An Extended Role of Continuous Flow Device in Pediatric Mechanical Circulatory Support

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.

Berlin Heart EXCOR Paediatric Ventricular Assist Device: Does Weight Matter?

BACKGROUND

Berlin Heart EXCOR (BH) ventricular assist devices provide mechanical long-term circulatory support in children with end-stage heart failure, as a bridge to transplantation or to recovery. Most studies are from large-volume paediatric cardiac centres.

AIM

The aim of this study was to analyse the experiences of three French centres and to compare these with available published data.

METHOD

We performed a retrospective observational study of three paediatric cardiac intensive care units. All children supported with BH devices were included. Morbidity and mortality data were collected and risk factors analysed.

RESULTS

Fifty-four (54) patients (54% male) were included. Survival rate was 73% while on a BH device. Median age at BH device implantation was 17 months (range 2-180 months). The predominant indication was dilated cardiomyopathy (61%). Bi-ventricular assist device was used in 25 (46%) cases. The total length of long-term circulatory support was 3,373 days, with a mean length per patient of 62.5 days (range 5-267 days). Thirty-two (32) patients were transplanted (59%) and seven (13%) were successfully weaned. Type and length of support did not influence morbidity. Main complications were renal dysfunction (57%), bleeding (41%), and infection (39%). In multivariate analysis, a weight <5 kg was significantly associated with higher mortality.

CONCLUSIONS

The weight seems to be the most important risk factor of mortality in this precarious condition.

Utilization and outcomes in biventricular assist device support in pediatrics

OBJECTIVE

Patients with biventricular assist devices (BiVADs) have worse outcomes than those with left ventricular assist devices (LVADs). It is unclear whether these outcomes are due to device selection or patient factors. We used propensity score matching to reduce patient heterogeneity and compare outcomes in pediatric patients supported with BiVADs with a similar LVAD cohort.

METHODS

The Pedimacs registry was queried for patients who were supported with BiVAD or LVAD. Patients were analyzed by BiVAD or LVAD at primary implant and the 2 groups were compared before and after using propensity score matching.

RESULTS

Of 363 patients who met inclusion criteria, 63 (17%) underwent primary BiVAD support. After propensity score matching, differences between cohorts were reduced. Six months after implant, in the BiVAD cohort (LVAD cohort) 52.5% (42.5%) had been transplanted; 32.5% (40%) were alive with device, and 15% (10%) had died. Survival was similar between cohorts (P = .31, log-rank), but patients with BiVADs were more likely to experience a major adverse event in the form of bleeding (P = .04, log-rank). At 1 week and 1 and 3 months' postimplant, the percentage of patients on mechanical ventilation, on dialysis, or with elevated bilirubin was similar between the 2 groups.

CONCLUSIONS

When propensity scores were used to reduce differences in patient characteristics, there were no differences in survival but more major adverse events in the patients with BiVADs, particularly bleeding. Differences in unmatched patient outcomes between LVAD and BiVAD cohorts likely represent differences in severity of illness rather than mode of support.

Impact of the 2016 revision of US Pediatric Heart Allocation Policy on waitlist characteristics and outcomes

US Pediatric Heart Allocation Policy was recently revised, deprioritizing candidates with cardiomyopathy while maintaining status 1A eligibility for congenital heart disease (CHD) candidates on "high-dose" inotropes. We compared waitlist characteristics and mortality around this change. Status 1A listings decreased (70% to 56%, P < .001) and CHD representation increased among status 1A listings (48% vs 64%, P < .001). Waitlist mortality overall (subdistribution hazard ratio [SHR] 0.96, P = .63) and among status 1A candidates (SHR 1.16, P = .14) were unchanged. CHD waitlist mortality trended better (SHR 0.82, P = .06) but was unchanged for CHD candidates listed status 1A (SHR 0.92, P = .47). Status 1A listing exceptions increased 2- to 3-fold among hypertrophic and restrictive cardiomyopathy candidates and 13.5-fold among dilated cardiomyopathy (DCM) candidates. Hypertrophic (SHR 6.25, P = .004) and restrictive (SHR 3.87, P = .03) cardiomyopathy candidates without status 1A exception had increased waitlist mortality, but those with DCM did not (SHR 1.26, P = .32). Ventricular assist device (VAD) use increased only among DCM candidates ≥1 years old (26% vs 38%, P < .001). Current allocation policy has increased CHD status 1A representation but has not improved their waitlist mortality. Excessive DCM status 1A listing exceptions and continued status 1A prioritization of children on stable VADs potentially diminish the intended benefits of policy revision.

