Computational Modeling of Hemodynamic Flows
Vascular access creation remains one of the most challenging problems in delivering adequate hemodialysis treatments. The three forms of chronic access currently available are synthetic grafts, catheters and native arteriovenous fistulas (AVF). Because grafts and catheters have higher morbidity rates and associated costs, AVF increasingly are becoming the preferred means of initial vascular access due to their longer life-span and lower incidence of complications, such as thrombosis or infection. Although the more common lower arm radiocephalic fistula typically leads to the best outcomes, it is often difficult to create and may fail to mature in diabetics; therefore, the upper arm brachiocephalic fistula is often used as a secondary means of vascular access when the radiocephalic fistula fails. Whereas the radiocephalic fistula most often fails in the anastomotic region where the AVF procedure was performed, failure of the brachiocephalic fistula is often the consequence of the onset of stenosis within the cephalic arch, which is located in the shoulder, and its associated complications, including thrombosis, aneurisms or swelling of the neck and shoulder.
Because the location of stenosis within the cephalic arch is well downstream of the location of the anastomosis, cephalic arch stenosis (CAS) is hypothesized to be related to the dramatic changes in the hemodynamics in the cephalic arch due to the AVF. However, very little is known about the influence of various geometric and flow features on the onset of stenosis, particularly in a clinical setting. Therefore, a better understanding of the influence of geometry and flow rate on the hemodynamics through the cephalic arch is sought using CFD. It is expected that this will lead to clear indicators for the onset of subsequent CAS. CFD provides a means by which to determine the details of blood flow through the vascular system of actual patients that cannot be obtained clinically. The present study has a large potential for impact on both the fundamental understanding of vascular flows and improvements in fistula procedures for actual patients in clinical environments. Ultimately, predictive capability is sought to determine the likelihood of CAS, thereby providing essential guidance to the surgeon executing the vascular access procedure and subsequent follow-up monitoring of the patient. It is anticipated that the project outcomes will both increase the long-term effectiveness of such procedures and decrease the overall cost of maintaining long-term vascular access for dialysis patients by reducing the need for follow-up procedures to improve existing access or establish new access after failure of an AVF.
National Institute of Health Collaborative Translational and Clinical Studies (CTSA) Grant, 2009
NASA Space Grant Fellowship, 2008
MMAE Outstanding Teaching Assistant Award, Illinois Institute of Technology, 2008
Pritzker Institute for Biomedical Science and Engineering Grant, 2007
Professional Society Memberships
Hammes, M., Boghosian, M., Cassel, K., Funaki, B., and Coe, F., "Characteristic Differences in Cephalic Arch Geometry for Diabetic and Non-diabetic ESRD Patients," Nephrology Dialysis Transplantation, Vol. 24, No. 7 (2009) pp. 2190–2194 (doi: 10.1093/ndt/gfp062).
Boghosian, M.E., and Cassel, K.W., "Origins of Vortex Shedding in Constricted Two-Dimensional Channels," Journal of Fluid Mechanics, submitted.