSPH Classification.

METHODS

1475 patients were enrolled into a multisite registry across the Pediatric Pulmonary Hypertension Network (PPHNet), comprised of 8 interdisciplinary PH programs.

RESULTS

WSPH Groups 1 (PAH) and 3 (lung disease) were the most common primary classifications (45% and 49% of subjects, respectively). The most common Group 3 conditions were BPD and CDH. Group 1 disease was predominantly associated with congenital heart disease (60%) and idiopathic (23% of Group 1 cases). In comparison with Group 1, Group 3 subjects had better disease resolution (HR=3.1, p<0.001), tended to be younger at diagnosis (0.3 (0.0,0.6) versus 1.6 (0.1,6.9) years (median (IQR); p<0.001), and were more often male (57% versus. 45%, p<0.001). Down syndrome (DS), the most common genetic syndrome in the registry, constituted 11% of the entire PH cohort.

CONCLUSIONS

We find a striking proportion of pediatric PH patients with Group 3 disorders, reflecting the growing recognition of PH in diverse developmental lung diseases. Greater precision of clinical phenotyping based on disease-specific characterization may further enhance care and research of pediatric PH.

Lower oxygen saturation targets in preterm infants are not associated with increased rates of pulmonary hypertension

BACKGROUND

The optimal oxygen saturation target in preterm infants is not known. In this study, we aimed to assess the effect of lower oxygen saturation targets on the rate of bronchopulmonary dysplasia (BPD), retinopathy of prematurity (ROP), and pulmonary hypertension (PH) in preterm infants.

METHODS

Retrospective cohort study comparing BPD, ROP, and PH incidence among two cohorts of infants born at≤32 weeks gestation with different oxygen saturation targets at≥34 weeks post-menstrual age (PMA): cohort 1, 94-98% (n = 126); cohort 2, 92-97% (n = 121). Groups compared by Chi-square test, t-test, and multivariable logistic regression.

RESULTS

When comparing cohort 1 (average gestational age 29.8 weeks, average birth weight 1271g) with cohort 2 (average gestational age 29.6 weeks, average birth weight 1299g), there was no difference in rate of BPD (24% vs. 19%, p = 0.38), ROP (4% vs. 3%, p = 0.49), or PH (2% vs. 4%, p = 0.44).

CONCLUSION

An oxygen saturation target of 92-97% at≥34 weeks PMA was not associated with a higher rate of PH or lower rate of BPD or ROP when compared with a higher target of 94-98%.

Adverse drug event rates in pediatric pulmonary hypertension: a comparison of real-world data sources

Objective

Real-world data (RWD) are increasingly used for pharmacoepidemiology and regulatory innovation. Our objective was to compare adverse drug event (ADE) rates determined from two RWD sources, electronic health records and administrative claims data, among children treated with drugs for pulmonary hypertension.

Materials and Methods

Textual mentions of medications and signs/symptoms that may represent ADEs were identified in clinical notes using natural language processing. Diagnostic codes for the same signs/symptoms were identified in our electronic data warehouse for the patients with textual evidence of taking pulmonary hypertension-targeted drugs. We compared rates of ADEs identified in clinical notes to those identified from diagnostic code data. In addition, we compared putative ADE rates from clinical notes to those from a healthcare claims dataset from a large, national insurer.

Results

Analysis of clinical notes identified up to 7-fold higher ADE rates than those ascertained from diagnostic codes. However, certain ADEs (eg, hearing loss) were more often identified in diagnostic code data. Similar results were found when ADE rates ascertained from clinical notes and national claims data were compared.

Discussion

While administrative claims and clinical notes are both increasingly used for RWD-based pharmacovigilance, ADE rates substantially differ depending on data source.

Conclusion

Pharmacovigilance based on RWD may lead to discrepant results depending on the data source analyzed. Further work is needed to confirm the validity of identified ADEs, to distinguish them from disease effects, and to understand tradeoffs in sensitivity and specificity between data sources.

Prostanoids in pediatric pulmonary hypertension: clinical response, time-to-effect, and dose-response

