Introduction of transcatheter edge-to-edge repair in patients with congenital heart disease at a children's hospital.

BACKGROUND: Atrioventricular valve regurgitation (AVVR) is a devastating complication in children and young adults with congenital heart disease (CHD), particularly in patients with single ventricle physiology. Transcatheter edge-to-edge repair (TEER) is a rapidly expanding, minimally invasive option for the treatment of AVVR in adults that avoids the morbidity and mortality associated with open heart surgery. However, application of TEER in in CHD and in children is quite novel. We describe the development of a peri-procedural protocol including image-derived pre-intervention simulation, with successful application to four patients. AIMS: To describe the initial experience using the MitraClip system for TEER of dysfunctional systemic atrioventricular valves in patients with congential heart disease within a pediatric hospital. METHODS: A standardized screening and planning process was developed using cardiac magnetic resonance imaging, three dimensional echocardiography and both virtual and physical simulation. Procedures were performed using the MitraClip G4 system and patients were clinically followed post-intervention. RESULTS: A series of four CHD patients with at least severe AVVR were screened for suitability for TEER with the MitraClip system: three patients had single ventricle physiology and Fontan palliation, and one had repair of a common atrioventricular canal defect. Each patient had at least severe systemic AVVR and was considered at prohibitively high risk for surgical repair. Each patient underwent a standardized preprocedural screening protocol and image-derived modeling followed by the TEER procedure with successful clip placement at the intended location in all cases. CONCLUSIONS: The early results of our protocolized efforts to introduce TEER repair of severe AV valve regurgitation with MitraClip into the CHD population within our institution are encouraging. Further investigations of the use of TEER in this challenging population are warranted.

Anesthetic challenges in patients with multicompartmental lymphatic failure after Fontan palliation undergoing transcatheter thoracic duct decompression.

Lymphatic flow abnormalities are central to the development of protein losing enteropathy, plastic bronchitis, ascites and pleural effusions in patients palliated to the Fontan circulation. These complications can occur in isolation or multicompartmental (two or more). The treatment of multicompartmental lymphatic failure aims at improving thoracic duct drainage. Re-routing the innominate vein to the pulmonary venous atrium decompresses the thoracic duct, as atrial pressure is lower than systemic venous pressure in Fontan circulation. Transcatheter thoracic duct decompression is a new minimally invasive procedure that involves placing covered stents from the innominate vein to the atrium. Patients undergoing this procedure require multiple general anesthetics, presenting challenges in managing the sequelae of disordered lymphatic flow superimposed on Fontan physiology. We reviewed the first 20 patients at the Center for Lymphatic Imaging and Intervention at a tertiary care children's hospital presenting for transcatheter thoracic duct decompression between March 2018 and February 2023. The patients ranged in age from 3 to 26 years. The majority had failed prior catheter-based lymphatic intervention, including selective embolization of abnormal lympho-intestinal and lympho-bronchial connections to treat lymphatic failure in a single compartment. Fourteen had failure in three lymphatic compartments. Patients were functionally impaired (ASA 3-5) with significant comorbidities. Concurrent with thoracic duct decompression, three patients required fenestration closure for the resultant decrease in oxygen saturation. Ten patients had improvement in symptoms, seven had no changes and three have limited follow up. Five (25%) of these patients were deceased as of January 2024 due to non-lymphatic complications from Fontan failure.

Dose Escalation Pharmacokinetic Study of Intranasal Atomized Dexmedetomidine in Pediatric Patients With Congenital Heart Disease.

