Clinical significance of organs vascularization: The role of vascular grafts for revascularization surgeries

Abstract

The use of vascular grafts to bypass occluded arteries is still an important therapeutic option for revascularization surgeries. However, it is still not clear which factors may play positively for the longer durability of the grafts. The objectives of the present study is to identify morphological and structural parameters which may explain the different behavior between the most frequently used vascular grafts and also help choosing the best conduit for myocardial revascularization.We have studied the morphology and the constitution of the extracellular matrix of the wall from the following vessels: coronary, internal thoracic, radial and gastromental arteries and saphena magna vein. Light microscopy, scanning electron microscopy and confocal microscopy were used for histological and morphometric study. The analyses of the vessel wall under different staining added to the information provided by the immunohistochemistry, allowed us to evaluate the extracellular matrix constitution of the arterial and venous grafts.The three arterial grafts presented the same architectural pattern except for differences in layer thickness and also in the extracellular matrix distribution pattern. The proximal segment of the internal thoracic artery showed a double elastic layer in the adventicia, and the distal segment showed multiple elastic membranes in the media. Radial artery presented a collagen distribution pattern similar to the saphenous vein. No outer elastic limitant was seen in the venous conduit; however it presented lots of elastic fibers and two layers of smooth muscle cells in the media. It is worthy saying that the saphenous vein presented a wavy intima which could enhance its contact with platelets, facilitating thrombosis. In none of the of the studied vessel it was possible to identify vasa vasorum in the media layer.We can conclude that there is not a major single factor that makes a vessel become the perfect graft. A combination of morphological features may help in the understanding of grafts behavior and give some clues of how we can deal with them to achieve better results.