For pediatric pulmonary arterial hypertension (PAH) patients treated with parenteral prostanoids, response predictors, and the dose-effect relationship are ill defined. We determined the following: (1) which pulmonary vascular hemodynamic variable, after initiating prostanoids, best correlates with a significant clinical response; (2) the time interval after treatment when if no pulmonary hemodynamic improvement has occurred, none is ever likely to; and (3) the relationship between the prostanoid dose and its hemodynamic effects. This is a retrospective cohort study of 31 pediatric patients with Group 1 PAH treated with parenteral prostanoids. We found the following: (1) A fall in mean pulmonary arterial pressure (mPAP) of ≥25% predicted freedom from adverse clinical events with 80.7% accuracy and was also associated with improved functional class. (2) Thirty-three percent of patients who avoided an adverse clinical event demonstrated a ≥25% reduction in mPAP after 1 year of treatment, and 65% by 2 years. (3) Lower mPAP was seldom seen with doses of epoprostenol >60 ng/kg/min (100 ng/kg/min for treprostinil). Cardiac index was positively correlated with the dose of epoprostenol but not treprostinil; cardiac index >4 l/min/m² was seen at modest as well as high doses. We conclude that a ≥25% fall in mPAP on prostanoids indicates a positive clinical response which, if validated in other studies, may be useful for patient management or clinical trials. Some patients take more than 2 years for this change. Exceptionally high doses were generally not more effective than lower, although we could not determine whether lower doses would have been as effective.

Long-Term Fate of the Truncal Valve

Background Long-term survival in patients with truncus arteriosus is favorable, but there remains significant morbidity associated with ongoing reinterventions. We aimed to study the long-term outcomes of the truncal valve and identify risk factors associated with truncal valve intervention. Methods and Results We retrospectively reviewed patients who underwent initial truncus arteriosus repair at our institution from 1985 to 2016. Analysis was performed on the 148 patients who were discharged from the hospital and survived ≥30 days postoperatively using multivariable competing risks Cox regression modeling. Median follow-up time was 12.6 years (interquartile range, 5.0-22.1 years) after discharge from full repair. Thirty patients (20%) underwent at least one intervention on the truncal valve during follow-up. Survival at 1, 10, and 20 years was 93.1%, 87.0%, and 80.9%, respectively. The cumulative incidence of any truncal valve intervention by 20 years was 25.6%. Independent risk factors for truncal valve intervention included moderate or greater truncal valve regurgitation (hazard ratio [HR], 4.77; P<0.001) or stenosis (HR, 4.12; P<0.001) before full truncus arteriosus repair and moderate or greater truncal valve regurgitation at discharge after full repair (HR, 8.60; P<0.001). During follow-up, 33 of 134 patients (25%) progressed to moderate or greater truncal valve regurgitation. A larger truncal valve root z-score before truncus arteriosus full repair and during follow-up was associated with worsening truncal valve regurgitation. Conclusions Long-term rates of truncal valve intervention are significant. At least moderate initial truncal valve stenosis and initial or residual regurgitation are independent risk factors associated with truncal valve intervention. Larger truncal valve root z-score is associated with significant truncal valve regurgitation and may identify a subset of patients at risk for truncal valve dysfunction over time.

Longitudinal Analysis of Ventilation Perfusion Mismatch in Congenital Diaphragmatic Hernia Survivors

OBJECTIVE

To determine the natural history of pulmonary function for survivors of congenital diaphragmatic hernia (CDH).

STUDY DESIGN

This was a retrospective cohort study of survivors of CDH born during 1991-2016 and followed at our institution. A generalized linear model was fitted to assess the longitudinal trends of ventilation (V), perfusion (Q), and V/Q mismatch. The association between V/Q ratio and body mass index percentile as well as functional status was also assessed with a generalized linear model.

RESULTS

During the study period, 212 patients had at least one V/Q study. The average ipsilateral V/Q of the cohort increased over time (P < .01), an effect driven by progressive reduction in relative perfusion (P = .012). A higher V/Q ratio was correlated with lower body mass index percentile (P < .001) and higher probability of poor functional status (New York Heart Association class III or IV) (P = .045).

CONCLUSIONS

In this cohort of survivors of CDH with more severe disease characteristics, V/Q mismatch worsens over time, primarily because of progressive perfusion deficit of the ipsilateral side. V/Q scans may be useful in identifying patients with CDH who are at risk for poor growth and functional status.

Improving Safety of Intravenous Prostacyclin Administration to Pediatric Patients With Pulmonary Hypertension

BACKGROUND

Pulmonary hypertension is a rare, life-threatening disease with limited therapeutic options and no definitive cure. Continuous intravenous prostacyclin therapy is indicated for treatment of severe disease. These medications have a narrow therapeutic index and a brief half-life; therefore, administration errors can be lethal.

OBJECTIVE

To reduce medication errors through an inpatient program to improve, standardize, and disseminate continuous intravenous prostacyclin therapy practice guidelines.

METHODS

Data were collected from the electronic safety reporting system of a single hospital to determine the number and types of continuous intravenous prostacyclin therapy errors that were reported over an 8-year period. A clinical database and hospital pharmacy records were used to determine the number of days on which hospitalized pediatric patients received the therapy.

