Comparative study of vasa vasorum and neointima in conduits for coronary artery bypass grafting

Abstract

This study was undertaken to investigate the preoperative incidence and severity of intimal hypertrophy, as well as the level of blood supply of arterial and venous conduits for coronary artery bypass grafting. Segments of the internal thoracic artery and great saphenous vein (n=13) were harvested pairwise during coronary artery bypass grafting and were then visualized by scanning electron microscopy in back-scattered electrons. The analysis of the incidence and thickness of intimal hypertrophy, as well as the calculation of the number and the area of the vasa vasorum were performed using the programme ImageJ. Intimal hypertrophy was more characteristic for the great saphenous vein as compared with the internal thoracic artery (9/13 (69.2%) and 7/13 (55.8%), respectively), although this difference did not reach statistical significance. The maximal-to-minimal neointimal thickness ratio correlated with the percentage of stenosis (r=0.875, p<0.0001), the area (r=0.45, p=0.023) and the number (r=0.47, p=0.015) of the vasa vasorum in the conduits, thus confirming the hypothesis on possible participation of these vessels in the development of intimal hypertrophy, with the area of the vasa vasorum being greater in the vessels with >10% stenosis (p=0.051). The number of the vasa vasorum in the great saphenous vein exceeded that in the internal thoracic artery (p=0.0005), with this difference remaining significant after adjustment for the area of the adventitia (p=0.027). The number of the vasa vasorum per the percentage of stenosis in the great saphenous vein also exceeded that in the internal thoracic artery (p=0.039) and more strongly correlated with intimal hypertrophy in the great saphenous vein as compared with that in the internal thoracic artery (r=0.53 and r=0.27, respectively). Intimal hypertrophy correlates with the area and number of the vasa vasorum in conduits. The great saphenous vein is characterised by a larger number and higher density of the vasa vasorum as compared with the internal thoracic artery. The number of the vasa vasorum is correlated with stenosis of the great saphenous vein more closely than with stenosis of the internal thoracic artery. This may be suggestive of significant predisposition of the great saphenous vein to the onset of adventitial inflammation followed by the development of intimal hypertrophy.