Current status and future perspectives of the PumpKIN trial

Current status and future directions in pediatric ventricular assist device

A ventricular assist device (VAD) is a form of mechanical circulatory support that uses a mechanical pump to partially or fully take over the function of a failed heart. In recent decades, the VAD has become a crucial option in the treatment of end-stage heart failure in adult patients. However, due to the lack of suitable devices and more complicated patient profiles, this therapeutic approach is still not widely used for pediatric populations. This article reviews the clinically available devices, adverse events, and future directions of design and implementation in pediatric VADs.

Outcomes of Intracorporeal Continuous and Paracorporeal Pulsatile Ventricular Assist Devices in Pediatric Patients 10-30 kg

Ventricular assist devices (VADs) have been increasingly implanted in pediatric patients. Paracorporeal VADs are generally chosen when intracorporeal continuous (IC) devices are too large. Superiority between IC and paracorporeal pulsatile (PP) devices remains unclear in smaller pediatric patients. Our study analyzes outcomes of IC and PP VADs in pediatric patients who could be considered for either of these options. Using the Advanced Cardiac Therapies Improving Outcomes Network (ACTION) database, we identified children between 10 and 30 kg who received a VAD between June 2018 and September 2021. Survival and stroke outcomes were analyzed based on VAD type. There were 41 patients in the IC group and 54 patients in the PP group. Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) profile at the time of implant was higher in the PP cohort ( p < 0.02). The PP cohort was younger ( p < 0.001) and smaller ( p < 0.001) than the IC cohort. The diagnosis was similar between cohorts. Overall survival was similar between groups. Stroke was more common in the PP cohort, but did not reach statistical significance ( p = 0.07). Discharge was possible only in the IC group, but the discharge rate was low (9.5%). Direct comparisons remain challenging given differences in INTERMACS profiles, age, and size.

Pediatric mechanical circulatory support - a review

The history of mechanical circulatory support began in 1953, as the first heart-lung machine enabled surgeons to perform complex open heart surgery. Heart failure is more prevalent in adults than pediatric patients which has led to the development of devices for adults with end-stage heart failure at a faster pace. Pediatric mechanical circulatory support has been derived from adult durable devices and subsequently applied in the adolescent population. The application of adult devices in children is inherently problematic due to size mismatch, especially in smaller patients. There has been an increasing interest in developing durable pumps that are appropriate for children for several reasons, with the primary factor being the number of children with end-stage heart failure far exceeding the number of potential donors. Mechanical circulatory support (MCS) for children can be divided into short-term temporary support and long-term durable support. The goal of this review is to discuss the devices available for the pediatric population and review the options for support in complex patients including single-ventricle anatomy, biventricular support, and total artificial heart options. We will also briefly discuss the Pumps for Kids, Infants, and Neonates (PumpKIN) Trial and MCS registries, including the Advanced Cardiac Therapies Improving Outcomes Network (ACTION).

The Jarvik 2000 Left Ventricular Assist Device: Results of the United States Bridge to Transplant Trial

The Jarvik 2000 bridge to transplant investigational device exemption study was a multicentered, prospective study of 150 UNOS status I patients implanted with the Jarvik 2000 between 2005 and 2012. During the study period, there were numerous modifications of the system that included converting from pin to cone bearings. Results were analyzed for three cohorts: total (n = 150), pin (n = 128), and cone (n = 22). Baseline demographics included age (52 ± 13), gender (79% male), size (BSA 1.98), and etiology (37% idiopathic dilated cardiomyopathy; 43% Ischemic). Seventy percent of patients were either INTERMACS 1 or 2. The primary endpoint-defined as successful transplantation or listing at 180 days (prespecified at 65%; 95% lower CI: 57%)-was successfully achieved for the total cohort (67.3%; 95% CI: 59.5%-74.3%; p = 0.006). In subgroup analysis of the more contemporary, cone-bearing group, the primary endpoint was met in 91% (95% CI: 72%-97.5%; p = 0.001). Compared with pin patients, cone-bearing patients had less hemolysis as well as decreased end-organ dysfunction. Functional and quality of life scores improved after implantation independent type of bearing. In conclusion, despite a particularly sick patient population, the Jarvik 2000 was shown to be effective in supporting the advanced HF patient.

