Rapid desensitization through immunoadsorption during cardiopulmonary bypass. A novel method to facilitate human leukocyte antigen incompatible heart transplantation

BACKGROUND

Anti-human leukocyte antigen (HLA)-antibody production represents a major barrier to heart transplantation, limiting recipient compatibility with potential donors and increasing the risk of complications with poor waiting-list outcomes. Currently there is no consensus to when desensitization should take place, and through what mechanism, meaning that sensitized patients must wait for a compatible donor for many months, if not years. We aimed to determine if intraoperative immunoadsorption could provide a potential desensitization methodology.

METHODS

Anti-HLA antibody-containing whole blood was added to a Cardiopulmonary bypass (CPB) circuit set up to mimic a 20 kg patient undergoing heart transplantation. Plasma was separated and diverted to a standalone, secondary immunoadsorption system, with antibody-depleted plasma returned to the CPB circuit. Samples for anti-HLA antibody definition were taken at baseline, when combined with the CPB prime (on bypass), and then every 20 min for the duration of treatment (total 180 min).

RESULTS

A reduction in individual allele median fluorescence intensity (MFI) to below clinically relevant levels (<1000 MFI), and in the majority of cases below the lower positive detection limit (<500 MFI), even in alleles with a baseline MFI >4000 was demonstrated. Reduction occurred in all cases within 120 min, demonstrating efficacy in a time period usual for heart transplantation. Flowcytometric crossmatching of suitable pseudo-donor lymphocytes demonstrated a change from T cell and B cell positive channel shifts to negative, demonstrating a reduction in binding capacity.

CONCLUSIONS

Intraoperative immunoadsorption in an ex vivo setting demonstrates clinically relevant reductions in anti-HLA antibodies within the normal timeframe for heart transplantation. This method represents a potential desensitization technique that could enable sensitized children to accept a donor organ earlier, even in the presence of donor-specific anti-HLA antibodies.

Oxygen delivery in pediatric cardiac surgery and its association with acute kidney injury using machine learning

OBJECTIVE

Acute kidney injury (AKI) after pediatric cardiac surgery with cardiopulmonary bypass (CPB) is a frequently reported complication. In this study we aimed to determine the oxygen delivery indexed to body surface area (Do2i) threshold associated with postoperative AKI in pediatric patients during CPB, and whether it remains clinically important in the context of other known independent risk factors.

METHODS

A single-institution, retrospective study, encompassing 396 pediatric patients, who underwent heart surgery between April 2019 and April 2021 was undertaken. Time spent below Do2i thresholds were compared to determine the critical value for all stages of AKI occurring within 48 hours of surgery. Do2i threshold was then included in a classification analysis with known risk factors including nephrotoxic drug usage, surgical complexity, intraoperative data, comorbidities and ventricular function data, and vasoactive inotrope requirement to determine Do2i predictive importance.

RESULTS

Logistic regression models showed cumulative time spent below a Do2i value of 350 mL/min/m2 was associated with AKI. Random forest models, incorporating established risk factors, showed Do2i threshold still maintained predictive importance. Patients who developed post-CPB AKI were younger, had longer CPB and ischemic times, and required higher inotrope support postsurgery.

CONCLUSIONS

The present data support previous findings that Do2i during CPB is an independent risk factor for AKI development in pediatric patients. Furthermore, the data support previous suggestions of a higher threshold value in children compared with that in adults and indicate that adjustments in Do2i management might reduce incidence of postoperative AKI in the pediatric cardiac surgery population.

Factors associated with unplanned reinterventions and their relation to early mortality after pediatric cardiac surgery

OBJECTIVE

Unplanned reintervention (uRE) is used as an indicator of patient morbidity and quality of care in pediatric cardiac surgery. We investigated associated factors and early mortality after uREs.

METHODS

Morbidity data were prospectively collected in 5 UK centers between 2015 and 2017; uRE included surgical cardiac, interventional transcatheter cardiac, permanent pacemaker, and diaphragm plication procedures. Mortality (30-day and 6-month) in uRE/no-uRE patients was reported before and after matching. Predicted 30-day mortality was calculated using the Partial Risk Adjustment in Surgery score.

RESULTS

A total of 3090 procedures (2861 patients) were included (median age, 228 days). There were 146 uREs, resulting in an uRE rate of 4.7%. Partial Risk Adjustment in Surgery score, 30-day mortality and 6-month mortality in uRE and no-uRE groups were 2.4% versus 1.3%, 8.9% versus 1%, and 17.1% versus 2.4%, respectively. After matching, mortality at 6 months remained higher in uRE compared with no-uRE (12.2% vs 1.4%; P = .02; 74 pairs). In the uRE group, 21 out of 25 deaths at 6 months occurred when at least 1 additional postoperative complication was present. In multivariable analysis, neonatal age (P = .002), low weight (P = .009), univentricular heart (P < .001), and arterial shunt (P < .001) were associated with increased risk of uRE, but Partial Risk Adjustment in Surgery score was not (only in univariable analysis).

CONCLUSIONS

uREs are a relatively frequent complication after pediatric cardiac surgery and are associated with some patient characteristics, but not the Partial Risk Adjustment in Surgery risk score. Early mortality was higher after uRE, independent of preoperative factors, but linked to other postoperative complications.

Cone reconstruction for Ebstein anomaly: Late biventricular function and possible remodeling

OBJECTIVES

To evaluate late-term tricuspid valve competence and biventricular function following cone reconstruction for Ebstein anomaly, and to explore biventricular remodeling.

METHODS

Consecutive adult and pediatric patients who underwent cone reconstruction from 2009 to 2019 were reviewed for inclusion in this retrospective cardiac magnetic resonance imaging study. Tricuspid valve competence was assessed with tricuspid regurgitation fraction. Biventricular systolic function was assessed by ejection fraction, cardiac index, indexed stroke volume, and indexed aortic and pulmonary artery beat volume. Biventricular remodeling was assessed by planimetered areas (right atrium, functional right ventricle, left heart), and indexed end-diastolic and end-systolic ventricular volumes. Paired t tests or Wilcoxon signed-rank tests were used for analyses.

