Mechanical circulatory support challenges in pediatric and (adult) congenital heart disease:

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.

Updates in the management of congenital heart disease in adult patients

INTRODUCTION

Adults with congenital heart disease represent a highly diverse, ever-growing population. Optimal approaches to management of problems such as arrhythmia, sudden cardiac death, heart failure, transplant, application of advanced therapies and unrepaired shunt lesions are incompletely established. Efforts to strengthen our understanding of these complex clinical challenges and inform evidence-based practices are ongoing.

AREAS COVERED

This narrative review summarizes evidence underpinning current approaches to congenital heart disease management while highlighting areas requiring further investigation. A search of literature published in 'Medline,' 'EMBASE,' and 'PubMed' using search terms 'congenital heart disease,' 'arrhythmia,' 'sudden cardiac death,' 'heart failure,' 'heart transplant,' 'advanced heart failure therapy,' 'ventricular assist device (VAD),' 'mechanical circulatory support (MSC),' 'intracardiac shunt' and combinations thereof was undertaken.

EXPERT OPINION

Application of novel technologies in the diagnosis and management of arrhythmia has and will continue to improve outcomes in this population. Sudden death remains a prevalent problem with many persistent unknowns. Heart failure is a leading cause of morbidity and mortality. Improved access to specialist care, advanced therapies and cardiac transplant is needed. The emerging field of cardio-obstetrics will continue to define state-of-the-art care for the reproductive health of women with heart disease.

Computational Evaluation of Cardiac Function in Children Supported with Heartware VAD, HeartMate 2 and HeartMate 3 Left Ventricular Assist Devices

Heart failure is one of the principal causes of morbidity and mortality in children. Treatment techniques may not work, and heart transplantation may be required as a result. The current state of donor-organ supply means that many patients cannot undergo transplantation. In these patients, ventricular assist devices (VADs) may be used to bridge the time until the transplantation. Continuous-flow VADs are increasingly being implanted to paediatric patients. The aim of this study was to evaluate cardiac function in children supported with Heartware HVAD, HeartMate2 and HeartMate3 devices using computational simulations. A lumped-parameter model simulating cardiac function in children around 12 years of age was used to simulate dilated cardiomyopathy and heart-pump support. The operating speeds in HVAD, HeartMate2 and HeartMate3 were selected as 2600 rpm, 8700 rpm and 5200 rpm constant speed, respectively, while the Lavare cycle and artificial-pulse modes were used to generate mean pump outputs at around 4.40 L/min and mean arterial pressures at around 82 mmHg in each device. Aortic pulse pressure was 11 mmHg, 14 mmHg and 6 mmHg under HVAD, HeartMate2 and HeartMate3 support, respectively. HVAD’s Lavare cycle and HeartMate3’s artificial pulse increased aortic pulse pressure to 15 mmHg and 20 mmHg. HeartMate3 with artificial-pulse mode may be more beneficial in reducing arterial-pulsatility-associated problems.

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.

Pediatric ventricular assist device registries: update and perspectives in the era of miniaturized continuous-flow pumps

The success of ventricular assist devices (VADs) in the treatment of end-stage heart failure in the adult population has led to industrial innovation in VAD design, focusing on miniaturization and the reduction of complications. A byproduct of these innovations was that newer generation devices could have clinical applications in the pediatric population. Over the last decade, VAD usage in the pediatric population has increased dramatically, and the newer generation continuous flow (CF) devices have begun to supplant the older, pulsatile flow (PF) devices, formerly the sole option for ventricular assist in the pediatric population. However, despite the increase in VAD implants in the pediatric population, patient numbers remain low, and the need to share data between pediatric VAD centers has become that much more important for the continued growth of VAD programs worldwide. The creation of pediatric VAD registries, such as the Pediatric Registry for Mechanical Circulatory Support (PediMACS), the European Registry for Patients with Mechanical Circulatory Support (EUROMACS) and the Advanced Cardiac Therapies Improving Outcomes Network (ACTION) has enabled the collection of aggregate data from VAD centers worldwide, and provides a valuable resource for clinicians and programs, as more and more pediatric heart failure patients are considered candidates for VAD therapy.

Mechanical Support for The Failing Single Ventricle at Pre-Fontan Stage: Current State of The Field and Future Directions

With the substantial growth of pediatric ventricular assist device (VAD) support, there has been an expansion of the target population towards more complex patients, including congenital heart disease (CHD) with single ventricle (SV) physiology. The outcomes of Stage I and Stage II SV-CHD patients on VAD support from the Pedimacs database are poor, with less than 50% survival on VAD by the 3-month mark in both. The primary objective of this article is to describe the current state of VAD support for the failing Stage I and II SV-CHD circulation, to provide insight into potential areas of outcome improvement. We reviewed the published literature in the form of database and registry reports as well as single-center studies to discuss the outcomes of Stage I and Stage II SV-CHD patients on VAD support. Registry-based studies suggest that VAD support for the failing Stage I and Stage II SV-CHD circulations is challenging. However, the more promising outcomes in several single-institutional reports for both Stage I and Stage II SV-VAD indicate that the grim picture from the databases does not reflect the best outcomes that are possible to be achieved, potentially at experienced centers with higher volumes. Areas of future study and potential improvement including timely initiation of VAD support in the cohort of patients expected to not be a candidate for standard SV palliations, pump selection and the benefits of continuous-flow devices, and the decision-making for setting up the optimum circulation for VAD support, be it Fontan completion if feasible or takedown to shunt physiology.