BACKGROUND: Atomized intranasal dexmedetomidine is an attractive option when sedation is required for pediatric patients as either premedication or the sole agent for noninvasive, nonpainful procedures. While intranasal dexmedetomidine is used frequently in this population, it is still unclear what dose and time of administration relative to the procedure will result in the optimal effect. Knowledge regarding the maximum concentration (C max ) and time to reach maximum concentration (T max ) of intranasally administered dexmedetomidine is the first step toward this. The risk of hemodynamic instability caused by increasing doses of dexmedetomidine necessitates a greater understanding of the pharmacokinetics in children. METHODS: Sixteen pediatric patients 2 to 6 years of age undergoing elective cardiac catheterization received 2 or 4 µg/kg dexmedetomidine intranasally. Plasma concentrations were determined by liquid chromatography-tandem mass spectrometry with a validated assay. Descriptive noncompartmental analysis provided estimates of peak concentrations and time to reach peak concentrations. A population pharmacokinetic model was developed using nonlinear mixed-effects modeling. Simulations were performed using the final model to assess dose concentrations with an alternative dosing regimen of 3 µg/kg. RESULTS: A median peak plasma concentration of 413 pg/mL was achieved 91 minutes after 2 µg/kg dosing, and a median peak plasma concentration of 1000 pg/mL was achieved 54 minutes after 4 µg/kg dosing. A 1-compartment pharmacokinetic model adequately described the data. Three subjects in the 4 µg/kg dosing cohort achieved a dose-limiting toxicity (DLT), defined as a plasma dexmedetomidine concentration >1000 pg/mL. None of these subjects had any significant hemodynamic consequences. Simulations showed that no subjects would experience a level >1000 pg/mL when using a dose of 3 µg/kg. CONCLUSIONS: Concentrations associated with adequate sedation can be achieved with intranasal dexmedetomidine doses of 2 to 4 µg/kg in children 2 to 6 years of age. However, 50% of our evaluable subjects in this cohort reached a plasma concentration >1000 pg/mL. Doses of 3 µg/kg may be optimal in this population, with simulated concentrations remaining below this previously established toxicity threshold. Further studies correlating concentrations with efficacy and adverse effects are needed.

Spillover of Early Extubation Practices From the Pediatric Heart Network Collaborative Learning Study.

OBJECTIVES: The Pediatric Heart Network Collaborative Learning Study used collaborative learning strategies to implement a clinical practice guideline that increased rates of early extubation after infant repair of tetralogy of Fallot and coarctation of the aorta. We assessed early extubation rates for infants undergoing cardiac surgeries not targeted by the clinical practice guideline to determine whether changes in extubation practices spilled over to care of other infants. DESIGN: Observational analyses of site's local Society of Thoracic Surgeons Congenital Heart Surgery Database and Pediatric Cardiac Critical Care Consortium Registry. SETTING: Four Pediatric Heart Network Collaborative Learning Study active-site hospitals. PATIENTS: Infants undergoing ventricular septal defect repair, atrioventricular septal defect repair, or superior cavopulmonary anastomosis (lower complexity), and arterial switch operation or isolated aortopulmonary shunt (higher complexity). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Aggregate outcomes were compared between the 12 month pre-clinical practice guideline and 12 months after study completion (Follow Up). In infants undergoing lower complexity surgeries, early extubation increased during Follow Up compared with Pre-Clinical Practice Guideline (30.2% vs 18.8%, p = 0.006), and hours to initial postoperative extubation decreased. We observed variation in these outcomes by surgery type, with only ventricular septal defect repair associated with a significant increase in early extubation during Follow Up compared with Pre-Clinical Practice Guideline (47% vs 26%, p = 0.006). Variation by study site was also seen, with only one hospital showing an increase in early extubation. In patients undergoing higher complexity surgeries, there was no difference in early extubation or hours to initial extubation between the study eras. CONCLUSIONS: We observed spillover of extubation practices promoted by the Collaborative Learning Study clinical practice guideline to lower complexity operations not included in the original study that was sustainable 1 year after study completion, though this effect differed across sites and operation subtypes. No changes in postoperative extubation outcomes following higher complexity surgeries were seen. The significant variation in outcomes by site suggests that center-specific factors may have influenced spillover of clinical practice guideline practices.

Standardization of the Perioperative Management for Neonates Undergoing the Norwood Operation for Hypoplastic Left Heart Syndrome and Related Heart Defects.

OBJECTIVES: In-hospital complications after the Norwood operation for single ventricle heart defects account for the majority of morbidity and mortality. Inpatient care variation occurs within and across centers. This multidisciplinary quality improvement project standardized perioperative management in a large referral center. DESIGN: Quality improvement project. SETTING: High volume cardiac center, tertiary care children's hospital. PATIENTS: Neonates undergoing Norwood operation. INTERVENTIONS: The quality improvement team developed and implemented a clinical guideline (preoperative admission to 48 hr after surgery). The composite process metric, Guideline Adherence Score, contained 13 recommendations in the guideline that reflected consistent care for all patients. MEASUREMENTS AND MAIN RESULTS: One-hundred two consecutive neonates who underwent Norwood operation (January 1, 2013, to July 12, 2016) before guideline implementation were compared with 50 consecutive neonates after guideline implementation (July 13, 2016, to May 4, 2018). No preguideline operations met the goal Guideline Adherence Score. In the first 6 months after guideline implementation, 10 of 12 operations achieved goal Guideline Adherence Score and continued through implementation, reaching 100% for the last 10 operations. Statistical process control analysis demonstrated less variability and decreased hours of postoperative mechanical ventilation and cardiac ICU length of stay during implementation. There were no statistically significant differences in major hospital complications or in 30-day mortality. A higher percentage of patients were extubated by postoperative day 2 after guideline implementation (67% [30/47] vs 41% [41/99], respectively; p = 0.01). Of these patients, reintubation within 72 hours of extubation significantly decreased after guideline implementation (0% [0/30] vs 17% [7/41] patients, respectively; p = 0.02). CONCLUSIONS: This initiative successfully implemented a standardized perioperative care guideline for neonates undergoing the Norwood operation at a large center. Positive statistical process control centerline shifts in Guideline Adherence Score, length of postoperative mechanical ventilation, and cardiac ICU length of stay were demonstrated. A higher percentage were successfully extubated by postoperative day 2. Establishment of standard processes can lead to best practices to decrease major adverse events.

