Platelet polyethylene catheters

A rapid, minimally invasive in vivo animal model was developed to evaluate continuously the process of thrombosis on biomaterials. Goats subjected acutely to bilateral polyethylene catheters are monitored for net retention of luln-oxine platelets on the separate catheters. Comparisons between continuous scintigraphic monitoring of platelet retention and thrombus recovered at catheter retrieval show that platelet retention and thrombus growth are dynamic processes for at least the first few hours of implantation, and that platelet retention is predictive for thrombus size. Mean recovered thrombus weight is 23 mg cm, which corresponds to a 44% increase in effective radius of the catheter-thrombus combination. 

Circulating radiolabeled platelets adhered and aggregated on two polyethylene catheters inserted retrograde into the carotid arteries. Increasing platelet retention is shown in the sequence A through EThe beginning of thrombus dissolution is seen in F . The small platelet collection is best shown in the precatheter sample (A). Blood was drawn... 

Figure 3. Net platelet retention behavior on polyethylene catheters in four goats. Thrombus platelet concentration catheter length was used to calibrate externally detected platelet retention curves. The repeatability of the initial slope ana the variable times to peak are shown. Key I, Goat 32 2, Goat 36 ...

A model that predicts accurately thromboembolic risk associated with the use of biomaterials is still needed. Utilizing minimal surgical techniques, catheters were placed in goat carotid arteries, and subsequent analysis in real time was performed noninvasively of net platelet retention of autologously labeled nlIn platelets. We concentrated on acute animal studies using polyethylene catheters. Price et al. used a very similar model in dogs, obtaining similar results (9). 

The large number of platelets and size of the thrombus retained by the polyethylene catheters are impressive. We calculated that in goats, 1.33% (range 0.3-10%) of the circulating platelet pool is accumulated by the catheter. In dogs, from 4 to 7% of the pool is accumulated by a similar, but longer catheter as calculated at peak value (9). A direct comparison can be made between our model and the ex vivo model of Ihlenfeld et al. (10). In their dog... 

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