In Vitro & Animal Studies

Surface Heparinization of Hemodialysis Catheters Reduces Thrombus and Fibrin Sheath Formation

Amy Dwyer, MD (University of Louisville, Louisville, KY)
Sivaprasad Sukavaneshvar (Medical Device Evaluation Center, Salt Lake City, UT)
Shekhar Nimkar (Spire Corporation)
George Aronoff, MD (University of Louisville, Louisville, KY)

INTRODUCTION

Hemodialysis catheters are prone to thrombosis and fibrin sheath formation. To prevent catheter thrombosis, dialysis catheters are stored with heparin between dialysis treatments. However, catheter thrombosis still occurs frequently and there are no measures to prevent biofilm formation.

Surface heparinization with Carmeda BioActive Surface™ (CBAS™) reduces platelet adhesion, thrombosis formation, inflammatory response and bacteremia in coronary stents, ventricular assist devices and central venous catheters.

To test the hypothesis that surface heparinization with CBAS would prevent thrombosis and fibrin sheath formation in hemodialysis catheters, we performed in vitro and in vivo studies using CBAS coated and uncoated Spire Biomedical Decathlon™ catheters.

HYPOTHESIS

Surface heparinization with CBAS prevents thrombus and fibrin sheath formation in Spire Biomedical Decathlon hemodialysis catheters.

METHODS

We performed in vitro and in vivo studies using CBAS coated and uncoated Spire Biomedical Decathlon catheters.

In the in vitro study, we inserted CBAS coated and uncoated Spire Biomedical Decathlon catheters into a 2L loop circuit of fresh Bovine blood. In each experiment, blood from a single animal was divided into separate reservoirs (2.5L each) to provide a simultaneous "paired" comparison. The blood was anticoagulated with 3.5 units/mL of heparin. We set catheter blood flow at 300mL/min for 2 hours and used radiolabeled bovine platelets to estimate platelet deposition and thrombosis. We monitored arterial catheter pressure during the study.

Photographs of the catheter were taken and platelet deposition on the catheter surface was measured in six replications.

In the in vivo study, we implanted CBAS coated and uncoated Spire Biomedical Decathlon catheters into the internal jugular veins of 3 sheep for 30 days. The sheep received hemodialysis with each catheter for 2 hours once weekly at a blood flow rate of 300mL/min. The catheters were explanted and evaluated for thrombus and fibrin sheath formation.

RESULTS

Animal and in vitro studies have demonstrated that the coating reduces total thrombus accumulation by 94% and 96%, respectively, compared to uncoated catheters. The coating was effective in mitigating both disturbed flow-mediated thrombosis (at the catheter tip) and fibrin sheath propogation (on the catheter shaft).

SUMMARY

Coating hemodialysis catheters with CBAS results in decreased fibrin sheath formation.

CONCLUSIONS

Coating hemodialysis catheters with Carmeda BioActive Surface may decrease the incidence of catheter thrombosis.

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