Aortic arch atheroma and the risk of stroke

Atherosclerosis in intracranial, extracranial, and coronary arteries with aortic plaques in patients with ischemic stroke of undetermined etiology

OBJECTIVE

We investigated the association of cerebral and coronary artery atherosclerosis with the presence, burden and type of atherosclerotic plaques of the aorta (AP) in patients with ischemic stroke of undetermined etiology.

METHODS

48 consecutive patients (32 males, mean age 68 ± 11 years) with acute ischemic stroke of unknown etiology after thorough stroke workup were investigated using ECG-gated CT-Angiography (CTA) for the detection of embolic AP. Intima media thickness (IMT), presence of carotid plaques and stenosis ≥ 50% and intracranial stenosis were assessed as parameters of cerebral atherosclerosis, the Agatston score (AS) and coronary artery stenosis ≥ 50% (CAS) in CTA as parameters of coronary atherosclerosis. Plaque burden was classified as mild or severe and plaque types were classified according to their morphology in calcified, non-calcified or mixed.

RESULTS

APs were found in 36 patients (75%). AP presence was associated with higher IMT values (p = 0.029), intracranial stenosis (p = 0.047), CAS (p = 0.033) and AS (p = 0.026). Twenty-three of 31 (74.2%) patients with both carotid atherosclerosis and AP revealed plaque calcification (p = 0.041). Ten of 14 (71.4%) patients with AP and intracranial stenosis had calcified plaques (p = 0.030). AP in more than one aortic segment was found in patients with bilateral carotid stenosis ≥ 50% (p = 0.038), intracranial stenosis (p = 0.042), high IMT (p = 0.040) and higher AS (p = 0.019).

CONCLUSIONS

Aortic atherosclerotic plaques are common in patients with ischemic stroke of undetermined etiology and in particular those with carotid, intracranial and coronary atherosclerosis or high IMT values. In these patients, CTA of aorta should be seriously considered.

Stroke in patients with occlusion of the internal carotid artery: options for treatment

Ischemic stroke may occur in patients in whom vascular imaging shows the ipsilateral internal carotid artery (ICA) to be occluded. In younger patients this is often due to carotid artery dissection, while in older people this most likely results from cardiac embolism or thrombosis secondary to high-grade stenosis at the carotid bifurcation. Interventional techniques aim at recanalization of the carotid artery for early restoration of cerebral blood flow and secondary prevention of future strokes. In chronic ICA occlusion the ischemic infarct may be related to hemodynamic compromise. In this situation, extracranial-intracranial bypass surgery was introduced, but its role remains still unclear. Ischemic stroke may also occur in patients with a chronic occlusion of the contralateral ICA. This situation demands the usual stroke treatment, but surgical and neuroradiological interventions face a higher risk than unilateral vascular pathology. Medical treatment supports stroke prevention in carotid artery occlusion.

M1-activated macrophages migration, a marker of aortic atheroma progression: a preclinical MRI study in mice

BACKGROUND

M1-activated Macrophages (M1M) play a major role in atherosclerotic lesions of aortic arch, promoting proinflammatory response. In vivo trafficking of M1M in aortic plaques is therefore critical.

METHODS

M1M from bone marrow cell culture were magnetically labeled, using iron nanoparticles, intravenously injected and followed up with 3 day magnetic resonance imaging (MRI) in mice developing macrophage-laden atheroma (ApoE2 knock-in mice). M1M recruitment in aortic arch lesions was assessed both by MRI and histology.

RESULTS

In all ApoE2 knock-in mice injected with labeled cells, high resolution MRI showed localized signal loss regions in the thickened aortic wall, with a maximal effect at day 2 (-34% +/- 7.3% P < 0.001 compared with baseline). This was confirmed with Prussian blue (iron) staining and corresponded to M1M (Major Histo-compatibility Complex II positive). Clear different intraplaque and adventitial dynamic distribution profiles of labeled cells were observed during the 3 days.

CONCLUSION

M1M dynamic MRI is a promising marker to noninvasively assess the macrophage trafficking underlying aortic arch plaque progression.

Capillary injury in the ischemic brain of hyperlipidemic, apolipoprotein B-100 transgenic mice

AIMS

Apolipoprotein B-100 (apoB-100) has been implicated in hyperlipidemia, which contributes to the pathogenesis of vascular disorders. Our aim was to investigate whether the expression of human apoB-100 in transgenic mice and/or a high-cholesterol diet cause cerebral microvascular lesions, and whether these conditions augment ischemia-related capillary damage.

MAIN METHODS

Human apoB-100 overexpressing transgenic (Tg(apoB-100), n=23) and wild-type mice (C5/B6, Wt, n=26) were supplied with standard or 2% cholesterol-enriched diet for 17-19 weeks. Cerebral ischemia was induced by unilateral common carotid artery occlusion. Cortical samples were embedded for electron microscopy. Microvascular density (number of microvascular profiles/examined area), lumen diameter, the swelling of astrocytic endfeet, the occurrence of endothelial microvilli (affected capillaries expressed as ratio of all capillaries encountered), and the ratio of intact capillaries (devoid of all the above pathology) were calculated.

KEY FINDINGS

The expression of apoB-100 coincided with decreased cortical microvascular density (195+/-7 vs. 223+/-8 vessels/mm(2), vs. Wt; P<0.008) and increased capillary lumen diameter (3.16+/-0.5 vs. 2.88+/-0.6 microm, vs. Wt; P<0.001). Cerebral ischemia promoted the swelling of perivascular astrocytes (62.1+/-4.2 vs. 36.5+/-4.0%, vs. contralateral, Wt; P<0.001), and reduced the ratio of intact capillaries (32.1+/-5.6 vs. 65.2+/-3.7%, vs. contralateral, Wt; P<0.001). Hyperlipidemia did not exacerbate the injury.

SIGNIFICANCE

The overexpression of human apoB-100 alters the density of the microvascular network and the diameter of capillaries, which may compromise cerebrovascular reactivity during ischemia.