Pathogenesis of carotid 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 (<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. In a recent study of the carotid bifurcation in elderly asymptomatic individuals, we found that one half had >50% stenosis and one third had >60% stenosis. 41 Nearly all individuals in the latter group had recent or old intraplaque hemorrhages, Received February 28, 1989; accepted June 2, 1989. and one half of them had ulcerations and/or recent mural thrombi. In addition, numerous healed ulcerations and endothelialized mural thrombi were seen. We concluded that all types of atherosclerotic complications are frequent in asymptomatic individuals but that the complications apparently have a great tendency for self-healing without deleterious effects on the cerebral circulation. Furthermore, we pointed out that all types of complications were correlated and that the clinical significance of each complication would therefore probably be difficult to elucidate.To study the pathogenesis of carotid thrombi more directly, we examined serial sections from 11 patients with recent thrombi. As will be described, atherosclerotic stenosis was clearly an important factor, but one half of the cases had only moderate narrowing. One half of the thrombi were precipitated by plaque complications, but no single complication was of particular importance. Subjects and MethodsWe collected 17 cases with suspected recent thrombi in the region of the carotid bifurcation in 1985 and 1986. We inspected the carotid bifurcation from all patients with a clinical history suggesting recent infarction in the territory of the middle cerebral artery, and we included all vessels showing local hyperemia in the region of the bifurcation. In our experience, local hyperemia of this type is strongly suggestive but is not a definite sign of recent thrombosis.The removed specimens were fixed unopened in 10% formaldehyde. When necessary, they were by guest on May 12, 2018 http://stroke.ahajournals.org/ Downloaded from

Rupture of atheromatous plaque as a cause of thrombotic occlusion of stenotic internal carotid artery.

“…On the contrary, all five patients in our series showed stenosis due to atherosclerotic plaque and plaque rupture. The reason for the difference between our results and those of Torvik et al 3 is not entirely clear. We examined details of the clinical profiles and postmortem pathologic findings of the whole body of five patients who died <60 days after developing cerebral infarction following thrombotic occlusion of the ICA.…”

Ultrasound Measurement of the Fibrous Cap in Symptomatic and Asymptomatic Atheromatous Carotid Plaques

“…1 The concept of atheroma instability is currently applied in neurology to explain artery-to-artery embolism that originates from the internal carotid artery (ICA). 2 On histological examination, 3 occluding thrombi have been found in the carotid arteries in the absence of plaques that cause flowlimiting stenosis. In patients dying after acute ischemic stroke, the presence of thrombus in the ICAs is associated with carotid plaque rupture, a thin FC, and inflammation.…”

Source of Microembolic Signals in Patients With High-Grade Carotid Stenosis

“…[23][24][25][26] Harrison and Marshall 26 found thrombus in 66% of the 24 carotid plaques taken within 4 weeks of the most recent ischemic event but in only 21% of 28 plaques taken Ͼ1 month after. However, surface thrombus is also a common finding in asymptomatic patients, present in Ϸ30% to 56% of patients.…”