Post-transplant outcomes of children bridged to transplant with the Berlin Heart EXCOR Pediatric ventricular assist device

Changes in waiting time, need for mechanical circulatory support and outcomes in paediatric heart transplant recipients

AIMS

Heart transplantation is a well-established treatment for end-stage heart failure in paediatric patients, demonstrating excellent long-term outcomes.

METHODS

This retrospective study analyses 35 years of data on 244 paediatric recipients (<18 years) at a single institution from 1986 to 2022. The analysis explores changes in diagnoses, survival, waiting times and mechanical circulatory support (MCS) over three decades (1991-2000, 2001-2010 and 2011-2020).

RESULTS

Survival outcomes significantly improved over the study period, with 1-year survival rates increasing from 79.3% (1991-2000) to 92.3% (2011-2020, P = 0.041). The median overall survival was 18.0 years, and median conditional survival to 1 year post-transplant was 20.9 years. Survival differences were noted among age groups, with infants under 1 year of age experiencing higher early mortality, and adolescents (aged 11-17 years) facing increased long-term risks, possibly linked to adult donor characteristics. Waiting times for heart transplantation increased, especially for younger age groups (0-5 and 6-10 years), reflecting the growing demand for donor organs. The use of MCS, including ventricular assist devices (VAD), surged, with 67% of recipients in the most recent decade receiving pre-transplant VAD support. Importantly, despite prolonged waiting times and increased VAD use, overall survival continued to be favourable.

CONCLUSIONS

Early and long-term results after paediatric heart transplantation have been continuously improving over the past decades. Despite an increased demand for donor organs and the growing reliance on VAD as bridge to transplantation, post-transplantation survival is not compromised.

Impact of Weight on Ventricular Assist Device Outcomes in Dilated Cardiomyopathy Patients in Pediatric Centers: An ACTION Registry Study

Ventricular assist device (VAD) options vary for children in different weight groups. This study evaluates contemporary device usage and outcomes for children based on weight. Data from the Advanced Cardiac Therapies Improving Outcomes Network (ACTION) registry were examined for patients with dilated cardiomyopathy (DCM) in 4 weight cohorts: <8 kg, 8-20 kg, 21-40 kg, and >40 kg, for devices implanted 3/2013-10/2020. Adverse event rates and ultimate outcome (deceased, alive on device, transplanted, or ventricular recovery) were analyzed. 222 DCM patients were identified with 24% in cohort 1, 23% in cohort 2, 15% in cohort 3, and 38% in cohort 4. Of 272 total implants, paracorporeal pulsatile devices were most common (95%) in cohorts 1 and 2 and intracorporeal continuous devices (81%) in cohorts 3 and 4. Stroke was noted in 17%, 12%, 6%, and 4% of cohorts, respectively (Cohort 1 vs. 4 and 2 vs. 4 - p = 0.01; other comparisons - not significant). Incidences of major bleeding, device malfunction, and infection was not different. All cohorts had >90% positive outcomes. Stroke incidence was higher in smaller cohorts, but other outcomes were similar. Positive outcomes were attained in over 90% across all weight groups, demonstrating excellent outcomes using current VADs in this DCM population.

Heart Transplantation in Patients Less Than 18 Years of Age: Comparison of 2 Eras Over 36 Years and 323 Transplants at a Single Institution

BACKGROUND

We reviewed our management strategy and outcome data for all 311 patients less than 18 years of age who underwent 323 heart transplants at our institution (1986 to 2022) in order to assess changes in patterns of practice and outcomes over time and to compare two consecutive eras: era 1 (154 heart transplants [1986 to 2010]) and era 2 (169 heart transplants [2011 to 2022]).

STUDY DESIGN

Descriptive comparisons between the two eras were performed at the level of the heart transplant for all 323 transplants. Kaplan-Meier survival analyses were performed at the level of the patient for all 311 patients, and log-rank tests were used to compare groups.

RESULTS

Transplants in era 2 were younger (6.6 ± 6.5 years vs 8.7 ± 6.1 years, p = 0.003). More transplants in era 2 were in infants (37.9% vs 17.5%, p < 0.0001), had congenital heart disease (53.8% vs 39.0%, p < 0.010), had high panel reactive antibody (32.1% vs 11.9%, p < 0.0001), were ABO-incompatible (11.2% vs 0.6%, p < 0.0001), had prior sternotomy (69.2% vs 39.0%, p < 0.0001), had prior Norwood (17.8% vs 0%, p < 0.0001), had prior Fontan (13.6% vs 0%, p < 0.0001), and were in patients supported with a ventricular assist device at the time of heart transplant (33.7% vs 9.1%, p < 0.0001). Survival at 1, 3, 5, and 10 years after transplant was as follows: era 1 = 82.4% (76.5 to 88.8), 76.9% (70.4 to 84.0), 70.7% (63.7 to 78.5), and 58.8% (51.3 to 67.4), respectively; era 2 = 90.3% (85.7 to 95.1), 85.4% (79.7 to 91.5), 83.0% (76.7 to 89.8), and 66.0% (49.0 to 88.8), respectively. Overall Kaplan-Meier survival in era 2 was better (log-rank p = 0.03).

CONCLUSIONS

Patients undergoing cardiac transplantation in the most recent era are higher risk but have better survival.