RESULTS

Of 58 included patients, 50 underwent cardiac magnetic resonance imaging. Twelve patients had both preoperative and late postoperative cardiac magnetic resonance imaging with a median follow-up of 5.11 years (interquartile range, 3.12-6.07 years). Focusing on these, tricuspid regurgitation fraction decreased (from 69% to 10%; P = .014), right ventricle ejection fraction remained stable, and antegrade pulmonary artery beat volume increased (from 26.7 to 41.6 mL/beat/m²; P = .037). The left ventricle stroke volume (from 30.4 to 44.1 mL/m²; P = .015) and antegrade aortic beat volume (from 28.5 to 41.1 mL/beat/m²; P = .014) also increased, and the left ventricle stroke volume improved progressively with time since surgery (P = .048). Whereas the right atrium area decreased (P = .004), the functional right ventricle and left heart area increased (cm², P = .021 and P = .004). Right ventricle volumes showed a tendency to normalize and left ventricle indexed end-diastolic volume increased (from 50 to 69 mL/m²; P = .03) over time.

CONCLUSIONS

Cone valve integrity was sustained. Biventricular function improved progressively during follow-up, and there are positive signs of biventricular remodeling late after cone reconstruction.

Right Ventricle Has Normal Myofilament Function But Shows Perturbations in the Expression of Extracellular Matrix Genes in Patients With Tetralogy of Fallot Undergoing Pulmonary Valve Replacement

Background Patients with repair of tetralogy of Fallot (rToF) who are approaching adulthood often exhibit pulmonary valve regurgitation, leading to right ventricle (RV) dilatation and dysfunction. The regurgitation can be corrected by pulmonary valve replacement (PVR), but the optimal surgical timing remains under debate, mainly because of the poorly understood nature of RV remodeling in patients with rToF. The goal of this study was to probe for pathologic molecular, cellular, and tissue changes in the myocardium of patients with rToF at the time of PVR. Methods and Results We measured contractile function of permeabilized myocytes, collagen content of tissue samples, and the expression of mRNA and selected proteins in RV tissue samples from patients with rToF undergoing PVR for severe pulmonary valve regurgitation. The data were compared with nondiseased RV tissue from unused donor hearts. Contractile performance and passive stiffness of the myofilaments in permeabilized myocytes were similar in rToF-PVR and RV donor samples, as was collagen content and cross-linking. The patients with rToF undergoing PVR had enhanced mRNA expression of genes associated with connective tissue diseases and tissue remodeling, including the small leucine-rich proteoglycans ASPN (asporin), LUM (lumican), and OGN (osteoglycin), although their protein levels were not significantly increased. Conclusions RV myofilaments from patients with rToF undergoing PVR showed no functional impairment, but the changes in extracellular matrix gene expression may indicate the early stages of remodeling. Our study found no evidence of major damage at the cellular and tissue levels in the RV of patients with rToF who underwent PVR according to current clinical criteria.

Early morbidities following paediatric cardiac surgery: a mixed-methods study

Background

Over 5000 paediatric cardiac surgeries are performed in the UK each year and early survival has improved to > 98%.

Objectives

We aimed to identify the surgical morbidities that present the greatest burden for patients and health services and to develop and pilot routine monitoring and feedback.

Design and setting

Our multidisciplinary mixed-methods study took place over 52 months across five UK paediatric cardiac surgery centres.

Participants

The participants were children aged < 17 years.

Methods

We reviewed existing literature, ran three focus groups and undertook a family online discussion forum moderated by the Children’s Heart Federation. A multidisciplinary group, with patient and carer involvement, then ranked and selected nine key morbidities informed by clinical views on definitions and feasibility of routine monitoring. We validated a new, nurse-administered early warning tool for assessing preoperative and postoperative child development, called the brief developmental assessment, by testing this among 1200 children. We measured morbidity incidence in 3090 consecutive surgical admissions over 21 months and explored risk factors for morbidity. We measured the impact of morbidities on quality of life, clinical burden and costs to the NHS and families over 6 months in 666 children, 340 (51%) of whom had at least one morbidity. We developed and piloted methods suitable for routine monitoring of morbidity by centres and co-developed new patient information about morbidities with parents and user groups.

Results

Families and clinicians prioritised overlapping but also different morbidities, leading to a final list of acute neurological event, unplanned reoperation, feeding problems, renal replacement therapy, major adverse events, extracorporeal life support, necrotising enterocolitis, surgical infection and prolonged pleural effusion. The brief developmental assessment was valid in children aged between 4 months and 5 years, but not in the youngest babies or 5- to 17-year-olds. A total of 2415 (78.2%) procedures had no measured morbidity. There was a higher risk of morbidity in neonates, complex congenital heart disease, increased preoperative severity of illness and with prolonged bypass. Patients with any morbidity had a 6-month survival of 81.5% compared with 99.1% with no morbidity. Patients with any morbidity scored 5.2 points lower on their total quality of life score at 6 weeks, but this difference had narrowed by 6 months. Morbidity led to fewer days at home by 6 months and higher costs. Extracorporeal life support patients had the lowest days at home (median: 43 days out of 183 days) and highest costs (£71,051 higher than no morbidity).

Limitations

Monitoring of morbidity is more complex than mortality, and hence this requires resources and clinician buy-in.

Conclusions

Evaluation of postoperative morbidity provides important information over and above 30-day survival and should become the focus of audit and quality improvement.

Future work

National audit of morbidities has been initiated. Further research is needed to understand the implications of feeding problems and renal failure and to evaluate the brief developmental assessment.

Funding

This project was funded by the NIHR Health Services and Delivery Research programme and will be published in full in Health Services and Delivery Research; Vol. 8, No. 30. See the NIHR Journals Library website for further project information.

