A three-dimensional transient numerical study and analysis of blood flow dynmaics in renal artery aneurysms.

Abstract

The kidney is one of the main components of the urinary system. The main function of the kidney is filtering the blood to eliminate unwanted substances and to keep a certain concentration of red blood cells. The kidney, also, produces some of the necessary hormones needed for grouth and daily activities. Aneurysm, in general, is bulge formed in the blood vessels due to the weakening of the vessel's wall. It could happen in many different locations with different sizes and forms. Renal artery aneurysm (RAA) is the type of aneurysm that appears on the main renal artery or one of the branches. Certain blood pressure is expected in the renal artery. When the pressure varies, the baroreceptors senses the change and trigger the renin-angiotensin-aldosterone system (RAAs) to react. There are multiple causes for the pressure change in the renal artery. One of these causes is the existence of an RAA. In this thesis, a 3D model was developed to study and analyze the blood flow in the renal artery network. The simulation was done using a finite element analysis (FEA) software COMSOL Multiphysics© (CMP) The analysis covered several different criteria such as; location, size, and blood flow. The simulation was done to test the pressure drop throughout the network by fixing the pressure at the exit and varying the blood flow at the inlet for a laminar, Newtonian, transient fluid. RAAS is triggered when pressure difference in the renal artery is 10mmHg average or 20mmHg at peak. It was concluded that at the extreme case of renal artery aneurysm (X-RAA), there is enough static pressure drop to trigger RAAS and subsequently causes secondary hypertension.