Durable left ventricular assist devices in pediatrics: impact of body size on outcomes and size limitations

Despite the range of body sizes in children, few ventricular assist devices (VAD) exist to support pediatric patients with end-stage heart failure. Large registry data identified weight < 20 kg to be associated with higher rates of VAD-related stroke, compared to > 40 kg. Moreover, patients < 1 years of age experience the highest post-implant mortality, with 1-year survival improving in an age-dependent manner. Within different VAD types, intracorporeal continuous (IC) devices confer the greatest clinical benefit and quality of life compared to paracorporeal alternatives. The major limitation of IC VADs is the technical challenge of implantation into patients of small body size, thus the majority of patients with IC devices are pre-adolescents or older. However, since 2021, the use of HeartMate 3™ (HM3) has expanded to patients as small as 17.7 kg. Although HM3 offers equally favorable survival outcomes irrespective of body size, patients of low body surface area are more likely to experience non-device-related major infections and renal dysfunction, with suggestion for elevated risk of major bleeding and stroke. Innovative imaging strategies have emerged to assess the feasibility of HM3 implantation and facilitate preoperative planning in small children. Moreover, the unmet need for an IC device in the infant population has revived interest in the axial pump, with a pivotal clinical trial currently underway. VAD outcomes in the pediatric population are not equivalent across all ages and body sizes, thus size-stratified analyses and device development to serve the full spectrum of body habitus are key considerations as this field rapidly evolves.