What are the important morbidities associated with paediatric cardiac surgery? A mixed methods study

OBJECTIVES

Given the current excellent early mortality rates for paediatric cardiac surgery, stakeholders believe that this important safety outcome should be supplemented by a wider range of measures. Our objectives were to prospectively measure the incidence of morbidities following paediatric cardiac surgery and to evaluate their clinical and health-economic impact over 6 months.

DESIGN

The design was a prospective, multicentre, multidisciplinary mixed methods study.

SETTING

The setting was 5 of the 10 paediatric cardiac surgery centres in the UK with 21 months recruitment.

PARTICIPANTS

Included were 3090 paediatric cardiac surgeries, of which 666 patients were recruited to an impact substudy.

RESULTS

Families and clinicians prioritised:Acute neurological event, unplanned re-intervention, feeding problems, renal replacement therapy, major adverse events, extracorporeal life support, necrotising enterocolitis, postsurgical infection and prolonged pleural effusion or chylothorax.Among 3090 consecutive surgeries, there were 675 (21.8%) with at least one of these morbidities. Independent risk factors for morbidity included neonatal age, complex heart disease and prolonged cardiopulmonary bypass (p<0.001). Among patients with morbidity, 6-month survival was 88.2% (95% CI 85.4 to 90.6) compared with 99.3% (95% CI 98.9 to 99.6) with none of the morbidities (p<0.001). The impact substudy in 340 children with morbidity and 326 control children with no morbidity indicated that morbidity-related impairment in quality of life improved between 6 weeks and 6 months. When compared with children with no morbidities, those with morbidity experienced a median of 13 (95% CI 10.2 to 15.8, p<0.001) fewer days at home by 6 months, and an adjusted incremental cost of £21 292 (95% CI £17 694 to £32 423, p<0.001).

CONCLUSIONS

Evaluation of postoperative morbidity is more complicated than measuring early mortality. However, tracking morbidity after paediatric cardiac surgery over 6 months offers stakeholders important data that are of value to parents and will be useful in driving future quality improvement.

Successful orthotopic heart transplantation using a donor heart with ALCAPA

With the imbalance between donation rates and potential recipients growing, transplant programs are increasingly using non-ideal organs from so-called marginal donors. This is the first reported case of the intentional use of a donor heart with ALCAPA. The recipient was aged one yr with restrictive cardiomyopathy who had been supported with BiVAD for over six months. Function of the donor left ventricle was shown to be well preserved, with no obvious signs of ischemia, except for a fibrotic layer on the anterolateral papillary muscle of the mitral valve. To prevent coronary steal, the anomalous left coronary artery ostium from the MPA was oversewn prior to implantation. The transplanted heart spontaneously regained sinus rhythm immediately following cross-clamp release and showed good contractility from the first postoperative echocardiogram. The patient continues to do well 18 months post-transplant, with excellent function on echocardiography, and good flow on coronary angiography.

Cardiothoracic surgery

Conjoined twins often have complex cardiac anomalies associated with other congenital defects. The correct cardiac diagnosis delineates the degree of cardiac fusion and the feasibility of separation. The outcome in twins with fused hearts remains poor.

Tetralogy of Fallot with pulmonary atresia and major aortopulmonary collateral vessels

Major aortopulmonary collateral arteries (MAPCAs) provide significant issues during cardiopulmonary bypass, including flooding of the surgical field which requires significant blood volumes to be returned to the extracorporeal circuit via handheld suckers. This has been shown to be the major source of gaseous microemboli and is associated with adverse neurological outcome. Use of pH-stat has been previously shown to decrease the shunt through MAPCAs via an unknown mechanism. Here, we report the associated benefits of pH-stat in decreasing sucker usage and gaseous microemboli in a patient with known MAPCAs presenting for repair of tetralogy of Fallot and pulmonary atresia.

Cardiomyocyte Ca2+ handling and structure is regulated by degree and duration of mechanical load variation

Cardiac transverse (t)-tubules are altered during disease and may be regulated by stretch-sensitive molecules. The relationship between variations in the degree and duration of load and t-tubule structure remains unknown, as well as its implications for local Ca²⁺-induced Ca²⁺ release (CICR). Rat hearts were studied after 4 or 8 weeks of moderate mechanical unloading [using heterotopic abdominal heart–lung transplantation (HAHLT)] and 6 or 10 weeks of pressure overloading using thoracic aortic constriction. CICR, cell and t-tubule structure were assessed using confocal-microscopy, patch-clamping and scanning ion conductance microscopy. Moderate unloading was compared with severe unloading [using heart-only transplantation (HAHT)]. Mechanical unloading reduced cardiomyocyte volume in a time-dependent manner. Ca²⁺ release synchronicity was reduced at 8 weeks moderate unloading only. Ca²⁺ sparks increased in frequency and duration at 8 weeks of moderate unloading, which also induced t-tubule disorganization. Overloading increased cardiomyocyte volume and disrupted t-tubule morphology at 10 weeks but not 6 weeks. Moderate mechanical unloading for 4 weeks had milder effects compared with severe mechanical unloading (37% reduction in cell volume at 4 weeks compared to 56% reduction after severe mechanical unloading) and did not cause depression and delay of the Ca²⁺ transient, increased Ca²⁺ spark frequency or impaired t-tubule and cell surface structure. These data suggest that variations in chronic mechanical load influence local CICR and t-tubule structure in a time- and degree-dependent manner, and that physiological states of increased and reduced cell size, without pathological changes are possible.

Surgical approaches for single ventricle palliation

In this document, we include under the heading of univentricular heart, complex cardiac malformations which have in common the presence of a functionally single ventricle. The evolution of the surgical management of univentricular hearts is discussed along with the indications, selection criteria, and operative approaches for staged palliation. Herein, we describe our technique for bidirectional cavopulmonary anastomosis and total cavopulmonary connection using an extracardiac conduit.

Rapid 2-stage Norwood I for high-risk hypoplastic left heart syndrome and variants

OBJECTIVES

Preoperative comorbidities (PCMs) are known risk factors for Norwood stage I (NW1). We tested the hypothesis that short-term bilateral pulmonary arterial banding (bPAB) before NW1 could improve the prognosis of these high-risk patients.

