COMPARATIVE THROMBOGENICITY OF PACEMAKER LEADS

To evaluate the thrombogenicity of transvenous silicone and polyuretha ne pacemaker leads, 9 of 12 anesthetized Yorkshire pigs (27-32 kg) wer e implanted with silicone (n = 5) or polyurethane (n = 4) pacemaker le ads via a femoral vein. The remaining three pigs served as controls. A ll 12 pigs were injected with autologous indium-111 labeled platelets (300-420 mu Ci) 24 hours before anesthesia induction. The pigs were mo nitored for 3 hours under a gamma camera. Radioactivity in blood and l ead segments was measured with a gamma counter. Platelet deposits were denser on silicone leads (441.58 +/- 915.0 to 2.19 +/- 2.07) than on polyurethane leads (2.21 +/- 2.33 to 0.27 +/- 0.14) (P > 0.05). Denser platelet deposits were detected at the tip of all leads. Density of p latelet deposits declined from tip to distal segments in silicone lead s. The percentage of injected platelet radioactivity in the lungs of p igs with either silastic leads (12.9 +/- 2.3%) or polyurethane leads ( 10.1 +/- 2.2%) was higher than in the controls (4.6 +/- 0.5%) (P < 0.0 5). This difference indicates thrombus formation and embolization in t he lungs early after lead implantation. Thrombogenicity of polyurethan e leads may be lower than that of silicone leads.