Outcomes in small children on Berlin Heart EXCOR support: age and body surface area as clinical predictive factors

OBJECTIVES

The Berlin Heart EXCOR (BHE) offers circulatory support across all paediatric ages. Clinically, the necessary care and the outcomes differ in various age groups. The EUROMACS database was used to study age- and size-related outcomes for this specific device.

METHODS

All patients <19 years of age from the EUROMACS database supported with a BHE between 2000 and November 2021 were included. Maximally selected rank statistics were used to determine body surface area (BSA) cut-off values. Multivariable Cox proportional hazard regression using ridge penalization was performed to identify factors associated with outcomes.

RESULTS

In total, 303 patients were included [mean age: 2.0 years (interquartile range: 0.6-8.0, males: 48.5%)]. Age and BSA were not significantly associated with mortality (n = 74, P = 0.684, P = 0.679). Factors associated with a transplant (n = 175) were age (hazard ratio 1.07, P = 0.006) and aetiology other than congenital heart disease (hazard ratio 1.46, P = 0.020). Recovery rates (n = 42) were highest in patients with a BSA of <0.53 m2 (21.8% vs 4.3-7.6% at 1 year, P = 0.00534). Patients with a BSA of ≥0.73 m2 had a lower risk of early pump thrombosis but a higher risk of early bleeding compared to children with a BSA of <0.73 m2.

CONCLUSIONS

Mortality rates in Berlin Heart-supported patients cannot be predicted by age or BSA. Recovery rates are remarkably high in the smallest patient category (BSA <0.53 m2). This underscores that the BHE is a viable therapeutic option, even for the smallest and youngest patients.

Pediatric heart transplantation: The past, the present, and the future

Heart transplantation (HTx) has a storied past, with origins dating back to the early twentieth century and the first pediatric orthotopic heart transplant performed in 1967 on a neonate with Ebstein abnormality. Today, approximately 500 pediatric HTx are performed annually, with survival times now measured in decades rather than days or weeks. In large part, advances in immunosuppression, critical care, dedicated transplant teams and mechanical circulatory support have paved the way for improvements in waitlist mortality and post-transplant survival, with future directions including the development of intracorporeal ventricular assist devices (VADs) for small children, expanding/standardizing donor criteria, and xenotransplantation.

Technology Landscape of Pediatric Mechanical Circulatory Support Devices- A Systematic Review 2010-2021

BACKGROUND

Mechanical circulatory support (MCS) devices, such as ventricular assist devices (VADs) and total artificial hearts (TAHs), have become a vital therapeutic option in the treatment of end-stage heart failure for adult patients. Such therapeutic options continue to be limited for pediatric patients. Clinicians initially adapted or scaled existing adult devices for pediatric patients; however, these adult devices are not designed to support the anatomical structure and varying flow capacities required for this population and are generally operated "off-design", which risks complications such as hemolysis and thrombosis. Devices designed specifically for the pediatric population that seek to address these shortcomings are now emerging and gaining FDA approval.

METHODS

To analyze the competitive landscape of pediatric MCS devices, we conducted a systematic literature review. Approximately 27 devices were studied in detail: 8 were established or previously approved designs, and 19 were under development (11 VADs, 5 Fontan assist devices, and 3 TAHs).

RESULTS

Despite significant progress, there is still no pediatric pump technology that satisfies the unique and distinct design constraints and requirements to support pediatric patients, including the wide range of patient sizes, increased cardiovascular demand with growth, and anatomic and physiologic heterogeneity of congenital heart disease.

CONCLUSIONS

Forward-thinking design solutions are required to overcome these challenges and to ensure the translation of new therapeutic MCS devices for pediatric patients.