METHODS

From January 2006 to October 2011, 17 high-risk patients with hypoplastic left heart syndrome (defined as having ≥4 of the following PCMs: prolonged mechanical ventilation; older age; sepsis; necrotizing enterocolitis; hepatic, renal, or heart failure; coagulopathy; pulmonary edema; high inotropic requirements; anasarca; weight <2.5 kg; and cardiac arrest) were identified. In addition to conventional treatment of PCMs, they underwent bPAB before NW1. bPAB was undertaken with Silastic slings and secured with ligaclips to a luminal diameter of approximately 3.5 to 4.0 mm. The patency of the ductus arteriosus was maintained with prostaglandin. NW1 was performed using a modified, right Blalock-Taussig shunt at a median interval of 8 days after bPAB. The data from these patients were retrospectively reviewed, and the 30-day mortality and 1-year survival were compared with the hypoplastic left heart syndrome population who underwent primary NW1 with <3 PCMs in the same period.

RESULTS

Of the bPAB patients, 5 (29.4%) died before NW1. All had ≥5 PCMs. Twelve patients (70.6%) survived to undergo NW1. One early death occurred after NW1 (8.3%). The 1-year survival rate for high-risk patients who underwent NW1 was 66.7%. The early mortality and 1-year survival for the 130 patients with <3 PCMs was 10% and 80%, respectively.

CONCLUSIONS

Optimizing the balance between the pulmonary and systemic blood flow with a short period of bPAB and ductal patency can improve the perioperative conditions of high-risk patients before NW1. Those who survived bPAB and underwent NW1 had early mortality and 1-year survival comparable to the standard risk category, despite the severity of their initial condition. A rapid 2-stage NW1 strategy with bPAB and prostaglandin to maintain ductal patency can avoid the risks of suboptimal palliation and vascular injuries associated with hybrid procedures.

Impact of shunt type on growth of pulmonary arteries after norwood stage I procedure: current best available evidence

The past decade has seen a substantial improvement in the outcome following surgical palliation for hypoplastic left heart syndrome. This has been attributed to modifications in the surgical as well as postoperative management strategies. One such modification is the reemergence of the right ventricle to pulmonary artery (RV-PA) shunt as an alternative to the modified Blalock-Taussig (mBT) shunt as the source of pulmonary blood flow. The RV-PA shunt has been shown to improve the immediate surgical outcome compared with the classic Norwood procedure with an mBT shunt. Despite the several reported advantages, the impact of the RV-PA shunt on growth of the pulmonary arteries and incidence of late development of central PA stenosis remains unclear. This systematic review evaluates the current best available evidence to address this issue and concludes that the evidence from retrospective studies and only available randomized controlled trial (RCT) is conflicting. The retrospective studies predominantly suggest that the Norwood procedure with RV-PA shunt may have favorable effects on the development of the pulmonary arteries due to even distribution of pulmonary blood flow with greater distal left pulmonary artery growth, resulting in more balanced distal branch pulmonary artery size albeit with a greater degree of central pulmonary artery hypoplasia needing surgical attention. On the contrary, the RCT reports that the overall size of the pulmonary artery on angiography before the stage II procedure was smaller in the RV-PA shunt group than in the mBT shunt group, with no information available on incidence of central pulmonary hypoplasia.

A mortality risk model to adjust for case mix in UK paediatric cardiac surgery

Background

Congenital heart disease (CHD) is a relatively common disorder in childhood, affecting approximately 8–9 per 1000 live-born infants annually in the UK. CHD often involves serious abnormalities and is an important cause of childhood mortality, morbidity and disability. It is generally recognised that it is important and valuable to monitor outcomes in cardiac surgery and that, to do so fairly and effectively, one needs to risk stratify the case load of each unit. There is evidence that, since outcome monitoring in adult cardiac surgery became mandatory and routine, outcomes have improved. At present, no process for routinely monitoring risk-adjusted outcomes in paediatric cardiac surgery exists.

Objectives

To establish whether or not a risk model can be developed that is fit for the purpose of adjusting for case mix severity to facilitate routine monitoring of outcomes for paediatric cardiac surgery in the UK and to assess whether or not and how diagnostic information can augment procedural information in risk adjustment.

Methods

Data from the Central Cardiac Audit Database (CCAD) for all cardiac surgery procedures, excluding reoperations within 30 days, performed in the UK for patients < 16 years between 2000 and 2010 (38,597 patient episodes) were included: 70% for model development and 30% quarantined for validation. The outcome was 30-day survival, as supplied to CCAD through the Central Register of NHS patients (now the Medical Research Information Service). The CCAD defines 36 ‘specific procedures’. Nine of these were merged as a ‘low-volume specific procedure’ group (< 90 cases each in the entire development set). Unassigned cases were grouped as ‘not a specific procedure’. Twenty-four ‘primary’ cardiac diagnoses and separately a categorisation of ‘univentricular’ status were defined using a hierarchical algorithm developed by the study team based on International Paediatric and Congenital Cardiac codes. Comorbidities considered included prematurity (< 37 weeks' gestation), Down syndrome, constellations of features that constitute a recognised syndrome, congenital structural defects of organs other than the heart and acquired conditions. Other candidate variables included use of bypass and patient age, weight and sex. Data were analysed using logistic regression.

Results

In the development set, there were 25,665 episodes that resulted in survival to 30 days, 693 episodes for which the vital status at 30 days was unknown and 854 episodes that resulted in death within 30 days in the development set (mortality 3.2% overall). The risk model developed includes the following factors: specific procedure, primary cardiac diagnosis grouped into low-, medium- and high-risk categories, univentricular heart status, age band (neonate, infant, child), continuous age, continuous weight, presence of a comorbidity other than Down syndrome and use of bypass. To account for decreasing mortality over time in the development set, a binary indicator for operations performed after 1 January 2007 is also included in the model. We were able to calculate a risk score for 95% of cases in the test set: weight was missing in 5% of cases. Data completeness improved over time. The proposed model discriminated well: the area under the receiver operating characteristic curve (AUC) for the test set was 0.77 (0.81 for post-2007 data). Removal of all but procedural information gave a reduced AUC of 0.72. The model performed well across the spectrum of predicted risk in the entire data set, but there was underestimation of mortality risk in the test set among neonates operated from 2007.