Clinical Update in Pediatric Sepsis: Focus on Children With Pre-Existing Heart Disease.

SEPSIS REMAINS one of the most common causes of childhood morbidity, mortality, and higher healthcare costs, with over 75,000 hospital admissions in the United States and an estimated 4 million cases worldwide per year. While standardized criteria to define sepsis are in flux, the general concept of sepsis is a severe infection that results in organ dysfunction. Although sepsis can affect previously healthy children, those with certain pre-existing comorbid conditions, including congenital and acquired heart disease, are at higher risk for both developing sepsis and having a poor outcome after sepsis. Multiple specialists including intensivists, cardiologists, surgeons, and anesthesiologists commonly contribute to the management and outcome of sepsis in children. In this article, the authors examine the evolving epidemiology of pediatric sepsis, including the subset of patients with underlying heart disease; contrast pediatric and adult sepsis; review the latest hemodynamic guidelines for management of pediatric septic shock and their application to children with heart disease; discuss the role of mechanical circulatory support; and review key aspects of anesthetic management for children with sepsis.

Damaging Variants in Proangiogenic Genes Impair Growth in Fetuses with Cardiac Defects.

OBJECTIVE: To determine the impact of damaging genetic variation in proangiogenic pathways on placental function, complications of pregnancy, fetal growth, and clinical outcomes in pregnancies with fetal congenital heart defect. STUDY DESIGN: Families delivering a baby with a congenital heart defect requiring surgical repair in infancy were recruited. The placenta and neonate were weighed and measured. Hemodynamic variables were recorded from a third trimester (36.4 ± 1.7 weeks) fetal echocardiogram. Exome sequencing was performed on the probands (N = 133) and consented parents (114 parent-child trios, and 15 parent-child duos) and the GeneVetter analysis tool used to identify damaging coding sequence variants in 163 genes associated with the positive regulation of angiogenesis (PRA) (GO:0045766). RESULTS: In total, 117 damaging variants were identified in PRA genes in 133 congenital heart defect probands with 73 subjects having at least 1 variant. Presence of a damaging PRA variant was associated with increased umbilical artery pulsatility index (mean 1.11 with variant vs 1.00 without; P = .01). The presence of a damaging PRA variant was also associated with lower neonatal length and head circumference for age z score at birth (mean -0.44 and -0.47 with variant vs 0.23 and -0.05 without; P = .01 and .04, respectively). During median 3.1 years (IQR 2.0-4.1 years) of follow-up, deaths occurred in 2 of 60 (3.3%) subjects with no PRA variant and in 9 of 73 (12.3%) subjects with 1 or more PRA variants (P = .06). CONCLUSIONS: Damaging variants in proangiogenic genes may impact placental function and are associated with impaired fetal growth in pregnancies involving a fetus with congenital heart defect.

Results of a phase 1 multicentre investigation of dexmedetomidine bolus and infusion in corrective infant cardiac surgery.

