Histomorphometric differences between the left and right internal thoracic arteries in humans.

OBJECTIVE The use of the left internal thoracic artery in coronary artery bypass surgery is currently recognized as the best option, providing lesser incidence of cardiovascular events and superior long-term survival. As a result, great expansion of bilateral internal thoracic artery (ITAs) grafts has been observed, with additional demonstration of improved long-term survival. Therefore the aim of this study was to examine and compare the histomorphometric structure among different segments of the left and right ITA. METHOD Specimens of ITAs harvested from 18 cadavers were divided in nine proportional segments. Cuts of each segment had been stained with hematoxylin-eosin and Verhoeff-Van Gieson technique. The following parameters had been analyzed: perimeter of the arterial lumen, thickness of the intima, thickness of the media layer and amount of elastic fiber in the media layer. RESULTS The perimeter of both ATIs decreases downstream its course, the proximal segments of the right ITA exhibit perimeter significantly greater than left ITA The analysis of the intima thickness revealed no significant difference between left and right ITA, except in the segment 9. The thickness of media layer showed no statistical difference between them, except in the segment 1. The number of elastic layers in the distal left ITA segments is significantly higher than right ITA. CONCLUSION Data analyses from this study suggest structural differences between the left and right internal thoracic arteries.