HVAD to HeartMate 3 left ventricular assist device exchange: Best practices recommendations

The HeartWare HVAD System (Medtronic) is a durable implantable left ventricular assist device that has been implanted in approximately 20,000 patients worldwide for bridge to transplant and destination therapy indications. In December 2020, Medtronic issued an Urgent Medical Device Communication informing clinicians of a critical device malfunction in which the HVAD may experience a delay or failure to restart after elective or accidental discontinuation of pump operation. Moreover, evolving retrospective comparative effectiveness studies of patients supported with the HVAD demonstrated a significantly higher risk of stroke and all-cause mortality when compared with a newer generation of a commercially available durable left ventricular assist device. Considering the totality of this new information on HVAD performance and the availability of an alternate commercially available device, Medtronic halted the sale and distribution of the HVAD System in June 2021. The decision to remove the HVAD from commercial distribution now requires the use of the HeartMate 3 left ventricular assist system (Abbott, Inc) if a patient previously implanted with an HVAD requires a pump exchange. The goal of this document is to review important differences in the design of the HVAD and HeartMate 3 that are relevant to the medical management of patients supported with these devices, and to assess the technical aspects of an HVAD-to-HeartMate 3 exchange. This document provides the best available evidence that supports best practices.

Ventricular assist device for Fontan: who, when and why?

PURPOSE OF REVIEW

Since the advent of the Fontan palliation, survival of patients with univentricular congenital heart disease has increased significantly. These patients will, however, ultimately develop heart failure requiring advanced therapies such as heart transplantation. As wait times are long, mechanical circulatory support (MCS) is an attractive therapy, both for bridge to transplantation and destination therapy in patients not suitable for transplantation. This review aims to summarize current thinking about how to determine which patients would benefit from a ventricular assist device (VAD), the optimal time for implantation and which device should be considered.

RECENT FINDINGS

VAD implantation in end-stage Fontan is still in its infancy; however, case reports and research interest have increased extensively in the past few years. Mortality is significantly higher than in noncongenital heart disease patients. Implantation in patients with primarily systolic dysfunction is indicated, whereas patients with increased transpulmonary gradient may not benefit from a single-VAD solution. When possible, implantation should occur prior to clinical decompensation with evidence of end-organ damage, as outcomes at this point are worse.

SUMMARY

Fontan patients demonstrating signs of heart failure should be evaluated early and often for feasibility and optimal timing of VAD implantation. The frequency of this procedure will likely increase significantly in the future.

The evolution of long-term pediatric ventricular assistance devices: a critical review

Introduction: The gap between the number of heart failure patients and the number of potential heart donors has never been larger than today, especially among the pediatric population. The use of mechanical circulatory support is seen as a potential alternative for clinicians to treat more patients. This treatment has proven its efficiency on short-term use. However, in order to replace heart transplant, the techniques should be used over longer periods of time.Areas covered: This review aims at furnishing an engineering vision of the evolution of ventricular assistance devices used in pediatrics. A critical analysis of the clinical complications related to devices generation is made to give an overview of the design improvements made since their inception.Expert opinion: The long-term use of a foreign device in the body is not without consequences, especially among fragile pediatric patients. Moreover, the size of their body parts increases the technical difficulties of such procedure. The balance between the living cells of the body is disturbed by the devices, mostly by the shear stress generated. To provide a safe mechanical circulatory support for long-term use, the devices should be more hemocompatible, preserving blood cells, adapted to the patient's systemic grid and miniaturized for pediatric use.

The influence of mechanical Circulatory support on post-transplant outcomes in pediatric patients: A multicenter study from the International Society for Heart and Lung Transplantation (ISHLT) Registry

BACKGROUND

Mechanical circulatory support (MCS) is increasingly being used as a bridge to transplant in pediatric patients. We compare outcomes in pediatric patients bridged to transplant with MCS from an international cohort.

METHODS

This retrospective cohort study of heart-transplant patients reported to the International Society for Heart and Lung Transplantation (ISHLT) registry from 2005-2017 includes 5,095 patients <18 years. Pretransplant MCS exposure and anatomic diagnosis were derived. Outcomes included mortality, renal failure, and stroke.

RESULTS

26% of patients received MCS prior to transplant: 240 (4.7%) on extracorporeal membrane oxygenation (ECMO), 1,030 (20.2%) on ventricular assist device (VAD), and 54 (1%) both. 29% of patients were <1 year, and 43.8% had congenital heart disease (CHD). After adjusting for clinical characteristics, compared to no-MCS and VAD, ECMO had higher mortality during their transplant hospitalization [OR 3.97 & 2.55; 95% CI 2.43-6.49 & 1.42-4.60] while VAD mortality was similar [OR 1.55; CI 0.99-2.45]. Outcomes of ECMO+VAD were similar to ECMO alone, including increased mortality during transplant hospitalization compared to no-MCS [OR 4.74; CI 1.81-12.36]. Patients with CHD on ECMO had increased 1 year, and 10 year mortality [HR 2.36; CI 1.65-3.39], [HR 1.82; CI 1.33-2.49]; there was no difference in survival in dilated cardiomyopathy (DCM) patients based on pretransplant MCS status.

