Oscillating Atherosclerotic Plaque in the Internal Carotid Artery

Abstract

Duplex ultrasound is used not only to detect atherosclerotic disease but also to define characteristics of the disease. Carotid plaque is often described by its echogenicity and surface characteristics. The following case report depicts the findings of atherosclerotic plaque that appeared to oscillate. An asymptomatic 60 year-old male presented with a right carotid bruit. His medical history is significant for type II diabetes mellitus, hypertension, hyperlipidemia and hypothyroidism. The ultrasound revealed the right internal carotid artery (ICA) peak systolic velocity (PSV) was 125 cm/s with an end diastolic velocity (EDV) of 33 cm/s. Heterogeneous atherosclerotic plaque was present at the origin of the ICA. A portion of the plaque was observed on real-time imaging to be oscillating with the cardiac cycle. The segment was approximately 5 mm in length and swayed from the wall of the vessel into the center stream of flow as normal flow/pressure variations occurred with the cardiac cycle. The right ICA was categorized as having a 50–69% stenosis. Mild atherosclerotic plaque was found in the left ICA with a PSV of 71 cm/s and EDV of 27 cm/s. These findings were categorized as a less than 50% stenosis. Bilaterally, the external carotid arteries demonstrated mild plaque while the common carotid arteries were free of disease. A magnetic resonance angiogram confirmed the presence of a stenosis and the patient underwent a successful right carotid endarterectomy. At surgery the plaque was found to be partially disrupted and described as mobile, correlating with the plaque features observed on ultrasound. This report describes the importance of fully evaluating the plaque characteristics during ultrasound examination. Based on velocities and the percent stenosis, this patient would have likely gone into surveillance and not to surgery. Identification of this potentially hazardous unstable plaque leads to rapid treatment, thus avoiding serious complications.