An Up-to-Date Literature Review on Ventricular Assist Devices Experience in Pediatric Hearts

Ventricular assist devices (VAD) have gained popularity in the pediatric population during recent years, as more and more children require a heart transplant due to improved palliation methods, allowing congenital heart defect patients and children with cardiomyopathies to live longer. Eventually, these children may require heart transplantation, and ventricular assist devices provide a bridge to transplantation in these cases. The FDA has so far approved two types of device: pulsatile and continuous flow (non-pulsatile), which can be axial and centrifugal. Potential eligible studies were searched in three databases: Medline, Embase, and ScienceDirect. Our endeavor retrieved 16 eligible studies focusing on five ventricular assist devices in children. We critically reviewed ventricular assist devices approved for pediatric use in terms of implant indication, main adverse effects, and outcomes. The main adverse effects associated with these devices have been noted to be thromboembolism, infection, bleeding, and hemolysis. However, utilizing left VAD early on, before end-organ dysfunction and deterioration of heart function, may give the patient enough time to recuperate before considering a more long-term solution for ventricular support.

Epidemiology of Pediatric Heart Failure in the USA-a 15-Year Multi-Institutional Study

The epidemiology of pediatric heart failure (HF) has been characterized for congenital heart disease (CHD) and cardiomyopathies (CM), but the impact of CM associated with CHD has not been studied. This study aims to describe the characteristics and outcomes of inpatient pediatric HF patients with CHD, CM, and CHD with CM (CHD + CM) across the USA. We included all HF patients with CM diagnoses with and without CHD using ICD 9/10 codes ≤ 19 years old from January 2004 to September 2019 using the Pediatric Health Information System database. We identified 67,349 unique patients ≤ 19 years old with HF, of which 87% had CHD, 7% had CHD + CM, and 6% had CM. Pediatric HF admissions increased significantly from 2004 to 2018 with an associated increase in extracorporeal circulatory support (ECLS) use. Heart transplantation (HTX) increased only in the CHD and CHD + CM groups. CHD patients required less ECLS with and without HTX; however, they had significantly higher inpatient mortality after those procedures than the other groups (p < 0.001). CM patients were older (median 115 months) and had the lowest inpatient mortality after HTX with and without ECLS (p < 0.05). CHD + CM showed the highest overall inpatient mortality (15%), and cumulative hospital billed charges (median US$ 541,374), all p < 0.001. Pediatric HF admissions have increased from 2004 to 2018. ECLS use and HTX have expanded in this population, with an associated decrease in inpatient mortality in the CHD and CM groups. CHD + CM patients are a growing population with the highest inpatient mortality.

Time in Therapeutic Range for Bivalirudin Among Pediatric Ventricular Assist Device Recipients

Given the adverse event rates involving bleeding and thrombosis among children on ventricular assist devices (VADs), anticoagulant management has become a focal point for quality improvement and innovation. There may be advantages to using direct thrombin inhibitors, such as bivalirudin, though this has not been fully explored. As the percent time in therapeutic range (%TTR) for anticoagulants is classically associated with improved clinical outcomes, we evaluated the %TTR for bivalirudin among pediatric VAD recipients. Using a modification of the Rosendaal method, %TTR was calculated using activated partial thromboplastin time measurements for 11 VAD recipients in the early postoperative period (postoperative days 0-14) and for the duration of VAD support. In the initial 2 weeks after VAD implant, mean %TTR was 68.7 (±13.0). During the entire support course, the mean %TTR improved to 79.6 (±11.0). There was an era effect with improving %TTR in the latter half of the study period. We report very good %TTR for bivalirudin both in the first 2 weeks post implant and this improved over the duration of support. Because %TTR reflects the degree of safety and efficacy in chronic anticoagulation, this relatively high %TTR among a diverse, often critically ill cohort suggests that bivalirudin may be a promising agent. Although this study was underpowered to comprehensively evaluate adverse events on bivalirudin, this represents an important next step for larger scale study.

Complications in children with ventricular assist devices: systematic review and meta-analyses

Heart failure is a significant cause of mortality in children with cardiovascular diseases. Treatment of heart failure depends on patients' symptoms, age, and severity of their condition, with heart transplantation required when other treatments are unsuccessful. However, due to lack of fitting donor organs, many patients are left untreated, or their transplant is delayed. In these patients, ventricular assist devices (VADs) are used to bridge to heart transplant. However, VAD support presents various complications in patients. The aim of this study was to compile, review, and analyse the studies reporting risk factors and aetiologies of complications of VAD support in children. Random effect risk ratios (RR) with 95% confidence intervals were calculated to analyse relative risk of thrombosis (RR = 3.53 [1.04, 12.06] I² = 0% P = 0.04), neurological problems (RR = 0.95 [0.29, 3.15] I² = 53% P = 0.93), infection (RR = 0.31 [0.05, 2.03] I² = 86% P = 0.22), bleeding (RR = 2.57 [0.76, 8.66] I² = 0% P = 0.13), and mortality (RR = 2.20 [1.36, 3.55] I² = 0% P = 0.001) under pulsatile-flow and continuous-flow VAD support, relative risk of mortality (RR = 0.45 [0.15, 1.37] I² = 36% P = 0.16) under left VAD and biVAD support, relative risk of thrombosis (RR = 1.72 [0.46, 6.44] I² = 0% P = 0.42), infection (RR = 1.77 [0.10, 32.24] I² = 46% P = 0.70) and mortality (RR = 0.92 [0.14, 6.28] I² = 45% P = 0.93) in children with body surface area < 1.2 m² and > 1.2 m² under VAD support, relative risk of mortality in children supported with VAD and diagnosed with cardiomyopathy and congenital heart diseases (RR = 1.31 [0.10, 16.61] I² = 73% P = 0.84), and cardiomyopathy and myocarditis (RR = 0.91 [0.13, 6.24] I² = 58% P = 0.92). Meta-analyses results show that further research is necessary to reduce complications under VAD support.

