Multiphoton Microscopy of Healthy and Aneurismal Human Ascending Aorta

The ascending aorta (AA) is the largest artery in the human body. It is responsible for transporting blood between the heart and the rest of the body. The structure of the AA allows it to withstand the resulting blood flow forces. This unique structure is due primarily to the proteins collagen and elastin. Collagen accounts for the strength of the aorta while the mechanical properties of the tissue, under healthy physiological conditions, is dominated by the elastin. Aneurysms are the primary disease associated with the AA, where the diameter of the vessel increases over 1.5 times its original size. Aneurysms can result in severe blood flow disturbances or rupture of the AA and almost always require surgical intervention. The development of an aneurysm is due to a weakening of the aortic wall, specifically the degradation of the structural proteins. This study examines the changes that occur to collagen and elastin in the ascending aorta with aneurysms using multiphoton microscopy. Specifically, the orientation of collagen fibers and the morphology of the fenestrations in the elastic lamina are compared between healthy and dilated human ascending aortas.