Dangerous beauty: coral reef carotid plaques as source of embolism

A. Zientara, I. Schwegler

Objective

Indication and timing for carotid endarterectomy depend among other factors on morphology of the plaque and the difference between hard and soft consistency. Soft plaques are assumed to be thrombogenic because of their floppy character, while hard plaques in an asymptomatic patient with a stenosis under 70% are not an indication for operation. Beside this distinction there exist complex morphologies including different components that can be classified by the conventional categories established by American Heart Association (AHA) as type IV-VI based on the histological structure. Moreover, in addition to luminal stenosis, certain morphological features of carotid plaques, such as large lipid cores, intraplaque haemorrhage, or thin or ruptured fibrous caps, are increasingly believed to be associated with heightened risk of stroke. Additionally, the knowledge of plaque biology emphasises that other characteristics than the degree of stenosis are important in risk assessment. Finally, the intraoperative view often reveals new information about the layers and the surface of the plaques leading to a clearer risk stratification of the consequences of the morphology.

Methods

Patient presentation: Two patients (female, 83y and 71y) presented with amaurosis fugax and hard plaques in the computed tomography with stenosis over 70%, which lead to an urgent carotid endarterectomy in general anesthesia with the use of an intraopertive shunt and patch closure technique. The intra- and postoperative course was uneventful in both patients.

Results

Intraoperative findings: Intraoperative findings confirmed a covered plaque surface with fragile, fine filaments, mimicking a coral reef (Fig. 1a+b, Fig. 2a+b). The histological analysis described a ruptured plaque formation partially covered with endothelium (Fig. 3a+b).

Fig. 1a:
A: part of the hard plaque as the basis for the "coral reef", B: outer layer of the media, C: fragile plaque with fine extensions
Fig. 1b:
Detailed view on the fragile plaque
Fig. 2a:
Nearly total occlusion of the carotid lumen by the coral plaque
Fig. 2b:
Dissected plaque with destructive growth into the media
Fig. 3a:
Histological findings (Elastica-van-Gieson): * luminal side; x adventitial side. The four black arrows show the ruptured plaque lying directly beneath the endothelial barrier (blue arrows)
Fig. 3b:
Histological findings (Elastica-van-Gieson): massive fibrosis of the "coral reef"

Conclusion

A coral reef configuration of carotid plaque demonstrates a seldom embolic risk. To our knowledge this is the first report describing this special coral reef morphology, comparable to the aortic disease, in carotid plaques, that underlines the severe and potential risk by its thrombogenic surface. The risk might be independent of the degree of the stenosis.