CONCLUSION

Survival in CHD and DCM is similar in patients with no MCS or VAD prior to transplant, while pretransplant ECMO use is strongly associated with mortality after transplant particularly in children with CHD. In children with DCM, long term survival was equivalent regardless of MCS status.

Kidney replacement therapy in pediatric patients on mechanical circulatory support: challenges for the pediatric nephrologist

The use of mechanical circulatory support (MCS) therapies in children with medically refractory cardiac failure has increased over the past two decades. With the growing experience and expertise, MCS is currently offered as a bridge to recovery or heart transplantation and in some cases even as destination therapy. Acute kidney injury (AKI) is common in patients with end-stage heart failure (ESHF). When severe AKI develops requiring kidney replacement therapy (KRT), these patients present unique challenges for the pediatric nephrology team. The use of KRT has not been adequately described in children with ESHF on the newer MCS. We also present original case series data from our center experience. The purpose of this review is to familiarize the reader with the current MCS technologies, approach to their selection, how they interact when combined with current KRT circuits, and distinguish similarities and differences. We will attempt to highlight the distinctive features of each technology, specifically focusing on growing trends in use of continuous-flow ventricular assist devices (CF-VAD) as it poses additional challenges to the pediatric nephrologist.

"Compassionate" Cases of the Jarvik 2015 Ventricular Assist Device

The Jarvik 2015 Ventricular Assist Device (VAD) (Jarvik Inc, New York, NY) is the first and currently only continuous-flow VAD specifically designed for small children, and it is being evaluated in the so-called Pump for Kids, Infants, and Neonates (PumpKIN) trial. Due to the strict inclusion criteria of the trial, there have been a group of patients who failed to meet the criteria and therefore received the Jarvik 2015 VAD under the designation of "compassionate use." This is the same phenomenon seen previously during the Berlin Heart EXCOR trial. While we await the results of the PumpKIN trial, which will report the device performance in a strictly selected population, the compassionate use cases represent actual "real world" experiences. We describe herein our experience of two compassionate use cases. In particular, this report has a special emphasis on the power consumption and hemolysis and inflammatory lab profile of the Jarvik 2015 VAD as hemocompatibility was the primary focus of the developmental and the preclinical phases.

Berlin Heart EXCOR Support in the First Year of Life: A Single Centre Experience

BACKGROUND

Berlin Heart EXCOR Pediatric Ventricular Assist Device (BHE) (Berlin Heart AG, Berlin, Germany, BHE) is used worldwide for mechanical circulatory support as a bridge to transplantation or recovery for children with end-stage heart failure. The study aim was to evaluate morbidity and mortality of children less than one year old supported with BHE to identify predictors of adverse outcomes.

METHODS

Data of all children aged less than one year supported with BHE between 2005 and 2018 at the Royal Children's Hospital, Melbourne were reviewed. Adverse events were defined using PediMACS criteria.

RESULTS

Fourteen (14) children under 1 year of age were implanted with BHE at a median age and weight of 0.37 years (IQR 0.09-0.7) and 5.7 kg (IQR 3.5-7.95) respectively. Four (4) patients were neonates, and 10 were older infants. Twelve (12) patients had cardiomyopathy and two, myocarditis. Preoperative extracorporeal membrane oxygenation (ECMO) support was required in six patients for a mean of 9 days (IQR 6-13). Sepsis occurred in five patients (36%) and thromboembolic stroke in two patients (14%). Survival to bridge to transplantation (11) and recovery (1) was achieved in 12 patients (86%). Mortality was 14%. The median duration of BHE support was 110 days (IQR 40-161). Both patients who died were neonates with myocarditis and required surgical re-intervention during BHE support.

CONCLUSIONS

BHE provides excellent support as a bridge to transplantation or recovery in infants, with a low incidence of neurological dysfunction. Neonates with myocarditis may be at greater risk for death after BHE implantation.