Limitations

An important limitation is that the model pertains to short-term 30-day outcomes (not long-term outcomes) and is designed for the purpose of routine monitoring for quality assurance rather than bedside-type predictions for individual patients. Over the recent period in the validation set (since 2007), the model was found to underestimate risk at the very high-risk end (> 10% risk), in particular among neonates. This indicates that risk adjustment based on the current parameterisation of the model will potentially give an unduly negative impression of outcomes at those centres with a high proportion of high-risk cases. Finally, any risk model used for ongoing quality improvement initiatives needs to be regularly updated as data quality improves and clinical practice evolves.

Conclusions

For the first time diagnostic information has been successfully incorporated into risk adjustment for short-term outcomes in this patient group, which added discriminatory power. The risk model is fit for purpose, although the underestimation of risk in recent neonates is an important caveat. Several centres have expressed an interest in piloting the risk model and the accompanying monitoring tool. Future work includes developing software to generate variable life-adjusted display charts within units using the risk model; using the risk model to explore trends in case mix over time; and informing future work in evaluating long-term outcomes for children with CHD.

Funding

The National Institute for Health Research Health Services and Delivery Research programme.

Pediatric heart transplantation for congenital and restrictive cardiomyopathy

BACKGROUND

Recent reports suggest worse outcomes in pediatric orthotopic heart transplantation (OHT) for congenital heart disease (CHD) and restrictive cardiomyopathy (RCM). We examined early outcomes in these diverse groups of patients in comparison with patients with dilatated cardiomyopathy (DCM).

METHODS

From 2000 to 2011, 209 patients were included: 50 with CHD, 23 with RCM, and 136 with DCM. Early survival was studied, as was the occurrence of acute rejection, donor-specific antibodies (DSAs) and nondonor-specific antibodies (NSDAs), incidence of pulmonary hypertension (PHT), right ventricular failure (RVF), and the need for mechanical circulatory support (MCS).

RESULTS

The incidence of preoperative PHT was greatest in the RCM group (χ(2)p = 0.0006); the requirement for mechanical support before OHT was greatest in patients with DCM. Thirty-day survival was 92.0%, 97.1%, and 100% for patients with CHD, DCM, and RCM respectively. The incidence of RVF was highest for patients with RCM (43.5%; versus CHD, 26.0%; versus DCM, 14.7%). One-year survival estimates for patients with CHD, DCM, and RCM were 92.0%, 97.8%, and 82.6%, respectively (log-rank p = 0.165). Multivariable analysis revealed 4 significant risk factors for mortality: age, incidence of acute rejection, preoperative PHT, and the presence of NDSAs. The occurrence of DSAs was similar, although there was a significantly higher incidence of NDSAs in the CHD and RCM groups (36.0% and 30.4%, respectively, versus 14.0% in the DCM group; χ(2)p = 0.0024).

CONCLUSIONS

Equivalent outcomes are achievable in pediatric OHT despite marked heterogeneity in anatomic and physiologic complexity in recipients. Physiologic factors such as PHT are likely to be more important than anatomic complexities in determining survival. The potential relevance of NDSAs warrants further investigation.

Incompatible ABO-plasma exchange and its impact on patient selection in paediatric cardiac transplantation

OBJECTIVES

A decade ago, the first series of ABO-incompatible heart transplants was published, with surprising and extremely promising results; drastically reduced waiting list mortalities of infants listed for heart transplantation. Essential to the procedure was the process of plasma exchange transfusion, required to reduce isohaemagglutinin titres and facilitate the crossing of ABO blood group boundaries. Since then, Great Ormond Street Hospital, London has offered ABO-incompatible heart transplants to infants who potentially would die waiting for a suitable organ. We report the results of a decade of evolving plasma exchange experience and its impact upon patient selection.

METHODS

A retrospective analysis was undertaken of all elective ABO-incompatible heart transplants at Great Ormond Street Children's Hospital from January 2001 until January 2011. Data were sought on underlying conditions and demographics of the patients, the isohaemagglutinin titre before and after plasma exchange and survival figures to date.

RESULTS

Twenty-one patients underwent ABO-incompatible heart transplantation, ranging from 3 to 44 months, with preoperative isohaemagglutinin titres ranging from 0 to 1:32. All patients underwent a "3 times" plasma exchange before transplantation, requiring exchange volumes of up to 3209 mL. Postoperative isohaemagglutinin titres ranged from 0 to 1:16. One patient died of causes unrelated to organ rejection.

CONCLUSIONS

Our data showed that eight patients (38.1%) were older than the previously suggested 12-month cut-off age. Using a combination of adult reservoir/paediatric oxygenator and extracorporeal circuit, ABO-incompatible plasma exchange transfusions can be undertaken safely using a simplified '3 times' method, reducing the circulating levels of isohaemagglutinins whilst providing minimal circuit size. This allows ABO-incompatible heart transplantation in a broader patient population than previously reported.

Tricuspid valve repair in single ventricle: timing and techniques

Tricuspid valve performance in the systemic circulation is known to have important implications for survival and functional status after univentricular palliation of hypoplastic left heart syndrome (HLHS). Moderate to severe tricuspid valve regurgitation is not an uncommon finding in patients with HLHS undergoing staged surgical reconstruction. It can result from either abnormal valve morphology or incomplete leaflet coaptation, or both. But first and foremost, any aortic arch re-obstruction must be excluded. Development of significant tricuspid regurgitation (TR) remains an obstacle in improving survival after the Norwood procedure and likely compromised functional health after the Fontan procedure. Thus, surgical intervention for minimizing tricuspid valve deterioration and significant TR seems pivotal to improving long-term outcomes for patients with HLHS. This article provides an overview of the etiology and mechanisms of development of significant TR, natural history, indications for surgical intervention, and focuses on timing, techniques, and clinical outcomes of tricuspid valve repair in the setting of single ventricle.