Transplantation in Congenital Heart Disease: A Challenge

BACKGROUND

Heart failure is the leading cause of death in grown-up congenital heart disease patients (GUCH). Although heart transplantation (OHT) remains the gold standard in end-stage heart failure, the ratio of GUCH patients undergoing this procedure remains low.

OBJECTIVE

Describe the cohort of GUCH patients undergoing heart transplantation at a third-level hospital.

METHODS

A retrospective review of GUCH patients undergoing OHT between 1997 and 2019 was conducted at a single tertiary university hospital. We included different preoperative (demographic and clinical data, cardiac catheterization data from the last routine hemodynamic monitoring) and postoperative variables (complications, survival).

RESULTS

Fourteen patients were enrolled. The median age was 25.5 years (range, 20.7-32.2). Eight patients (57.1%) were male. The median preoperative left ventricular ejection fraction was 37% (range, 22.5%-55%). As for preoperative hemodynamic evaluation, the median for the mean arterial pulmonary pressure was 19 mm Hg (range, 12-22.5), for the capillary wedge pressure was 16 mm Hg (range, 13.5-19.5), and for pulmonary vascular resistance was 1.83 Wood units (range, 1-4). After OHT, 6 patients (42.9%) suffered an infection, the most common of which was respiratory (3 out of 6). Four patients (28.6%) needed renal replacement therapy, and 4 patients (28.6%) presented liver failure. Four patients (28.6%) developed graft failure, thus requiring mechanical support with extracorporeal membrane oxygenation during a median of 6 days (range, 1-17.5). Survival rate of patients under extracorporeal membrane oxygenation was 50%, and overall survival rate was 78.6%.

CONCLUSION

OHT represents a good option for GUCH patients, with good overall survival rates.

Pulmonary Artery Banding for Ventricular Rehabilitation in Infants With Dilated Cardiomyopathy: Early Results in a Single-Center Experience

Background: Pulmonary artery banding (PAB) is reported as an innovative strategy for children with end-stage heart failure (ESHF) to bridge to transplantation or recovery. We report our early experience with PAB to evaluate outcomes, indications, and limitations. Materials and Methods: This is a single-center prospective clinical study, including infants and children admitted for ESHF owing to dilated cardiomyopathy (DCM) with preserved right ventricular function after failure of maximal conventional therapy. All patients underwent perioperative anticongestive medical therapy with ACE inhibitor, beta blocker, and spironolactone. Post-operatively, all patients underwent echocardiographic follow-up to assess myocardial recovery. Results: We selected five patients (four males) who underwent PAB at a median age of 8.6 months (range 3.9-42.2 months), with preoperative ejection fraction (EF) <30%. Sternal closure was delayed in all. One patient did not improve after PAB and underwent Berlin Heart implantation after 33 days, followed by heart transplant after 13 months. Four patients were discharged home on full anticongestive therapy. However, 2 months after discharge, one patient experienced severe acute heart failure secondary to pneumonia, which required mechanical circulatory support, and the patient underwent a successful heart transplant after 21 days. The remaining three patients are doing well at home, 22.4, 16.9, and 15.4 months after PAB. They all underwent elective percutaneous de-banding, 18.5, 4.8, and 10.7 months after PAB. EF increased from 17.7 ± 8.5% to 63.3 ± 7.6% (p = 0.03), and they have all been delisted. Conclusion: Use of PAB may be an effective alternative to mechanical support in selected infants for bridging to transplant or recovery. Better results seem to occur in patients aged <12 months. Further experience and research are required to identify responders and non-responders to this approach.

Heart Failure in Adult Patients with Congenital Heart Disease

Adult patients with congenital heart disease are a complex population with a variety of pathophysiologic conditions based on the anatomy and type of surgery or intervention performed, usually during the first years of life. Nowadays, the majority of patients survive childhood and present for a number of noncardiac surgeries or interventions needing appropriate perioperative management. Heart failure is a major contributing factor to perioperative morbidity and mortality. In this review, we present an overview of the most common types of adult patients with congenital heart disease and actual knowledge on therapy and specific risks in this challenging patient population.

Antithrombin Population Pharmacokinetics in Pediatric Ventricular Assist Device Patients

OBJECTIVES

Describe the pharmacokinetics of antithrombin in pediatric patients undergoing ventricular assist device therapy and provide dosing recommendations for antithrombin in this population.

DESIGN

A retrospective population pharmacokinetic study was designed.

SETTING

Large tertiary care children's hospital Subject inclusion criteria consisted of less than 19 years old.

PATIENTS

Subjects less than 19 years old undergoing therapy with a HeartWare ventricular assist device (HeartWare, Framingham, MA) or Berlin EXCOR ventricular assist device (Berlin GmbH, Berlin, Germany), who received a dose of antithrombin with a postdose antithrombin activity level from January 1, 2011, to June 30, 2017.

