School age and adolescent heart failure following the Norwood procedure.

BACKGROUND: Heart failure results in significant morbidity and mortality for young children with hypoplastic left heart syndrome (HLHS) following the Norwood procedure. The trajectory in later childhood is not well described. METHODS: We studied the outcome into adolescence of participants enrolled in the Single Ventricle Reconstruction trial who underwent the Fontan procedure or survived to 6 years without having undergone Fontan procedure. The primary outcome was heart failure events, defined as heart transplant listing or death attributable to heart failure. Symptomatic heart failure for participants surviving 10 or more years was also assessed utilizing the Pediatric Quality of Life Inventory (PedsQL). RESULTS: Of the 345 participants who underwent a Fontan operation or survived to 6 years without Fontan, 25 (7.2%) had a heart failure event before the age of 12 years. Among these, 21 were listed for heart transplant, and 4 died from heart failure. Nineteen participants underwent heart transplant, all of whom survived to age 12 years. Factors associated with a heart failure event included longer Norwood hospital length of stay, aortic atresia, and no Fontan operation by age 6 years. Assessment of heart failure symptoms at 12 years of age revealed that 24 (12.2%) of 196 PedsQL respondents "often" or "almost always" had difficulty walking more than one block. CONCLUSIONS: Heart failure events occur in over 5% of children with palliated HLHS between preschool age and adolescence. Outcomes for children listed for transplant are excellent. However, a substantial portion of palliated HLHS children have significant symptoms of heart failure at 12 years of age.

Novel handheld ultrasound technology to enhance non-expert screening for rheumatic heart disease in the Republic of Palau: A descriptive study.

AIM: Non-expert training in rheumatic heart disease (RHD) detection is a valuable strategy in resource-limited settings. Here we present an innovative handheld ultrasound application featuring views of correct probe position, imaging protocol and echocardiographic loops of RHD pathology versus normal, accessible during real-time scanning. METHODS: This prospective study was implemented into a pre-existing school health screening programme at an elementary school in Koror, Palau. Six learners with no prior ultrasound experience were taught a simplified screening protocol in which a mitral regurgitation jet ≥1.5 cm and/or presence of aortic insufficiency were considered a positive screen. All consented children underwent echocardiographic screening by experts with standard portable echocardiography. All positive cases and 25% of negative cases were referred for handheld scans by learners. RESULTS: A total of 26 (4.1%) children were diagnosed with borderline or definite RHD. Mean sensitivity and specificity compared to expert RHD diagnosis over all learners was 71% (standard deviation (SD) 11.3) and 92% (SD 4.9), respectively. For the three highest scanning learners, mean sensitivity was 88% (SD 4.9) and mean specificity was 90% (SD 5.7). For all definite RHD cases, sensitivity was 100% for all but one learner, who achieved sensitivity of 60%. The novel application was used in 229 of 624 (36%) of all handheld scans and 50 of 112 (45%) of expert-diagnosed positive scans, with protocol and reference features most frequently used. Utilisation of the novel application overall decreased per day of scanning per learner. CONCLUSION: Adjunctive handheld ultrasound technology may help ease non-experts into RHD screening.

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.

Hospital Costs Related to Early Extubation After Infant Cardiac Surgery.

BACKGROUND: The Pediatric Heart Network Collaborative Learning Study (PHN CLS) increased early extubation rates after infant tetralogy of Fallot (TOF) and coarctation of the aorta (CoA) repair across participating sites by implementing a clinical practice guideline (CPG). The impact of the CPG on hospital costs has not been studied. METHODS: PHN CLS clinical data were linked to cost data from Children's Hospital Association by matching on indirect identifiers. Hospital costs were evaluated across active and control sites in the pre- and post-CPG periods using generalized linear mixed-effects models. A difference-in-difference approach was used to assess whether changes in cost observed in active sites were beyond secular trends in control sites. RESULTS: Data were successfully linked on 410 of 428 eligible patients (96%) from four active and four control sites. Mean adjusted cost per case for TOF repair was significantly reduced in the post-CPG period at active sites ($42,833 vs $56,304, p < 0.01) and unchanged at control sites ($47,007 vs $46,476, p = 0.91), with an overall cost reduction of 27% in active versus control sites (p = 0.03). Specific categories of cost reduced in the TOF cohort included clinical (-66%, p < 0.01), pharmacy (-46%, p = 0.04), lab (-44%, p < 0.01), and imaging (-32%, p < 0.01). There was no change in costs for CoA repair at active or control sites. CONCLUSIONS: The early extubation CPG was associated with a reduction in hospital costs for infants undergoing repair of TOF but not CoA. This CPG represents an opportunity to both optimize clinical outcome and reduce costs for certain infant cardiac surgeries.