The role of ventricular assist device in children

The first and successful implantation of a ventricular assist device in 1990 has allowed an 8-year-old child with an end-stage heart failure to undergo a heart transplantation. This milestone paved the way to consider support with ventricular assist in the armamentarium of heart failure management in infants, children and adolescents. Several systems have evolved and faded owing to unacceptable complications. Indications and contraindications to implantation have been established. Anticoagulation management is still on its way to impeccability. Despite the challenges, issues and concerns revolving around ventricular assist devices, the system definitely supports pediatric patients with end-stage heart failure until heart transplantation and could allow recovery of the myocardium.

Impact of mechanical circulatory support on survival in pediatric heart transplantation

Evidence on the impact of MCS on pediatric heart transplant survival is still scarce related to congenital heart disease patients including univentricular physiology as well as the risk factors for complications. We performed a retrospective review of all urgent pediatric (aged ≤16 years) HT from 2004 to 2014 in the Spanish Pediatric Heart Transplant Registry Group. Patients were stratified into two groups: urgent 0 (MCS at HT) and urgent 1 (non-MCS at HT). The primary outcome measure was post-transplant survival; secondary outcome measures were complications and absence of infections and rejection during the first post-transplant year. One hundred twenty-one pediatric patients underwent urgent HT, 58 (47.9%) urgent 0 and 63 (52%) urgent 1. There were 30 (24.8%) deaths: 12 in the urgent 0 group and 18 in the urgent 1 group, P = n.s. Regarding the type of MCS, patients on ECMO had the highest rate of complications (80%) and mortality (40%). Patients in the urgent 1 group showed a higher risk of hospital re-admission for infection during the first year after transplantation (OR 2.31 [1.1-4.82]), P = .025. We did not identify a risk factor for mortality. MCS does not impact negatively on survival after HT. However, there is a significant increase in 30-day and 1-year mortality and complications in ECMO patients compared with VAD patients. Infants, congenital heart disease, and PediMACS were not found to be risk factors for mortality.

Direct Echocardiographic Imaging of Berlin Heart Valves Can Aid in Early Detection of Berlin Heart Valve Dysfunction

Mechanical circulatory support options remain limited for pediatric patients, especially neonates. The only U.S. Food and Drug Administration-approved pediatric device remains the Berlin Heart EXCOR, which unfortunately carries with it a 20-30% risk of neurologic complications, such as strokes. We demonstrate a new technique of direct echocardiographic color-Doppler imaging of the Berlin Heart valves to detect valve regurgitation. Increases in valve regurgitation could indicate issues with pump-valve thrombosis or increased afterload leading to valve insufficiency. Early recognition of valve thrombosis or insufficiency may reduce neurologic complications and lead to timely pump adjustments or replacement.

Heart Transplantation from Biventricular Support in Infant with Novel SMYD1 Mutation

SET and MYND domain-containing protein 1 (SMYD1) has been shown to be responsible for the development of fast twitch and cardiac muscle. Mutations in SMYD1 have been shown to be uniformly fatal in laboratory studies, and not previously described in living humans. We describe here the care of an infant suffering from cardiac failure due to an SMYD1 mutation requiring biventricular assist devices as a bridge to successful heart transplantation. The patient is now doing well 2 years post-transplant and represents a known survivor of a suspected uniformly fatal genetic mutation.

Cost-utility of continuous-flow ventricular assist devices as bridge to transplant in pediatrics

OBJECTIVE

The initial costs of a CF-VAD exceed those of a PF-VAD. However, the safety profile of CF-VAD is superior and the possibility of outpatient device support may justify the additional initial costs. This study analyzed the cost-utility of CF-VAD use in the pediatric population.

METHODS

A Markov-state transition model was constructed for the clinical course of the two VAD subtypes from implantation until death with variables extracted from internal financial records and the published literature. The modeled population consisted of pediatric heart failure patients who met indications for VAD implant (INTERMACS profile 1 or 2) and were size-eligible for either a PF-VAD or CF-VAD.

RESULTS

The cost-utility analysis illustrated that CF-VAD is both more effective and less costly compared to PF-VAD at base-case conditions. Sensitivity analyses demonstrated that only in extreme conditions did a CF-VAD strategy not meet criteria for cost-effectiveness (if readmission rate >20% weekly, neurologic event rate >8% weekly, or CF-VAD discharge rates <18% in a month) or VAD support duration shortens to ≤12 weeks.

CONCLUSION

While the implantation costs of a CF-VAD exceed those of a PF-VAD, after 12 weeks of device support CF-VAD becomes the more cost-effective strategy if the anticipated outpatient device care is sufficiently long. The cost efficacy of the CF-VAD will be further heightened as initiatives that result in earlier and safer discharges, as well as reductions in readmission rates continue to be successful.

Extracorporeal membrane oxygenation, Berlin, and ventricular assist devices: a primer for the cardiologist

PURPOSE OF REVIEW

Mechanical circulatory support (MCS) has become an indispensable tool in the management of children with impending respiratory and cardiac failure. Though extracorporeal membrane oxygenation (ECMO) was classically the only form of support available to pediatric patients, considerable advances have allowed ventricular assist devices (VADs) to become increasingly utilized in children. This review provides an update of recent advances in ECMO and VAD management in children.

RECENT FINDINGS

The options for mechanical support in infants and small children with end-stage heart failure are limited. As such, the greatest advances in the past decade have come in the successful adoption of the Berlin Heart EXCOR device, with a marked improvement in survival to transplant over ECMO. Further advances have been made in the use of adult VADs in children. For instance, the HeartWare HVAD has been utilized in children as young as 3 years of age, despite being designed for use in adult patients.

SUMMARY

The availability of mechanical support options for children remains limited to ECMO and a small number of VADs. While outcomes of VAD support in pediatric patients have been promising, further study in smaller and more complex pediatric patients is necessary.