How to avoid crimping during valve sparing aortic root replacement using the Valsalva graft

The reimplantation technique for valve sparing aortic root replacement (David I) has improved management of patients with aortic root aneurysm and structurally normal aortic valves. The Valsalva graft (Gelweave Valsalva, Sultzer Vascutek, Renfrewshire, Scotland) further simplified the procedure by offering a root prosthesis with preformed neo-sinuses that may reduce physiologic stresses on valve leaflets and improve long-term valve durability. However, in-conduit suturing of the aortic valve annulus and a small rim of sinus remnant to the graft sinuses may create folds of the sinus remnant that lead to bleeding or distortion of the prosthetic root. We report a method to minimize crimping of the aortic graft sinuses.

Congenital heart surgery databases around the world: do we need a global database?

The question posed in the title of this article is: "Congenital Heart Surgery Databases Around the World: Do We Need a Global Database?" The answer to this question is "Yes and No"! Yes--we need to create a global database to track the outcomes of patients with pediatric and congenital heart disease. No--we do not need to create a new "global database." Instead, we need to create a platform that allows for the linkage of currently existing continental subspecialty databases (and continental subspecialty databases that might be created in the future) that will allow for the seamless sharing of multi-institutional longitudinal data across temporal, geographical, and subspecialty boundaries. This review article will achieve the following objectives: (A) Consider the current state of analysis of outcomes of treatments for patients with congenitally malformed hearts. (B) Present some principles that might make it possible to achieve life-long longitudinal monitoring and follow-up. (C) Describe the rationale for the creation of a Global Federated Multispecialty Congenital Heart Disease Database. (D) Propose a methodology for the creation of a Global Federated Multispecialty Congenital Heart Disease Database that is based on linking together currently existing databases without creating a new database. To perform meaningful multi-institutional analyses, any database must incorporate the following six essential elements: (1) Use of a common language and nomenclature. (2) Use of a database with an established uniform core dataset for collection of information. (3) Incorporation of a mechanism to evaluate the complexity of cases. (4) Implementation of a mechanism to assure and verify the completeness and accuracy of the data collected. (5) Collaboration between medical and surgical subspecialties. (6) Standardization of protocols for life-long longitudinal follow-up. Analysis of outcomes must move beyond recording 30-day or hospital mortality, and encompass longer-term follow-up, including cardiac and non-cardiac morbidities, and importantly, those morbidities impacting health-related quality of life. Methodologies must be implemented in our databases to allow uniform, protocol-driven, and meaningful long-term follow-up. We need to create a platform that allows for the linkage of currently existing continental subspecialty databases (and continental subspecialty databases that might be created in the future) that will allow for the seamless sharing of multi-institutional longitudinal data across temporal, geographical, and subspecialty boundaries. This "Global Federated Multispecialty Congenital Heart Disease Database" will not be a new database, but will be a platform that effortlessly links multiple databases and maintains the integrity of these extant databases. Description of outcomes requires true multi-disciplinary involvement, and should include surgeons, cardiologists, anesthesiologists, intensivists, perfusionists, neurologists, educators, primary care physicians, nurses, and physical therapists. Outcomes should determine primary therapy, and as such must be monitored life-long. The relatively small numbers of patients with congenitally malformed hearts requires multi-institutional cooperation to accomplish these goals. The creation of a Global Federated Multispecialty Congenital Heart Disease Database that links extant databases from pediatric cardiology, pediatric cardiac surgery, pediatric cardiac anesthesia, and pediatric critical care will create a platform for improving patient care, research, and teaching related to patients with congenital and pediatric cardiac disease.

Late magnetic resonance surveillance of repaired coarctation of the aorta

OBJECTIVE

Coarctation of the aorta has often been described as a simple form of congenital heart disease. However, rates of re-coarctation reported in the literature vary from 7% to 60%. Re-coarctation of the aorta may lead to worsening systemic hypertension, coronary artery disease and/or congestive cardiac failure. We aimed to describe the rates of re-coarctation in subjects who had undergone early coarctation repair (<2 years of age) and referred for clinically indicated or routine magnetic resonance (MR) surveillance.

METHODS

We retrospectively identified 50 consecutive subjects (20.2+/-6.9 years post-repair) imaged between 2004 and 2008. Patient characteristics, rates of re-coarctation and LV/aortic dimensions were examined.

RESULTS

Forty percent of subjects had bicuspid aortic valves (BAV). There were 40 cases of end-to-end repair and 10 cases of subclavian flap repair. Re-intervention with balloon angioplasty or repeat surgery had been performed in 32% of subjects. The MRI referrals were clinically indicated in 34% and routine in 66% of patients. Re-coarctation was considered moderate or severe in 34%, mild in 34% and no re-coarctation was identified in 32% of patients. There was no significant difference in the number of cases of re-coarctation identified in the clinically indicated versus routine referrals for MR imaging (p=0.20). There were no cases of aortic dissection or aneurysm formation identified amongst the subjects. The mean indexed left ventricular mass and ejection fraction was 72+/-16g/m(2) and 66+/-6%, respectively. Amongst those subjects with BAV there were larger aortic sinus (30+/-1mm vs 27+/-1mm, p=0.03) and ascending aortic (27+/-1mm vs 23+/-1mm, p=0.01) dimensions when compared to subjects with morphologically tricuspid aortic valves.

CONCLUSIONS

We demonstrate that many years after early repair of coarctation of the aorta, MR surveillance detects significant rates of re-coarctation. These findings were independent of whether or not there was a clinical indication for imaging. Those patients with BAV disease had larger ascending aortic dimensions and may require more frequent non-invasive surveillance.

