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Introduction: Prolonged intra-luminal arterial shunting for traumatic vascular injuries has become important for limb salvage. Recent international military conflict has confirmed the utility of staged repair of such injuries using these devices. Commercially available shunts may be limited by their diameter for use in large peripheral vessels. Shunt thrombosis remains an under-reported and major concern for surgeons where systemic anti-coagulation may be hazardous. We aimed to study the efficacy of a doppler probe enabled intra-arterial shunt coated with a commercially available anti-thrombotic lining in the setting of prolonged arterial shunting in a bench-top model.
Methods: A closed-loop system using cardio-pulmonary bypass tubing and a centrifugal pump (Sarns Delphin II, Terumo, Somerset, NJ) was designed to support a Pruiit-Inahara shunt with an implanted doppler probe (Implantable Devices, Pinellas Park, FL). The shunts were prepared with a commercially available anti-thrombotic lining (DUALITYTM-EF50L, Hydromer, Branchberg, NJ). Sheep blood (125 ml) was introduced into the closed circuit and its anti-coagulation for storage (CPDA) reversed with calcium chloride. The system was run at 2000 rpm using uncoated (control) and coated (experimental) shunts for 3, 6, 9, and 12 hours or until thrombosis was observed in the shunt. The 12 hour samples were preserved in glutaraldehyde, treated with an ethanol drying series, and evaluated using scanning electron microscopy (SEM) to identify platelet adherence.
Results: All four control shunts (3,6,9,12 hours) achieved the established endpoint of complete system thrombosis with loss of doppler signal. All four experimental shunts using the anti-thrombotic coating remained patent without evidence of doppler signal loss or attentuation. Minor thrombus was observed in the running system using the coated shunts, but this did not affect blood flow. Under SEM, significant platelet aggregation was observed in the control shunt at 12 hours. The coated shunt at 12 hours did not show any evidence of platelet adherence. The coating was additionally found to be intact at 12 hours.
Conclusion: These preliminary results suggest future shunt design may include anti-thrombotic linings to prevent thrombosis and maintain patency when systemic anti-coagulation is not possible.