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Pathogenesis of carotid thrombosis
A Torvik1, A Svindland, C F Lindboe
1Department of Pathology, Ullevål University Hospital, Oslo, Norway.
Insights
Carotid bifurcation thrombi formation is not solely due to severe stenosis. Plaque complications like ulcerations and rupture can also cause thrombosis, even with moderate narrowing.
Area of Science:
- Vascular pathology
- Cardiovascular research
- Cerebrovascular disease
Background:
- Thrombosis at the carotid bifurcation is a significant cause of stroke.
- Understanding local vessel wall factors precipitating thrombi is crucial for risk stratification.
Purpose of the Study:
- To investigate histological factors in the carotid artery wall associated with recent occluding thrombi.
- To determine the role of atherosclerotic stenosis and plaque complications in thrombus formation.
Main Methods:
- Histological examination of 11 patient specimens with carotid bifurcation thrombi.
- Morphometric analysis to determine the degree of lumenal stenosis.
- Assessment for plaque complications such as ulcerations, intraplaque hemorrhage, and plaque rupture.
Main Results:
- Severe atherosclerotic stenosis was common but not always present; moderate stenosis (<60%) was observed in nearly half the patients.
- Plaque complications (ulcerations, hemorrhage, rupture) were identified in some cases but were not predominant.
- Half of the specimens showed no identifiable plaque complications, suggesting other factors may be involved.
Conclusions:
- Carotid artery stenosis screening alone is insufficient to identify all individuals at risk for thrombosis.
- Plaque complications contribute to thrombogenesis but their role appears moderate in unselected cases.
- Further research is needed to fully elucidate the multifactorial nature of carotid bifurcation thrombosis.
Abstract:
We histologically examined specimens from 11 patients with recent occluding thrombi at the carotid bifurcation to study local factors in the vessel wall that precipitated the thrombi. The area of stenosis of the vessel lumen was determined morphometrically. Severe atherosclerotic stenosis was frequent but was not a prerequisite for thrombus formation since specimens from almost one half of the patients had only moderate narrowing of the lumen (less than 60% stenosis). Specimens from three patients showed ulcerations, those from one showed intraplaque hemorrhage, and those from one massive plaque rupture, all of which were thought to be important in thrombogenesis. All such types of plaque complications may thus precipitate thrombi but no single complication was particularly predominant, and specimens from one half of the patients showed no complications at all. Screening of the carotid arteries for stenosis can therefore detect only one half of the individuals who ultimately will develop thrombosis, and the risk caused by plaque complications seems to be moderate in unselected materials.