Effective transcatheter valve implantation after pulmonary homograft failure: a new perspective on the Ross operation

Objective

The Ross procedure offers good autograft function and low reoperation rates for the neoaortic valve; however, the rate of conduit dysfunction in the right ventricular outflow tract remains a concern. This study assessed percutaneous pulmonary valve implantation in this setting.

Methods

We retrospectively analyzed outcomes of 12 patients (mean age 28 ± 5 years) referred for percutaneous pulmonary valve implantation to treat right ventricle–pulmonary artery conduit failure 11.1 ± 3.3 years after Ross procedure.

Results

Percutaneous pulmonary valve implantation was feasible in all 12 patients, with no procedural complications (procedure time 99 ± 16 minutes, fluoroscopy time 21 ± 6 minutes). Right ventricular outflow tract gradient during catheterization and pulmonary regurgitant fraction on magnetic resonance imaging fell after valve implantation (gradient 34 ± 6 to 14 ± 3 mm Hg, P < .01, regurgitant fraction 20% ± 6% to 2% ± 1%, P < .05). After restoration of right ventricular outflow tract function, indexed right ventricular end-diastolic volume decreased (91 ± 13 to 78 ± 12 mL · beat⁻¹ · m⁻², P < .01) and maximal cardiopulmonary exercise performance improved (peak oxygen consumption 25.4 ± 2.3 to 30.8 ± 3.0 mL · kg⁻¹ · min⁻¹, P < .01). During follow-up (18.8 ± 4.6 months), there was 1 device explantation (restenosis). The probabilities of freedom from right ventricular outflow tract reoperation were 100% at 1 year and 90% at 3 years.

Conclusions

Percutaneous pulmonary valve implantation provides an effective transcatheter treatment strategy to prolong the lifespan of right ventricle–pulmonary artery conduits after the Ross procedure, reducing the reoperation burden on patients with aortic valve disease.

The molecular phenotype of human cardiac myosin associated with hypertrophic obstructive cardiomyopathy

AIM

The aim of the study was to compare the functional and structural properties of the motor protein, myosin, and isolated myocyte contractility in heart muscle excised from hypertrophic cardiomyopathy patients by surgical myectomy with explanted failing heart and non-failing donor heart muscle.

METHODS

Myosin was isolated and studied using an in vitro motility assay. The distribution of myosin light chain-1 isoforms was measured by two-dimensional electrophoresis. Myosin light chain-2 phosphorylation was measured by sodium dodecyl sulphate-polyacrylamide gel electrophoresis using Pro-Q Diamond phosphoprotein stain.

RESULTS

The fraction of actin filaments moving when powered by myectomy myosin was 21% less than with donor myosin (P = 0.006), whereas the sliding speed was not different (0.310 +/- 0.034 for myectomy myosin vs. 0.305 +/- 0.019 microm/s for donor myosin in six paired experiments). Failing heart myosin showed 18% reduced motility. One myectomy myosin sample produced a consistently higher sliding speed than donor heart myosin and was identified with a disease-causing heavy chain mutation (V606M). In myectomy myosin, the level of atrial light chain-1 relative to ventricular light chain-1 was 20 +/- 5% compared with 11 +/- 5% in donor heart myosin and the level of myosin light chain-2 phosphorylation was decreased by 30-45%. Isolated cardiomyocytes showed reduced contraction amplitude (1.61 +/- 0.25 vs. 3.58 +/- 0.40%) and reduced relaxation rates compared with donor myocytes (TT(50%) = 0.32 +/- 0.09 vs. 0.17 +/- 0.02 s).

CONCLUSION

Contractility in myectomy samples resembles the hypocontractile phenotype found in end-stage failing heart muscle irrespective of the primary stimulus, and this phenotype is not a direct effect of the hypertrophy-inducing mutation. The presence of a myosin heavy chain mutation causing hypertrophic cardiomyopathy can be predicted from a simple functional assay.

Right ventricular outflow tract reconstruction for pulmonary regurgitation after repair of tetralogy of Fallot. Preliminary results

BACKGROUND

Pulmonary regurgitation after tetralogy of Fallot (ToF) repair is associated with right ventricular dilatation, failure and arrhythmia. Timing and technique for re-intervention remain controversial.

METHODS

Our recent approach is to reconstruct the dilated right ventricle outflow tract (RVOT) as a fibro-muscular sleeve to support a pulmonary homograft valve conduit in orthotopic position. Indication is based on clinical and magnetic resonance (MR) criteria. We reviewed all patients who underwent RVOT reconstruction between January 2004 and February 2005. There were seven children (mean age 14+/-2 years) operated 13+/-2 years after ToF repair, and 12 adults (mean age 30+/-15 years) operated 23+/-10 years after ToF repair. Exercise testing and MR evaluation prior to surgery and at 1 year postoperative follow-up were compared.

RESULTS

There was no operative mortality. At 1 year, pulmonary regurgitation was mild or less in 16/19 patients. Right ventricular (RV) end-diastolic (158+/-51 to 103+/-36ml/m(2), p<0.001) and end-systolic volumes (85+/-42 to 49+/-24ml/m(2), p=0.001) fell significantly. Importantly, effective RV stroke volume (43+/-10 to 48+/-7ml/m(2), p=0.019) and left ventricular (LV) stroke volume (43+/-7 to 47+/-7ml/m(2), p=0.009) increased significantly. The mean RV/LV end-diastolic volume ratio fell markedly in both children and adults (2.22+/-0.62 to 1.38+/-0.52). However, no improvement in maximal VO(2) on exercise was noted in either group.

CONCLUSIONS

RVOT reconstruction restored valve function, improved RV dimensions and left and right stroke volumes. Maximal exercise capacity did not improve in either children or adults.

Is complete heart block after surgical closure of ventricular septum defects still an issue?

