Randomized controlled trials in children's heart surgery in the 21st century: a systematic review

OBJECTIVES

Randomized controlled trials are the gold standard for evaluating health care interventions, yet are uncommon in children's heart surgery. We conducted a systematic review of clinical trials in paediatric cardiac surgery to evaluate the scope and quality of the current international literature.

METHODS

We searched MEDLINE, CENTRAL and LILACS, and manually screened retrieved references and systematic reviews to identify all randomized controlled trials reporting the effect of any intervention on the conduct or outcomes of heart surgery in children published in any language since January 2000; secondary publications and those reporting inseparable adult data were excluded. Two reviewers independently screened studies for eligibility and extracted data; the Cochrane Risk of Bias tool was used to assess for potential biases.

RESULTS

We identified 333 trials from 34 countries randomizing 23 902 children. Most were early phase (313, 94.0%), recruiting few patients (median 45, interquartile range 28-82), and only 11 (3.3%) directly evaluated a surgical intervention. One hundred and nine (32.7%) trials calculated a sample size, 52 (15.6%) reported a CONSORT diagram, 51 (15.3%) were publicly registered and 25 (7.5%) had a Data Monitoring Committee. The overall risk of bias was low in 22 (6.6%), high in 69 (20.7%) and unclear in 242 (72.7%).

CONCLUSIONS

The recent literature in children's heart surgery contains few late-phase clinical trials. Most trials did not conform to the accepted standards of reporting, and the overall risk of bias was low in few studies. There is a need for high-quality, multicentre clinical trials to provide a robust evidence base for contemporary paediatric cardiac surgical practice.

Approaches to Pulmonary Atresia With Major Aortopulmonary Collateral Arteries

Pulmonary atresia with major aortopulmonary collateral arteries (MAPCAs) is one of the most challenging surgical conditions to manage-not only because of the technical complexity of the surgery but also in terms of defining the anatomy of the pulmonary vasculature, the timing of surgery, and decision making on staged vs complete repair. The importance of early definition of pulmonary blood supply is paramount, establishing which areas of the lung are supplied by MAPCAs alone and which have dual supply with the native system (noting that 20% of patients have absent intrapericardial native vessels). Early unifocalization (3-6 months) is ideal, with closure of the ventricular septal defect (VSD) performed if 15 or more out of 20 lung segments can be recruited. Leaving the ventricular septal defect open with a limiting right ventricle-pulmonary artery conduit can be a useful interim or even definitive circulation in patients with borderline vasculature. Rehabilitation of small native vessels with central shunts can be very effective, but best outcomes are achieved by a combination of unifocalization of MAPCAs together with the native vessels (if present). A variety of reconstructive techniques are necessary to be able to effect these complex repairs with careful choice of materials. Ideally, surgery can be completed through sternotomy alone, but separate thoracotomies may be necessary to control and access some MAPCAs.

Re-evaluation of hypoplastic left heart syndrome from a developmental and morphological perspective

Background

Hypoplastic left heart syndrome (HLHS) covers a spectrum of rare congenital anomalies characterised by a non-apex forming left ventricle and stenosis/atresia of the mitral and aortic valves. Despite many studies, the causes of HLHS remain unclear and there are conflicting views regarding the role of flow, valvar or myocardial abnormalities in its pathogenesis, all of which were proposed prior to the description of the second heart field. Our aim was to re-evaluate the patterns of malformation in HLHS in relation to recognised cardiac progenitor populations, with a view to providing aetiologically useful sub-groupings for genomic studies.

Results

We examined 78 hearts previously classified as HLHS, with subtypes based on valve patency, and re-categorised them based on their objective ventricular phenotype. Three distinct subgroups could be identified: slit-like left ventricle (24%); miniaturised left ventricle (6%); and thickened left ventricle with endocardial fibroelastosis (EFE; 70%). Slit-like ventricles were always found in combination with aortic atresia and mitral atresia. Miniaturised left ventricles all had normally formed, though smaller aortic and mitral valves. The remaining group were found to have a range of aortic valve malformations associated with thickened left ventricular walls despite being described as either atresia or stenosis. The degree of myocardial thickening was not correlated to the degree of valvar stenosis. Lineage tracing in mice to investigate the progenitor populations that form the parts of the heart disrupted by HLHS showed that whereas Nkx2–5-Cre labelled myocardial and endothelial cells within the left and right ventricles, Mef2c-AHF-Cre, which labels second heart field-derived cells only, was largely restricted to the endocardium and myocardium of the right ventricle. However, like Nkx2–5-Cre, Mef2c-AHF-Cre lineage cells made a significant contribution to the aortic and mitral valves. In contrast, Wnt1-Cre made a major contribution only to the aortic valve. This suggests that discrete cardiac progenitors might be responsible for the patterns of defects observed in the distinct ventricular sub-groups.