INTERVENTIONS

A nursing-directed quality improvement initiative to enhance the safety of continuous intravenous prostacyclin therapy for pediatric patients was begun in January 2009. Efforts to improve safety fell into 4 domains: policy, process, education, and hospital-wide safety initiatives.

RESULTS

The number of therapy errors per 1000 patient days fell from 19.28 in 2009 to 5.95 in 2016. Chi-square analysis was used to compare the result for 2009 with that for each subsequent year, with P values of .66, .35, .16, .09, .03, .12, and .25 found for 2010 through 2016, respectively.

CONCLUSIONS

The trend in reduction of continuous intravenous prostacyclin therapy errors suggests that proactive processes to standardize its administration, emphasizing both policy and education, reduce medication errors and increase patient safety.

Standardized outcomes in reproductive cardiovascular care: The STORCC initiative

BACKGROUND

Validated protocols for diagnostic testing and management of pregnant women with cardiovascular disease (CVD) do not exist. Our objective was to establish a prospective standardized protocol for the clinical evaluation of pregnant women with CVD.

METHODS

The Standardized Outcomes in Reproductive Cardiovascular Care (STORCC) initiative prospectively enrolled pregnant women with CVD into a standardized diagnostic testing and assessment protocol. Detailed cardiac and obstetric data were collected during the antepartum, intrapartum, and postpartum periods. Each woman was assigned a STORCC color code of perceived risk at a monthly multidisciplinary conference.

RESULTS

In 250 pregnancies of 207 women with CVD, the standardized care protocol was followed in 136 and routine care in 114. The median age of the subjects was 32 years, and the most common form of heart disease was congenital heart disease (77%). Women enrolled in standardized care protocol had high compliance with second- and third-trimester visits (93%) and postpartum visits (76%). Maternal cardiac complications occurred in 10%. The STORCC cardiac and obstetric color codes predicted adverse outcomes within each respective category (P = .02, .01).

CONCLUSIONS

The STORCC protocol for prospective diagnostic testing and follow-up of pregnant women with CVD was successfully established, and compliance was high. The strength of a standardized testing and care protocol as well as detailed classification of labor and delivery characteristics allows for robust analyses into specific questions regarding testing protocols, and mode and timing of delivery.

Phenotype characterisation of TBX4 mutation and deletion carriers with neonatal and paediatric pulmonary hypertension

Rare variants in the T-box transcription factor 4 gene (TBX4) have recently been recognised as an emerging cause of paediatric pulmonary hypertension (PH). Their pathophysiology and contribution to persistent pulmonary hypertension in neonates (PPHN) are unknown. We sought to define the spectrum of clinical manifestations and histopathology associated with TBX4 variants in neonates and children with PH.We assessed clinical data and lung tissue in 19 children with PH, including PPHN, carrying TBX4 rare variants identified by next-generation sequencing and copy number variation arrays.Variants included six 17q23 deletions encompassing the entire TBX4 locus and neighbouring genes, and 12 likely damaging mutations. 10 infants presented with neonatal hypoxic respiratory failure and PPHN, and were subsequently discharged home. PH was diagnosed later in infancy or childhood. Three children died and two required lung transplantation. Associated anomalies included patent ductus arteriosus, septal defects, foot anomalies and developmental disability, the latter with a higher prevalence in deletion carriers. Histology in seven infants showed abnormal distal lung development and pulmonary hypertensive remodelling.TBX4 mutations and 17q23 deletions underlie a new form of developmental lung disease manifesting with severe, often biphasic PH at birth and/or later in infancy and childhood, often associated with skeletal anomalies, cardiac defects, neurodevelopmental disability and other anomalies.

Oral treprostinil in transition or as add-on therapy in pediatric pulmonary arterial hypertension

Treprostinil, a prostacyclin analogue, is approved for the treatment of pulmonary arterial hypertension (PAH) in adults. Transition from parenteral to oral treprostinil has been successfully accomplished in adults with PAH but not in children. In this multicenter study, pediatric patients treated with parenteral (Cohort 1) or inhaled (Cohort 2) treprostinil were transitioned to oral treprostinil. Prostacyclin-naïve individuals on background oral PAH therapy received oral treprostinil as add-on therapy (Cohort 3). Successful transition was oral treprostinil dose maintenance through week 24. Patients were monitored for adverse events (AEs), 6-min walk distance (6MWD), PAH symptoms, World Health Organization (WHO) Functional Class (FC), cardiac magnetic resonance imaging (cMRI), cardiopulmonary exercise testing (CPET), and quality of life through 24 weeks. A total of 32 patients were enrolled in the study; 23 (72%) were girls (mean age = 12.2 years). All patients were on background oral PAH therapy. Overall, patients (96.9%) maintained transition to oral treprostinil; one patient (Cohort 1) transitioned to oral treprostinil, then back to parenteral after experiencing syncope and WHO FC change from II to III. Cohorts 1, 2, and 3 received a final mean oral treprostinil dose of 5.6, 3.3, and 4.5 mg t.i.d., respectively. All cohorts had variable changes in 6MWD, cMRI, and CPET. Overall, 12 serious AEs were reported. All patients had drug-related AEs including headache (81%), diarrhea (69%), nausea (66%), vomiting (66%), and flushing (56%). Pediatric patients maintained transition to oral treprostinil with preservation of exercise capacity and WHO FC. Prostanoid-related AEs were most common and similar to those reported in adults.

