Hypercholesterolemia and common carotid wall thickness

In vivo imaging of the extracranial carotid arteries can be obtained using a high resolution real-time echotomographic system, a non invasive technique able to provide real-time information on both lumen and vessel wall characteristics. These instruments visualize the arterial wall as a pair of roughly parallel echogenic lines: the external one generated by the media-adventitia transition, and the internal one by the blood-intima interface . In this study we have evaluated the association between the presence of known risk factors for atherosclerosis (hyperlipidemia, cigarette smoke) and the magnitude of the thickness of the intimal + medial complex in living human subjects. Thirty-six hypercholesterolemic patients with type IIa hyperlipoproteinemia were recruited in our Lipid Clinic (E, Grossi Paoletti Center): thirty-one normolipidemic subjects, of similar age and with similar smokers/non smokers and males/females ratios were selected as controls. Carotid ultrasound imaging was performed with a BioSound echotomographic system, model Phase-one (Bio Dynamycs, Indianapolis, IN, USA). Scanning of the extracranial carotid arteries in the neck was performed in three different projections (anterior, posterior and lateral). The thickness of the intimal medial complex of the common carotid arteries (IMCT) was determined on the images taken through a video-printer during a standardized scan, as the ratio between the area limited by the luminal and the deeper echoes and the length of the arterial segment of interest . The mean values of the common carotid arteries of the hyperlipoproteinemic patients was significantly greater than that of control subjects (0,674±0,124 mm vs 0,548±0,065 mm, respectively, p <0.01) . When the thickness values of control subjects and of hyperlipidemic patients were analyzed controlling for the smoking status, a significant difference was demonstrated between smokers and non smokers in hyperlipidemic but not in normolipidemic subjects (0,760±0,150 mm vs 0,646±0,094 mm, p<0,05 and 0,560±0,076 mm vs 0,546±0,054 mm, P "'ns, respectively). Localized lesions thicker than 2 mm (plaques) were found in 8 patients (total: 9 lesions) and in one control subject (1 lesion) (p<0,05, Fisher exact test). In normolipidemic patients, but not in the hypercholesterolemic, on the other hand, a significant correlation between IMCT and age could be shown (r=0.46 p<0.01). Preliminary data obtained from a cohort of free living healthy subjects (employee of IBM Italy) confirm these observations, indicating that an increased thickness of the intimal + medial complex is found in hypercholesterolemic vs normocholesterolemic individuals. We think that the determination of the IMCT, and its follow up with time, being inexpensive, noninvasive, and safe, can represent a good model of spontaneous or of induced progression of regression of the atherosclerotic disease in living human subjects.