SCMR expert consensus statement for cardiovascular magnetic resonance of acquired and non-structural pediatric heart disease.

Cardiovascular magnetic resonance (CMR) is widely used for diagnostic imaging in the pediatric population. In addition to structural congenital heart disease (CHD), for which published guidelines are available, CMR is also performed for non-structural pediatric heart disease, for which guidelines are not available. This article provides guidelines for the performance and reporting of CMR in the pediatric population for non-structural ("non-congenital") heart disease, including cardiomyopathies, myocarditis, Kawasaki disease and systemic vasculitides, cardiac tumors, pericardial disease, pulmonary hypertension, heart transplant, and aortopathies. Given important differences in disease pathophysiology and clinical manifestations as well as unique technical challenges related to body size, heart rate, and sedation needs, these guidelines focus on optimization of the CMR examination in infants and children compared to adults. Disease states are discussed, including the goals of CMR examination, disease-specific protocols, and limitations and pitfalls, as well as newer techniques that remain under development.

The Diagnostic Role of Echocardiographic Strain Analysis in Patients Presenting with Chest Pain and Elevated Troponin: A Multicenter Study.

BACKGROUND: Myocarditis presenting as acute chest pain with elevated troponins without significant cardiac compromise is rare in previously healthy children, often referred to as myopericarditis. Diagnosis is challenging, as conventional echocardiographic measures of systolic function can be normal. The aim of this study was to demonstrate the diagnostic utility of strain imaging in this scenario. METHODS: This was a multicenter, retrospective study including patients presenting with chest pain and elevated troponin from 10 institutions who underwent cardiac magnetic resonance imaging and transthoracic echocardiography within 30 days of each other (group 1). Findings were compared with those among 19 control subjects (group 2). Clinical data and conventional echocardiographic and cardiac magnetic resonance imaging data were collected. Echocardiography-derived strain was measured at the core laboratory. Group 1 was divided into subgroups as myocarditis positive (group 1a) or negative (group 1b) on cardiac magnetic resonance imaging on the basis of established criteria. RESULTS: Group 1 included 108 subjects (88 in group 1a, 20 in group 1b). Although all groups had normal mean fractional shortening and mean left ventricular ejection fraction, group 1 had significantly lower ejection fraction (56.8 ± 7.0%) compared with group 2 (62.3 ± 4.9%; P < .005) and fractional shortening (31.2 ± 4.9%) compared with group 2 (34.1 ± 3.5%; P < .05). Additionally, peak global longitudinal strain (GLS) was markedly abnormal in group 1 (-13.9 ± 3.4%) compared with group 2 (-19.8 ± 2.1%; P < .001). In subgroup analysis, GLS was markedly abnormal in group 1a (-13.2 ± 3.0%) compared with group 1b (-17.3 ± 2.6%; P < .001). Fifty-four subjects underwent follow-up echocardiography (46 in group 1a, eight in group 1b), with mean a follow-up time of 10 ± 11 months. At follow-up, whereas ejection fraction and fractional shortening returned to normal in all patients, abnormalities in strain persisted in group 1, with 22% still having abnormal GLS. Moreover, mean GLS was more abnormal in group 1a (-16.1 ± 2.6%) compared with group 1b (-17.4 ± 1.2%; P < .05). CONCLUSIONS: The present study demonstrates that echocardiographic GLS is significantly worse in subjects with myopericarditis presenting with chest pain and elevated troponins compared with control subjects even when conventional measures of systolic function are largely normal and that these abnormalities persisted over time.

Survey of centers performing cardiovascular magnetic resonance in pediatric and congenital heart disease: a report of the Society for Cardiovascular Magnetic Resonance.