INTERVENTIONS

Population pharmacokinetic analysis and simulation using NONMEM v.7.4 (Icon, PLC, Dublin, Ireland).

MEASUREMENTS AND MAIN RESULTS

A total of 41 patients met study criteria (median age, 5.8 years [interquartile range, 1.6-9.9 yr]), and 53.7% underwent therapy with the pulsatile Berlin EXCOR pediatric ventricular assist device (Berlin Heart GmbH, Berlin, Germany). All patients received unfractionated heparin continuous infusion at a mean ± SD dose of 29 ± 14 U/kg/hr. A total of 181 antithrombin doses (44.1 ± 24.6 U/kg/dose) were included, and baseline antithrombin activity levels were 77 ± 12 U/dL. Antithrombin activity levels were drawn a median 19.9 hours (interquartile range, 8.8-41.6 hr) after antithrombin dose. A one-compartment proportional error model best fit the data, with allometric scaling of fat-free mass providing a better model fit than actual body weight. Unfractionated heparin and baseline antithrombin were identified as significant covariates. A 50 U/kg dose of antithrombin had a simulated half-life 13.2 ± 6.6 hours.

CONCLUSIONS

Antithrombin should be dosed on fat-free mass in pediatric ventricular assist device patients. Unfractionated heparin dose and baseline antithrombin activity level should be considered when dosing antithrombin in pediatric ventricular assist device patients.

Mechanical circulatory support in children: past, present and future

Rapid advances in the field of mechanical circulatory support (MCS) have dramatically changed the management of pediatric patients with heart failure. There is now emphasis on timely implantation of ventricular assist devices (VADs) to preserve or recover end-organ function, and increased focus on post-implant management to improve the stroke rate. Transplant waitlist mortality has significantly decreased in the era of VAD use. Devices approved for adults are being used off-label in children with excellent outcomes, allowing chronic therapy and discharge home to become part of pediatric VAD therapy.

Utilization of an Abiomed Impella Device as a Rescue Therapy for Acute Ventricular Failure in a Fontan Patient

Progressive ventricular dysfunction is not uncommon in patients with univentricular hearts as they age. In the acute setting vasoactive support can be employed, but is not always sufficient and patients occasionally require mechanical support. We report the successful implantation and subsequent challenges of a percutaneous Abiomed Impella ventricular assist device as a rescue therapy for a 15-year old-patient with Fontan circulation and severe ventricular dysfunction after cardiac arrest.

Effects of pulmonary artery banding in doxorubicin-induced left ventricular cardiomyopathy

OBJECTIVE

Central pulmonary banding has been proposed as a novel alternative for the treatment of left ventricular dilated cardiomyopathy in children. We sought to investigate the effects of central pulmonary banding in an experimental model of doxorubicin-induced left ventricular dilated cardiomyopathy.

METHODS

Four-month-old sheep (n = 28) were treated with intermittent intracoronary injections of doxorubicin (0.75 mg/kg/dose) into the left main coronary artery. A total dose of up to 2.15 mg/kg of doxorubicin was administered until signs of left ventricular dilation with functional impairment occurred by transthoracic echocardiography evaluation. Animals that survived were treated with surgical central pulmonary banding through a left anterior thoracotomy or sham surgery. Transthoracic echocardiography and pressure-volume loop measurements were used to compare left ventricular function preoperatively and 3 months later. Macroscopic and microscopic histologic examinations followed after hearts were harvested.

RESULTS

Nine animals from the central pulmonary banding group and 8 animals from the sham group survived and were included in the final analysis. Both groups showed similar inflammation and fibrosis upon histologic examination consistent with the toxic myocardial effects of doxorubicin. There were no differences in the echocardiographic measurements before central pulmonary banding or sham operation. Baseline measurements before the central pulmonary banding/sham operation were considered as 100%. The central pulmonary banding group had better left ventricular ejection fraction (102.5% ± 21.6% vs 76.7% ± 11.7%, P = .01), with a tendency for smaller left ventricular end-diastolic (101.2% ± 7.4% vs 120.4% ± 10.8%, P = .18) and significantly smaller end-systolic (100.3% ± 12.9% vs 116.5 ± 9.6%, P = .02) diameter of the left ventricle in comparison with the sham animals at 3 months. The end-systolic volume (101.4% ± 31.6% vs 143.4% ± 28.6%, P = .02) was significantly lower in the central pulmonary banding group 3 months postoperatively. Fractional shortening in the long axis (118.5% ± 21.5% vs 85.2% ± 22.8%, P = .016) and short axis (122.5% ± 18% vs 80.9% ± 13.6%, P = .0005) revealed significantly higher values in the central pulmonary banding group. In the conductance catheter measurements, no significant differences were seen between the groups for the parameters of systolic and diastolic function.

CONCLUSIONS

Central pulmonary artery banding in the setting of experimental toxic left ventricular dilated cardiomyopathy improved left ventricular echocardiographic function and dimensions.