Article

Computational fluid dynamics simulations of intracranial aneurysms at varying heart rates: a "patient-specific" study.

Department of Medical Physics, University of Wisconsin-Madison, Madison, WI 53705, USA.
Journal of Biomechanical Engineering (impact factor: 1.9). 10/2009; 131(9):091001. DOI:10.1115/1.3127251
Source: PubMed

ABSTRACT Rupture of an intracranial aneurysm (IA) is frequently associated with intense physical exertion and/or emotional excitement, events that are typically also accompanied by sudden significant changes in both heart rate and blood pressure. Very few experimental studies of aneurysm hemodynamics have examined the impact on hemodynamic parameters in and around an aneurysm resulting from changes in heart rate. In order to further understanding these changes, as they relate to hemodynamic features that may contribute to rupture of an IA, we examined the characteristics of pulsatile flow in and around two "patient-specific" intracranial aneurysms at three different cardiac frequencies. Three dimensional X-ray angiographic data (3D-DSA) were used to reconstruct accurate and patient-specific aneurysm geometries. Then, computational fluid dynamics techniques were utilized to analyze the characteristics of blood flow in and around the two aneurysms. Physiologically realistic flow conditions, as measured by transcranial Doppler ultrasound, were used in the simulations. Our results showed that there were significant changes in the overall flow patterns (e.g., vortex formation and translation) associated with the changes of heart rates. In both aneurysms, the calculated wall shear stress exhibited substantial increases with an increase in heart rate. Our results suggest that the changes in local hemodynamic forces associated with variations in heart rate are dependent not only on the heart rate but also on the aneurysm geometry. This thus precludes applying our observations about the impact of variations in cardiac rate to aneurysms in general.

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Keywords

aneurysm hemodynamics
 
blood flow
 
blood pressure
 
cardiac rate
 
computational fluid dynamics techniques
 
different cardiac frequencies
 
dimensional X-ray angiographic data
 
emotional excitement
 
experimental studies
 
flow patterns
 
hemodynamic parameters
 
intense physical exertion
 
intracranial aneurysms
 
patient-specific aneurysm geometries
 
Physiologically realistic flow conditions
 
precludes applying
 
pulsatile flow
 
sudden significant changes
 
transcranial Doppler ultrasound
 
two aneurysms