The Use of Bivalirudin in Pediatric Cardiac Surgery and in the Interventional Cardiology Suite

Anticoagulation is an essential component for patients undergoing cardiopulmonary bypass or extracorporeal membrane oxygenation and for those with ventricular assist devices. However, thrombosis and bleeding are common complications. Heparin continues to be the agent of choice for most patients, likely owing to practitioners' comfort and experience and the ease with which the drug's effects can be reversed. However, especially in pediatric cardiac surgery, there is increasing interest in using bivalirudin as the primary anticoagulant. This drug circumvents certain problems with heparin administration, such as heparin resistance and heparin-induced thrombocytopenia, but it comes with additional challenges. In this manuscript, the authors review the literature on the emerging role of bivalirudin in pediatric cardiac surgery, including its use with cardiopulmonary bypass surgery, extracorporeal membrane oxygenation, ventricular assist devices, and interventional cardiology. Moreover, they provide an overview of bivalirudin's pharmacodynamics and monitoring methods.

Outcomes of Infants Supported With Extracorporeal Membrane Oxygenation Using Centrifugal Versus Roller Pumps: An Analysis From the Extracorporeal Life Support Organization Registry

OBJECTIVES

To determine whether mortality differs between roller and centrifugal pumps used during extracorporeal membrane oxygenation in infants weighing less than 10 kg.

DESIGN

Retrospective propensity-matched cohort study.

SETTING

All extracorporeal membrane oxygenation centers reporting to the Extracorporeal Life Support Organization.

PATIENTS

All patients less than 10 kg supported on extracorporeal membrane oxygenation during 2011-2016 within Extracorporeal Life Support Organization Registry.

INTERVENTIONS

Centrifugal and roller pump recipients were propensity matched (1:1) based on predicted probability of receiving a centrifugal pump using demographic variables, indication for extracorporeal membrane oxygenation, central versus peripheral cannulation, and pre-extracorporeal membrane oxygenation patient management.

MEASUREMENTS AND MAIN RESULTS

A total of 12,890 patients less than 10 kg were supported with extracorporeal membrane oxygenation within the Extracorporeal Life Support Organization registry during 2011-2016. Patients were propensity matched into a cohort of 8,366. Venoarterial and venovenous extracorporeal membrane oxygenation runs were propensity matched separately. The propensity-matched cohorts were similar except earlier year of extracorporeal membrane oxygenation (standardized mean difference, 0.49) in the roller pump group. Within the propensity-matched cohort, survival to discharge was lower in the centrifugal pump group (57% vs 59%; odds ratio, 0.91; 95% CI, 0.83-0.99; p = 0.04). Hemolytic, infectious, limb injury, mechanical, metabolic, neurologic, pulmonary, and renal complications were more frequent in the centrifugal pump group. Hemorrhagic complications were similar between groups. Hemolysis mediated the relationship between centrifugal pumps and mortality (indirect effect, 0.023; p < 0.001).

CONCLUSIONS

In this propensity score-matched cohort study of 8,366 extracorporeal membrane oxygenation recipients weighing less than 10 kg, those supported with centrifugal pumps had increased mortality and extracorporeal membrane oxygenation complications. Hemolysis was evaluated as a potential mediator of the relationship between centrifugal pump use and mortality and met criteria for full mediation.

Developments in Pediatric Ventricular Assist Device Support

Mechanical support devices have revolutionized the management of circulatory failure. This has been met by a dramatic increase in ventricular assist device (VAD) utilization in children over the last two decades. Previous wide gaps in experience and knowledge have significantly narrowed in the recent years. As we continue to gain experience with this technology, we face new challenges such as complex congenital circulations and small patient size. The emergence of new pharmacologic therapies and device technology offers more opportunities and requires constant adjustment in practice. As we continue to embark on this journey, constant insight is needed to refine patient selection criteria, minimize complications, and continue to push the field for safer smaller devices to accommodate these complex patient populations. In this review focused at inpatient critical care environment, we discuss the recent field developments and focus on challenging patient populations, the emergence of temporary support, management of anticoagulation, and diagnostic approach to stroke in the setting of VAD support.