Reduction in thrombus formation by placement of endovascular stents at endarterectomy sites in baboon carotid arteries.
BACKGROUND
Although antithrombotic therapies with aspirin, dipyridamole, and heparin have decreased thrombo-occlusive events, they have not abolished these complications. Endovascular mechanical support, first reported by Dotter in 1969, has been proposed as a means to reduce both acute and chronic vessel closure by providing a supporting framework for the disrupted and sometimes dissected arterial wall.


RESULTS
To determine the effects of placing self-expanding stainless steel wire endoprostheses on the accumulation of thrombus at sites of carotid artery endarterectomy we measured platelet deposition continuously for 90 minutes and at 24 and 48 hours by gamma camera imaging of autologous 111In-labeled platelets in six stented and nonstented endarterectomized baboons that received heparin but no antiplatelet agents. At nonstented endarterectomy sites 5.36 +/- 1.25 x 10(8), 4.78 +/- 0.98 x 10(8), and 4.55 +/- 0.81 x 10(8) platelets per cm were deposited at 30, 60, and 90 minutes, respectively. In contrast, stented endarterectomy sites accumulated 0.99 +/- 0.31 x 10(8), 0.66 +/- 0.33 x 10(8), and 0.80 +/- 0.36 x 10(8) platelets per cm at 30 minutes (p = 0.02), 60 minutes (p = 0.004), and 90 minutes (p = 0.002), respectively. Platelet deposition remained reduced at 24 and 48 hours in stented endarterectomized carotid arteries (ECAs) when assessed as a ratio between net radioactivity in the endarterectomized region versus whole blood radioactivity (p = 0.006 and p = 0.009, respectively). Both stented and nonstented ECAs remained patent acutely, although two of six nonstented ECAs occluded by 30 days. By comparison 11 of 14 nonstented ECAs remained patent in another group of control animals. Scanning electron microscopy of control and stented arteries at 30 days demonstrated equivalently confluent endothelium.


CONCLUSIONS
We postulate that endovascular stents reduce the thrombogenic effects of flap formation, tearing, dissection, and vasospasm in ECAs.
Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322.
W C
WC
Krupski
A
A
Bass
A B
AB
Kelly
S R
SR
Hanson
L A
LA
Harker
D000818:Animals; D001792:Blood Platelets; D002341:Carotid Artery Thrombosis / Q000000981:diagnostic imaging / Q000517:prevention & control*; D016894:Endarterectomy, Carotid; D007205:Indium Radioisotopes; D008297:Male; D010215:Papio; D010973:Platelet Adhesiveness; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000517:prevention & control; D011877:Radionuclide Imaging; D013193:Stainless Steel; D015607:Stents; D013997:Time Factors; D014463:Ultrasonography
D007205:Indium Radioisotopes; D013193:Stainless Steel