Challenges in the Patient With Pulmonary Hypertension and Atrial Septal Defect: Understanding When and How to Close the Defect

Atrial septal defects (ASDs) are common congenital heart defects in children and adults. Pulmonary arterial hypertension (PAH) is found in subsets of both pediatric and adult patients with atrial defects under varied clinical contexts. The pulmonary hypertension specialist is often faced with questions surrounding timing and method of defect closure, which may have significant impact on procedural and long-term morbidity and survival. This review highlights important differences in management between children and adults with ASDs associated with PAH, highlighting indications for closure, operability, types of closure, and long-term outcomes.

Genotypes and Phenotypes: Making Progress Toward a Precision Medicine Approach in Pediatric Pulmonary Hypertension

Pediatric pulmonary hypertension (PH) is a heterogeneous disease that includes etiologies related to growth and development that are unique to children. Recent pediatric registry studies have characterized diverse phenotypes even within recognized PH subtypes, including PH associated with congenital heart disease and developmental lung disease. Advances in genetics are resulting in increased understanding of the genetic basis for PH, with recent discoveries such as TBX4 mutations specific for pediatric-onset pulmonary arterial hypertension (PAH) and SOX17 related to congenital heart disease–associated PAH. In addition to potential genetic underpinnings, PAH risk and clinical presentation in children with congenital heart disease may vary by cardiac condition, such as single-ventricle physiology or transposition of the great arteries. Growth and development of the pulmonary vasculature likely plays a role in all pediatric PH, which is highlighted by the disruption of normal lung growth in patients with PH related to prematurity and developmental lung disease. These diverse pediatric genotypes and phenotypes underscore a need for an individualized approach to diagnose and treat the complex pediatric PH population. Magnetic resonance imaging (MRI) is increasingly being used to improve clinical characterization of PH in children, with recent identification of specific MRI biomarkers associated with PH severity and outcomes. While much progress has been made, additional understanding of the important genetic causes and developmental concepts in pediatric PH is needed to develop a precision medicine approach to diagnosis and treatment of children with PH.

A Computable Phenotype Improves Cohort Ascertainment in a Pediatric Pulmonary Hypertension Registry

OBJECTIVES

To compare registry and electronic health record (EHR) data mining approaches for cohort ascertainment in patients with pediatric pulmonary hypertension (PH) in an effort to overcome some of the limitations of registry enrollment alone in identifying patients with particular disease phenotypes.

STUDY DESIGN

This study was a single-center retrospective analysis of EHR and registry data at Boston Children's Hospital. The local Informatics for Integrating Biology and the Bedside (i2b2) data warehouse was queried for billing codes, prescriptions, and narrative data related to pediatric PH. Computable phenotype algorithms were developed by fitting penalized logistic regression models to a physician-annotated training set. Algorithms were applied to a candidate patient cohort, and performance was evaluated using a separate set of 136 records and 179 registry patients. We compared clinical and demographic characteristics of patients identified by computable phenotype and the registry.

RESULTS

The computable phenotype had an area under the receiver operating characteristics curve of 90% (95% CI, 85%-95%), a positive predictive value of 85% (95% CI, 77%-93%), and identified 413 patients (an additional 231%) with pediatric PH who were not enrolled in the registry. Patients identified by the computable phenotype were clinically distinct from registry patients, with a greater prevalence of diagnoses related to perinatal distress and left heart disease.

CONCLUSIONS

Mining of EHRs using computable phenotypes identified a large cohort of patients not recruited using a classic registry. Fusion of EHR and registry data can improve cohort ascertainment for the study of rare diseases.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02249923.

Learning a Comorbidity-Driven Taxonomy of Pediatric Pulmonary Hypertension

RATIONALE

Pediatric pulmonary hypertension (PH) is a heterogeneous condition with varying natural history and therapeutic response. Precise classification of PH subtypes is, therefore, crucial for individualizing care. However, gaps remain in our understanding of the spectrum of PH in children.