Conclusions

Only the slit-like ventricle grouping was found to map to the current nomenclature: the combination of mitral atresia with aortic atresia. It appears that slit-like and miniature ventricles also form discrete sub-groups. Thus, reclassification of HLHS into subgroups based on ventricular phenotype, might be useful in genetic and developmental studies in investigating the aetiology of this severe malformation syndrome.

Improving Risk Adjustment for Mortality After Pediatric Cardiac Surgery: The UK PRAiS2 Model

BACKGROUND

Partial Risk Adjustment in Surgery (PRAiS), a risk model for 30-day mortality after children's heart surgery, has been used by the UK National Congenital Heart Disease Audit to report expected risk-adjusted survival since 2013. This study aimed to improve the model by incorporating additional comorbidity and diagnostic information.

METHODS

The model development dataset was all procedures performed between 2009 and 2014 in all UK and Ireland congenital cardiac centers. The outcome measure was death within each 30-day surgical episode. Model development followed an iterative process of clinical discussion and development and assessment of models using logistic regression under 25 × 5 cross-validation. Performance was measured using Akaike information criterion, the area under the receiver-operating characteristic curve (AUC), and calibration. The final model was assessed in an external 2014 to 2015 validation dataset.

RESULTS

The development dataset comprised 21,838 30-day surgical episodes, with 539 deaths (mortality, 2.5%). The validation dataset comprised 4,207 episodes, with 97 deaths (mortality, 2.3%). The updated risk model included 15 procedural, 11 diagnostic, and 4 comorbidity groupings, and nonlinear functions of age and weight. Performance under cross-validation was: median AUC of 0.83 (range, 0.82 to 0.83), median calibration slope and intercept of 0.92 (range, 0.64 to 1.25) and -0.23 (range, -1.08 to 0.85) respectively. In the validation dataset, the AUC was 0.86 (95% confidence interval [CI], 0.82 to 0.89), and the calibration slope and intercept were 1.01 (95% CI, 0.83 to 1.18) and 0.11 (95% CI, -0.45 to 0.67), respectively, showing excellent performance.

CONCLUSIONS

A more sophisticated PRAiS2 risk model for UK use was developed with additional comorbidity and diagnostic information, alongside age and weight as nonlinear variables.

A Comparison of GPS Workload Demands in Match Play and Small-Sided Games by the Positional Role in Youth Soccer

The external demands of small-sided games (SSGs) according to the positional role are currently unknown. Using a Catapult Minimax X3 5 Hz GPS, with a 100 Hz tri-axial accelerometer, we compared the accumulated tri-axial player workload per min (PLacc·min-1) during friendly youth match play (MP) (11 vs. 11) and SSGs (2 vs. 2, 3 vs. 3, and 4 vs. 4). Significant differences existed between all SSGs and MP for PLacc·min-1 (F = 21.91, p < 0.001, η2 = 0.38), and individual X (F = 27.40, p < 0.001, η2 = 0.43), Y (F = 14.50, p < 0.001, η2 = 0.29) and Z (F = 19.28, p < 0.001, η2 = 0.35) axis loads. Across all conditions, mean PLacc·min-1 was greater for midfielders (p = 0.004, CI: 0.68, 4.56) and forwards (p = 0.037, CI: 0.08, 3.97) than central defenders. In all conditions, greater Y axis values existed for wide defenders (p = 0.024, CI: 0.67, 1.38), midfielders (p = 0.006, CI: 0.18, 1.50) and forwards (p = 0.007, CI: 0.17, 0.15) compared to central defenders. Midfielders reported greater Z axis values compared to central defenders (p = 0.002, CI: 0.40, 2.23). We concluded that SSGs elicited greater external loads than MP, and previous studies may have underestimated the demands of SSGs.

Ethnic and socioeconomic variation in incidence of congenital heart defects

INTRODUCTION

Ethnic differences in the birth prevalence of congenital heart defects (CHDs) have been reported; however, studies of the contemporary UK population are lacking. We investigated ethnic variations in incidence of serious CHDs requiring cardiac intervention before 1 year of age.