BACKGROUND: Dexmedetomidine (DEX) is increasingly used intraoperatively in infants undergoing cardiac surgery. This phase 1 multicentre study sought to: (i) determine the safety of DEX for cardiac surgery with cardiopulmonary bypass; (ii) determine the pharmacokinetics (PK) of DEX; (iii) create a PK model and dosing for steady-state DEX plasma levels; and (iv) validate the PK model and dosing. METHODS: We included 122 neonates and infants (0-180 days) with D-transposition of the great arteries, ventricular septal defect, or tetralogy of Fallot. Dose escalation was used to generate NONMEM® PK modelling, and then validation was performed to achieve low (200-300 pg ml-1), medium (400-500 pg ml-1), and high (600-700 pg ml-1) DEX plasma concentrations. RESULTS: Five of 122 subjects had adverse safety outcomes (4.1%; 95% confidence interval [CI], 1.8-9.2%). Two had junctional rhythm, two had second-/third-degree atrioventricular block, and one had hypotension. Clearance (CL) immediately postoperative and CL on CPB were reduced by approximately 50% and 95%, respectively, compared with pre-CPB CL. DEX clearance after CPB was 1240 ml min-1 70 kg-1. Age at 50% maximum clearance was approximately 2 days, and that at 90% maximum clearance was 18 days. Overall, 96.1% of measured DEX concentrations fell within the 5th-95th percentile prediction intervals in the PK model validation. Dosing strategies are recommended for steady-state DEX plasma levels ranging from 200 to 1000 pg ml-1. CONCLUSIONS: When used with a careful dosing strategy, DEX results in low incidence and severity of adverse safety events in infants undergoing cardiac surgery with cardiopulmonary bypass. This validated PK model should assist clinicians in selecting appropriate dosing. The results of this phase 1 trial provide preliminary data for a phase 3 trial of DEX neuroprotection. CLINICAL TRIALS REGISTRATION: NCT01915277.

Changes in Anesthetic and Postoperative Sedation-Analgesia Practice Associated With Early Extubation Following Infant Cardiac Surgery: Experience From the Pediatric Heart Network Collaborative Learning Study.

OBJECTIVES: The Pediatric Heart Network sponsored the multicenter Collaborative Learning Study that implemented a clinical practice guideline to facilitate early extubation in infants after repair of isolated coarctation of the aorta and tetralogy of Fallot. We sought to compare the anesthetic practice in the operating room and sedation-analgesia management in the ICU before and after the implementation of the guideline that resulted in early extubation. DESIGN: Secondary analysis of data from a multicenter study from January 2013 to April 2015. Predefined variables of anesthetic, sedative, and analgesia exposure were compared before and after guideline implementation. Propensity score weighted logistic regression analysis was used to determine the independent effect of intraoperative dexmedetomidine administration on early extubation. SETTING: Five children's hospitals. PATIENTS: A total of 240 study subjects who underwent repair of coarctation of the aorta or tetralogy of Fallot (119 preguideline implementation and 121 postguideline implementation). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Clinical practice guideline implementation was accompanied by a decrease in the median total intraoperative dose of opioids (49.7 vs 24.0 µg/kg of fentanyl equivalents, p < 0.001) and benzodiazepines (1.0 vs 0.4 mg/kg of midazolam equivalents, p < 0.001), but no change in median volatile anesthetic agent exposure (1.3 vs 1.5 minimum alveolar concentration hr, p = 0.25). Intraoperative dexmedetomidine administration was associated with early extubation (odds ratio 2.5, 95% CI, 1.02-5.99, p = 0.04) when adjusted for other covariates. In the ICU, more patients received dexmedetomidine (43% vs 75%), but concomitant benzodiazepine exposure decreased in both the frequency (66% vs 57%, p < 0.001) and cumulative median dose (0.5 vs 0.3 mg/kg of ME, p = 0.003) postguideline implementation. CONCLUSIONS: The implementation of an early extubation clinical practice guideline resulted in a reduction in the dose of opioids and benzodiazepines without a change in volatile anesthetic agent used in the operating room. Intraoperative dexmedetomidine administration was independently associated with early extubation. The total benzodiazepine exposure decreased in the early postoperative period.

Risk factors for mortality in paediatric cardiac ICU patients managed with extracorporeal membrane oxygenation.

