Flow Dynamics in the Human Aorta

The aorta is the major blood vessel transporting blood pumped by the left ventricle to the systemic circulation. The tricuspid aortic valve at the root of the aorta provides a centralized flow with nearly uniform velocity profile into the ascending aorta. The aorta consisting of the ascending limb, the aortic arch, and the descending segment is a vessel of complex geometry including curvature in multiple planes, branches and bifurcation as well as taper. The understanding of the development of blood flow in this distensible vessel has been the subject of several theoretical as well as experimental investigations. Flow development in the aorta and in the branch vessels has been of interest in delineating the role of wall shear stresses on the etiology of atherosclerosis. In this paper, a review of the current status on our understanding of the complex flow dynamics in the aorta is presented. With the advent of transesophageal echocardiography and magnetic resonance velocity mapping, further evidence of the presence of secondary flows even in the descending aorta has been reported. The importance of the effect of secondary flow in the descending aorta on the perfusion of distal blood vessels (such as superior mesenteric and renal arterial branches) as well as in the iliac bifurcation is also included in the discussion.