Dispersive Aortic Cannulas Reduce Aortic Wall Shear Stress Affecting Atherosclerotic Plaque Embolization

Abstract

Neurologic complications during on-pump cardiovascular surgery are often induced by mobilization of atherosclerotic plaques, which is directly related to enhanced wall shear stress. In the present study, we numerically evaluated the impact of dispersive aortic cannulas on aortic blood flow characteristics, with special regard to the resulting wall shear stress profiles. An idealized numerical model of the human aorta and its branches was created and used to model straight as well as bent dispersive aortic cannulas with meshlike tips inserted in the distal ascending aorta. Standard cannulas with straight beveled or bent tips served as controls. Using a recently optimized computing method, simulations of pulsatile and nonpulsatile extracorporeal circulation were performed. Dispersive aortic cannulas reduced the maximum and average aortic wall shear stress values to approximately 50% of those with control cannulas, while the difference in local values was even larger. Moreover, under pulsatile circulation, dispersive cannulas shortened the time period during which wall shear stress values were increased. The turbulent kinetic energy was also diminished by utilizing dispersive cannulas, reducing the risk of hemolysis. In summary, dispersive aortic cannulas decrease aortic wall shear stress and turbulence during extracorporeal circulation and may therefore reduce the risk of endothelial and blood cell damage as well as that of neurologic complications caused by atherosclerotic plaque mobilization.

Modification of Aortic Cannula With an Inlet Chamber to Induce Spiral Flow and Improve Outlet Flow

“…Because the aortic cannula attached to the ascending aorta is the smallest cross‐sectional area during CPB to the patient undergoing open heart surgery, a high velocity jet from the aortic cannula tip is suspected to have a sandblasting effect on the aortic endothelium and dislodgement of atherosclerotic plaque This is especially true if a standard end‐hole cannula is used, where it is deemed to be extraordinarily harmful even if the patient's aorta is in a healthy condition without any contraindication for cannula placement . The outcome of this study showed that, by placing an eccentric inlet at the cannula inlet, spiral flow can be induced and compared with standard cannula, there were several significant reductions of hemodynamics parameters, most notably the reduction of jet flow force by 58%.…”

“…This is most probably due to the high velocity of blood flow that was suddenly disturbed by the stator within the cannula wall. This proposed design of integrating a stator is also similar to the recent cannula design by Assmann et al but is further improved by incorporating a dispersive mesh‐like and funnel‐shape tip . In addition, the modification to the internal profile of the tube at the body part of the cannula was also proposed by several studies .…”

Artificial Organs 2015: A Year in Review

“…Alexander Assmann et al of the Heinrich Heine University, Düsseldorf, Germany numerically evaluated the impact of dispersive aortic cannulas on aortic blood flow characteristics, with special regard to the resulting wall shear stress profiles. Simulations of pulsatile and nonpulsatile extracorporeal circulation were performed.…”

Computational investigation of hemodynamics in hardshell venous reservoirs: A comparative study

“…Computational fluid dynamics (CFD) based procedures are being increasingly used to investigate blood flow characteristics. Various computational models, for the vascular blood flow with different emphases, were presented by a number of researchers . Computational investigation of the blood flow in artificial organs and biomedical devices such as heart pumps in various designs has equally attracted attention .…”

“…Various computational models, for the vascular blood flow with different emphases, were presented by a number of researchers. [5][6][7][8][9][10][11] Computational investigation of the blood flow in artificial organs and biomedical devices such as heart pumps in various designs has equally attracted attention. [12][13][14][15] A further field where CFD approaches have been extensively utilized comprises design engineering and performance monitoring of heart valves.…”