BACKGROUND: There are few data on practice patterns and trends for cardiovascular magnetic resonance (CMR) in pediatric and congenital heart disease. The Society for Cardiovascular Magnetic Resonance (SCMR) sought to address this deficiency by performing an international survey of CMR centers. METHODS: Surveys consisting of 31 (2014) and 33 (2018) items were designed to collect data on the use of CMR for the evaluation of pediatric and congenital heart disease patients. They were sent to all SCMR members in 2014 and 2018. One response per center was collected. RESULTS: There were 93 centers that responded in 2014 and 83 in 2018. The results that follow show data from 2014 and 2018 separated by a dash. The median annual number of pediatric/congenital CMR cases per center was 183-209. The median number of scanners for CMR was 2-2 (range, 1-8) with 58-63% using only 1.5T scanners and 4-4% using only 3T scanners. The mean number of attending/staff reading CMRs was 3.7-2.6; among them, 52-61% were pediatric or adult cardiologists and 47-38% were pediatric or adult radiologists. The median annual case volume per attending was 54-86. The median number of technologists per center doing CMRs was 4-5. The median scanner time allocated for a non-sedated examination was 75-75 min (range, 45-120). Among the 21 centers responding to both surveys, the mean annual case volume increased from 320 in 2014 to 445 in 2018; 17 (81%) of the centers had an increase in annual case volume. For this subgroup, the median attending/staff per center was 4 in both 2014 and 2018. The median scanner time allotted per study was unchanged at 90 min. The mean time for an attending/staff physician to perform a typical CMR examination including reporting was 143-141 min. CONCLUSION: These survey data provide a novel comprehensive view of CMR practice in pediatric and congenital heart disease. This information is useful for internal benchmarking, resource allocation, addressing practice variation, quality improvement initiatives, and identifying unmet needs.

Estimating filling pressures in paediatric heart transplant recipients using echocardiographic parameters and B-type natriuretic peptide.

BACKGROUND: Longitudinal evaluation of allograft diastolic function in paediatric heart transplant recipients is important for early detection of acute rejection, cardiac allograft vasculopathy, and graft dysfunction. Mean diastolic right atrial and pulmonary capillary wedge pressures obtained at catheterisation are the reference standards for assessment. Echocardiography is non-invasive and more suitable for serial surveillance, but individual parameters have lacked accuracy. This study aimed to identify covariates of post-transplant mean right atrial and pulmonary capillary wedge pressures, including B-type natriuretic peptide and certain echocardiographic parameters. METHODS: A retrospective review of 143 scheduled cardiac catheterisations and echocardiograms from 56 paediatric recipients transplanted from 2007 to 2011 was performed. Samples with rejection were excluded. Univariate and multivariate linear regression models using backward selection were applied to a database consisting of B-type natriuretic peptide, haemodynamic, and echocardiographic data. RESULTS: Ln B-type natriuretic peptide, heart rate z-score, left ventricular end-diastolic dimension z-score, mitral E/e', and percent interventricular septal thickening in systole were independently associated with mean right atrial pressure. Ln B-type natriuretic peptide, heart rate z-score, left ventricular end-diastolic dimension z-score, left ventricular mass (observed/predicted), and mitral E/e' were independently associated with mean pulmonary capillary wedge pressure. Covariates of B-type natriuretic peptide included mean pulmonary artery and pulmonary capillary wedge pressures, height, haemoglobin, fractional shortening, percent interventricular septal thickening in systole, and pulmonary vascular resistance index. CONCLUSIONS: B-type natriuretic peptide and echocardiographic indices of diastolic function were independently related to post-transplant mean right atrial and pulmonary capillary wedge pressures in paediatric heart transplant recipients without rejection.

3D models improve understanding of congenital heart disease.