Current State of Pediatric Heart Failure

Pediatric heart failure (HF) represents an important cause of morbidity and mortality in childhood. There is an overlapping relationship of HF, congenital heart disease, and cardiomyopathy. The goal of treatment of HF in children is to maintain stability, prevent progression, and provide a reasonable milieu to allow somatic growth and optimal development. Current management and therapy for HF in children are extrapolated from treatment approaches in adults. There are significant barriers in applying adult data to children because of developmental factors, age variation from birth to adolescence, and differences in the genetic expression profile and &beta;-adrenergic signaling. At the same time, there are significant challenges in performing well-designed drug trials in children with HF because of heterogeneity of diagnoses identifying a clinically relevant outcome with a high event rate, and a difficulty in achieving sufficient enrollment. A judicious balance between extrapolation from adult HF guidelines and the development of child-specific data on treatment represent a wise approach to optimize pediatric HF management. This approach is helpful as reflected by the increasing role of ventricular assist devices in the management of advanced HF in children. This review discusses the causes, epidemiology, pathophysiology, clinical manifestations, conventional medical treatment, clinical trials, and the role of device therapy in pediatric HF.

Comparison of Transplant Waitlist Outcomes for Pediatric Candidates Supported by Ventricular Assist Devices Versus Medical Therapy

OBJECTIVES

Ventricular assist devices have gained popularity in the management of refractory heart failure in children listed for heart transplantation. Our primary aim was to compare the composite endpoint of all-cause pretransplant mortality and loss of transplant eligibility in children who were treated with a ventricular assist device versus a medically managed cohort.

DESIGN

This was a retrospective cohort analysis.

SETTINGS

Data were obtained from the Scientific Registry of Transplant Recipients.

PATIENTS

The at-risk population (n = 1,380) was less than 18 years old, either on a ventricular assist device (605 cases) or an equivalent-severity, intensively medically treated group (referred to as MED, 775 cases).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The impact of ventricular assist devices was estimated via Cox proportional hazards regression (hazard ratio), dichotomizing 1-year outcomes to "poor" (22%: 193 deaths, 114 too sick) versus all others (940 successful transplants, 41 too healthy, 90 censored), while adjusting for conventional risk factors. Among children 0-12 months old, ventricular assist device was associated with a higher risk of poor outcomes (hazard ratio, 2.1; 95% CI, 1.5-3.0; p < 0.001). By contrast, ventricular assist device was associated with improved outcomes for ages 12-18 (hazard ratio, 0.3; 95% CI, 0.1-0.7; p = 0.003). For candidates 1-5 and 6-11 years old, there were no differences in outcomes between the ventricular assist device and MED groups (hazard ratio, 0.8 and 1.0, p = 0.43 and 0.9). The interaction between ventricular assist devices and age group was strongly significant (p < 0.001).

CONCLUSIONS

This is a comparative study of ventricular assist devices versus medical therapy in children. Age is a significant modulator of waitlist outcomes for children with end-stage heart failure supported by ventricular assist device, with the impact of ventricular assist devices being more beneficial in adolescents.

An overview of mechanical circulatory support in single-ventricle patients

The population of people with a single-ventricle is continually increasing due to improvements across the spectrum of medical care. Unfortunately, a proportion of these patients will develop heart failure. Often, for these patients, mechanical circulatory support (MCS) represents the only available treatment option. While single-ventricle patients currently represent a small proportion of the total number of patients who receive MCS, as the single-ventricle patient population increases, this number will increase as well. Outcomes for these complex single-ventricle patients who require MCS has begun to be evaluated. When considering the entire population, survival to hospital discharge is 30-50%, though this must be considered with the significant heterogeneity of the single-ventricle patient population. Patients with a single-ventricle have unique anatomy, mechanisms of failure, indications for MCS and the type of support utilized. This has made the interpretation and the generalizability of the limited available data difficult. It is likely that some subsets will have a significantly worse prognosis and others a better one. Unfortunately, with these limited data, indications of a favorable or poor outcome have not yet been elucidated. Though currently, a database has been constructed to address this issue. While the outcomes for these complex patients is unclear, at least in some situations, they are poor. However, significant advances may provide improvements going forward, including new devices, computer simulations and 3D printed models. The most important factor, however, will be the increased experience gained by the heart failure team to improve patient selection, timing, device and configuration selection and operative approach.

Outcomes and Trends of Ventricular Assist Device Selection in Children with End-Stage Heart Failure

We aimed to examine trends in ventricular assist device (VAD) selection, continuous flow devices (CFD) versus pulsatile flow devices (PFD), and their associated outcomes in children eligible for both device types. To accomplish this, the United Network for Organ Sharing database was reviewed for pediatric patients listed for heart transplant (HT) from January 2007 to June 2014. Patients were included if a durable VAD was present at wait listing or when removed from the waiting list and who met size eligibility for a CFD (BSA > 1.0 m). In total, 253 patients met inclusion criteria, 144 (57%) CFD and 109 (43%) PFD. Device type varied significantly based on year with CFD increasing from 11% in 2007 to 88% in 2014 (p < 0.01). PFD patients were younger, had a lower BSA, and an increased rate of extracorporeal membrane oxygenation and biventricular assist device support at listing. Survival to transplant or recovery was similar for CFDs and PFDs (96 vs. 94%; p = 0.57), as was the post-HT survival, 95% for both device types. Despite PFD patients having more risk factors for a poor outcome, survival was similar between device types. Even so, there is a dramatic trend toward CFD utilization in patients who are large enough to support one.

