Comparative histological and biometric study of the coronary, radial and left internal thoracic arteries

Abstract

In an attempt to elucidate the causes of occlusion of radial arteries used for coronary artery bypass grafts and to improve the results of these procedures, we studied the biometry and histology of the coronary, radial and left internal thoracic arteries. These arteries were harvested from 20 cadavers (13 males, 7 females). The specimens were calibrated to the various bypass graft sites using coronary calibrators, and were then submitted to histological examination to determine the structure and innervation of the vessel wall. No correlation was observed between the internal calibers of these various arteries, with the exception of the anterior interventricular and right coronary arteries. Intimal changes and the presence of atheromatous plaque were observed in coronary and radial arteries, but never in the internal thoracic artery. Like the coronary arteries and their branches, the radial artery is a muscular artery. Aging of muscular arteries results in thickening of the intima, which becomes fibrotic due to migration of myocytes from the media and duplication of the internal elastic lamina. The media becomes fibrous, hypertrophic or atrophic. The walls of the radial and coronary arteries contain several adventitial nerves (sympathetic and parasympathetic nerve fibers), but these nerve fibers were not observed in the wall of the left internal thoracic artery. In contrast, the internal thoracic artery, like the aorta, is an elastic artery. Aging of elastic arteries is first observed between the ages of 20 and 29 years and is characterized by loss of one or several elastic laminae of the media and more marked intimal thickening, over a variable length. Even if a radial artery's caliber is similar to that of the coronary artery, histological evolution and graft patency depend on its muscular identity.

Conduits Used in Coronary Artery Bypass Grafting: A Review of Morphological Studies

“…The AIA, RCA, and CX are muscular arteries, with a tunica media bounded by two distinct internal and external elastic laminae. 21,24) The amount of elastic fibers in the tunica media is low, being only 2-7 fibers. 17) Saphenous vein Favaloro (1968) reported the first CABG using the SV as a graft.…”

“…12) Although in studies in which unspecified segments were evaluated, the luminal diameter ranged between 1.6 and 2.75 mm. 4,5,21,24) In studies in which the artery segment evaluated is not specified, a wall thickness of 350 µm is reported. 5,41) The amount of elastic fibers in the tunica media varies along with the length of the ITA.…”

“…4,20,[46][47][48]50,52) The luminal diameter reported in studies that do not specify the evaluated segment varies between 2 and 3 mm. 12,20,21,47) The wall thickness reported in studies do not specify the segment evaluated, varying from 254 to 529 µm. 12,41) Histologically, the RA is a muscular artery.…”

“…17) The luminal diameter is the most studied and irregular parameter. Most studies only analyzed a single segment, [19][20][21][22][23] whereas others analyzed the segments that are most often occluded 17) or an unspecified segment (Barry et al, 2007 24) ; Ballesteros and Ramirez, 2008 25) ) ( Table 1).…”

“…12,41) Histologically, the RA is a muscular artery. 5,21,24,41) It has a thin intima presenting mild to moderate hyperplasia 5) and a thick tunica media with abundant smooth muscle cells. 4,5,41,47,51) Reportedly, it has an 18.84% of elastic fibers in the tunica media.…”