BACKGROUND

A serious complication after surgical closure of ventricular septal defect (VSD) is complete heart block. In this retrospective study, we reviewed the incidence of complete heart block after surgical closure of a VSD at Great Ormond Street Hospital from 1976 to 2001 to identify any particular anatomic features that still predisposed patients to surgically-induced complete heart block and to provide anatomic guidelines to avoid this in future.

METHODS

Data were extracted from our local database for patients having (1) isolated VSD or VSD in the setting of (2) tetralogy of Fallot with pulmonary stenosis or (3) tetralogy of Fallot with pulmonary atresia; (4) absent pulmonary valve syndrome; (5 and 6) coarctation or interruption of the aortic arch; and (7) subaortic fibrous shelf. We carefully reviewed the operative notes from all patients with postoperative complete heart block to discover any predisposing anatomical reasons to explain the complication.

RESULTS

Two thousand seventy-nine patients had a VSD closure. Permanent complete heart block developed in 7 of 996 patients (0.7%) with an isolated defect and in 1 of 847 patients (0.1%) with tetralogy of Fallot. Four more patients had postoperative complete heart block.

CONCLUSIONS

Instances of iatrogenic complete heart block continue to occur after surgical VSD closure, either because of unexpected biological variations or because of unawareness of the disposition of the atrioventricular conduction axis in particular circumstances. This report emphasizes the latter aspect in details and suggests a risk of iatrogenic complete heart block of less than 1%.

Transplantation for adults with congenital heart disease☆

Heart transplantation is a recognised treatment for end-stage heart failure of any cause including congenital heart disease. Congenital heart disease has contributed relatively little to the adult heart transplant activities in the past two decades. However, this is likely to change as an increasing number of children with congenital heart disease reach adulthood because of the advances in paediatric cardiology and surgery. Some of these grown-ups with congenital heart disease (GUCH patients) will need transplantation for late myocardial dysfunction either secondary to uncorrected lesions, or despite previous repair or palliative surgery. These patients are managed along the same clinical principles as those with cardiac failure of other aetiologies, despite the lack of any evidence to support this approach. Nevertheless, they introduce new challenges. First, some may have pulmonary vascular disease and require heart-lung transplantation, or lung transplantation combined with repair of their cardiac defects. Second, those with failing Fontan circulation are usually much sicker than other transplant candidates, with protein-losing enteropathy along with renal and hepatic dysfunction. Third, a suitable donor organ may not be found due to elevated levels of antibodies in response to previous blood transfusions and possibly the previous implantation of homografts. Fourth, the operation may be technically difficult because of the presence of adhesions secondary to previous operations, collaterals, and unusual anatomy. Fifth, postoperative care may be complicated because of predisposition to bleeding, infection and pulmonary hypertension, and the presence of residual aortopulmonary collaterals resulting in a significant left-to-right shunt. Despite a higher early mortality, the overall results of heart transplantation so far have been encouraging with survivals similar to that of adults with acquired heart disease and that of the paediatric population. However, this may change as the proportion of high-risk patients (failing Fontans) increases. GUCH patients with Eisenmenger's syndrome may be offered lung transplantation with repair of the cardiac defect or heart-lung transplantation. However, because of the limited success of these approaches, and improved management of pulmonary hypertension, patient selection remains difficult.

Does the Aristotle Score predict outcome in congenital heart surgery?☆

OBJECTIVE

The Aristotle Score has been proposed as a measure of 'complexity' in congenital heart surgery, and a tool for comparing performance amongst different centres. To date, however, it remains unvalidated. We examined whether the Basic Aristotle Score was a useful predictor of mortality following open-heart surgery, and compared it to the Risk Adjustment in Congenital Heart Surgery (RACHS-1) system. We also examined the ability of the Aristotle Score to measure performance.

METHODS

The Basic Aristotle Score and RACHS-1 risk categories were assigned retrospectively to 1085 operations involving cardiopulmonary bypass in children less than 18 years of age. Multiple logistic regression analysis was used to determine the significance of the Aristotle Score and RACHS-1 category as independent predictors of in-hospital mortality. Operative performance was calculated using the Aristotle equation: performance = complexity x survival.

RESULTS

Multiple logistic regression identified RACHS-1 category to be a powerful predictor of mortality (Wald 17.7, p < 0.0001), whereas Aristotle Score was only weakly associated with mortality (Wald 4.8, p = 0.03). Age at operation and bypass time were also highly significant predictors of postoperative death (Wald 13.7 and 33.8, respectively, p < 0.0001 for both). Operative performance was measured at 7.52 units.

CONCLUSIONS

The Basic Aristotle Score was only weakly associated with postoperative mortality in this series. Operative performance appeared to be inflated by the fact that the overall complexity of cases was relatively high in this series. An alternative equation (performance = complexity/mortality) is proposed as a fairer and more logical method of risk-adjustment.

Quality assurance in congenital heart surgery☆

OBJECTIVE

The aim of this study was to develop a graphical method of risk-stratified outcome analysis in paediatric cardiac surgery to provide a means of continuous, prospective performance monitoring and allow real-time detection of change in outcomes.

METHODS

Risk-adjusted survival following open-heart surgery was prospectively measured over a 15-month period (n=460). Outcomes were charted using variable life-adjusted display (VLAD) charts, which indicate the cumulative difference in observed minus expected survival against the cumulative number of cases performed. Risk stratification was based on RACHS-1 (risk adjustment in congenital heart surgery) risk category and age at surgery, using our previously published risk model. The probability of deviation in performance from the expected baseline level was determined using a mathematical model.

RESULTS

By the end of the series, observed survival (443/460=96.3%) exceeded that predicted by the risk model (434.5/460=94.5%), equivalent to a one-third reduction in expected mortality. Mathematical modelling indicated a 1-5% likelihood that this difference would have occurred by random variation alone, suggesting the outcomes represented genuine improvement.

CONCLUSIONS

VLAD charts provide an effective, easily visualised display of surgical performance and can be applied to paediatric cardiac surgery. Early detection of change, whether improvement or deterioration, is important for ongoing quality assurance within a cardiac surgery programme.