Fluid Dynamic Study of the Penn State Pediatric Total Artificial Heart

Penn State University is developing a pediatric total artificial heart (TAH) as a bridge-to-transplant device that supports infants and small children with single ventricle anomalies or biventricular heart failure to address high waitlist mortality rates for pediatric patients with severe congenital heart disease (CHD). Two issues with mechanical circulatory support devices are thrombus formation and thromboembolic events. This in vitro study characterizes flow within Penn State's pediatric total artificial heart under physiological operating conditions. Particle image velocimetry (PIV) is used to quantify flow within the pump and to calculate wall shear rates (WSRs) along the internal pump surface to identify potential thrombogenic regions. Results show that the diastolic inflow jets produce sufficient wall shear rates to reduce thrombus deposition potential along the inlet side of the left and right pumps. The inlet jet transitions to rotational flow, which promotes wall washing along the apex of the pumps, prevents flow stasis, and aligns flow with the outlet valve prior to systolic ejection. However, inconsistent high wall shear rates near the pump apex cause increased thrombogenic potential. Strong systolic outflow jets produce high wall shear rates near the outlet valve to reduce thrombus deposition risk. The right pump, which has a modified outlet port angle to improve anatomical fit, produces lower wall shear rates and higher thrombus susceptibility potential (TSP) compared to the left pump. In summary, this study provides a fluid dynamic understanding of a new pediatric total artificial heart and indicates thrombus susceptibility is primarily confined to the apex, consistent with similar pulsatile heart pumps.

EXCOR membrane motion analyzer (EMMA) to quantify and assess hemodynamic performance of the EXCOR pediatric heart assist device

BACKGROUND

Pediatric heart failure is associated with high mortality rates and is a current clinical burden. There is only one FDA approved pediatric VAD, Berlin Heart EXCOR, for treatment. Thrombo-embolic complications are a significant clinical challenge, which can lead to devastating complications such as stroke and impair efficient EXCOR function. Currently, clinicians perform largely qualitative periodic assessment of EXCOR operation by observing the motion of a rapidly moving membrane, which can be prone to human error and can lead to missing out on crucial information.

METHODS

In this study, we design and implement a quantitative early warning system for accurate and quantitative assessment of the EXCOR membrane, named EXCOR Membrane Motion Analyzer (EMMA). Using a combination of image analysis, computer vision and custom designed algorithm, we perform rigorous frame by frame analysis of EXCOR membrane video data. We developed specialized metrics to identify relative smoothness between successive peaks, time between peaks and overall smoothness indicators to quantify and compare between multiple cases.

RESULTS

Our results demonstrate that EMMA can successfully identify the motion and wrinkles on each video frame and quantify the smoothness and identify the phases of each cardiac cycle. Moreover, EMMA can obtain the smoothness of each frame and the temporal evolution of membrane smoothness across all image frames for the video sequence.

CONCLUSIONS

EMMA allows for a fast, accurate, quantitative assessment to be completed and reduces user error. This enables EMMA to be used effectively as an early warning system to rapidly identify device abnormalities.

Successful explantation of children from the Berlin Heart EXCOR® ventricular assist device: A systematic review

BACKGROUND

The Berlin Heart EXCOR® (BHE) can bridge children with severe heart failure to transplantation, but some are successfully weaned and spared transplantation. This study seeks to identify characteristics of children amenable to successful explantation with BHE support.

METHODS

Preferred Reporting Items for Systematic reviews and Meta-Analyses 2020 guidelines were used. Five databases were screened for original, English articles measuring BHE support in patients <18 years old based on title and abstract. Exclusion criteria were applied: full-text availability, <10 total pediatric BHE patients, zero successful explantations from BHE, nonprimary literature, adult and pediatric results that could not be separated, and studies with overlapping patient information. Studies were analyzed with descriptive statistics.

RESULTS

From 41 857 potential studies, 14 were analyzed with data from 58 hospitals on four continents from 1990 to 2020. There were 984 BHE patients. The most common diagnosis was dilated cardiomyopathy (n = 318, 32.3%), followed by congenital heart disease (n = 249, 25.3%). There were 85 (8.6%) children explanted with favorable outcomes. The underlying diagnosis was known in 44 (51.8%) cases: 14 (8.4%) of 166 cardiomyopathies, 17 (48.6%) of 35 myocarditis, and 12 (16.7%) of 72 with congenital heart disease were explanted. When the type of support was known, the rate of LVAD patients explanted was 21.3% (n = 19/89) and 2.4% (n = 1/42) of BiVAD patients were explanted.

CONCLUSION

Explantation from BHE is not uncommon at 8.6%, but significant variation exists in the explantation data reported. Myocarditis and LVAD support may be populations suitable for weaning. Standardization of reporting measures and prospective registries may help identify patients suitable for this alternative to transplant and help develop weaning protocols.