METHODS

All infants who had a cardiac intervention in England and Wales between 1 January 2005 and 31 December 2010 were identified in the national congenital heart disease surgical audit and matched with paediatric intensive care admission records to create linked individual child records. Agreement in reporting of ethnic group by each audit was evaluated. For infants born 1 January 2006 to 31 December 2009, we calculated incidence rate ratios (IRRs) for CHDs by ethnicity and investigated age at intervention, antenatal diagnosis and area deprivation.

RESULTS

We identified 5350 infants (2940 (55.0%) boys). Overall CHD incidence was significantly higher in Asian and Black ethnic groups compared with the White reference population (incidence rate ratios (IRR) (95% CIs): Asian 1.5 (1.4 to 1.7); Black 1.4 (1.3 to 1.6)); incidence of specific CHDs varied by ethnicity. No significant differences in age at intervention or antenatal diagnosis rates were identified but affected children from non-White ethnic groups were more likely to be living in deprived areas than White children.

CONCLUSIONS

Significant ethnic variations exist in the incidence of CHDs, including for specific defects with high infant mortality. It is essential that healthcare provision mitigates ethnic disparity, including through timely identification of CHDs at screening, supporting parental choice and effective interventions. Future research should explore the factors underlying ethnic variation and impact on longer-term outcomes.

Changes in potassium concentration and haematocrit associated with cardiopulmonary bypass in paediatric cardiac surgery

Introduction: A blood prime is frequently required for paediatric bypass surgery to maintain adequate haematocrit (Hct). However, stored blood can have high extracellular potassium levels and this study aims to investigate the effect of stored blood on the potassium concentration, both in the prime and subsequently in the patient after cardiopulmonary bypass (CPB) has been established. In neonatal surgery, the stored blood may be irradiated if there is a question of impaired immunity. Irradiation may cause a further increase in potassium levels.

Methods: Blood-primed circuits prepared for 320 consecutive paediatric bypass cases were analysed for electrolyte levels, Hct and acid-base status before and immediately after establishment of CPB. Patients were divided into three groups according to body weight (<5kg, 5—10 kg and > 10 kg) and both stored blood and irradiated blood primes were compared.

Results: The potassium concentration was above the physiological range in all bypass primes pre-CPB and was significantly higher when using irradiated blood (8.12 ± 2.54 mmol/L versus 4.94 ± 3.35 mmol/L, p < 0.0001).

Despite this, on commencing CPB, the potassium level remained within the physiological range in the majority of patients (4.16 ± 2.72 mmol/L for stored blood prime and 4.55 ± 1.01 mmol/L for irradiated blood, p = 0.02). However, in smaller patients (< 5 kg) who had irradiated blood prime potassium level > 7.0 mmol/L, there was resultant hyperkalaemia (5.60 ± 0.90 mmol/L) on commencing CPB, that returned to normal later. No adverse clinical events were associated with the hyperkalaemia. Hct was well maintained on CPB (22—25%) in all groups and was not related to patient weight.

Conclusion: Blood primes result in high potassium concentrations in the prime fluid that is more severe if irradiated blood is used. The concentration is not sufficient to cause hyperkalaemia in the patients on commencing CPB except when irradiated blood prime is used in infants < 5 kg. Hct is well maintained in all patient groups with the use of blood prime. Perfusion (2007) 22, 87—92.

Death and Emergency Readmission of Infants Discharged After Interventions for Congenital Heart Disease: A National Study of 7643 Infants to Inform Service Improvement

Background

Improvements in hospital‐based care have reduced early mortality in congenital heart disease. Later adverse outcomes may be reducible by focusing on care at or after discharge. We aimed to identify risk factors for such events within 1 year of discharge after intervention in infancy and, separately, to identify subgroups that might benefit from different forms of intervention.

Methods and Results

Cardiac procedures performed in infants between 2005 and 2010 in England and Wales from the UK National Congenital Heart Disease Audit were linked to intensive care records. Among 7976 infants, 333 (4.2%) died before discharge. Of 7643 infants discharged alive, 246 (3.2%) died outside the hospital or after an unplanned readmission to intensive care (risk factors were age, weight‐for‐age, cardiac procedure, cardiac diagnosis, congenital anomaly, preprocedural clinical deterioration, prematurity, ethnicity, and duration of initial admission; c‐statistic 0.78 [0.75–0.82]). Of the 7643, 514 (6.7%) died outside the hospital or had an unplanned intensive care readmission (same risk factors but with neurodevelopmental condition and acquired cardiac diagnosis and without preprocedural deterioration; c‐statistic 0.78 [0.75–0.80]). Classification and regression tree analysis were used to identify 6 subgroups stratified by the level (3–24%) and nature of risk for death outside the hospital or unplanned intensive care readmission based on neurodevelopmental condition, cardiac diagnosis, congenital anomaly, and duration of initial admission. An additional 115 patients died after planned intensive care admission (typically following elective surgery).