Role of paediatric assist device in bridge to transplant

Background

While heart transplantation has gained recognition as the gold standard therapy for advanced heart failure, the scarcity of donor organs has become an important concern. The evolution of surgical alternatives such as ventricular assist devices (VADs), allow for recovery of the myocardium and ensure patient survival until heart transplantation becomes possible. This report elaborates the role of VADs as a bridge to heart transplantation in infants and children (≤18 years old) with end-stage heart failure.

Methods

A retrospective review of the medical records of 201 heart transplant recipients between May 1986 and September 2014 identified 78 children [38.8%; mean age 7.2 (7.8±6.0) years old; IQR: 2.6-11.8 years] with advanced heart failure who were supported with a VAD [left VAD (LVAD) =21; biventricular VAD (BVAD) =57] as a bridge to heart transplantation. Fourteen (17.9%) patients were less than 1 year old; 15 (19.2%) children had a cardiac arrest and underwent cardiopulmonary resuscitation, with 7 of these patients also requiring extracorporeal membrane oxygenation (ECMO) support prior to implantation of a VAD. The aetiology of heart failure was primarily cardiomyopathy (dilative, restrictive from endocardial fibrosis, idiopathic or toxic-induced), reported in 56 (71.8%) patients. The VADs employed were primarily Berlin Heart EXCOR^® (n=63), HeartWare (n=13), Berlin Heart INCOR^® (n=1), and Toyobo (n=1).

Results

Mean duration of VAD support was 59 (133.37±191.57) days (range, 1-945 days; IQR: 23-133 days) before a donor heart became available. The primary complication encountered while patients were being bridged to transplant was mediastinal bleeding (7.8%). The main indication for pump exchanges was thrombus formation in the valves. There was no incidence of technical failure of the blood pump or driving system components. Skin infections around the cannulae occurred in 2.5%. Adverse neurological symptoms (thromboembolism 11.1%, cerebral haemorrhage 3.6%) that occurred did not have any permanent neurological sequelae that could be detected on clinical examination in this study. Mean duration of follow-up was 9.4 (10.3±7.6) years (IQR: 3.74-15.14 years). Cumulative survival rates of patients bridged to transplantation with VAD were 93.6%±2.8%, 84.6%±4.1%, 79.1%±4.7%, 63.8%±6.2%, 61.6%±7.1%, and 52.1%±9.3% at 30 days, 1, 5, 10, 15 and 20 years, respectively. There was no statistically significant difference (P=0.79) in survival rates of patients bridged to heart transplantation with VAD compared to those who underwent primary heart transplantation. Post-transplant survival rates stratified according to the type of VAD implanted and number of ventricles supported were not statistically different (P=0.93 and 0.73, respectively). In addition, post-transplant survival rates were not significantly different when age, gender and diagnosis were adjusted for. Furthermore, no statistically significant difference was found when post-transplant survival rates of children who had episodes of rejection were compared to those who did not have episodes of rejection.

Conclusions

The results in this series demonstrate that VADs satisfactorily support paediatric patients with advanced heart failure from a variety of aetiologies until heart transplantation. The data further suggests that patients bridged with VADs have comparable long-term post-transplant survival as those undergoing primary heart transplantation.

Pediatric cardiac transplantation

Heart transplantation in pediatric patients generally arises as a treatment option of last resort, that is, the indication is for patients with heart failure of various etiologies, with potential or actual end-organ dysfunction, in whom there are no reasonable, long-term options for life-prolonging therapy. The concept of heart failure is complex in a pediatric population, particularly those with congenital heart disease. While heart failure may refer simply to systolic dysfunction leading to low cardiac output, it can also encompass: diastolic dysfunction in restrictive cardiomyopathy; single ventricle physiology without an option for stable palliation. A good candidate should have a predicted life expectancy less than the median lifetime of a transplanted heart. Significant improvement in survival has been observed over time with 1- and 5-year survival approximately 90% and 80% in the contemporary era.

Selection of Patients for Initial Clinical Trials of Solid Organ Xenotransplantation

Several groups have reported extended survival of genetically engineered pig organs in nonhuman primates, varying from almost 10 months for life-supporting kidney grafts and more than 2 years for non-life-supporting heart grafts to less than 1 month for life-supporting liver and lung grafts. We have attempted to define groups of patients who may not have an option to wait for an allograft. These include kidney, heart, and lung candidates who are highly-allosensitized. In addition, some kidney candidates (who have previously lost at least 2 allografts from rapid recurrence of native kidney disease) have a high risk of further recurrence and will not be offered a repeat allotransplant. Patients with complex congenital heart disease, who may have undergone previous palliative surgical procedures, may be unsuitable for ventricular assist device implantation. Patients dying of fulminant hepatic failure, for whom no alternative therapy is available, may be candidates for a pig liver, even if only as a bridge until an allograft becomes available. When the results of pig organ xenotransplantation in nonhuman primates suggest a realistic potential for success of a pilot clinical trial, highly selected patients should be offered participation.

Functional status of United States children supported with a left ventricular assist device at heart transplantation

BACKGROUND

As survival with pediatric left ventricular assist devices (LVADs) has improved, decisions regarding the optimal support strategy may depend more on quality of life and functional status (FS) rather than mortality alone. Limited data are available regarding the FS of children supported with LVADs. We sought to compare the FS of children supported with LVADs vs vasoactive infusions to inform decision making around support strategies.

METHODS

Organ Procurement and Transplant Network data were used to identify all United States children aged between 1 and 21 years at heart transplant (HT) between 2006 and 2015 for dilated cardiomyopathy and supported with an LVAD or vasoactive infusions alone at HT. FS was measured using the 10-point Karnofsky and Lansky scale.