Case Report: Sustained ventricular arrhythmia in a child supported by a Berlin heart EXCOR ventricular assist device

Mechanical circulatory support is an established therapy to support failing hearts as a bridge to transplantation. Although tolerated overall, arrhythmias may occur after ventricular assist device implantation and can complicate patient management. We report on an infant with dilated cardiomyopathy who developed ventricular tachycardia followed by recalcitrant ventricular fibrillation, refractory to comprehensive medical therapy post Berlin Heart EXCOR® (BHE) implant.

Echocardiographic imaging and ventricular mechanics in pulsatile-flow LVAD pediatric patients: a systematic approach

Echocardiography plays a crucial role in determining the eligibility for left ventricular assist device (LVAD) placement in patients experiencing advanced heart failure (HF) and in monitoring patient care after the implantation procedure. Because of its unique nature, pediatric population and pulsatile-flow LVADs used in pediatrics require specific skills so that pediatric echocardiographers must develop a systematic approach in order to image the patients pre and post LVAD implantation. Therefore, the purpose of this narrative review is to delineate a systematic echocardiographic approach for pediatric patients supported by pulsatile-flow LVADs.

Mechanical Circulatory Assistance in Children: Clinical Outcome

BACKGROUND

In countries where organ donation is scarce, mortality in the pediatric heart transplant waiting list is high, and ventricular assist devices (VADs) are therapeutic alternatives in these situations. Berlin Heart EXCOR is currently 1 of the few VADs specific for children.

METHODS

This retrospective study includes pediatric patients who underwent Berlin Heart EXCOR placement in a Brazilian hospital between 2012 and 2021. Clinical and laboratory data at the time of VAD implantation and the occurrence of complications and outcomes (success as a bridge to transplant or death) were analyzed.

RESULTS

Eight patients, from 8 months to 15 years, were included: 6 with cardiomyopathy and 2 with congenital heart disease. Six were on Intermacs 1 and 2 on Intermacs 2. The most common complications observed were stroke and right ventricular dysfunction. Six were transplanted, and 2 died. Those submitted to transplant had a higher mean weight than those who died, with no statistically significant difference. The underlying disease had no impact on the outcome. The group undergoing transplant had lower brain natriuretic peptide and lactate values, but no laboratory variable showed a statistically significant difference in the outcome.

CONCLUSION

A VAD is an invasive treatment with potentially serious adverse effects and is still poorly available in Brazil. However, as a bridge to transplant, it is a useful treatment for children in progressive clinical decline. In this study, we did not observe any clinical or laboratory factor at the time of VAD implantation that implied better outcomes.

Mechanical circulatory support devices and treatment strategies for right heart failure

The importance of right heart failure (RHF) treatment is magnified over the years due to the increased risk of mortality. Additionally, the multifactorial origin and pathophysiological mechanisms of RHF render this clinical condition and the choices for appropriate therapeutic target strategies remain to be complex. The recent change in the United Network for Organ Sharing (UNOS) allocation criteria of heart transplant may have impacted for the number of left ventricular assist devices (LVADs), but LVADs still have been widely used to treat advanced heart failure, and 4.1 to 7.4% of LVAD patients require a right ventricular assist device (RVAD). In addition, patients admitted with primary left ventricular failure often need right ventricular support. Thus, there is unmet need for temporary or long-term support RVAD implantation exists. In RHF treatment with mechanical circulatory support (MCS) devices, the timing of the intervention and prediction of duration of the support play a major role in successful treatment and outcomes. In this review, we attempt to describe the prevalence and pathophysiological mechanisms of RHF origin, and provide an overview of existing treatment options, strategy and device choices for MCS treatment for RHF.

Application of Different Ventilation Modes Combined with AutoFlow Technology in Thoracic Surgery

To investigate the effect of AutoFlow on airway pressure and hemodynamics in mechanical ventilation constant volume-control ventilation mode, 100 patients receiving mechanical ventilation were randomly divided into observation group (SIMV-PSV-PEEP + AutoFlow) and control group (SIMV-PSV-PEEP). The results showed that the peak airway pressure and average airway pressure decreased with different flow rate settings and automatic flow conversion (P < 0.05). The peak airway pressure and mean airway pressure decreased with different resistance settings (P < 0.05). With different compliance settings, the peak airway pressure and average airway pressure decreased after being assisted with an automatic converter (P < 0.05). Adding AutoFlow on the basis of SIMV-PSV mode can significantly reduce peak inspiratory pressure (PIP), mean airway pressure (Pmean), and airway resistance (R). There was no significant difference in hemodynamic monitoring results between the observation group and the control group. It is proved that the SIMV constant volume-controlled ventilation mode combined with AutoFlow can not only ensure tidal volume but also avoid excessive airway pressure, which has little effect on hemodynamics.

