Overcoming failure of venous vascular prostheses

Area of Science:

• Vascular Surgery
• Biomaterials Science
• Hemodynamics

Background:

• Vascular prostheses in the venous system face high occlusion rates due to graft thrombogenicity, low blood flow velocity, and graft wall collapsibility.
• Addressing these factors is critical for improving the success of venous vascular grafts.

Purpose of the Study:

• To evaluate measures aimed at overcoming the primary causes of vascular prosthesis failure in the venous system.
• To assess the impact of heparin coating and arteriovenous fistula creation on graft patency and thrombogenicity.

Main Methods:

• Assessed expanded polytetrafluoroethylene (ePTFE) graft thrombogenicity using radionuclide-labeled platelet and fibrin deposition in dogs.
• Studied the effects of flow velocity and external support on graft patency in dogs undergoing iliocaval bypass.
• Compared patency rates between ePTFE grafts and autogenous vein grafts with and without an arteriovenous fistula.

Main Results:

• Heparin wetting significantly decreased platelet deposition on ePTFE grafts but did not significantly reduce fibrin deposition.
• An arteriovenous fistula was essential for maintaining the patency of ePTFE grafts.
• External ring support did not significantly improve early patency of ePTFE grafts.
• Autogenous vein grafts did not benefit from the presence of an arteriovenous fistula for patency.

Conclusions:

• Reducing graft thrombogenicity with heparin and increasing blood flow via an arteriovenous fistula are effective strategies to improve venous vascular prosthesis patency.
• Heparinization and arteriovenous fistula creation are key interventions for enhancing the performance of ePTFE grafts in venous applications.