Predictors of Rapid Aortic Root Dilation and Referral for Aortic Surgery in Marfan Syndrome.

Few data exist regarding predictors of rapid aortic root dilation and referral for aortic surgery in Marfan syndrome (MFS). To identify independent predictors of the rate of aortic root (AoR) dilation and referral for aortic surgery, we investigated the data from the Pediatric Heart Network randomized trial of atenolol versus losartan in young patients with MFS. Data were analyzed from the echocardiograms at 0, 12, 24, and 36 months read in the core laboratory of 608 trial subjects, aged 6 months to 25 years, who met original Ghent criteria and had an AoR z-score (AoRz) > 3. Repeated measures linear and logistic regressions were used to determine multivariable predictors of AoR dilation. Receiver operator characteristic curves were used to determine cut-points in AoR dilation predicting referral for aortic surgery. Multivariable analysis showed rapid AoR dilation as defined by change in AoRz/year > 90th percentile was associated with older age, higher sinotubular junction z-score, and atenolol use (R2 = 0.01) or by change in AoR diameter (AoRd)/year > 90th percentile with higher sinotubular junction z-score and non-white race (R2 = 0.02). Referral for aortic root surgery was associated with higher AoRd, higher ascending aorta z-score, and higher sinotubular junction diameter:ascending aorta diameter ratio (R2 = 0.17). Change in AoRz of 0.72 SD units/year had 42% sensitivity and 92% specificity and change in AoRd of 0.34 cm/year had 38% sensitivity and 95% specificity for predicting referral for aortic surgery. In this cohort of young patients with MFS, no new robust predictors of rapid AoR dilation or referral for aortic root surgery were identified. Further investigation may determine whether generalized proximal aortic dilation and effacement of the sinotubular junction will allow for better risk stratification. Rate of AoR dilation cut-points had high specificity, but low sensitivity for predicting referral for aortic surgery, limiting their clinical use. Clinical Trial Number ClinicalTrials.gov number, NCT00429364.

Heart failure after the Norwood procedure: An analysis of the Single Ventricle Reconstruction Trial.

BACKGROUND: Heart failure results in significant morbidity and mortality in young children with hypoplastic left heart syndrome (HLHS) after the Norwood procedure. METHODS: We studied subjects enrolled in the prospective Single Ventricle Reconstruction (SVR) Trial who survived to hospital discharge after a Norwood operation and were followed up to age 6 years. The primary outcome was heart failure, defined as heart transplant listing after Norwood hospitalization, death attributable to heart failure, or symptomatic heart failure (New York Heart Association [NYHA] Class IV). Multivariate modeling was undertaken using Cox regression methodology to determine variables associated with heart failure. RESULTS: Of the 461 subjects discharged home following a Norwood procedure, 66 (14.3%) met the criteria for heart failure. Among these, 15 died from heart failure, 39 were listed for transplant (22 had a transplant, 12 died after listing, and 5 were alive and not yet transplanted), and 12 had NYHA Class IV heart failure but were never listed. The median age at heart failure identification was 1.28 (interquartile range 0.30 to 4.69) years. Factors associated with early heart failure included post-Norwood lower fractional area change, need for extracorporeal membrane oxygenation, non-Hispanic ethnicity, Norwood perfusion type, and total support time (p < 0.05). CONCLUSIONS: By 6 years of age, heart failure developed in nearly 15% of children after the Norwood procedure. Although transplant listing was common, many patients died from heart failure before receiving a transplant or without being listed. Shunt type did not impact the risk of developing heart failure.

Transplant-Free Survival and Interventions at 6 Years in the SVR Trial.