INTRODUCTION: Understanding congenital heart disease (CHD) is vital for medical personnel and parents of affected children. While traditional 2D schematics serve as the typical approach used, several studies have shown these models to be limiting in understanding complex structures. Recent world-emphasis has shifted to 3D printed models as a complement to 2D imaging to bridge knowledge and create new opportunities for experiential learning. We sought to systematically compare 3D digital and physical models for medical personnel and parent education compared to traditional methods. METHODS: 3D printed and digital models were made out of MRI and CT data for 20 common CHD. Fellows and nurse practitioners used these models to explore intra-cardiac pathologies following traditional teaching. The models were also used for parent education in outpatient settings after traditional education. The participants were then asked to fill out a Likert scale questionnaire to assess their understanding and satisfaction with different teaching techniques. These ratings were compared using paired t-tests and Pearson's correlation. RESULTS: Twenty-five medical personnel (18 fellows; 2 nurses; 4 nurse practitioners and one attending) and twenty parents participated in the study. The diagnosis varied from simple mitral valve pathology to complex single ventricle palliation. Parent and medical personnel perceived understanding with digital models was significantly higher than traditional (p = 0.01). Subjects also felt that physical models were overall more useful than digital ones (p = 0.001). Physicians using models for parent education also perceived the models to be useful, not significantly impacting their clinical workflow. CONCLUSIONS: 3D models, both digital and printed, enhance medical personnel and parental perceived understanding of CHD.

Is biventricular vascular coupling a better indicator of ventriculo-ventricular interaction in congenital heart disease?

BACKGROUND: Ventriculo-ventricular interactions are known to exist, though not well quantified. We hypothesised that the ventricular-vascular coupling ratio assessed by cardiovascular MRI would provide insight into this relationship. We also sought to compare MRI-derived ventricular-vascular coupling ratio to echocardiography and patient outcomes. METHODS: Children with cardiac disease and biventricular physiology were included. Sanz's and Bullet methods were used to calculate ventricular-vascular coupling ratio by MRI and echocardiography, respectively. Subgroup analysis was performed for right and left heart diseases. Univariate and multivariate regressions were performed to determine associations with outcomes. RESULTS: A total of 55 patients (age 14.3 ± 2.5 years) were included. Biventricular ventricular-vascular coupling ratio by MRI correlated with each other (r = 0.41; p = 0.003), with respect to ventricle's ejection fraction (r = -0.76 to -0.88; p < 0.001) and other ventricle's ejection fraction (r = -0.42 to -0.47; p < 0.01). However, biventricular ejection fraction had only weak correlation with each other (r = 0.31; p = 0.02). Echo underestimated ventricular-vascular coupling ratio for the left ventricle (p < 0.001) with modest correlation to MRI-derived ventricular-vascular coupling ratio (r = 0.43; p = 0.002). There seems to be a weak correlation between uncoupled right ventricular-vascular coupling ratio with the need for intervention and performance on exercise testing (r = 0.33; p = 0.02). CONCLUSION: MRI-derived biventricular ventricular-vascular coupling ratio provides a better estimate of ventriculo-ventricular interaction in children and adolescents with CHD. These associations are stronger than traditional parameters and applicable to right and left heart conditions.

A Quality Initiative to Improve Appropriate Use of Initial Outpatient Echocardiography Among Pediatric Cardiologists.

INTRODUCTION: Appropriate use criteria (AUC) guide initial transthoracic echocardiogram (TTE) use in outpatient pediatrics. We sought to improve pediatric cardiologist TTE ordering appropriateness (mean AUC score) with a quality improvement initiative. METHODS: The outcome of interest was the prospective AUC score for all initial outpatient TTEs ordered between November 2016 and August 2017, categorized per the AUC: "appropriate" (score 7-9), "may be appropriate" (4-6), "rarely appropriate" (1-3). Interventions included a didactic review of 2014 AUC and participant documentation of AUC criteria for each TTE. Participants met quarterly to evaluate outcome, process, and balancing measures, intervention effectiveness, and to identify and mitigate barriers. RESULTS: Twenty-two pediatric cardiologists participated. TTE appropriateness level before (n = 216) and after (n = 557) intervention was high. There was no significant difference in mean baseline and post-intervention AUC score (7.42 ± 1.87 versus 7.16 ± 2.87, P = 0.1), nor in TTE sensitivity (27% versus 25%, P > 0.1) as a balancing measure. Among baseline studies, 81% were "appropriate," and 6% "rarely appropriate." Among post-intervention studies, 76% were "appropriate," and 11% "rarely appropriate." Barriers identified to implementing AUC include TTE indications not specified by current AUC, expectations of referring provider or parent to perform TTE, consistent provider application of AUC, and ability of AUC to capture comprehensive clinical judgment. CONCLUSIONS: Although the mean AUC appropriateness level was high, we were able to identify significant barriers to the implementation of AUC. Future efforts should focus on the reduction of "rarely appropriate" TTE ordering.