Current spectrum, challenges and new developments in the surgical care of adults with congenital heart disease

Today, more than two thirds of patients with congenital heart disease (CHD) are adults. Cardiac surgery plays an essential role in restoring and maintaining cardiac function, aside from evolving medical treatment and catheter-based interventions. The aim of the present publication was to describe the spectrum of operations performed on adults with CHD (ACHD) by reviewing current literature. Currently, surgery for ACHD is predominantly valve surgery, since valvular pathologies are often either a part of the basic heart defect or develop as sequelae of corrective or palliative surgery. Surgical techniques for valve repair, established in patients with acquired heart disease (non-ACHD), can often be transferred to ACHD. New valve substitutes may help to reduce the number of redo operations. Most of valve operations yield good results in terms of survival and quality of life, with the precondition that the ventricular function is preserved. Heart failure due to end-stage CHD is the most frequent cause of mortality in ACHD. However, surgical treatment by means of mechanical circulatory support (MCS) is still uncommon and the mortality exceeds the one following other operations in ACHD. Currently, different devices are used and new technical developments are in progress. However, there still is no ideal assist device available. Therefore, heart transplantation remains the only valid option for end-stage CHD. Despite higher early mortality following heart transplantation in ACHD compared to non-ACHD, the long-term survival compares favorably to non-ACHD. There is room for improvement by refining the indications, the time of listing, and the perioperative care of ACHD transplant patients. Sudden death is the second most frequent cause of mortality in ACHD. Ventricular tachycardia is the most frequent cause of sudden death followed by coronary artery anomaly. Due to the increasing awareness of physicians and the improved imaging techniques, coronary artery anomalies are coming more into the focus of cardiac surgeons. However, the reported experience is limited and it is currently difficult to provide a standardized and generally applicable recommendation for the indication and the adequate surgical technique. With the increasing age and complexity of ACHD, treatment of rhythm disturbances by surgical ablation, pacemaker or implantable cardioverter defibrillator (ICD) implantation and resynchronisation gains importance. A risk score specifically designed for surgery in ACHD is among the newest developments in predicting the outcome of surgical treatment of ACHD. This evidence-based score, derived from and validated with data from the Society of Thoracic Surgeons Congenital Heart Surgery Database, enables comparison of risk-adjusted performance of the whole spectrum of procedures performed in ACHD and helps in understanding the differences in surgical outcomes. The score is thus a powerful tool for quality control and quality improvement. In conclusion, new developments in surgery for ACHD are currently made with regard to valve surgery, which comprises more than half of all operations in ACHD and in treatment of end-stage CHD, which still yields high mortality and morbidity.

Current status and future perspectives of the PumpKIN trial

Similar to the adult experience, the use of continuous-flow ventricular assist devices (VADs) has been increasing in the pediatric population. According to the PediMACS registry, continuous-flow VAD currently accounts for >60% of the durable device implantations in the U.S. Nonetheless, the continuous-flow VADs currently in use are designed for adults; this inevitably causes the patient-device size mismatch issue, especially when applied for small children. Pulsatile VADs, therefore, represent the only practical option for this group of patients despite the known risk profile of pulsatile VADs. To address such a frustrating reality, the National Heart, Lung, and Blood Institute (NHLBI) launched the Pediatric Circulatory Support Program in 2004, which is the predecessor of the so-called PumpKIN (Pump for Kids, Infants, and Neonates) program. The goal of this program was to develop mechanical circulatory support devices specifically designed for small children. As a result of extensive efforts of the multi-disciplinary team involving clinicians, scientists, manufactures, and federal agencies, the Infant Jarvik 2015, one of the original devices within the Pediatric Circulatory Support Program, has become the first continuous-flow VAD specifically designed for small children that obtained the Investigational Device Exemption (IDEs) from the U.S. Food and Drug Administration (FDA). This approval is a prerequisite to initiate a clinical trial (i.e., the PumpKIN trial). This article describes the history, current status, and future perspectives of this extremely challenging project, with a focus on the lessons we have learned over the decade.

Biventricular support with HeartWare ventricular assist device in a pediatric patient

Use of ventricular assist devices is increasing in the pediatric population. This has included the extended use of adult continuous-flow devices in the pediatric population. In a minority of cases, biventricular support may be needed. In these situations, biventricular support with continuous-flow devices can be surgically challenging, and therefore, only few cases have been reported. Here, we present a case of implantation of two HeartWare HVAD devices for biventricular support for a decompensating patient with acute myocarditis as well as present an alternative implantation surgical strategy.

