Carolinas Research Day 2021

Biomedical Studies

03 The Long-Range Effect of the Anatomical Variation of the Left Common Carotid Artery Severe Left Internal Carotid Artery Atherosclerosis

Eshaan Zaveri, OMSII, Hunter Peden, MA, OMS II, Zachary Kline, OMSII, Michael Pavy, OMSIII, Artem Boyev, DO, Zoltan Hajdu, MD

Edward Via College of Osteopathic Medicine-Carolinas

Background: One of six deaths in the United States from cardiovascular diseases is due to stroke. With more than 795,000 people suffering from a stroke each year, this disease is the leading cause of long- term disability with a huge economic impact. The prevalence of stroke attributed to extracranial internal carotid artery (ICA) atherosclerosis is about 13.4 per 100,000 persons. We have previously reported that there is a strong correlation between the anatomical variations of the left common carotid artery (LCCA) origin and intimal thickening in this vascular segment. Hypothesis: Based on palpatory findings during anatomical dissections, we hypothesize that anatomical variations of the LCCA origin have a direct effect on the left ICA atherosclerosis. Methods: The carotid arteries of 34 anatomic cadavers were investigated in VCOM anatomy labs between 2018-2020. Of these, 17 cases presented

the anatomic variation of the LCCA originating from the brachiocephalic trunk (BT); the other 17 were arbitrarily selected controls where the LCCA originated from the aortic arch (AA). Measurements of the AA and the primary branches were taken in situ and these were used for 3D reconstruction of the arterial trees using the SimVascular software. Histological samples of ICAs were used for internal measurements and structural evaluation of the walls. Computational fluid dynamics (CFD) calculations were applied to evaluate the flow and shear stress in the ICAs. Results: The CFD calculations on the 3D-reconstructed arterial trees predicted that, beside the previously reported LCCA intimal thickening, serious flow disturbances exist at the level of the left ICA when the LCCA originates from the BT. Initial palpatory assessment indicated hardening of the left ICA walls in these cases. Sectioning of the

paraffin-embedded samples of ICA further indicated severe atherosclerosis on the left side. Internal measurements of the samples from the cases with the anatomical variation revealed a 37% reduction of the arterial lumen compared to the control group. Von Kossa staining showed evidence of severe calcification in all 17 cases with the anatomical variation, while only six ICAs showed low or moderate levels of calcium in the control group. Conclusion: We extended our previous observation regarding the anatomical variations and intimal thickening of the LCCA. An LCCA originating from the BT instead of the AA will have a long-range effect in the left ICA in the form of severe atherosclerosis. Early screening for anatomical variations in the carotid artery could identify a risk factor for ICA atherosclerosis and potentially reduce the incidence of strokes with timely intervention.

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