OBJECTIVE

We seek to study the manifestations of PH in children and to assess the feasibility of applying a network-based approach to discern disease subtypes from comorbidity data recorded in longitudinal data sets.

METHODS AND RESULTS

A retrospective cohort study comprising 6 943 263 children (<18 years of age) enrolled in a commercial health insurance plan in the United States, between January 2010 and May 2013. A total of 1583 (0.02%) children met the criteria for PH. We identified comorbidities significantly associated with PH compared with the general population of children without PH. A Bayesian comorbidity network was constructed to model the interdependencies of these comorbidities, and network-clustering analysis was applied to derive disease subtypes comprising subgraphs of highly connected comorbid conditions. A total of 186 comorbidities were found to be significantly associated with PH. Network analysis of comorbidity patterns captured most of the major PH subtypes with known pathological basis defined by the World Health Organization and Panama classifications. The analysis further identified many subtypes documented in only a few case studies, including rare subtypes associated with several well-described genetic syndromes.

CONCLUSIONS

Application of network science to model comorbidity patterns recorded in longitudinal data sets can facilitate the discovery of disease subtypes. Our analysis relearned established subtypes, thus validating the approach, and identified rare subtypes that are difficult to discern through clinical observations, providing impetus for deeper investigation of the disease subtypes that will enrich current disease classifications.

Lung Pathology in Pediatric Pulmonary Vein Stenosis

Pulmonary vein stenosis is a rare progressive narrowing of the extrapulmonary pulmonary veins, presenting predominantly in infancy and virtually always lethal. It typically arises following repair of congenital heart disease, particularly anomalous pulmonary venous return. Histologic characterization of pediatric pulmonary vein stenosis, not previously well described, may provide insight into the disease pathobiology. We retrieved archival lung specimens (biopsy, explant, or autopsy) from patients with pediatric pulmonary vein stenosis. Medical records were reviewed. Microscopic examination included hematoxylin and eosin (H&E)-stained slides, and for a subset of patients, elastic, trichrome, smooth-muscle actin, and D2-40. Groups with different clinical disease features were compared using Fisher's exact test. A total of 33 patients (median age, 7 months) had available tissue and 52% had congenital heart disease; 18% were premature. Within the lungs, interlobular septal veins showed thickened muscular coats (in 58%), proliferation/tortuosity (in 6%), and fibromyxoid intimal proliferation (in 3%). Associated arterial hypertensive changes were seen in 30 (91%). The one patient with intrapulmonary venous fibromyxoid intimal proliferation was the only patient with apparent primary familial disease. Lymphangiectasia and arterial medial hypertrophy were histologic features that correlated with clinical grouping. We conclude that in pediatric pulmonary vein stenosis, intrapulmonary pulmonary veins commonly show muscular thickening, best interpreted as venous hypertensive remodeling. Fibromyxoid intimal proliferation resembling that of the extrapulmonary pulmonary veins is uncommon. Awareness of intrapulmonary features in various clinical subtypes of pulmonary vein stenosis may be diagnostically and therapeutically informative considering that current catheter-based and surgical therapy is directed at the extrapulmonary component of pulmonary vein stenosis.

Central venous line complications with chronic ambulatory infusion of prostacyclin analogues in pediatric patients with pulmonary arterial hypertension

Chronic infusion of prostacyclin (PGI2) via a Broviac central venous line (CVL) is attended by risk of CVL-related complications, but we know of only one report regarding CVL-associated bloodstream infection (BSI) with PGI2 in children and none regarding other complications. We conducted a retrospective cohort study involving pediatric patients with pulmonary hypertension treated with chronic intravenous infusion of PGI2 at Boston Children's Hospital and determined the rate (per 1,000 line-days) of various CVL-related complications. We also determined how often complications necessitated line replacement and hospitalization, time to replacement of CVLs, and interpatient variability in the incidence of complications. From 1999 until 2014, 26 patients meeting follow-up criteria had PGI2 infusion, representing 43,855 line-days; mean follow-up was 56 months (range, 1.4-161 months). The CVL complication rates (per 1,000 line-days) were as follows: CVL-BSI, 0.25; superficial line infection, 0.48; impaired integrity, 0.59; occlusion, 0.09; and malposition, 0.32. The total complication rate was 1.73 cases per 1,000 line-days. All CVL-BSI and malposition cases were treated with CVL removal and replacement. Of CVLs with impaired integrity, 23 could be repaired and 3 required replacement. Six of 21 superficial CVL infections required replacement of the CVL. Three of 4 occluded CVLs were replaced. CVL complications occasioned 65 hospitalizations. There was marked interpatient variability in the rate of complications, much but not all of which appeared to be related to duration of CVL placement. We conclude that non-BSI complications are very significant and that efforts to teach and emphasize other aspects of line care are therefore very important.