Conclusions

Adverse outcomes in the year after discharge are of similar magnitude to in‐hospital mortality, warrant service improvements, and are not confined to diagnostic groups currently targeted with enhanced monitoring.

Infant deaths in the UK community following successful cardiac surgery: building the evidence base for optimal surveillance, a mixed-methods study

Background

While early outcomes of paediatric cardiac surgery have improved, less attention has been given to later outcomes including post-discharge mortality and emergency readmissions.

Objectives

Our objectives were to use a mixed-methods approach to build an evidenced-based guideline for postdischarge management of infants undergoing interventions for congenital heart disease (CHD).

Methods

Systematic reviews of the literature – databases used: MEDLINE (1980 to 1 February 2013), EMBASE (1980 to 1 February 2013), Cumulative Index to Nursing and Allied Health Literature (CINAHL; 1981 to 1 February 2013), The Cochrane Library (1999 to 1 February 2013), Web of Knowledge (1980 to 1 February 2013) and PsycINFO (1980 to 1 February 2013). Analysis of audit data from the National Congenital Heart Disease Audit and Paediatric Intensive Care Audit Network databases pertaining to records of infants undergoing interventions for CHD between 1 January 2005 and 31 December 2010. Qualitative analyses of online discussion posted by 73 parents, interviews with 10 helpline staff based at user groups, interviews with 20 families whose infant either died after discharge or was readmitted urgently to intensive care, and interviews with 25 professionals from tertiary care and 13 professionals from primary and secondary care. Iterative multidisciplinary review and discussion of evidence incorporating the views of parents on suggestions for improvement.

Results

Despite a wide search strategy, the studies identified for inclusion in reviews related only to patients with complex CHD, for whom adverse outcome was linked to non-white ethnicity, lower socioeconomic status, comorbidity, age, complexity and feeding difficulties. There was evidence to suggest that home monitoring programmes (HMPs) are beneficial. Of 7976 included infants, 333 (4.2%) died postoperatively, leaving 7634 infants, of whom 246 (3.2%) experienced outcome 1 (postdischarge death) and 514 (6.7%) experienced outcome 2 (postdischarge death plus emergency intensive care readmissions). Multiple logistic regression models for risk of outcomes 1 and 2 had areas under the receiver operator curve of 0.78 [95% confidence interval (CI) 0.75 to 0.82] and 0.78 (95% CI 0.75 to 0.80), respectively. Six patient groups were identified using classification and regression tree analysis to stratify by outcome 2 (range 3–24%), which were defined in terms of neurodevelopmental conditions, high-risk cardiac diagnosis (hypoplastic left heart, single ventricle or pulmonary atresia), congenital anomalies and length of stay (LOS) > 1 month. Deficiencies and national variability were noted for predischarge training and information, the process of discharge to non-specialist services including documentation, paediatric cardiology follow-up including HMP, psychosocial support post discharge and the processes for accessing help when an infant becomes unwell.

Conclusions

National standardisation may improve discharge documents, training and guidance on ‘what is normal’ and ‘signs and symptoms to look for’, including how to respond. Infants with high-risk cardiac diagnoses, neurodevelopmental conditions or LOS > 1 month may benefit from discharge via their local hospital. HMP is suggested for infants with hypoplastic left heart, single ventricle or pulmonary atresia. Discussion of postdischarge deaths for infant CHD should occur at a network-based multidisciplinary meeting. Audit is required of outcomes for this stage of the patient journey.

Future work

Further research may determine the optimal protocol for HMPs, evaluate the use of traffic light tools for monitoring infants post discharge and develop the analytical steps and processes required for audit of postdischarge metrics.

Study registration

This study is registered as PROSPERO CRD42013003483 and CRD42013003484.

