Effect of prolonged blood contact time on deposition of cellular and amorphous material on teflon-coated guidewires: a scanning electron microscopy study.

Prolonged contact of blood with guidewires and catheters has been implicated in leading to thromboembolic complications during cardiac catheterization. To study the effect of exposure time on blood product deposition on Teflon-coated guidewires, 35 patients undergoing routine coronary arteriography were randomly assigned to three time groups with exposure of the guidewire to blood of 3, 5, and 10 min, respectively. The exposed wires were examined by scanning electron microscopy, and the micrographs were graded by a pathologist "blinded" as to the exposure time. Deposition of cellular and amorphous material on the guidewire surface and interstices was graded using an arbitrary scale of 1-10 (1, least amount; 10, abundant amount of material). All patients received low-dose systemic administration of heparin (2,500 units) at the beginning of the procedure. The overall activated clotting time (ACT) was 147 +/- 39 sec (mean +/- SD) prior to heparin dose. The mean ACT after low-dose systemic heparin, measured at sheath removal immediately after exposure of the wire to blood had been completed, rose to 241 +/- 79 sec (P < 0.0001). The deposition of cellular and amorphous material on the surface and grooves of the wire was not significantly different at 3, 5, and 10 min. Thus, in this study, Teflon-coated guidewires showed no increase in cellular or amorphous deposits from 3 min to 10 min of blood-wire contact time in the presence of low-dose heparinization.