RESULTS

Of 701 children who met the inclusion criteria, 430 (61%) were supported with vasoactive infusions, and 271 (39%) were supported with an LVAD at HT. Children in the LVAD group had higher median FS scores at HT than children in the vasoactive infusion group (6 vs 5, p < 0.001) but lower FS scores at listing (4 vs 6, p < 0.001). The effect persisted regardless of patient location at HT (home, hospital, intensive care) or device type. Discharge by HT occurred in 46% of children in the LVAD group compared with 26% of children in the vasoactive infusion cohort (p = 0.001). Stroke was reported at HT in 3% of children in the LVAD cohort and in 1% in the vasoactive infusion cohort (p = 0.04).

CONCLUSIONS

Among children with dilated cardiomyopathy undergoing HT, children supported with LVADs at HT have higher FS than children supported with vasoactive infusions at HT, regardless of device type or hospitalization status. Children supported with LVADs at HT were more likely to be discharged from the hospital but had a higher prevalence of stroke at HT.

Early Single Institutional Experience of Berlin Heart EXCOR® Pediatric Ventricular Assist Device in Japan

BACKGROUND

Since August 2015, the pediatric ventricular assist device (VAD), Berlin Heart EXCOR^®, has been accepted for use in Japan.Methods and Results:Between August 2015 and July 2016, 4 pediatric patients with endstage heart failure underwent LVAD implantation with the EXCOR^®device. The median age and body weight at operation were 8 months and 4.8 kg. During a median follow-up of 7.3 months (range, 5.0-10.3), all patients survived. Two patients went on to heart transplantation and the remaining 2 are on a waiting list with stable hemodynamics.

CONCLUSIONS

The early outcomes of the Berlin Heart EXCOR^®pediatric VAD were satisfactory. (Circ J 2016; 80: 2552-2554).

Ventricular Assist Devices in Pediatric Cardiac Intensive Care

OBJECTIVES

The objectives of this review are to discuss the process of patient and mechanical device selection, operative management, and postoperative care with a focus on the management of right ventricular failure, anticoagulation strategies, device-related infections and neurologic sequelae.

DATA SOURCES

MEDLINE, PubMed.

CONCLUSION

The number of patients with advanced heart failure due to either acquired or congenital heart disease continues to increase, necessitating in some mechanical circulatory support and in others cardiac transplantation. With a limited cardiac donor pool, mechanical circulatory support is playing a greater role in the management of this population. The perioperative morbidity associated with mechanical circulatory support has lessened with improved postoperative management strategies.

Early Biventricular Assist Device Use in Children: A Single-Center Review of 31 Patients

Biventricular assist device (BiVAD) support is considered a risk factor for worse outcomes compared with left ventricular assist device (LVAD) alone for children with end-stage heart failure. It remains unclear whether this is because of the morbidity associated with a second device or the underlying disease severity. We aimed to show that early BiVAD support can result in good survival by analyzing our prospectively collected database for all pediatric patients who underwent BiVAD implantation. From 2005 to 2009, BiVADs were used exclusively. From 2010 to 2014, LVAD alone was considered, maintaining a low threshold for BiVAD support. All BiVADs were pulsatile devices. Thirty-one patients with median age of 3.5 years received BiVAD support. Diagnoses included dilated cardiomyopathy in 17 (55%), myocarditis in 6 (19%), and congenital heart disease in 3 (10%). Survival to transplant was achieved in 27 (87%) with a median duration of 41 days (interquartile range, 15-69). Adverse event rates (per 100 days of support) were bleeding at 0.52, infection at 1.17, and central nervous system dysfunction at 0.78. Of those who survived to transplant, 26 (96%) remain alive with a median follow-up of 55 months. These results show that BiVAD support can bridge patients to transplant with excellent long-term survival.

A contemporary review of paediatric heart transplantation and mechanical circulatory support

Improvements in the care of children with cardiomyopathy, CHDs, and acquired heart disease have led to an increased number of children surviving with advanced heart failure. In addition, the advent of more durable mechanical circulatory support options in children has changed the outcome for many patients who otherwise would have succumbed while waiting for heart transplantation. As a result, more children with end-stage heart failure are being referred for heart transplantation, and there is increased demand for a limited donor organ supply. A review of important publications in the recent years related to paediatric heart failure, transplantation, and mechanical circulatory support show a trend towards pushing the limits of the current therapies to address the needs of this growing population. There have been a number of publications focussing on previously published risk factors perceived as barriers to successful heart transplantation, including elevated pulmonary vascular resistance, medication non-adherence, re-transplantation, transplantation of the failed Fontan patient, and transplantation in an infant or child bridged with mechanical circulatory support. This review will highlight some of these key articles from the last 3 years and describe recent advances in the understanding, diagnosis, and management of children with end-stage heart disease.

Modern Outcomes of Mechanical Circulatory Support as a Bridge to Pediatric Heart Transplantation

BACKGROUND

Pediatric patients awaiting orthotopic heart transplantation frequently require bridge to transplantation (BTT) with mechanical circulatory support. Posttransplant survival outcomes and predictors of mortality have not been thoroughly described in the modern era using a large-scale analysis.

METHODS

The United Network for Organ Sharing database was reviewed to identify pediatric heart transplant recipients from 2005 through 2012. Patients were stratified into three groups: extracorporeal membrane oxygenation (ECMO), ventricular assist device (VAD), and direct transplantation (DTXP). The primary outcome was posttransplant survival.

