Peripheral Vascular Surgery Society
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Peripheral Vascular Surgery Society |
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#26 TISSUE FACTOR EXPRESSION IN EXPERIMENTAL PSEUDOANEURYSM
Krish Soundararajan, MD, Mark B. Taubman, MD, John T. Fallon, MD, Anita Shrivastava, Larry A. Hollier, MD, and Ernane D. Reis, MD.
Mount Sinai School of Medicine New York, NY
Introduction: Tissue factor (TF) is a transmembrane glycoprotein that initiates thrombosis and is normally present in the adventitia. Arterial injury induces TF expression in the neointima, which is associated with a high potential for thrombosis. Although pseudoaneurysm is essentially a contained disruption of the arterial wall, there is persistent blood flow and no thrombus formation. The expression of TF in pseudoaneurysm has not been reported. Because this may have significant clinical implications, we studied the presence and location of TF in pseudoaneurysms in a rodent model.
Methods: Pseudoaneurysms were collected from anastomotic sites, two months after carotid artery interposition grafting in Sprague-Dawley rats. They were sectioned and stained with a combined Mason-Elastin, and representative sections were immunohistochemically stained for TF and factor VII-associated antigen. The pseudoaneurysms were analyzed in transverse and longitudinal sections to include both native and engrafted arterial segments. Balloon-injured rat carotid arteries were used for comparing the distribution of TF.
Results: TF was found in all the layers of the injured arteries, including the full thickness of the neointima. In pseudoaneurysms, TF was expressed with a decreasing gradient from outer to inner portions of the wall, and was absent in the luminal border. There was no endothelialization, as seen by negative staining for factor VIII-associated antigen. There was no evidence of luminal thrombus.
Conclusions: The expression of TF in pseudoaneurysm differs from that found in the balloon-injured artery. The absence of thrombus in pseudoaneurysms may be due to lack of TF in the luminal border. The gradual decrease in TF expression, from out to inner layers of the pseudoaneurysm wall, suggests that it is induced by perianeurysmal tissues. The efficacy of compression therapy for pseudoaneurysm may be dependent on the disruption of the inner layer and exposure of tissue factor to blood. Finally, this model can be used to further study the links between tissue factor, endothelium and thrombosis
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Last updated January 10, 1999