BACKGROUND: In the SVR trial (Single Ventricle Reconstruction), 1-year transplant-free survival was better for the Norwood procedure with right ventricle-to-pulmonary artery shunt (RVPAS) compared with a modified Blalock-Taussig shunt in patients with hypoplastic left heart and related syndromes. At 6 years, we compared transplant-free survival and other outcomes between the groups. METHODS: Medical history was collected annually using medical record review, telephone interviews, and the death index. The cohort included 549 patients randomized and treated in the SVR trial. RESULTS: Transplant-free survival for the RVPAS versus modified Blalock-Taussig shunt groups did not differ at 6 years (64% versus 59%, P=0.25) or with all available follow-up of 7.1±1.6 years (log-rank P=0.13). The RVPAS versus modified Blalock-Taussig shunt treatment effect had nonproportional hazards (P=0.009); the hazard ratio (HR) for death or transplant favored the RVPAS before stage II surgery (HR, 0.66; 95% confidence interval, 0.48-0.92). The effect of shunt type on death or transplant was not statistically significant between stage II to Fontan surgery (HR, 1.36; 95% confidence interval, 0.86-2.17; P=0.17) or after the Fontan procedure (HR, 0.76; 95% confidence interval, 0.33-1.74; P=0.52). By 6 years, patients with RVPAS had a higher incidence of catheter interventions (0.38 versus 0.23/patient-year, P<0.001), primarily because of more interventions between the stage II and Fontan procedures (HR, 1.72; 95% confidence interval, 1.00-3.03). Complications did not differ by shunt type; by 6 years, 1 in 5 patients had had a thrombotic event, and 1 in 6 had had seizures. CONCLUSIONS: By 6 years, the hazards of death or transplant and catheter interventions were not different between the RVPAS versus modified Blalock-Taussig shunt groups. Children assigned to the RVPAS group had 5% higher transplant-free survival, but the difference did not reach statistical significance, and they required more catheter interventions. Both treatment groups have accrued important complications. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT00115934.

Longitudinal Outcomes of Patients With Single Ventricle After the Fontan Procedure.

BACKGROUND: Multicenter longitudinal objective data for survival into adulthood of patients who have undergone Fontan procedures are lacking. OBJECTIVES: This study sought to describe transplant-free survival and explore relationships between laboratory measures of ventricular performance and functional status over time. METHODS: Exercise testing, echocardiography, B-type natriuretic peptide, functional health assessment, and medical history abstraction were repeated 9.4 ± 0.4 years after the Fontan Cross-Sectional Study (Fontan 1) and compared with previous values. Cox regression analysis explored risk factors for interim death or cardiac transplantation. RESULTS: From the original cohort of 546 subjects, 466 were contacted again, and 373 (80%) were enrolled at 21.2 ± 3.5 years of age. Among subjects with paired testing, the percent predicted maximum oxygen uptake decreased (69 ± 14% vs. 61 ± 16%; p < 0.001; n = 95), ejection fraction decreased (58 ± 11% vs. 55 ± 10%; p < 0.001; n = 259), and B-type natriuretic peptide increased (median [interquartile range] 13 [7 to 25] pg/mol vs. 18 [9 to 36] pg/mol; p < 0.001; n = 340). At latest follow-up, a lower Pediatric Quality of Life Inventory physical summary score was associated with poorer exercise performance (R2 adjusted = 0.20; p < 0.001; n = 274). Cumulative complications since the Fontan procedure included additional cardiac surgery (32%), catheter intervention (62%), arrhythmia treatment (32%), thrombosis (12%), and protein-losing enteropathy (8%). Since Fontan 1, 54 subjects (10%) have received a heart transplant (n = 23) or died without transplantation (n = 31). The interval risk of death or/cardiac transplantation was associated with poorer ventricular performance and functional health status assessed at Fontan 1, but it was not associated with ventricular morphology, the subject's age, or the type of Fontan connection. CONCLUSIONS: Interim transplant-free survival over 12 years in this Fontan cohort was 90% and was independent of ventricular morphology. Exercise performance decreased and was associated with worse functional health status. Future interventions might focus on preserving exercise capacity. (Relationship Between Functional Health Status and Ventricular Performance After Fontan-Pediatric Heart Network; NCT00132782).

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.

