Thrombosis of angiographic catheters in humans: experimental study

One of the major problems in the use of catheters is their thrombogenicity since the embolization of clots near the central nervous system or the coro nary arteries can cause permanent damage. Catheter thrombogenicity was evaluated in humans during angiographic proced ures by their tendency to become occluded. Characterization of catheters wa s achieved using roughness measurements, FTIR with ATR, DSC and ESCA. The c atheters were 5 commercially available catheters, made mainly of polyethyle ne, Pebaux(R) or polyamide sterilized and ready for clinical use. Thirty-on e patients due to have an angiographic procedure and with normal blood and hemodynamic parameters were included in the study. The 50 cm catheter test sample was inserted through an introducer into the femoral artery at the be ginning of an angiographic procedure. The outcoming blood flow rate (BFR) w as continuously monitored by a special computerized device for 15 min or un til the total amount of blood reached 30 ml. The angiographic procedure was then normally resurned. DSC and FTIR showed results consistent with the expected composition of cat heters. ESCA results showed very high Si/C ratios and could not be explaine d in all instances. Occlusion of the catheters occurred in 44 % of the cases and the average ti me to obtain occlusion was 8.5 min (3-15 min). Values of the decrease rate of BFR in ml/min(2) allowed separate of the catheters into 3 groups of low, medium and high thrombogenicity. However, occlusion occurred at least one time for each type of catheter. Blood volume and BFR curves vs. time allowed the determination of 3 main ty pes of thrombotic behavior: type I shows no significant reduction of BFR; t ype II shows a progressive decrease in flow rate; type III is much less fre quent and shows an abrupt decrease of BFR either quickly followed by a comp ensatory increase and resuming of a steady flow or by abrupt occlusion. in type N curves the pattern of occlusion follows a classical diffusion model because the Peclet number is greater than I and then the classical Higble s olution for diffusion could be used (33). The most thrombogenic material was the smoothest. There was no correlation between surface chemical composition and thrombogenicity. However, catheter s that were based on PE appeared less thrombogenic than PA catheters in thi s study.