A Closed-Circuit Ex Vivo Perfusion System for Pediatric Solid Organ Transplantation

Abstract

<h3>Purpose</h3> Donation after cardiac death and ex-vivo organ perfusion are increasingly used strategies to mitigate donor organ shortage in cardiac transplantation. These concepts have mainly been established in adults, while neglecting the specific needs for application in children. To address this gap, we have developed an adjustable closed-circuit ex-vivo perfusion system that reduces priming volume, accommodates a wide range of organ sizes, and allows longer support times. <h3>Methods</h3> Silicone-infused thermoplastic polyurethane was used to construct a flexible biocompatible structure to closely envelop the heart. The cone-shaped bottom of the envelope serves as a drainage port to recirculate coronary sinus blood to a pump and oxygenator. Additional ports allow for aortic perfusion, left ventricular venting, deairing, pacing, ECG, and other monitoring. T-slot aluminum extrusion frames were constructed to suspend the device. A microprocessor with custom-built software was incorporated into the design to monitor and store key parameters, such as ECG, temperature, pressure in various compartments, and flow. <h3>Results</h3> Feasibility of ex-vivo perfusion was tested in a mock-loop setup. The design allowed use of commercially available and clinically approved oxygenators (Quadrox-i, Getinge, Sweden) and pumps (Rotaflow, Getinge, Sweden). Envelope design eliminated blood-air contact, while maintaining flow rates up to and above expected resting coronary blood flow values in adult hearts of 300ml/min. Flow consistency could be shown for extended runs of >3h. Perfusion of an isolated pig heart was performed to prove technical validity of the model. <h3>Conclusion</h3> We have developed an initial prototype for a novel ex-vivo organ perfusion capable of accommodating hearts of variable sizes from neonates to adults, ideally suited for the pediatric population. The system further aims at a reduction of blood trauma and foreign surface contact to increase support times without increasing inflammatory response and organ damage.