Electrocardiogram in Preparticipation Athletic Evaluations among Insured Youths.

OBJECTIVE: To retrospectively characterize electrocardiogram (ECG) use among preparticipation history and examinations (PPEs). STUDY DESIGN: Using the 2005 to 2010 MarketScan insurance database, we identified subjects aged 5-21 years with either a PPE with an ECG or a PPE alone, excluding those with known cardiac diagnoses. We described cardiology referrals and subspecialty testing within 180 days and cardiac diagnoses within 1 year of the PPE, and the costs of testing in each group. RESULTS: From 2005-2009, 503 304 PPEs occurred in 419 456 subjects, of which 8621 (2%) included an ECG. ECG use increased from 12-20 per 1000 PPEs from 2005-2009. Females, lower socioeconomic status, and rural settings were associated with fewer ECGs. Thirteen percent of PPEs with ECG and 0.5% of PPEs alone led to a cardiology referral. After PPEs with ECG, cardiac disease was identified in 18% (2% sports-limiting); after PPEs alone, cardiac disease was identified in 0.5% (0.03% sports-limiting). The PPE had a sensitivity of 44% and a specificity of 98.6% of identifying cardiac disease. The total reimbursement cost of PPEs plus testing was $80 396 464 ($160 per PPE). CONCLUSIONS: These real-world data demonstrate that community providers selectively use the ECG as part of the PPE with a high rate of identification of cardiac disease. Mass ECG screening would need to be more efficient at identifying disease than this selective approach.

Synthesis and evaluation of a selective fluorogenic Pup derived assay reagent for Dop, a potential drug target in Mycobacterium tuberculosis.

A litter of pups: The synthesis and in vitro evaluation of new Pup-based fluorogenic substrates for Dop, the mycobacterial depupylase, are described. A full-length Pup-amidomethylcoumarin conjugate as well as an amino-terminus-truncated analogue exhibited high sensitivity and specificity towards hydrolysis by Dop. The substrates developed here might find application as high-throughput screening assay reagents for the identification of Dop inhibitors.

Crystal structure of a sulfur carrier protein complex found in the cysteine biosynthetic pathway of Mycobacterium tuberculosis.

The structure of the protein complex CysM-CysO from a new cysteine biosynthetic pathway found in the H37Rv strain of Mycobacterium tuberculosis has been determined at 1.53 A resolution. CysM (Rv1336) is a PLP-containing beta-replacement enzyme and CysO (Rv1335) is a sulfur carrier protein with a ubiquitin-like fold. CysM catalyzes the replacement of the acetyl group of O-acetylserine by CysO thiocarboxylate to generate a protein-bound cysteine that is released in a subsequent proteolysis reaction. The protein complex in the crystal structure is asymmetric with one CysO protomer binding to one end of a CysM dimer. Additionally, the structures of CysM and CysO were determined individually at 2.8 and 2.7 A resolution, respectively. Sequence alignments with homologues and structural comparisons with CysK, a cysteine synthase that does not utilize a sulfur carrier protein, revealed high conservation of active site residues; however, residues in CysM responsible for CysO binding are not conserved. Comparison of the CysM-CysO binding interface with other sulfur carrier protein complexes revealed a similarity in secondary structural elements that contribute to complex formation in the ThiF-ThiS and MoeB-MoaD systems, despite major differences in overall folds. Comparison of CysM with and without bound CysO revealed conformational changes associated with CysO binding.

Reconstitution of a new cysteine biosynthetic pathway in Mycobacterium tuberculosis.

A new pathway for cysteine biosynthesis has been elucidated in Mycobacterium tuberculosis. This pathway involves a protein-bound thiocarboxylate (CysO-SH) as the sulfide donor, similar to thiamin biosynthesis. Cysteine synthase M (CysM) catalyzes the addition of cysteine to the carboxy terminus of the protein-bound thiocarboxylate to generate a CysO-cysteine adduct. A protease, Mec+, hydrolyzes the CysO-cysteine adduct to release cysteine and regenerate CysO. Mec+ contains a JAMM motif, and this work provides the first functional characterization of the JAMM motif in prokaryotes. MoeZ, a paralogue of ThiF, has been shown to transfer sulfur onto CysO.