Patient and Device Selection in Pediatric MCS: A Review of Current Consensus and Unsettled Questions.

The field of pediatric ventricular assist device (VAD) support has expanded significantly over the past 20 years, with one third of pediatric heart transplant recipients currently being bridged to transplant with a VAD. Despite increased pediatric VAD utilization, however, there remains little formalized guidance for patient or device selection. The population of children with advanced heart failure is quite heterogeneous, and the available data suggest that VAD outcomes vary significantly based upon patient size, anatomy, level of illness, and type of device implanted. In an effort to better understand current practice patterns and identify populations for whom there does not appear to be a consensus approach to achieving optimal VAD outcomes, the Advanced Cardiac Therapies Improving Outcomes Network (ACTION) has surveyed clinical decision-making among member sites and conducted a review of the available literature regarding patient population-specific VAD outcomes and center-specific practices related to patient and device selection. Rather than aiming to provide clinical guidelines, this document offers an overview of contemporary approaches to patient and device selection, highlighting specific populations for whom there is not a consensus approach to achieving reliably good VAD outcomes, as these populations may benefit most from future research and quality improvement efforts directed toward identifying best practice.

Expanding the donor pool for congenital heart disease transplant candidates by implementing 3D imaging-derived total cardiac volumes.

BACKGROUND: Heart transplant waitlist mortality remains high in infants <1 year of age and among those with CHD. Currently, the median accepted donor-to-recipient weight percentage is approximately 130% of the recipient's weight. We hypothesized that patients with CHD may accept a larger organ using novel 3D-derived imaging data to estimate donor and recipient TCV. METHODS: A single-center, retrospective study was performed using CT data for 13 patients with CHD and 94 control patients. 3D visualization software was used to create digital 3D heart models that provide an estimate of TCV. In addition, echocardiograms obtained prior to cross-sectional imaging were reviewed for presence of ventricular chamber dilation. RESULTS: Sixty-two percent (8/13) of patients with CHD had 3D-derived TCV resulting in a weight that was >130% larger than their actual weight. This was seen in single-ventricle patients following Blalock-Taussig shunt and Fontan palliation, and patients with biventricular repair. Of those, 75% (6/8) had reported moderate-to-severe ventricular chamber dilation by echocardiogram or cardiac magnetic resonance imaging. CONCLUSIONS: In a large portion of patients with CHD, 3D-derived TCV place the recipient at a higher listing weight than their actual weight. We propose obtaining cross-sectional imaging to better assess TCV in a recipient, which may increase the donor range for CHD recipients and improve organ utilization in pediatrics.

Post-operative Assessment of the Arterial Switch Operation: A Comparison of Magnetic Resonance Imaging and Echocardiography.

After an arterial switch operation (ASO), serial imaging is necessary to monitor for maladaptive changes. We compared cardiac magnetic resonance imaging (CMR) to 2-D transthoracic echocardiography (TTE) in assessing post-operative ASO patients. We performed a retrospective review of patients at a single tertiary care center who underwent an ASO and subsequently had a CMR performed from 7/2010 to 7/2016. Those with single ventricle anatomy, congenitally corrected transposition of the great arteries, or previous atrial switch operation were excluded. TTE obtained within 6 months of the CMR was used for comparison. Parameters compared included ventricular size and systolic function, semilunar valve regurgitation, neo-aortic root dimension, and the presence of branch pulmonary artery (PA) stenosis (on CMR by the Nakata index or right/left flow differential; on TTE by peak velocity > 2 m/s or PA diameter Z score < - 2). Forty-seven patients with 90 CMR and 86 TTE studies met inclusion criteria. CMR and TTE assessment of right ventricular (RV) and left ventricular function did not statistically differ. RV dilation was overdetected by TTE (p = 0.046). Right pulmonary artery and left pulmonary artery (LPA) visualization by TTE was worse than CMR (p < 0.01). There was no statistically significant difference between CMR and TTE assessment of branch PA stenosis; however, there was poor agreement between the use of Z score and velocity when determining branch PA stenosis by TTE (κ < 0). Assessment of neo-pulmonary regurgitation (PR) and neo-aortic regurgitation (AR) was significantly different between CMR and TTE (p < 0.05). Assessment for delayed enhancement was performed in 18% of CMR studies (n = 16), with perfusion defects appreciated in three patients. Substantial differences between CMR and TTE exist when examining the post-operative ASO patient. CMR was superior for evaluation of the branch PAs, which commonly require re-intervention. TTE failed to recognize altered ventricular function in several cases. Differences between TTE and CMR could alter management is some cases. Incorporation of CMR into the routine surveillance of patients who received an ASO is warranted.