Challenges and lessons learned from the Pediatric Heart Network Normal Echocardiogram Database study.

BACKGROUND: The Pediatric Heart Network Normal Echocardiogram Database Study had unanticipated challenges. We sought to describe these challenges and lessons learned to improve the design of future studies. METHODS: Challenges were divided into three categories: enrolment, echocardiographic imaging, and protocol violations. Memoranda, Core Lab reports, and adjudication logs were reviewed. A centre-level questionnaire provided information regarding local processes for data collection. Descriptive statistics were used, and chi-square tests determined differences in imaging quality. RESULTS: For the 19 participating centres, challenges with enrolment included variations in Institutional Review Board definitions of "retrospective" eligibility, overestimation of non-White participants, centre categorisation of Hispanic participants that differed from National Institutes of Health definitions, and exclusion of potential participants due to missing demographic data. Institutional Review Board amendments resolved many of these challenges. There was an unanticipated burden imposed on centres due to high numbers of echocardiograms that were reviewed but failed to meet submission criteria. Additionally, image transfer software malfunctions delayed Core Lab image review and feedback. Between the early and late study periods, the proportion of unacceptable echocardiograms submitted to the Core Lab decreased (14 versus 7%, p < 0.01). Most protocol violations were from eligibility violations and inadvertent protected health information disclosure (overall 2.5%). Adjudication committee reviews led to protocol changes. CONCLUSIONS: Numerous challenges encountered during the Normal Echocardiogram Database Study prolonged study enrolment. The retrospective design and flaws in image transfer software were key impediments to study completion and should be considered when designing future studies collecting echocardiographic images as a primary outcome.

Echocardiographic surveillance in children after tetralogy of Fallot repair: Adherence to guidelines?

BACKGROUND: Longitudinal clinical surveillance by transthoracic echocardiography (TTE) is an established practice in children with repaired tetralogy of Fallot (TOF). Non-Invasive Imaging Guidelines recommends a list of reporting elements that should be addressed during routine TTE in this population. In this study, we assessed the adherence to these recommendations. METHODS: This was a multi-center (n = 8) retrospective review of TTE reports in children ≤11 years of age who have had complete TOF repair. We included 10 patients from each participating center (n = 80) and scored 2 outpatient follow-up TTE reports on each patient. The adherence rate was based on completeness of TTE reporting elements derived from the guidelines. RESULTS: We reviewed 160 TTE reports on 80 patients. Median age was 4.4 months (IQR 1.5-6.6) and 3.6 years (IQR 1.3-6.4) at the time of complete surgical repair and first TTE report, respectively. The median adherence rate to recommended reporting elements was 61% (IQR 53-70). Of the 160 reports, 9 (7%) were ≥80% adherent and 40 (25%) were ≥70% adherent. Quantitative measurements of right ventricular outflow tract (RVOT), right ventricular (RV) size and function, and branch pulmonary arteries were least likely to be reported. CONCLUSIONS: Overall adherence to the most recent published imaging guidelines for surveillance of children with repaired TOF patients was suboptimal, especially for reporting of RVOT, RV size and function, and branch pulmonary arteries. Further studies are needed to explore the barriers to adherence to guidelines and most importantly, whether adherence is associated with clinical outcomes.

Challenges With Left Ventricular Functional Parameters: The Pediatric Heart Network Normal Echocardiogram Database.

