This is a multicenter retrospective study conducted in the six Spanish hospitals performing pediatric heart transplants. Data were collected from patients under 18 years of age who underwent durable VAD implantation between 2006 and 2020.
Most patients were young children with a body surface area (BSA) below 0.7 m², accounting for 63% of the cohort. The predominant initial diagnoses were cardiomyopathy (63.6%, mostly dilated), congenital heart disease (24.6%), myocarditis (9.3%), and early cardiac failure post-heart transplantation (2.5%). Nearly half of the patients were in INTERMACS 2 pre-implantation; 90% required intravenous inotropic support, 72% were on mechanical ventilation, 32% had experienced cardiac arrest, 38% were on extracorporeal membrane oxygenation (ECMO), 28% had renal failure, and 16.5% exhibited hepatic dysfunction (bilirubin >34 µmol/L).
The primary indications for VAD implantation were bridge-to-transplantation (85.6%), bridge-to-decision (9.3%), and bridge-to-recovery (5.1%). Paracorporeal VADs were implanted in 118 children, with the majority being pulsatile-flow (Berlin Heart EXCOR®, 63.3%), followed by continuous-flow (Levitronix®, 30.5%), and a minority using both types (5.9%). Most devices were univentricular and left-sided (64.4%), with biventricular support in 33.9%. Right ventricular support was rarely employed. The median support duration was 30 days, during which 62% of children were weaned off mechanical ventilation.
Common complications included non-cerebral bleeding (39%), stroke (38%), and pump exchange due to device-related issues (34%). Complications were more frequent in continuous-flow devices compared to pulsatile-flow. Despite this, outcomes were favorable, with 70% of patients either transplanted, recovered, or remaining on support at the study’s end. VAD explantation was primarily due to transplantation (62%), with a smaller percentage due to recovery (5%). Hospital discharge survival was achieved in 65% of cases, while in-hospital mortality was 29%, primarily due to multiorgan failure (42.5%) or stroke (27.5%).
Factors associated with higher in-hospital mortality included body weight <5 kg, congenital heart disease, pre-implantation bilirubin >34 µmol/L, and bridge-to-decision strategy. These factors were also inversely related to late survival. INTERMACS category and prior cardiac arrest were linked to reduced long-term survival. However, no significant increase in mortality was observed in children with pre-implantation renal failure or those requiring ECMO before VAD implantation.
In conclusion, VAD implantation in children allows 67% to reach transplantation or recovery. Pre-implantation factors associated with higher mortality were weight <5 kg, congenital heart disease diagnosis, cholestatic liver dysfunction, bridge-to-decision strategy, INTERMACS category, and prior cardiac arrest. Neither renal failure nor pre-implant ECMO use was linked to increased mortality.
COMMENTARY:
This report represents the first collective experience in Spain of medium- and long-term VAD implantation in the pediatric population. The primary indication for these devices in children has been as a bridge-to-transplantation. VAD implantation in children reduces waiting list mortality and increases the likelihood of reaching transplantation. Similar to adult populations, the use of VADs have steadily increased over time, with over 40% of transplanted children now receiving VAD support.
Advancements in anticoagulation protocols and perioperative hemostasis management, including the use of bivalirudin, bedside aggregometry in intensive care units, and meticulous surgical techniques, have reduced VAD-associated complications.
The Berlin Heart EXCOR®, a paracorporeal, pulsatile-flow VAD, supports patients across a range of body sizes, from neonates to adults. In pediatric cases, definitive VAD cannulas are occasionally connected to a centrifugal continuous-flow pump (Levitronix®) to stabilize postoperative inflammatory phases and optimize anticoagulation before transitioning to a Berlin Heart EXCOR® pump. Intracorporeal continuous-flow devices and total artificial hearts, commonly used in adults, are limited to larger children (BSA >0.7 m²) and cannot be used in smaller children.
These Spanish outcomes compare favorably with European and American registries, particularly considering the higher prevalence of small children (BSA <0.7 m²), critical pre-implantation conditions, and the predominance of congenital heart disease compared to cardiomyopathy in this cohort. Durable pediatric VADs provide time to achieve transplantation or recovery in 67% of cases. The main complications are bleeding and thrombosis due to the anticoagulation and antiplatelet therapies required by these devices.
Mortality risk factors in this study align with international data and include low body weight (<5 kg), congenital heart disease, unstable clinical conditions, hepatic dysfunction, and bridge-to-decision indication. However, renal failure and pre-implantation ECMO use were not associated with increased risk. These findings underscore the importance of optimizing the timing of VAD implantation to balance risks of premature exposure against the progression of end-organ dysfunction.
Judicious ECMO use for patient stabilization and organ recovery may enhance outcomes in bridge-to-decision cases. Identifying modifiable factors, such as timing and stabilization strategies, remains critical for improving pediatric VAD outcomes in Spain.
REFERENCE:
Menéndez JJ, Sánchez-Galindo AC, Balcells J, Tejero-Hernández MÁ, Ferrer-Barba Á, Ibiza-Palacios E, et al. Short- and long-term survival of children treated with ventricular assist devices in Spain, based on 15 years’ experience. Eur J Cardiothorac Surg. 2023;63(2):ezad050. doi: 10.1093/ejcts/ezad050.
de By TMMH, Schweiger M, Hussain H, Amodeo A, Martens T, Bogers AJJC, et al. The European Registry for Patients with Mechanical Circulatory Support (EUROMACS): third Paediatric (Paedi-EUROMACS) report. Eur J Cardiothorac Surg. 2022 Jul 11;62(2):ezac355. doi: 10.1093/ejcts/ezac355.
Rossano JW, VanderPluym CJ, Peng DM, Hollander SA, Maeda K, Adachi I, et al; Pedimacs Investigators. Fifth Annual Pediatric Interagency Registry for Mechanical Circulatory Support (Pedimacs) Report. Ann Thorac Surg. 2021;112(6):1763-1774. doi: 10.1016/j.athoracsur.2021.10.001.
