Among patients with atherosclerosis of the aorta and its branches, the quantity of plaque is always greater in the distal (abdominal) aorta than in the proximal (ascending) aorta.1 Indeed, except for its presence at the sinotubular junction, plaque is usually absent or nearly absent in the ascending portion, even when the wall of the abdominal aorta contains plaque in every square millimeter of its lining (Figure). If this were not the case, coronary bypass probably would have never become standard practice. Additionally, when the abdominal aortic wall contains considerable plaque, the quantity of plaque in the descending thoracic aorta is usually not as extensive as the plaque present in the abdominal aorta. The aortic isthmus (the portion of aorta just distal to the origin of the left subclavian artery) is a particularly vulnerable site for heavy atherosclerotic plaque. The exception to the principle that aortic atherosclerosis begins in the abdominal portion and progresses retrograde with near-sparing of the ascending portion is the aortic plaque distribution in patients with homozygous familial hypercholesterolemia.2 In that condition (which occurs in approximately 1 in 1 000 000 persons2), the ascending aorta contains the most plaque and the descending aorta the least. Rarely, the same holds true in patients with heterozygous familial hypercholesterolemia.
Roberts WC, Schussler JM. Frequency of Plaque Dislodgement and Embolization in Transradial vs Transfemoral Approaches for Left-Sided Cardiac Catheterization: Clinically Silent vs Clinically Apparent Embolism. JAMA Cardiol. 2018;3(7):551–552. doi:10.1001/jamacardio.2018.0981
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