BACKGROUND: The reliability of left ventricular (LV) systolic functional indices calculated from blinded echocardiographic measurements of LV size has not been tested in a large cohort of healthy children. The objective of this study was to estimate interobserver variability in standard measurements of LV size and systolic function in children with normal cardiac anatomy and qualitatively normal function. METHODS: The Pediatric Heart Network Normal Echocardiogram Database collected normal echocardiograms from healthy children ≤18 years old distributed equally by age, gender, and race. A core lab used two-dimensional echocardiograms to measure LV dimensions from which a separate data coordinating center calculated LV volumes and systolic functional indices. To evaluate interobserver variability, two independent expert pediatric echocardiographic observers remeasured LV dimensions on a subset of studies, while blinded to calculated volumes and functional indices. RESULTS: Of 3,215 subjects with measurable images, 552 (17%) had a calculated LV shortening fraction (SF) < 25% and/or LV ejection fraction (EF) < 50%; the subjects were significantly younger and smaller than those with normal values. When the core lab and independent observer measurements were compared, individual LV size parameter intraclass correlation coefficients were high (0.81-0.99), indicating high reproducibility. The intraclass correlation coefficients were lower for SF (0.24) and EF (0.56). Comparing reviewers, 40/56 (71%) of those with an abnormal SF and 36/104 (35%) of those with a normal SF based on core lab measurements were calculated as abnormal from at least one independent observer. In contrast, an abnormal EF was less commonly calculated from the independent observers' repeat measures; only 9/47 (19%) of those with an abnormal EF and 8/113 (7%) of those with a normal EF based on core lab measurements were calculated as abnormal by at least one independent observer. CONCLUSIONS: Although blinded measurements of LV size show good reproducibility in healthy children, subsequently calculated LV functional indices reveal significant variability despite qualitatively normal systolic function. This suggests that, in clinical practice, abnormal SF/EF values may result in repeat measures of LV size to match the subjective assessment of function. Abnormal LV functional indices were more prevalent in younger, smaller children.

An unusual case of concordant ventriculoarterial connections, subpulmonary infundibulum, and parallel arterial trunks: a diagnostic challenge.

We present an unusual case of concordant ventriculoarterial connections, subpulmonary infundibulum, and parallel arterial trunks. This case was complicated by extreme pulmonary artery tortuosity and low arching aorta causing severe tracheal compression. We discuss the difficulty in prenatal diagnosis, necessity for advanced imaging postnatally, and associated airway complications.

Etanercept With IVIg for Acute Kawasaki Disease: A Randomized Controlled Trial.

OBJECTIVES: Patients with Kawasaki disease can develop life-altering coronary arterial abnormalities, particularly in those resistant to intravenous immunoglobulin (IVIg) therapy. We tested the tumor necrosis factor α receptor antagonist etanercept for reducing both IVIg resistance and coronary artery (CA) disease progression. METHODS: In a double-blind multicenter trial, patients with Kawasaki disease received either etanercept (0.8 mg/kg; n = 100) or placebo (n = 101) subcutaneously starting immediately after IVIg infusion. IVIg resistance was the primary outcome with prespecified subgroup analyses according to age, sex, and race. Secondary outcomes included echocardiographic CA measures within subgroups defined by coronary dilation (z score >2.5) at baseline. We used generalized estimating equations to analyze z score change and a prespecified algorithm for change in absolute diameters. RESULTS: IVIg resistance occurred in 22% (placebo) and 13% (etanercept) of patients (P = .10). Etanercept reduced IVIg resistance in patients >1 year of age (P = .03). In the entire population, 46 (23%) had a coronary z score >2.5 at baseline. Etanercept reduced coronary z score change in those with and without baseline dilation (P = .04 and P = .001); no improvement occurred in the analogous placebo groups. Etanercept (n = 22) reduced dilation progression compared with placebo (n = 24) by algorithm in those with baseline dilation (P = .03). No difference in the safety profile occurred between etanercept and placebo. CONCLUSIONS: Etanercept showed no significant benefit in IVIg resistance in the entire population. However, preplanned analyses showed benefit in patients >1 year. Importantly, etanercept appeared to ameliorate CA dilation, particularly in patients with baseline abnormalities.

Results of the combined U.S. multicenter postapproval study of the Nit-Occlud PDA device for percutaneous closure of patent ductus arteriosus.