BACKGROUND: Veno-arterial extracorporeal membrane oxygenation is frequently used in patients with cardiac disease. We evaluated short-term outcomes and identified factors associated with hospital mortality in cardiac patients supported with veno-arterial extracorporeal membrane oxygenation. METHODS: A retrospective review of patients supported with veno-arterial extracorporeal membrane oxygenation at a university-affiliated children's hospital was performed. RESULTS: A total of 253 patients with cardiac disease managed with extracorporeal membrane oxygenation were identified; survival to discharge was 48%, which significantly improved from 39% in an earlier era (1995-2001) (p=0.01). Patients were categorised into surgical versus non-surgical groups on the basis of whether they had undergone cardiac surgery before or not, respectively. The most common indication for extracorporeal membrane oxygenation was extracorporeal cardiopulmonary resuscitation: 96 (51%) in the surgical group and 45 (68%) in the non-surgical group. In a multiple covariate analysis, single-ventricle physiology (p=0.01), duration of extracorporeal membrane oxygenation (p<0.01), and length of hospital stay (p=0.03) were associated with hospital mortality. Weekend or night shift cannulation was associated with mortality in non-surgical patients (p=0.05). CONCLUSION: We report improvement in survival compared with an earlier era in cardiac patients supported with extracorporeal membrane oxygenation. Single-ventricle physiology continues to negatively impact survival, along with evidence of organ dysfunction during extracorporeal membrane oxygenation, duration of extracorporeal membrane oxygenation, and length of stay.

Neurological Injury and Cerebral Blood Flow in Single Ventricles Throughout Staged Surgical Reconstruction.

BACKGROUND: Patients with a single ventricle experience a high rate of brain injury and adverse neurodevelopmental outcome; however, the incidence of brain abnormalities throughout surgical reconstruction and their relationship with cerebral blood flow, oxygen delivery, and carbon dioxide reactivity remain unknown. METHODS: Patients with a single ventricle were studied with magnetic resonance imaging scans immediately prior to bidirectional Glenn (pre-BDG), before Fontan (BDG), and then 3 to 9 months after Fontan reconstruction. RESULTS: One hundred sixty-eight consecutive subjects recruited into the project underwent 235 scans: 63 pre-BDG (mean age, 4.8±1.7 months), 118 BDG (2.9±1.4 years), and 54 after Fontan (2.4±1.0 years). Nonacute ischemic white matter changes on T2-weighted imaging, focal tissue loss, and ventriculomegaly were all more commonly detected in BDG and Fontan compared with pre-BDG patients (P<0.05). BDG patients had significantly higher cerebral blood flow than did Fontan patients. The odds of discovering brain injury with adjustment for surgical stage as well as ≥2 coexisting lesions within a patient decreased (63%-75% and 44%, respectively) with increasing amount of cerebral blood flow (P<0.05). In general, there was no association of oxygen delivery (except for ventriculomegaly in the BDG group) or carbon dioxide reactivity with neurological injury. CONCLUSIONS: Significant brain abnormalities are commonly present in patients with a single ventricle, and detection of these lesions increases as children progress through staged surgical reconstruction, with multiple coexisting lesions more common earlier than later. In addition, this study demonstrated that BDG patients had greater cerebral blood flow than did Fontan patients and that an inverse association exists of various indexes of cerebral blood flow with these brain lesions. However, CO2 reactivity and oxygen delivery (with 1 exception) were not associated with brain lesion development. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT02135081.

Hearing Loss after Cardiac Surgery in Infancy: An Unintended Consequence of Life-Saving Care.

OBJECTIVES: To investigate the prevalence of hearing loss after cardiac surgery in infancy, patient and operative factors associated with hearing loss, and the relationship of hearing loss to neurodevelopmental outcomes. STUDY DESIGN: Audiologic and neurodevelopmental evaluations were conducted on 348 children who underwent repair of congenital heart disease at the Children's Hospital of Philadelphia as part of a prospective study evaluating neurodevelopmental outcomes at 4 years of age. A prevalence estimate was calculated based on presence and type of hearing loss. Potential risk factors and the impact of hearing loss on neurodevelopmental outcomes were evaluated. RESULTS: The prevalence of hearing loss was 21.6% (95% CI, 17.2-25.9). The prevalence of conductive hearing loss, sensorineural hearing loss, and indeterminate hearing loss were 12.4% (95% CI, 8.8-16.0), 6.9% (95% CI, 4.1-9.7), and 2.3% (95% CI, 0.6-4.0), respectively. Only 18 of 348 subjects (5.2%) had screened positive for hearing loss before this study and 10 used a hearing aid. After adjusting for patient and operative covariates, younger gestational age, longer postoperative duration of stay, and a confirmed genetic anomaly were associated with hearing loss (all P < .01). The presence of hearing loss was associated with worse language, cognition and attention (P <.01). CONCLUSIONS: These findings suggest that the prevalence of hearing loss in preschool children after heart surgery in infancy may be 20-fold higher than in the 1% prevalence seen in the general population. Younger gestational age, presence of a genetic anomaly, and longer postoperative duration of stay were associated with hearing loss. Hearing loss was associated with worse neurodevelopmental outcomes.