RESULTS

Two thousand seven hundred seventy-seven pediatric patients underwent orthotopic heart transplantation. There were 617 patients who required BTT with mechanical circulatory support (22.2%), of whom there were 428 VAD BTT (69.4%) and 189 ECMO BTT (30.6%). An increase in VAD use was observed during the study period (p < 0.0001). Compared with DTXP, patients in the ECMO BTT group had a lower median age (<1 versus 5 years; p < 0.0001) and were significantly smaller (8 versus 14 kg; p < 0.001), whereas patients in the VAD BTT group were older (8 versus 5 years; p = 0.0002) and larger (24 versus 14 kg; p < 0.001). Actuarial survival was greater in the DTXP group compared with ECMO BTT, but similar to VAD BTT at 30 days and 1, 3, and 5 years. However, this survival difference was lost after censoring the first 4 months after transplant. In multivariable analysis, when restricted to the first 4 months of survival, independent predictors for mortality were ECMO BTT, age, diagnosis, and functional status, whereas VAD BTT was not.

CONCLUSIONS

Pediatric patients with DTXP or VAD BTT have equivalent posttransplant survival. However, those requiring ECMO BTT have inferior early posttransplant survival compared with those receiving DTXP.

Pediatric mechanical circulatory support: available devices and outcomes as bridge-to-transplant therapy

PURPOSE OF REVIEW

The use of mechanical circulatory support in children has increased dramatically over the current decade. A review of the pediatric ventricular assist device (VAD) literature is timely and relevant in order to improve outcomes and refine patient selection as new devices become available and current VADs are used in smaller patients.

RECENT FINDINGS

Outcomes of pediatric patients bridged to transplant with VAD therapy continue to improve. Patient selection in children continues to be complex as size and anatomy make decision-making unique from the adult practice. In addition, device selection and surgical planning are evolving in children. The use of temporary devices for long-term use is an example of an innovative application of current technology. Sensitization and adverse events are important issues that are necessary to understand in order to improve outcomes. The importance of a national registry to help monitor patient outcomes is critical to assessing this highly technological therapy.

SUMMARY

There are many implications of improving and expanding durable device use in children. VAD therapy is evolving as a standard of care as a bridge to transplant in children. Continued surveillance of outcomes is critical to improving patient selection and decreasing adverse events in children with advanced heart failure.

Advances in mechanical assist devices and artificial hearts for children

PURPOSE OF REVIEW

Mechanical circulatory support (MCS) has rapidly evolved toward continuous flow technology in adults. In the pediatric population, the Berlin EXCOR, a paracorporeal pulsatile pump, is the only MCS device specifically approved for pediatric use. The current era of pediatric MCS includes an increasing application of adult continuous flow pumps to pediatric patients.

RECENT FINDINGS

The Berlin EXCOR pulsatile pump has been studied in over 200 patients. The major limitations of this device are neurologic dysfunction (which occurs in about 30% of supported patients) and the requirement for in-hospital care until transplant. Two continuous flow pumps (HVAD and HeartMate II) have been successfully applied in children and adolescents, and the SynCardia total artificial heart has been used in adolescents. The National Heart, Lung, and Blood Institute - sponsored Pediatric Mechanically Assisted Circulatory Support registry has collected pediatric MCS data since 2012 and will provide valuable outcomes data to help refine this field. Survival with these durable devices has been generally good (except for small infants and patients with complex congenital heart disease), with nearly 50% receiving a heart transplant within 6 months. Patients with single ventricle physiology continue to pose major challenges. Two clinical trials for miniaturized adult continuous flow devices and one trial for a new pediatric pump will begin within the next year.

SUMMARY

New continuous flow devices are entering or poised to enter clinical trials. If approved, these devices will enhance the safety and variety of options for longer-term pediatric support.

Potential alternative approaches to xenotransplantation

There is an increasing worldwide shortage of organs and cells for transplantation in patients with end-stage organ failure or cellular dysfunction. This shortage could be resolved by the transplantation of organs or cells from pigs into humans. What competing approaches might provide support for the patient with end-stage organ or cell failure? Four main approaches are receiving increasing attention - (i) implantable mechanical devices, although these are currently limited almost entirely to devices aimed at supporting or replacing the heart, (ii) stem cell technology, at present directed mainly to replace absent or failing cells, but which is also fundamental to progress in (iii) tissue engineering and regenerative medicine, in which the ultimate aim is to replace an entire organ. A final novel potential approach is (iv) blastocyst complementation. These potential alternative approaches are briefly reviewed, and comments added on their current status and whether they are now (or will soon become) realistic alternative therapies to xenotransplantation.

Ventricular assist device use in congenital heart disease with a comparison to heart transplant

Despite advances in medical and surgical therapies, some children with congenital heart disease (CHD) are not able to be adequately treated or palliated, leading them to develop progressive heart failure. As these patients progress to end-stage heart failure they pose a unique set of challenges. Heart transplant remains the standard of care; the donor pool, however, remains limited. Following the experience from the adult realm, the pediatric ventricular assist device (VAD) has emerged as a valid treatment option as a bridge to transplant. Due to the infrequent necessity and the uniqueness of each case, the pediatric VAD in the CHD population remains a topic with limited information. Given the experience in the adult realm, we were tasked with reviewing pediatric VADs and their use in patients with CHD and comparing this therapy to heart transplantation when possible.

Pediatric Quality of Life while Supported with a Ventricular Assist Device

OBJECTIVE

Ventricular assist devices (VADs) have emerged as an important treatment option for bridging pediatric patients with heart failure to transplant. VADs have shown improved survival; however, the pediatric quality of life (QoL) while on VAD support is unknown. We aimed to evaluate the QoL of our pediatric patients while supported with a VAD.

DESIGN

In this prospective study, pediatric patients who underwent VAD placement, and their parents, were administered a generic Pediatric Quality of Life Inventory (PedsQL) 4.0 pre-VAD implant, when feasible, after the acute postoperative period, and then periodically until heart transplant or death. Their final scores while on support were compared with three previously reported groups: healthy controls, outpatients with severe heart disease, and children after heart transplant.