OBJECTIVES: To report the results of the Nit-Occlud PDA prospective postapproval study (PAS) along with a comparison to the results of the pivotal and continued access trials. BACKGROUND: The Nit-Occlud PDA (PFM Medical, Cologne, Germany), a nitinol coil patent ductus arteriosus (PDA) occluder, was approved by the Food and Drug Administration in 2013. METHODS: The PAS enrolled a total of 184 subjects greater than 6 months of age, weighing at least 5 kg, with PDAs less than 4 mm by angiography at 11 centers. Patients were followed prospectively at 2 months, 12 months, and 24 months postprocedure. These outcomes were compared to the 357 subjects enrolled in the pivotal and continued access protocols. Efficacy and safety data were reported. RESULTS: Among 184 subjects enrolled for the PAS between 2014 and 2017, 180 (97.8%) had successful device implantation. After 12 months, 98.7% (150/152) had trivial or no residual shunt by echocardiography and two subjects had only small residual shunts. There were three device embolizations that were all retrieved by snare without clinical consequence. Together with the pivotal and continued access study, 97.4% (449/461) had complete echocardiographic closure at 12 months in 541 enrolled subjects. The composite success was 94.4%. There were no mortalities and no serious device-related adverse events. CONCLUSIONS: The Nit-Occlud PDA is a safe and effective device for closure of a small to moderate sized PDA. There were no serious device-related adverse events in a large cohort of three clinical trials.

Discovery, characterization, and remediation of a C-terminal Fc-extension in proteins expressed in CHO cells.

Protein-based biotherapeutics are produced in engineered cells through complex processes and may contain a wide variety of variants and post-translational modifications that must be monitored or controlled to ensure product quality. Recently, a low level (~1-5%) impurity was observed in a number of proteins derived from stably transfected Chinese hamster ovary (CHO) cells using mass spectrometry. These molecules include antibodies and Fc fusion proteins where Fc is on the C-terminus of the construct. By liquid chromatography-mass spectrometry (LC-MS), the impurity was found to be ~1177 Da larger than the expected mass. After tryptic digestion and analysis by LC-MS/MS, the impurity was localized to the C-terminus of Fc in the form of an Fc sequence extension. Targeted higher-energy collision dissociation was performed using various normalized collision energies (NCE) on two charge states of the extended peptide, resulting in nearly complete fragment ion coverage. The amino acid sequence, SLSLSPEAEAASASELFQ, obtained by the de novo sequencing effort matches a portion of the vector sequence used in the transfection of the CHO cells, specifically in the promoter region of the selection cassette downstream of the protein coding sequence. The modification was the result of an unexpected splicing event, caused by the resemblance of the commonly used GGU codon of the C-terminal glycine to a consensus splicing donor. Three alternative codons for glycine were tested to alleviate the modification, and all were found to completely eliminate the undesirable C-terminal extension, thus improving product quality.

Determinants of Physician, Sonographer, and Laboratory Productivity: Analysis of the Third Survey from the American Society of Echocardiography Committee on Pediatric Echocardiography Laboratory Productivity.

BACKGROUND: The American Society of Echocardiography Committee on Pediatric Echocardiography Laboratory Productivity was formed in 2011 to study institutional factors that could influence the clinical productivity of physicians and sonographers in academic pediatric echocardiography laboratories. In the previous two surveys, staff clinical productivity remained stable while total echocardiography volumes increased. This third survey was designed to assess how clinical productivity is associated with laboratory infrastructure elements such as training, administrative tasks, quality improvement, research, and use of focused cardiac ultrasound (FCU). METHODS: Survey questions were sent by e-mail to North American laboratories. The aims were to assess (1) educational and training obligations, (2) academic productivity and research, (3) laboratory medical director satisfaction, (4) quality improvement, (5) laboratory leadership roles, and (6) impact and use of FCU. Survey responses were compared with clinical productivity metrics defined in the first two surveys. RESULTS: There were 38 responses. Academic productivity was higher at institutions with more dedicated imaging personnel, personnel with dedicated protected academic time, and advanced imaging fellows. Academic productivity did not correlate with clinical productivity and was not significantly affected by the presence of dedicated research sonographers. The satisfaction level of laboratory medical directors was related to dedicated administrative time and an administrative stipend. The majority of administrative roles were tasked to the laboratory medical director with support of the technical director. FCU was listed as a hospital privilege at four institutions (13%). Twenty-two (58%) were training FCU providers in one or more subspecialties. FCU was not associated with clinical or academic productivity. CONCLUSIONS: This third survey gathered supplemental data to complement the clinical productivity data collected from the first two surveys. Together, the results of these surveys further describe the range of factors that can affect North American academic pediatric echocardiography laboratories.

