Effect of increased intracranial pressure on blood flow through cerebral arteries and aneurysms -a fluid-structure interaction study

Abstract

The pathological changes due to many cerebral diseases lead to increase in intracranial pressure (ICP), which is a life threatening condition especially in severe head injuries such as traumatic brain injury, hydrocephalus, sub arachnoid hemorrhage etc. Elevated intracranial pressure (ICP) is a major contributor to morbidity and mortality in severe head injuries. Maintaining the ICP within acceptable range is important to contain the failure of auto regulation which maintains and regulates adequate cerebral blood flow inside the brain. These increased intracranial pressures are found to significantly affect the Wall Shear Stresses (WSS) distribution in the artery, which is an important hemodynamic parameter and may lead to the formation, progression and rupture of cerebral aneurysms (pathological dilatations in cerebral arteries) which go unnoticed until a stage when they are severe. Earlier research on cerebral arteries and aneurysms involves using constant mean ICP values. Recent advancements in ICP monitoring techniques have led to measurement of the ICP waveform and by incorporating time varying ICP waveform in the analysis of cerebral arteries helps in better understanding their effects on wall deformation and shear stresses. To date, such a robust computational study on the effect of increasing intracranial pressures on the cerebral arterial walls and aneurysms has not been attempted to the best of our knowledge. In this work, fully coupled fluid structural interaction (FSI) simulations are carried out to investigate the effect of variation of intracranial pressure (ICP) waveforms on the cerebral arterial walls and aneurysms. Three time varying ICP waveforms and three constant ICP profiles acting on the cerebral arterial wall are analyzed in this work. It has been found that the arterial and aneurysmal walls experiences significant deformation depending on the time varying ICP waveforms, while the WSS changes at peak systole for all the ICP profiles. Also, the maximum wall shear stresses decreased with increase in ICP inside the aneurysm dome and the minimum area of WSS distribution increased.