RESULTS

From January 2008 to July 2014, 13 pediatric patients required VAD support greater than 2 weeks and completed a PedsQL. The mean age at implant was 10.0 ± 4.2 years and median duration of support was 1.6 (0.5-19.7) months. Eleven (85%) patients survived to transplant with one (8%) patient remaining alive on support. The median duration of support prior to their final PedsQL was 1.4 (0.5-11.4) months. Patients self-reported significantly (P < .05) lower total and physical QoL scores when compared with all three comparison groups. Self-reported psychosocial QoL scores were significantly lower than healthy controls only. Parent proxy-reported scores were significantly lower than all three comparison groups for all three categories (P < .05).

CONCLUSIONS

A large deficit exists in the total QoL of pediatric patients supported by a VAD compared with outpatient management of severe heart disease or postheart transplant patients; however, VAD patients do represent a group with more severe heart failure. Improvements in QoL must be made, as time spent with a VAD will likely continue to increase.

Current approaches to device implantation in pediatric and congenital heart disease patients

The pediatric ventricular assist device (VAD) has recently shown substantial improvements in survival as a bridge to heart transplant for patients with end-stage heart failure. Since that time, its use has become much more frequent. With increasing utilization, additional questions have arisen including patient selection, timing of VAD implantation and device selection. These challenges are amplified by the uniqueness of each patient, the recent abundance of literature surrounding VAD use as well as the technological advancements in the devices themselves. Ideal strategies for device placement must be sought, for not only improved patient care, but also for optimal resource utilization. Here, we review the most relevant literature to highlight some of the challenges facing the heart failure specialist, and any physician, who will care for a child with a VAD.

Outcomes and risk factors for heart transplantation in children with end-stage cardiomyopathy†

OBJECTIVES

Heart transplantation (HT) is the treatment of choice in children with end-stage cardiomyopathy. Several clinical, morphological, demographic, donor and recipient transplant factors have been demonstrated to affect survival in those patients following listing for HT and following HT. We aim to report our single institution results of HT in children with cardiomyopathy, and explore variables affecting survival and the need for heart retransplantation (RHT).

METHODS

Between 1988 and 2013, 125 children with cardiomyopathy underwent HT. Competing risks analysis modelled events after HT (RHT, death without RHT). Multivariable regression analysis examined risk factors affecting outcomes and parametric models were used to compare survival between diverse groups of patients.

RESULTS

There were 62 males (50%). Cardiomyopathy types were dilated (n = 104, 83%), restrictive (n = 10, 8%), chemotherapy-induced (n = 7, 6%), and other (n = 4, 3%). Median age at listing was 6.9 years and median age at HT was 7.0 years with median waiting list duration of 29 days. Thirty-four patients were infants <1 year. At time of HT, 106 patients (85%) were at United Network for Organ Sharing status-1, 25 (20%) were ventilated and 17 (14%) had mechanical circulatory support. There was 1 operative death. Competing risks analysis showed that at 10 years following HT, 10% of patients have undergone RHT, 32% have died without RHT and 58% of patients were alive without RHT. On multivariable analysis, risk factors for death following HT were panel-reactive antibodies >10% {hazard ratio [HR]: 4.1 [95% confidence interval (CI): 1.7-9.9], P = 0.002}, age group >10 years [HR: 3.2 (95% CI: 1.4-8.1), P = 0.009] and pre-HT mechanical circulatory support [HR: 2.9 (95% CI: 1.1-7.7), P = 0.033]. Additionally, earlier era <2000 was a significant risk factor for early phase mortality [HR: 8.7 (95% CI: 1.8-42.5), P = 0.017] but not for constant or late phase mortality [HR: 0.8 (95% CI 0.3-1.8), P = 0.6]. Following RHT, 6/11 (55%) expired yielding overall parametric survival estimates of 92, 77 and 57% at 1, 5 and 15 years, respectively.

CONCLUSIONS

Despite remarkable improvement in operative mortality and 1-year survival of children undergoing HT for cardiomyopathy in the current era, that advantage is reduced at the later follow-up, especially in teenagers indicating ongoing compliance and chronic management challenges. In children requiring pre-HT mechanical support, mid-term attrition is higher despite low operative mortality.

Peri-operative kidney injury and long-term chronic kidney disease following orthotopic heart transplantation in children

Significant advances in cardiac intensive care including extracorporeal life support have enabled children with complex congenital heart disease and end-stage heart failure to be supported while awaiting transplantation. With an increasing number of survivors after heart transplantation in children, the complications from long-term immunosuppression, including renal insufficiency, are becoming more apparent. Severe renal dysfunction after heart transplant is defined by a serum creatinine level >2.5 mg/dL (221 μmol/L), and/or need for dialysis or renal transplant. The degree of renal dysfunction is variable and is progressive over time. About 3-10 % of heart transplant recipients will go on to develop severe renal dysfunction within the first 10 years post-transplantation. Multiple risk factors for chronic kidney disease post-transplant have been identified, which include pre-transplant worsening renal function, recipient demographics and morbidity, peri-transplant haemodynamics and long-term exposure to calcineurin inhibitors. Renal insufficiency increases the risk of post-transplant morbidity and mortality. Hence, screening for renal dysfunction pre-, peri- and post-transplantation is important. Early and timely detection of renal insufficiency may help minimize renal insults, and allow prompt implementation of renoprotective strategies. Close monitoring and pre-emptive management of renal dysfunction is an integral aspect of peri-transplant and subsequent post-transplant long-term care.