Surgical strategies for the management of end-stage heart failure in infants and children: A 15-year experience with a patient-tailored approach

End‐stage heart failure (ESHF) in pediatric age is an ongoing challenge. Heart transplantation is the final option, but its long‐term outcomes are still suboptimal in children. An alternative patient‐tailored surgical protocol to manage ESHF in children is described. Retrospective, single‐center analysis of pediatric patients admitted to our institution between April 2004 and February 2021 for ESHF. Our current protocol is as follows: (a) Patients <1 year with isolated left ventricular dysfunction due to dilated cardiomyopathy underwent pulmonary artery banding (PAB). (b) Patients <10 years and <20 kg, who did not meet previous criteria were managed with Berlin Heart EXCOR. (c) Patients >10 years or >20 kg, underwent placement of intracorporeal Heartware. Primary outcomes were survival, transplant incidence, and postoperative adverse events. A total of 24 patients (mean age 5.3 ± 5.9 years) underwent 26 procedures: PAB in 6 patients, Berlin Heart in 11, and Heartware in 7. Two patients shifted from PAB to Berlin Heart. Overall survival at 1‐year follow‐up and 5‐year follow‐up was 78.7% (95%CI = 62%‐95.4%) and 74.1% (95%CI = 56.1%‐92.1%), respectively. Berlin Heart was adopted in higher‐risk settings showing inferior outcomes, whereas a PAB enabled 67% of patients to avoid transplantation, with no mortality. An integrated, patient‐tailored surgical strategy, comprehensive of PAB and different types of ventricular assist devices, can provide satisfactory medium‐term results for bridging to transplant or recovery. The early postoperative period is critical and requires strict clinical vigilance. Selected infants can benefit from PAB that has demonstrated to be a safe bridge to recovery.

Cardiac MRI Detection of Left Ventricular Aneurysm in Children After Ventricular Assist Device Explantation

Consensus is lacking regarding screening for complications such as ventricular aneurysms after ventricular assist device explant. We report two pediatric patients, status-post explantation, who developed true left ventricular apical aneurysms diagnosed by cardiac magnetic resonance imaging. Imaging also suggested laminated thrombus versus postoperative changes which were treated with antiplatelet therapy.

Neurologic complications of pediatric congenital heart disease

Improved medical management and surgical outcomes have significantly decreased mortality in children with congenital heart disease; however, with increased survival, there is a greater lifetime exposure to neurologic complications with serious long-term neurodevelopmental consequences. Thus, recent focus has shifted to recognition and reduction of these extracardiac comorbidities. Vascular and infective complications, such as arterial ischemic stroke, infective endocarditis, and localization-related epilepsy are some of the most common neurologic comorbidities of congenital heart disease. In addition, it is now well recognized that congenital heart disease has an impact on overall brain development and contributes to adverse neurodevelopmental outcomes across multiple domains. The goal of this chapter is to summarize the most common neurologic comorbidities of congenital heart disease and its management.

The First Pediatric Heart Transplantation Bridged by a Durable Left Ventricular Assist Device in Korea

Treatment options for children with end-stage heart failure are limited. We report the first case of a successful pediatric heart transplantation bridged with a durable left ventricular assist device in Korea. A 10-month-old female infant with dilated cardiomyopathy and left ventricular non-compaction was listed for heart transplantation. During the waiting period, the patient’s status deteriorated. Therefore, we decided to provide support with a durable left ventricular assist device as a bridge to transplantation. The patient was successfully bridged to heart transplantation with effective support and without any major adverse events.

Pediatric ventricular assist device therapy for advanced heart failure-Hong Kong experience

Ventricular assist devices (VADs) are life-saving options for children with heart failure unresponsive to medical therapy as a bridge to transplantation or cardiac recovery. We present a retrospective review of 13 consecutive children who underwent implantation of VAD between 2001 and 2018 in our center. The median age was 12 years (1-17 years), weight was 45 kg (10-82 kg). Etiologies of heart failure were dilated cardiomyopathy (CMP) (n = 8), myocarditis (n = 2), ischemic CMP (n = 1), restrictive CMP (n = 1) and congenital heart disease (n = 1). Pre-implantation ECMO was used in 5, mechanical ventilation in 4, renal replacement therapy in 2 and IABP in 1. Devices used were: Berlin Heart EXCOR left VAD (LVAD), biventricular VAD (BIVAD) (n = 5, 2), CentriMag LVAD, BIVAD (n = 1, 2), HeartWare (n = 2), HeartMate II (n = 1). Median duration of support was 45 days (3-823 days). Overall survival was 85%. Four patients were successfully bridged to transplantation, 2 died while on a device, 4 remain on support and 3 were weaned from VAD. Late death occurred in 2 transplanted patients. Complications included bleeding requiring reoperation in 1, neurologic events in 3, driveline infections and pericardial effusion in 2 each. In one patient, CentriMag BIVAD provided support for 235 days, which is longest reported duration on such a VAD in the Asia Pacific region. Survival for pediatric patients of all ages is excellent using VADs. Given the severity of illness in these children morbidity and mortality is acceptable. VADs could potentially be used as a long-term bridge to transplantation in view of the donor shortage in the pediatric population.