Consensus Statement by the Congenital Cardiac Anesthesia Society: Milestones for the Pediatric Cardiac Anesthesia Fellowship.

Pediatric cardiac anesthesiology has evolved as a subspecialty of both pediatric and cardiac anesthesiology and is devoted to caring for individuals with congenital heart disease ranging in age from neonates to adults. Training in pediatric cardiac anesthesia is a second-year fellowship with variability in both training duration and content and is not accredited by the Accreditation Council on Graduate Medical Education. Consequently, in this article and based on the Accreditation Council on Graduate Medical Education Milestones Model, an expert panel of the Congenital Cardiac Anesthesia Society, a section of the Society of Pediatric Anesthesiology, defines 18 milestones as competency-based developmental outcomes for training in the pediatric cardiac anesthesia fellowship.

Lymphatic imaging and intervention in a pediatric population: Anesthetic considerations.

The recent adoption of an improved lymphatic access technique coupled with Dynamic Contrast-enhanced Magnetic Resonance Lymphangiography has introduced the ability to diagnose and treat severe lymphatic disorders unresponsive to other therapies. All pediatric patients presenting for lymphatic procedures require general anesthesia presenting challenges in managing highly morbid and comorbid conditions both from logistical as well as medical aspects. General anesthesia is used because of the procedural requirement for immobility to accurately place needles and catheters, treat pain secondary to contrast and glue injections, and to accommodate additional procedures. We reviewed a one-year cohort of all pediatric patients in a newly created Center for Lymphatic Imaging and Intervention at a tertiary care children's hospital presenting for lymphatic procedures. The patients ranged in age from 4 days to 17 years and weighed from 2.5 to 92 kg. There were 106 anesthetics for 68 patients. Patients were functionally impaired (98% ASA 3 or 4) and included significant comorbidities (79.4%). Concurrent with lymphatic imaging and intervention additional procedures were frequently performed (76%). They included cardiac catheterization, bronchoscopy, endoscopy, and drain placement (thoracic or abdominal). Paralysis and controlled ventilation was used for all interventions. Reversal of paralysis and tracheal extubation occurred in all patients not previously managed by invasive respiratory support. All patients having an intervention were admitted to intensive care for observation where escalation of care or complications (fever, hypotension, bleeding, or stroke) occurred in 25% in the first 24 hours.

Early postoperative remodelling following repair of tetralogy of Fallot utilising unsedated cardiac magnetic resonance: a pilot study.

IntroductionThe right ventricular adaptations early after surgery in infants with tetralogy of Fallot are important to understand the changes that occur later on in life; this physiology has not been fully delineated. We sought to assess early postoperative right ventricular remodelling in patients with tetralogy of Fallot by cardiac MRI.Materials and methodSubjects with tetralogy of Fallot under 1 year of age were recruited following complete surgical repair for tetralogy of Fallot. Protocol-based cardiac MRI to assess anatomy, function, and flows was performed before hospital discharge using the feed and sleep technique, an unsedated imaging technique. RESULTS: MRI was completed in 16 subjects at a median age of 77 days (interquartile range 114). There was normal ventricular ejection fraction and indexed right ventricular end-diastolic volume (48±13 cc/m2), but elevated right ventricular mass (z score 6.2±2.4). Subjects requiring a transannular patch or right ventricle to pulmonary artery conduit had moderate pulmonary insufficiency (regurgitant fraction 27±16%).DiscussionEarly right ventricular remodelling after surgical repair for tetralogy of Fallot is characterised by significant pulmonary regurgitation, right ventricular hypertrophy, and lack of dilation. Performing cardiac MRI using the feed and sleep technique is feasible in infants younger than 5 months. These results might open new avenues to study longitudinal right ventricular changes in tetralogy of Fallot and to further explore the utility of unsedated MRI in patients with other types of CHDs.

A vascular endothelial growth factor A genetic variant is associated with improved ventricular function and transplant-free survival after surgery for non-syndromic CHD.