Chromosome microarray testing for patients with congenital heart defects reveals novel disease causing loci and high diagnostic yield

Background

Congenital heart defects (CHD), as the most common congenital anomaly, have been reported to be frequently associated with pathogenic copy number variants (CNVs). Currently, patients with CHD are routinely offered chromosomal microarray (CMA) testing, but the diagnostic yield of CMA on CHD patients has not been extensively evaluated based on a large patient cohort. In this study, we retrospectively assessed the detected CNVs in a total of 514 CHD cases (a 422-case clinical cohort from Boston Children's Hospital (BCH) and a 92-case research cohort from Shanghai Children’s Medical Center (SCMC)) and conducted a genotype-phenotype analysis. Furthermore, genes encompassed in pathogenic/likely pathogenic CNVs were prioritized by integrating several tools and public data sources for novel CHD candidate gene identification.

Results

Based on the BCH cohort, the overall diagnostic yield of CMA testing for CHD patients was 12.8(pathogenic CNVs)-18.5% (pathogenic and likely pathogenic CNVs). The diagnostic yield of CMA for syndromic CHD was 14.1-20.6% (excluding aneuploidy cases), whereas the diagnostic yield for isolated CHD was 4.3-9.3%. Four recurrent genomic loci (4q terminal region, 15q11.2, 16p12.2 and Yp11.2) were more significantly enriched in cases than in controls. These regions are considered as novel CHD loci. We further identified 20 genes as the most likely novel CHD candidate genes through gene prioritization analysis.

Conclusion

The high clinical diagnostic yield of CMA in this study provides supportive evidence for CMA as the first-line genetic diagnostic tool for CHD patients. The CNVs detected in our study suggest a number of CHD candidate genes that warrant further investigation.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-1127) contains supplementary material, which is available to authorized users.

Global proteomic characterization of uterine histotroph recovered from beef heifers yielding good quality and degenerate day 7 embryos

The objective was to analyze the proteomic composition of uterine flushes collected from beef heifers on day 7 after insemination. Estrus was synchronized in crossbred beef heifers by using a protocol with a controlled intravaginal drug releasing device. Heifers detected in standing estrus (within 24-48 h after removal of controlled intravaginal drug releasing device) were inseminated (estrus = day 0) with frozen-thawed semen from a single ejaculate of a bull with proven fertility. Heifers from which an embryo was recovered (after slaughter on day 7) were classified as either having a viable embryo (morula/blastocyst stage) or a degenerate embryo (arrested at the 2- to 16-cell stage). The overall recovery rate (viable and degenerate combined) was 64%. Global liquid chromatography coupled to tandem mass spectrometry proteomic analysis of the histotroph collected identified 40 high-confidence proteins present on day 7; 26 proteins in the viable group, 10 in the degenerate group, and 4 shared between both groups. Five proteins (platelet-activating factor acetylhydrolase IB subunit γ [PAFAH1B3], tubulin α-1D chain, tubulin β-4A chain, cytochrome C, and dihydropyrimidinase-related protein-2) were unique or more abundant in the histotroph collected from animals with a viable embryo, and 1 protein (S100-A4) was more abundant in the histotroph collected from animals with a degenerate embryo. Of interest, PAFAH1B3, detected only in histotroph from the group yielding viable embryos, belongs to the group of platelet-activating factors that are known to be important for the development of the pre-implantation embryo in other species. To our knowledge this is the first report of PAFAH1B3 in relation to bovine early embryonic development.

Within- and across-breed imputation of high-density genotypes in dairy and beef cattle from medium- and low-density genotypes

The objective of this study was to evaluate, using three different genotype density panels, the accuracy of imputation from lower- to higher-density genotypes in dairy and beef cattle. High-density genotypes consisting of 777,962 single-nucleotide polymorphisms (SNP) were available on 3122 animals comprised of 269, 196, 710, 234, 719, 730 and 264 Angus, Belgian Blue, Charolais, Hereford, Holstein-Friesian, Limousin and Simmental bulls, respectively. Three different genotype densities were generated: low density (LD; 6501 autosomal SNPs), medium density (50K; 47,770 autosomal SNPs) and high density (HD; 735,151 autosomal SNPs). Imputation from lower- to higher-density genotype platforms was undertaken within and across breeds exploiting population-wide linkage disequilibrium. The mean allele concordance rate per breed from LD to HD when undertaken using a single breed or multiple breed reference population varied from 0.956 to 0.974 and from 0.947 to 0.967, respectively. The mean allele concordance rate per breed from 50K to HD when undertaken using a single breed or multiple breed reference population varied from 0.987 to 0.994 and from 0.987 to 0.993, respectively. The accuracy of imputation was generally greater when the reference population was solely comprised of the breed to be imputed compared to when the reference population comprised of multiple breeds, although the impact was less when imputing from 50K to HD compared to imputing from LD.