Diagnostic role of strain imaging in atypical myocarditis by echocardiography and cardiac MRI.

BACKGROUND: The diagnosis of myocarditis presenting as isolated acute chest pain with elevated troponins but normal systolic function is challenging with significant drawbacks even for the gold-standard endomyocardial biopsy. OBJECTIVE: This study aimed to evaluate the diagnostic role of strain imaging by echocardiography and cardiac MRI in these patients. MATERIALS AND METHODS: This was a retrospective review of children with cardiac MRI for acute chest pain with elevated troponins compared to normal controls. Echocardiographic fractional shortening, ejection fraction, speckle-tracking-derived peak longitudinal, radial, and circumferential strain were compared to cardiac MRI ejection fraction, T2 imaging, late gadolinium enhancement, speckle-tracking-derived peak longitudinal strain, radial strain, and circumferential strain. RESULTS: Group 1 included 10 subjects diagnosed with myocarditis, 9 (90%) males with a median age of 15.5 years (range: 14-17 years) compared with 10 age-matched controls in group 2. All subjects in group 1 had late gadolinium enhancement consistent with myocarditis and troponin ranged from 2.5 to >30 ng/ml. Electrocardiogram changes included ST segment elevation in 6 and abnormal Q waves in 1. Qualitative echocardiographic function was normal in both groups and mean fractional shortening was similar (35±6% in group 1 vs. 34±4% in group 2, P=0.70). Left ventricle ejection fraction by cardiac MRI, however, was lower in group 1 (52±9%) compared to group 2 at (59±4%) (P=0.03). Cardiac MRI derived strain was lower in group 1 vs. group 2 for speckle-tracking-derived peak longitudinal strain (-12.8±2.8% vs. -17.1±1.5%, P=0.001), circumferential strain (-12.3±3.8% vs. -15.8±1.2%, P=0.020) and radial strain (13.6±3.7% vs. 17.2±3.2%, P=0.040). Echocardiography derived strain was also lower in group 1 vs. group 2 for speckle-tracking-derived peak longitudinal strain (-15.6±3.9% vs. -20.8±2.2%, P<0.002), circumferential strain (-16±3% vs. -19.8±1.9%, P<0.003) and radial strain (17.3±6.1% vs. 24.8±6.3%, P=0.010). CONCLUSION: In previously asymptomatic children, myocarditis can present with symptoms of acute chest pain suspicious for coronary ischemia. Cardiac MRI and echocardiographic strain imaging are noninvasive, radiation-free tests of immense diagnostic utility in these situations. Long-term studies are needed to assess prognostic significance of these findings.

Relationship of Echocardiographic Z Scores Adjusted for Body Surface Area to Age, Sex, Race, and Ethnicity: The Pediatric Heart Network Normal Echocardiogram Database.

