The miniaturization of continuous-flow ventricular assist devices has launched the era of continuous-flow VAD support in pediatric patients, and the trend may accelerate with the introduction of a continuous-flow device designed specifically for small children. In an expert opinion in the Journal of Thoracic and Cardiovascular Surgery, Iki Adachi, MD, of Baylor College of Medicine in Houston, said the emerging science of continuous-flow VADs in children promises to solve problems like device size mismatch, hospital-only VADs, and chronic therapy (J Thorac Cardiovasc Surg. 2017 Oct;154:1358-61). “With ongoing device miniaturization, enthusiasm has been growing among pediatric physicians for the use of continuous-flow VADs in children,” Dr. Adachi said. He noted the introduction of a continuous-flow device for small children, the Infant Jarvik 2015, “may further accelerate the trend.”
Dr. Adachi cited PediMACS reports that stated that more than half of the long-term devices now registered are continuous-flow devices, and that continuous-flow VADs comprised 62% of all durable VAD implants in the third quarter of 2016. “With the encouraging results recorded to date, the use of continuous-flow devices in the pediatric population is rapidly increasing,” he said.
Miniaturization has addressed the problem of size mismatch when using continuous-flow VAD devices in children, he said, noting that use of the Infant Jarvik device may be expanded even further to children as small at 8 kg or less. The PumpKIN trial(Pumps for Kids, Infants, and Neonates), which is evaluating the Infant Jarvik 2015 vs. the Berlin Heart EXCOR, could provide answers on the feasibility of continuous-flow VADs in small children.
“Based on experience with the chronic animal model, I believe that the Infant Jarvik device will properly fit the patients included in the trial,” he said.
Continuous-flow VAD in children also holds potential for managing these patients outside the hospital setting. “Outpatient management of children with continuous-flow VADs has been shown to be feasible,” he said, adding that the PediMACS registry has reported that only 45% of patients have been managed this way. “Nonetheless, with maturation of the pediatric field, outpatient management will become routine rather than the exception,” he said.
Greater use of continuous-flow VADs also may create opportunities to improve the status and suitability for transplantation of children with severe heart failure, he said. He gave as an example his group’s practice at Houston’s Texas Children’s Hospital, which is to deactivate patients on the transplant wait list for 3 months once they start continuous-flow VAD support. “A postoperative ‘grace period’ affords protected opportunities for both physical and psychological recovery,” he said. This timeout of sorts also affords the care team time to assess the myocardium for possible functional recovery.
In patients who are not good candidates for transplantation, durable continuous-flow VADs may provide chronic therapy, and in time, these patients may become suitable transplant candidates, said Dr. Adachi. “Bypassing such an unfavorable period for transplantation with prolonged VAD support may be a reasonable approach,” he said.
Patients with failing single-ventricle circulation also may benefit from VAD support, although the challenges facing this population are more profound than in other groups, Dr. Adachi said. VAD support for single-ventricle disease is sparse, but these patients require careful evaluation of the nature of their condition. “If systolic dysfunction is the predominant cause of circulatory failure, then VAD support for the failing systemic ventricle will likely improve hemodynamics,” said Dr. Adachi. VAD support also could help the patient move through the various stages of palliation.
“Again, the emphasis is not just on simply keeping the patient alive until a donor organ becomes available; rather, attention is refocused on overall health beyond survival, which may eventually affect transplantation candidacy and even post transplantation outcome,” Dr. Adachi concluded.
Dr. Adachi serves as a consultant and proctor for Berlin Heart and HeartWare, and as a consultant for the New England Research Institute related to the PumpKIN trial.