Anti-Thrombogenic Effects of 2-Hydroxyethylmethacrylate-Styrene Block Copolymer and Argatroban in Synthetic Small-Caliber Vascular Grafts in a Rabbit Inferior Vena Cava Model

ABSTRACT

The high anti-thrombogenicity of 2-hydroxyethylmethacrylate (HEMA)-styrene block copolymer (HS) and argatroban-coated polyurethane tubes in a rabbit inferior vena cava model is reported. Polyurethane tubes (i.d. 3.0 mm, o.d. 4.0 mm, 1 2.5 cm) were implanted into the inferior vena cavas of 36 rabbits, weighing 2.5 to 3.5 kg, using the sleeve anastomotic technique. The animals were divided into four groups according to the type of prosthesis: uncoated tubes (Group 1, n = 9); HS-coated tubes (Group 2, n = 9); heparin-coated tubes (Group 3, n = 9); and HS/argatroban-coated tubes (Group 4, n = 9). Patency was evaluated at 1 week by ultrasonic flowmetry and microscopic examination of the grafts. Patency rates were 0 percent (0/9) in Group 1; 56 percent (5/9) in Group 2; 67 percent (6/9) in Group 3; and 100 percent (9/9) in Group 4. Groups 2 and 3 animals demonstrated statistically significantly superior patency compared to those of Group 1. Group 4 animals exhibited significantly superior anti-thrombogenicity compared to those of both Groups 1 and 2. Although Group 3 animals had an excellent patency rate, transmission and scanning electron microscopic views showed a thick protein layer and activated platelets adhering to the surface of Group 3 vessels. On the contrary, only a thin protein layer was noted in Group 4 animals. The HS-treated surface combined with the argatroban slow-release system exhibited excellent anti-thrombogenicity under venous-flow conditions.