BACKGROUND: Published nomograms of pediatric echocardiographic measurements are limited by insufficient sample size to assess the effects of age, sex, race, and ethnicity. Variable methodologies have resulted in a wide range of Z scores for a single measurement. This multicenter study sought to determine Z scores for common measurements adjusted for body surface area (BSA) and stratified by age, sex, race, and ethnicity. METHODS AND RESULTS: Data collected from healthy nonobese children ≤18 years of age at 19 centers with a normal echocardiogram included age, sex, race, ethnicity, height, weight, echocardiographic images, and measurements performed at the Core Laboratory. Z score models involved indexed parameters (X/BSAα) that were normally distributed without residual dependence on BSA. The models were tested for the effects of age, sex, race, and ethnicity. Raw measurements from models with and without these effects were compared, and <5% difference was considered clinically insignificant because interobserver variability for echocardiographic measurements are reported as ≥5% difference. Of the 3566 subjects, 90% had measurable images. Appropriate BSA transformations (BSAα) were selected for each measurement. Multivariable regression revealed statistically significant effects by age, sex, race, and ethnicity for all outcomes, but all effects were clinically insignificant based on comparisons of models with and without the effects, resulting in Z scores independent of age, sex, race, and ethnicity for each measurement. CONCLUSIONS: Echocardiographic Z scores based on BSA were derived from a large, diverse, and healthy North American population. Age, sex, race, and ethnicity have small effects on the Z scores that are statistically significant but not clinically important.

Glycan profiling of proteins using lectin binding by Surface Plasmon Resonance.

Glycan profiling of proteins was studied through their lectin binding activity by Surface Plasmon Resonance (SPR). To validate the method, we monitored specific lectin binding with sequential removal of sugar moieties from human transferrin using specific glycosidases. The results clearly indicated that glycans on the protein can be identified by their selective binding activity to various lectins. Using this method, we characterized Fc glycosylation profiles of therapeutic peptibodies and antibodies expressed in mammalian cells (CHO and HEK 293 6E cells), with E. coli expressed proteins as the negative controls. We observed that antibodies expressed in CHO cells did not contain any sialic acid, while antibodies expressed in 293 6E cells contained sialic acid. CHO cell expressed antibodies were also more heavily fucosylated than the ones expressed by 293 6E cells. We further applied this method to measure the fucose composition of glycan engineered mouse antibodies, as well as to determine mannose composition of human antibody variants with depletion or enrichment of high mannose. The glycan profiles generated using this method were comparable to results from 2-AB labeled glycan analysis of normal-phase separated glycans, and Fc gamma receptor binding activity of the glycan engineered antibodies were consistent with their glycan profiles. Hence, we demonstrated that SPR lectin binding analysis can be a quick alternative method to profile protein glycosylation.

Engineering Antibody Reactivity for Efficient Derivatization to Generate NaV1.7 Inhibitory GpTx-1 Peptide-Antibody Conjugates.

The voltage-gated sodium channel NaV1.7 is a genetically validated pain target under investigation for the development of analgesics. A therapeutic with a less frequent dosing regimen would be of value for treating chronic pain; however functional NaV1.7 targeting antibodies are not known. In this report, we describe NaV1.7 inhibitory peptide-antibody conjugates as an alternate construct for potential prolonged channel blockade through chemical derivatization of engineered antibodies. We previously identified NaV1.7 inhibitory peptide GpTx-1 from tarantula venom and optimized its potency and selectivity. Tethering GpTx-1 peptides to antibodies bifunctionally couples FcRn-based antibody recycling attributes to the NaV1.7 targeting function of the peptide warhead. Herein, we conjugated a GpTx-1 peptide to specific engineered cysteines in a carrier anti-2,4-dinitrophenol monoclonal antibody using polyethylene glycol linkers. The reactivity of 13 potential cysteine conjugation sites in the antibody scaffold was tuned using a model alkylating agent. Subsequent reactions with the peptide identified cysteine locations with the highest conversion to desired conjugates, which blocked NaV1.7 currents in whole cell electrophysiology. Variations in attachment site, linker, and peptide loading established design parameters for potency optimization. Antibody conjugation led to in vivo half-life extension by 130-fold relative to a nonconjugated GpTx-1 peptide and differential biodistribution to nerve fibers in wild-type but not NaV1.7 knockout mice. This study describes the optimization and application of antibody derivatization technology to functionally inhibit NaV1.7 in engineered and neuronal cells.