Pulmonary hypertension associated with scurvy and vitamin deficiencies in an autistic child

Restricted dietary intake is common among children with behavioral issues. Here we report a case of a severely autistic child who presented initially with limp but who soon developed cough, tachypnea, hypoxia, and tachycardia. An echocardiogram revealed evidence of pulmonary hypertension (PH) with severely dilated right ventricle and elevated right-sided pressures. The etiology of his PH was unclear but further laboratory evaluation demonstrated severe nutritional deficiencies, in particular an undetectable ascorbic acid (vitamin C) level as well as deficient levels of thiamine (vitamin B1), pyridoxine (vitamin B6), cobalamin (vitamin B12), and vitamin D. Repletion of these vitamins was associated with resolution of his PH and his musculoskeletal complaints. We report this case and a review of the relevant literature as a clinical lesson to expand the differential diagnosis of limp in children who may be difficult to assess as well as to report on an unusual association between severe vitamin deficiencies and PH.

Effect of inhaled iloprost on the exercise function of Fontan patients: a demonstration of concept

BACKGROUND

Exercise capacity following Fontan surgery is often depressed. An inability to reduce pulmonary vascular resistance appropriately during exercise may contribute to this phenomenon. The aim of this study was to determine whether administration of iloprost, a selective pulmonary vasodilator, would improve exercise function after Fontan procedure.

METHODS

Double-blind, randomized, placebo controlled, crossover trial. Patients performed two cardiopulmonary exercise tests (CPX) separated by <1 month. A single nebulizer treatment (iloprost or placebo) was administered before each CPX.

RESULTS

18 patients aged 12-49 (median 17) years were recruited. Mild throat discomfort developed in 10/18 patients during iloprost administration; all but 1 were able to complete treatment. No symptoms developed during placebo treatments (p<0.001). Two additional patients did not complete CPX: one with atrial flutter; another with developmental issues that precluded adequate CPX. In the 15 remaining subjects oxygen pulse (a surrogate for forward stroke volume) at peak exercise was higher following iloprost (median increase 1.2 ml/beat; p<0.001). Peak VO2 also rose (median increase 1.3 ml/kg/min; p<0.04). Nine patients had peak VO2 <30 ml/kg/min; each of these patients had higher peak VO2 following iloprost. Only 3/6 patients with peak VO2 >30 ml/kg/min had higher peak VO2 following iloprost (p<0.04).

CONCLUSIONS

Iloprost improves the peak oxygen pulse and peak VO2 of patients with Fontan physiology and appears to be particularly beneficial among patients with impaired exercise function. Treatment is associated with minor side effects. These findings support the concept of pulmonary vasodilator therapy in Fontan patients with limited functional capacity.

Bilateral lung transplant for hereditary hemorrhagic telangiectasia in a pediatric patient

HHT is an autosomal dominant vascular dysplasia, in which abnormalities of endothelial cells cause patients to develop mucocutaneous telangiectasias, and AVMs of the pulmonary, hepatic, and cerebral circulations. Pulmonary AVMs occur in more than 20% of patients with HHT, and presentation varies from simple diffuse telangiectasias to large complex structures. Surgical management is usually indicated for large pulmonary AVMs. Treatment options for pulmonary AVMs include therapeutic embolization, segmental or lobar resection of the affected lung, and less commonly lung transplantation. Here we report the first successful case of a bilateral lung transplant for a four-yr-old girl with HHT.

Pulmonary arterial hypertension: what the large pulmonary arteries tell us

The morphology of the large intrapulmonary arteries (PAs) in pulmonary hypertension (PH) has received limited attention. Dilation, pruning, abrupt tapering, and tortuosity of PAs occur, but whether different patients have distinct PA phenotypes is unknown. Pulmonary arteriograms from 41 pediatric patients with PH were blindly reviewed by four experts who assigned each angiogram one of three designations: straight (S), tortuous (T), or ambiguous (A). Hemodynamic variables and outcomes were compared to the phenotypes. Thirty patients were either T (19) or S (11); 11 were A. The phenotypes were not associated with age. Tortuous patients had higher PA pressure and resistance than the S group and less likely to react to inhaled nitric oxide than S patients (p < 0.05). Clinical outcomes were similar for the three groups. Thus, in PH patients two subtypes of PA morphology can often be discerned, a reflection of variability in PA tortuosity. These morphological subtypes have differing hemodynamic characteristics. The mechanism(s) underlying these differences is unknown, but neither hydrodynamic factors nor duration of PH are fully explanatory. Because PA morphology might reveal information regarding the biology of pathological remodeling, it might prove enlightening to assess the large PA phenotype in future studies of PH.