BACKGROUND: We have previously shown that the minor alleles of vascular endothelial growth factor A (VEGFA) single-nucleotide polymorphism rs833069 and superoxide dismutase 2 (SOD2) single-nucleotide polymorphism rs2758331 are both associated with improved transplant-free survival after surgery for CHD in infants, but the underlying mechanisms are unknown. We hypothesised that one or both of these minor alleles are associated with better systemic ventricular function, resulting in improved survival. METHODS: This study is a follow-up analysis of 422 non-syndromic CHD patients who underwent neonatal cardiac surgery with cardiopulmonary bypass. Echocardiographic reports were reviewed. Systemic ventricular function was subjectively categorised as normal, or as mildly, moderately, or severely depressed. The change in function was calculated as the change from the preoperative study to the last available study. Stepwise linear regression, adjusting for covariates, was performed for the outcome of change in ventricular function. Model comparison was performed using Akaike's information criterion. Only variables that improved the model prediction of change in systemic ventricular function were retained in the final model. RESULTS: Genetic and echocardiographic data were available for 335/422 subjects (79%). Of them, 33 (9.9%) developed worse systemic ventricular function during a mean follow-up period of 13.5 years. After covariate adjustment, the presence of the VEGFA minor allele was associated with preserved ventricular function (p=0.011). CONCLUSIONS: These data support the hypothesis that the mechanism by which the VEGFA single-nucleotide polymorphism rs833069 minor allele improves survival may be the preservation of ventricular function. Further studies are needed to validate this genotype-phenotype association and to determine whether this mechanism is related to increased vascular endothelial growth factor production.

Rationale and methodology of a collaborative learning project in congenital cardiac care.

BACKGROUND: Collaborative learning is a technique through which individuals or teams learn together by capitalizing on one another's knowledge, skills, resources, experience, and ideas. Clinicians providing congenital cardiac care may benefit from collaborative learning given the complexity of the patient population and team approach to patient care. RATIONALE AND DEVELOPMENT: Industrial system engineers first performed broad-based time-motion and process analyses of congenital cardiac care programs at 5 Pediatric Heart Network core centers. Rotating multidisciplinary team site visits to each center were completed to facilitate deep learning and information exchange. Through monthly conference calls and an in-person meeting, we determined that duration of mechanical ventilation following infant cardiac surgery was one key variation that could impact a number of clinical outcomes. This was underscored by one participating center's practice of early extubation in the majority of its patients. A consensus clinical practice guideline using collaborative learning was developed and implemented by multidisciplinary teams from the same 5 centers. The 1-year prospective initiative was completed in May 2015, and data analysis is under way. CONCLUSION: Collaborative learning that uses multidisciplinary team site visits and information sharing allows for rapid structured fact-finding and dissemination of expertise among institutions. System modeling and machine learning approaches objectively identify and prioritize focused areas for guideline development. The collaborative learning framework can potentially be applied to other components of congenital cardiac care and provide a complement to randomized clinical trials as a method to rapidly inform and improve the care of children with congenital heart disease.

Dexmedetomidine Pharmacology in Neonates and Infants After Open Heart Surgery.

BACKGROUND: Dexmedetomidine is a highly selective α2-agonist with hypnotic, analgesic, and anxiolytic properties. Despite off-label administration, dexmedetomidine has found a niche in critically ill neonates and infants with congenital heart disease because of its minimal effects on respiratory function at sedative doses, facilitating early extubation and fast-track postoperative care. There are little pharmacokinetic data regarding newborns who have immature drug metabolizing capacity and who are at risk for reduced dexmedetomidine clearance and drug toxicity. The aim of this study was to determine the pharmacokinetics of dexmedetomidine in neonates and infants after open heart surgery. This study included 23 evaluable neonates (age, 1 day-1 month) and 36 evaluable infants (age, 1 month-24 months) after open heart surgery. METHODS: Full-term neonates and infants requiring mechanical ventilation after open heart surgery received dexmedetomidine in a dose-escalation study. Dexmedetomidine was administered as a loading dose over 10 minutes followed by a continuous IV infusion up to 24 hours. Cohorts of 12 infants were enrolled sequentially to receive 0.35, 0.7, or 1 µg/kg dexmedetomidine followed by 0.25, 0.5, or 0.75 µg/kg/h dexmedetomidine, respectively. Cohorts of 9 neonates received 0.25, 0.35, or 0.5 µg/kg dexmedetomidine followed by 0.2, 0.3, or 0.4 µg/kg/h dexmedetomidine, respectively. Plasma dexmedetomidine concentrations were determined using a validated high-performance liquid chromatography-tandem mass spectrometry assay. A population nonlinear mixed effects modeling approach was used to characterize dexmedetomidine pharmacokinetics. RESULTS: Pharmacokinetic parameters of dexmedetomidine were estimated using a 2-compartment disposition model with weight allometrically scaled as a covariate on drug clearance, intercompartmental clearance, central and peripheral volume of distributions and age, total bypass time, and intracardiac shunting on clearance. Dexmedetomidine demonstrated a plasma drug clearance of 657 × (weight/70) mL/min, intercompartmental clearance of 6780 × (weight/70) mL/min, central volume of distribution of 88 × (weight/70) L and peripheral volume of distribution of 112 × (weight/70) L for a typical subject with age >1 month with a cardiopulmonary bypass time of 60 minutes and without right-to-left intracardiac shunt. Dexmedetomidine pharmacokinetics may be influenced by age during the neonatal period, weight, total bypass time, and presence of intracardiac shunt. CONCLUSIONS: Dexmedetomidine clearance is significantly diminished in full-term newborns and increases rapidly in the first few weeks of life. The dependence of clearance on age during the first few weeks of life reflects the relative immaturity of metabolic processes during the newborn period. Continuous infusions of up to 0.3 µg/kg/h in neonates and 0.75 µg/kg/h in infants were well tolerated after open heart surgery.

