Analysis of In-Vivo Coronary Flows from a Fluid Mechanics Perspective as the Cardiovascular System is Conceptualized as a Network of Pumps and Pipes ,*

The cardiovascular system is conceptualized as a network of pumps and pipes. The distinct characteristics of flows and phenomena in pipes are used as key parameters to analyze analogous in vivo arterial phenomena. At first, antegrade coronary laminar flow in diastole and retrograde flow in systole are identified. As they flow in opposing directions, the retrograde systolic flow could clash against the antegrade diastolic flow similar to a water hammer event. This results in turbulence injuring the intima, starting atherosclerosis. Lesion will grow if LDL cholesterol is plentiful. The second phenomenon is the separation of flows after the blood turns around a curve. Here the layers at the center flows faster than at border. Once the gradient between the two velocities reaches a critical level, separation and rupture of peripheral flow layers occur. These separated layers could turn, twist and form vortex which degenerates into turbulent flow. This is the mechanism of lesion at the ostium of the left circumflex artery. The 3rd arterial phenomenon is the possible vibration of coronary artery due to cyclic pounding by the alternating systolic contraction and diastolic relaxation of the left ventricle. If the frequency of this vibration matches the natural frequency of coronary artery, resonance happens. This enhanced pressure surge could rupture an atheroslerotic plaque and precipitates acute coronary syndrome. This same mechanim may cause critical limb ischemia in peripheral artery, stroke in cerebral artery.