Polymorphisms in genes of the somatotrophic axis are independently associated with milk production, udder health, survival and animal size in Holstein-Friesian dairy cattle

The somatotrophic axis consisting of pituitary-derived growth hormone and circulating insulin-like growth factor 1 has been well established as key regulators of animal health, metabolism, lactation, fertility, body composition and growth rate. The aim of this study was to simultaneously quantify the associations between SNPs in candidate genes of the somatotrophic axis (i.e., IGF-1, GH1 and GHR) with performance traits in Holstein-Friesian (HF) dairy cattle. Both novel SNPs identified previously by this group alongside other published SNPs within these genes were analysed for associations with performance in dairy cattle. Multiple regression analyses regressing genetic merit of up to 848 HF sires on novel SNPs (n = 76) and published SNPs (n = 33) were undertaken using weighted animal mixed linear models. Twenty-three SNPs were significantly associated with at least one of 18 traits analysed and involved in milk production, udder health, fertility and growth. Eight traits including milk fat composition, carcass conformation, stature, chest width, body depth, rump width, carcass and cull cow weight were independently associated with SNPs in two genes. Furthermore, for several traits including milk fat yield, somatic cell count, survival and carcass fat, SNPs in all three genes were independently associated with performance. Milk fat yield and carcass fat showed the highest number of independent associations across all three genes with five SNPs associated with both traits. The cumulative effects of the favourable alleles of all five SNPs across GH1, GHR and IGF-1 result in an increase of 5.9 kg and 28.6 units of milk fat and carcass fat, respectively. Cow survival was associated with a single SNP in each of the three genes with a cumulative allele effect of 1.5%. Independent effects of polymorphisms in GH1, GHR and IGF-1 reinforce the central role of the somatotrophic axis on animal development and performance.

Single nucleotide polymorphisms in the imprinted bovine insulin-like growth factor 2 receptor gene (IGF2R) are associated with body size traits in Irish Holstein-Friesian cattle

The regulation of the bioavailability of insulin-like growth factors (IGFs) is critical for normal mammalian growth and development. The imprinted insulin-like growth factor 2 receptor gene (IGF2R) encodes a transmembrane protein receptor that acts to sequester and degrade excess circulating insulin-like growth factor 2 (IGF-II) - a potent foetal mitogen - and is considered an important inhibitor of growth. Consequently, IGF2R may serve as a candidate gene underlying important growth- and body-related quantitative traits in domestic mammalian livestock. In this study, we have quantified genotype-phenotype associations between three previously validated intronic bovine IGF2R single nucleotide polymorphisms (SNPs) (IGF2R:g.64614T>C, IGF2R:g.65037T>C and IGF2R:g.86262C>T) and a range of performance traits in 848 progeny-tested Irish Holstein-Friesian artificial insemination sires. Notably, all three polymorphisms analysed were associated (P ≤ 0.05) with at least one of a number of performance traits related to animal body size: angularity, body depth, chest width, rump width, and animal stature. In addition, the C-to-T transition at the IGF2R:g.65037T>C polymorphism was positively associated with cow carcass weight and angularity. Correction for multiple testing resulted in the retention of two genotype-phenotype associations (animal stature and rump width). None of the SNPs analysed were associated with any of the milk traits examined. Analysis of pairwise r(2) measures of linkage disequilibrium between all three assayed SNPs ranged between 0.41 and 0.79, suggesting that some of the observed SNP associations with performance may be independent. To our knowledge, this is one of the first studies demonstrating associations between IGF2R polymorphisms and growth- and body-related traits in cattle. These results also support the increasing body of evidence that imprinted genes harbour polymorphisms that contribute to heritable variation in phenotypic traits in domestic livestock species.

Idiopathic and Heritable Pulmonary Hypertension in Children: New Insights into Causes, Evaluation, and Treatment

Over the past decade, major progress has occurred in the care of children and adults with pulmonary arterial hypertension (PAH). Recent insights into molecular mechanisms implicated in the development of pulmonary vascular disease have led to revised clinical classification and diagnostic strategies.1 Data from multicenter pulmonary hypertension registries have provided increased understanding of the clinical course and natural history of many subtypes of disease.2–4 Additionally, the development of multiple therapies targeting important pathways of disease and the translation of those treatments to pediatrics have led to improved life experience and survival for many children with PAH.5