Utilizing a Collaborative Learning Model to Promote Early Extubation Following Infant Heart Surgery.

OBJECTIVE: To determine whether a collaborative learning strategy-derived clinical practice guideline can reduce the duration of endotracheal intubation following infant heart surgery. DESIGN: Prospective and retrospective data collected from the Pediatric Heart Network in the 12 months pre- and post-clinical practice guideline implementation at the four sites participating in the collaborative (active sites) compared with data from five Pediatric Heart Network centers not participating in collaborative learning (control sites). SETTING: Ten children's hospitals. PATIENTS: Data were collected for infants following two-index operations: 1) repair of isolated coarctation of the aorta (birth to 365 d) and 2) repair of tetralogy of Fallot (29-365 d). There were 240 subjects eligible for the clinical practice guideline at active sites and 259 subjects at control sites. INTERVENTIONS: Development and application of early extubation clinical practice guideline. MEASUREMENTS AND MAIN RESULTS: After clinical practice guideline implementation, the rate of early extubation at active sites increased significantly from 11.7% to 66.9% (p < 0.001) with no increase in reintubation rate. The median duration of postoperative intubation among active sites decreased from 21.2 to 4.5 hours (p < 0.001). No statistically significant change in early extubation rates was found in the control sites 11.7% to 13.7% (p = 0.63). At active sites, clinical practice guideline implementation had no statistically significant impact on median ICU length of stay (71.9 hr pre- vs 69.2 hr postimplementation; p = 0.29) for the entire cohort. There was a trend toward shorter ICU length of stay in the tetralogy of Fallot subgroup (71.6 hr pre- vs 54.2 hr postimplementation, p = 0.068). CONCLUSIONS: A collaborative learning strategy designed clinical practice guideline significantly increased the rate of early extubation with no change in the rate of reintubation. The early extubation clinical practice guideline did not significantly change postoperative ICU length of stay.

Managing Disruptions to Patient Flow Capacity: Rapid-Cycle Improvement in a Pediatric Cardiac Procedure Complex.

BACKGROUND: Managing service disruptions is a challenge in every health care environment. Discrete event simulation (DES)--a computer modeling tool used to build in silico (that is, in a digital computer) testbeds for potential changes in complex systems--has been deployed in health care for research and quality improvement (QI), specifically in surgical suite management. A strategy for managing a 6-week planned service disruption needed to be enacted 12 weeks after the announcement, in late October 2014, of the closure of the Hybrid Suite (operating room/catheterization laboratory) for renovation, at The Children's Hospital of Philadelphia's Cardiac Center's Cardiac Operative and Imaging Complex (COIC). METHODS: A previously developed DES was queried to determine theoretical system throughput capacity during the temporary disruption. On the basis of this analysis, a rapid improvement event (RIE) was enacted to address systemic challenges to meeting demand with diminished capacity. During the RIE, system stakeholders (physicians, nurses, and technicians) engaged with performance improvement personnel to identify potential improvements, test those changes in rapid succession, and then implement successful candidates for the disruption. RESULTS: First-case start time was 43 minutes earlier during the period of diminished capacity. Turnaround time between cases was reduced by 23 minutes. Length of day increased by 1 hour, in accordance with simulated predictions. System throughput was 138 patients during the disruption, compared with 135 patients during the same period the previous year. CONCLUSION: A combination of systems analysis and QI methodologies enabled the Cardiac Center to meet demand during a six-week period of diminished capacity. Planned, temporary service disruptions, which must be managed by clinical personnel, can be addressed proactively with promising results.