Funding

The National Institute for Health Research Health Services and Delivery Research programme. The National Congenital Heart Diseases Audit (NCHDA) and Paediatric Intensive Care Audit Network (PICANet) are funded by the National Clinical Audit and Patient Outcomes Programme, administered by the Healthcare Quality Improvement Partnership (HQIP). PICAnet is also funded by Welsh Health Specialised Services Committee; NHS Lothian/National Service Division NHS Scotland, the Royal Belfast Hospital for Sick Children, National Office of Clinical Audit Ireland, and HCA International. The study was supported by the National Institute for Health Research Biomedical Research Centre at Great Ormond Street Hospital for Children NHS Foundation Trust and University College London. Sonya Crowe was supported by the Health Foundation, an independent charity working to continuously improve the quality of health care in the UK.

Mortality as a measure of quality of care in infants with congenital cardiovascular malformations following surgery

INTRODUCTION

Mortality has traditionally been perceived as a straightforward measure of outcome and has been used to evaluate surgical performance. In the rapidly developing arena of paediatric cardiac surgery, the insightful analysis of mortality figures is challenging.

SOURCES OF DATA

This report discusses the issues involved when mortality is used as a marker for surgical outcome, referring to national and international audit and research data.

AREAS OF AGREEMENT

Mortality is an important variable and should be transparently defined, reported and monitored.

AREAS OF CONTROVERSY

Definitions of mortality, assessments of risk and interpretations of reported statistics all have limitations that must be recognized.

GROWING POINTS

Traditional use of raw early mortality as a simplistic indicator of outcome and performance is evolving to include risk-adjusted mortality, longer-term survival, reinterventions and complications.

AREAS TIMELY FOR DEVELOPING RESEARCH

As the vast majority of children undergoing cardiac surgery now survive beyond 30 days, the focus for measures of quality is shifting towards morbidity.

Catheter rehabilitation of occluded aberrant pulmonary artery

A 10-year old girl underwent a CT angiogram to investigate right lung hypoplasia. This showed a normal bronchial tree, lung parenchyma and pulmonary venous drainage, but an absent right pulmonary artery. Cardiac catheterization with pulmonary vein wedge injections identified a disconnected hypoplastic right pulmonary artery system supplied by an occluded right-sided ductus arteriosus. Transcatheter recanalization of the ductus re-established right pulmonary artery flow and growth. Ultimately, this allowed for complete surgical repair and restoration of normal perfusion of the right lung, leading to complete functional rehabilitation.

Tetralogy of Fallot

Management of the cyanotic neonate with tetralogy of Fallot (ToF) remains a challenging condition. Outcomes for single-stage repair of ToF have steadily improved over the past 30 years and the best results have been achieved with repair between 3 and 9 months of age. The traditional management of cyanotic neonates and small infants has been palliation with a Blalock–Taussig shunt, but this continues to carry a significant mortality that has remained relatively constant even in the contemporary series. This has led to the promotion of neonatal complete repair, but analysis of published outcomes would suggest that this also carries significant risk compared to repair at an older age. Low birth weight and small pulmonary arteries (PAs) remain the greatest independent risk factors. Right ventricular outflow tract (RVOT) stenting may offer an alternative approach to neonatal repair in high-risk neonates and allow for PA growth and delay of repair until the child reaches a safer age. A stratified approach to early management utilizing RVOT stenting in high-risk cases may lead to better overall outcomes.

The Norwood procedure: in favor of the RV-PA conduit

Evolution of the Norwood procedure has culminated in there currently being three treatment strategies available for initial management: the 'classical' Norwood (utilizing a Blalock-Taussig shunt), the Norwood with right-ventricle to pulmonary artery (RV-PA) conduit, and the 'hybrid' Norwood procedure utilizing bilateral pulmonary artery banding and ductal stenting. Each variant has its potential advantages and disadvantages, and this paper looks to examine the evidence in favor of each strategy, with emphasis on the supportive data for the RV-PA conduit. The 'classical' procedure has the benefit of the greatest accumulated surgical experience and avoids any incision into the ventricle. However, the diastolic run-off of the Blalock-Taussig shunt can cause hemodynamic instability and unpredictable coronary steal phenomenon. The RV-PA conduit has the advantage of maintaining diastolic pressure with a more stable postoperative course, but at the cost of a ventriculotomy that may have detrimental long-term sequelae. The 'hybrid' procedure has the advantage of avoiding cardiopulmonary bypass, but does not always secure coronary blood flow and has a high inter-stage morbidity and reintervention rate. The evidence shows that each technique may have its place in future management, and that treatment algorithms could emerge that direct the choice of procedure for specific patient groups.