Transcatheter Axial Pump Use in Pediatric Patients on Veno-Arterial Extracorporeal Membrane Oxygenation: An ACTION Collaborative Experience.

We report the largest pediatric multicenter experience with Impella pump use and peripheral veno-arterial extracorporeal membrane oxygenation (VA-ECMO) support. Utilizing the Advanced Cardiac Therapies Improving Outcomes Network (ACTION) collaborative database, we conducted a retrospective, multicenter study of all patients with cardiogenic shock requiring VA-ECMO support with subsequent Impella implant between October 2014 and December 2021. The primary outcome was defined as death while on Impella support. Secondary outcomes were recovery, transplantation, and transition to durable ventricular assist device (VAD) at the time of Impella explantation. Adverse events were defined according to the ACTION registry criteria. Twenty subjects were supported with Impella; Impella 2.5 (n = 3), CP (n = 12), 5.0/5.5 (n = 5). The median Interquartile range (IQR) age, weight, and body surface area at implantation were 15.6 years (IQR = 13.9-17.2), 65.7 kg (IQR = 53.1-80.7), and 1.74 m2 (IQR = 1.58-1.98). Primary cardiac diagnoses were dilated cardiomyopathy/myocarditis in nine (45%), congenital heart disease in four (20%), graft failure/rejection in four (20%), and three (15%) others. Most common adverse events included hemolysis (50%) and bleeding (20%). There were two deaths (10%) in the cohort. Nine patients (45%) were explanted for recovery, eight (40%) were transitioned to a durable VAD, and one (5%) underwent heart transplantation. Impella percutaneous pump support should be considered in the older pediatric population supported with peripheral VA-ECMO, as a means of left heart decompression, and a strategy to come off ECMO to achieve endpoints of myocardial recovery, transition to a durable VAD, or transplantation.

Seventh Annual Society of Thoracic Surgeons Pedimacs Report.

BACKGROUND: The Pediatric Interagency Registry for Mechanical Circulatory Support (Pedimacs), supported by The Society of Thoracic Surgeons, provides detailed information on pediatric patients supported with ventricular assist devices (VADs). METHODS: From September 19, 2012, to December 31, 2022, 1463 devices in 1219 patients aged <19 years were reported to the registry from 40 North American hospitals. RESULTS: Cardiomyopathy remains the most common underlying etiology (59%), followed by congenital heart disease (26%) and myocarditis (8%). Implantable continuous devices were most common (39%) type, followed by paracorporeal pulsatile (28%) and paracorporeal continuous (27%) devices. At 6 months after VAD implantation, a favorable outcome (transplant, recovery, or alive on device) was achieved in 85% of patients, which was greatest among those on implantable continuous VADs (92%) and least for paracorporeal continuous VADs (68%), although the patient population supported on these devices is different. CONCLUSIONS: This Seventh Pedimacs Report demonstrates the continued importance of VADs in the treatment of children. With the complexity of cardiac physiologies and sizes of patients, multiple types of devices are used, including paracorporeal continuous, paracorporeal pulsatile, and implantable continuous devices. The preoperative risk factors and differences in patient populations may account for some of the differences in survival observed among these devices. This report, along with other collaborative work, continues to advance the care of this challenging and vulnerable population.

Heart transplantation in survivors of childhood cancer.

There are approximately 450,000 survivors of childhood cancer due, in large part, to successes of therapeutic regimens. With this success comes an increase in the number of patients developing cardiotoxicity as a result of cancer therapies. In certain cases, this includes heart failure recalcitrant to medical therapy, and consideration for heart transplantation may be necessary. However, this group of patients has unique comorbidities that may affect outcomes. Despite this, available data show that complications and overall survival are similar for patients transplanted for anthracycline-induced cardiomyopathy compared to those with other cardiomyopathies, demonstrating that this is a viable treatment option for this population. As other cancer therapies become more common, new cardiovascular toxicities are recognized. Whether heart transplantation will be appropriate for all patients with cancer-therapy related cardiotoxicity (CTRC) will require demonstration of similarly good outcomes to ensure proper allocation of organs.

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.