Antithrombotic Therapy in a Prospective Trial of a Pediatric Ventricular Assist Device

Efficacious ventricular assist device (VAD) support in pediatric patients depends on successful antithrombotic management. The experience with antithrombotic management for the EXCOR Pediatric VAD Investigational Device Exemption (IDE) study is described. All 68 children in North America enrolled in the IDE study from May 9, 2007 to December 10, 2010 are included. The Edmonton Anticoagulation and Platelet Inhibition Protocol was provided for management guidance. Monitoring parameters, drug dosing, targeted serious adverse events, and pump changes were reviewed. Major bleeding occurred in 43% of all subjects with most events occurring within 14 days of implantation. Bleeding events were probably/definitely related in 24% to antithrombotic management. Neurologic events occurred in 28% of subjects and were probably/definitely related in 9% to antithrombotic therapy intensity. Most neurologic events occurred between 4 and 30 days postimplantation and sporadically thereafter. Pump change occurred in 56% of subjects. Use of an antithrombotic protocol for enrolled subjects was possible in this multicenter study. Incidence of significant bleeding and thromboembolic events was acceptable when balanced against life-saving benefits of VADs. Further studies are needed to optimize the antithrombotic management of this patient population.

Comparison of paracorporeal and continuous flow ventricular assist devices in children: preliminary results

Objectives

With the scarcity of organs, a durable, reliable ventricular assist device (VAD) is required. The Berlin Heart EXCOR ® (BH) remains the most established VAD in the paediatric population. Implantable continuous flow (CF) VADs have been introduced to the paediatric field with encouraging early results. In this study, we compared the results of a newly introduced CF VAD (HeartWare VAD [HVAD] ® ) to results in a matched group of BH recipients.

Methods

The study included patients aged <16 years who received mechanical left VAD (LVAD) support between December 2005 and January 2016. The preimplant characteristics and postimplant outcomes of patients who received the HVAD were compared with those of a matched group who received the BH. Patients with congenital heart disease were excluded.

Results

Thirty patients were included in the study: 13 had received the HVAD and were matched with 17 patients who had received the BH LVAD. The only difference in preimplant characteristics was the need for higher inotropic support in the BH group. There was no difference in the need for right ventricular (RV) support (58.8% for BH vs 53.8% for HVAD, P  = 1.00) or in the incidence of cerebrovascular accidents (12.5% vs 7.7%, respectively, P  = 1.00), though the BH group showed prolonged mechanical ventilation (31.3% vs 0%, P  = 0.047). There were no deaths while on VAD support in either group. Patients with the HVAD showed a bimodal distribution for the primary end point (transplant/explant): All HVAD recipients who also required early RV support reached this end point within 30 days of receiving the implant.

Conclusions

Our early experience with the CF intracorporeal LVAD system (HVAD) indicates outcomes comparable to those with the well-established pulsatile flow paracorporeal LVAD (BH). The theoretical durability of the CF device, which might also allow for the possibility of hospital discharge and better quality of life, is yet to be proven.

Pediatric ventricular assist devices: current challenges and future prospects

The field of mechanical circulatory support has made great strides in the preceding 2 decades. Although pediatric mechanical circulatory support has lagged behind that of adults, the gap between them is expected to close soon. The only device currently approved by the US Food and Drug Administration for use in children is the Berlin Heart EXCOR ventricular assist device (VAD). The prospective Berlin Heart Investigational Device Exemption Trial demonstrated good outcomes, such as bridge to transplantation or recovery, in ~90% of children supported with this device. However, a high incidence of hemorrhagic and thrombotic complications was also noted. As a result, pediatric centers have just started implanting adult intracorporeal continuous-flow devices in children. This paradigm shift has opened a new era in pediatric mechanical circulatory support. Whereas children on VAD were previously managed exclusively in hospital, therapeutic options such as outpatient management and even destination therapy have been becoming a reality. With continued miniaturization and technological refinements, devices currently in development will broaden the range of options available to children. The HeartMate 3 and HeartWare MVAD are two such compact VADs, which are anticipated to have great potential for pediatric use. Additionally, a pediatric-specific continuous-flow VAD, the newly redesigned Jarvik Infant 2015, is currently undergoing preclinical testing and is expected to undergo a randomized clinical trial in the near future. This review aims to discuss the challenges posed by the use of intracorporeal adult continuous-flow devices in children, as well as to provide our perspective on the future prospects of the field of pediatric VADs.