title: Basic Principles of Hemodynamics and Cerebral Aneurysms.
abstract: BACKGROUND
  Rupture is the most serious consequence of cerebral aneurysms, and its likelihood depends on nonmodifiable and modifiable risk factors. Recent efforts have focused on analyzing the effects of hemodynamic forces on the initiation, growth, and rupture of cerebral aneurysms. Studies of the role of hemodynamics in the physiopathology of intracranial aneurysms fall between mechanical engineering and molecular biology.
  
  
  METHODS
  This review summarizes the basic principles of the effect of hemodynamic forces on the cerebral vascular wall.
  
  
  CONCLUSIONS
  The size of the aneurysm dome is the most common parameter used in clinical practice to estimate the risk of rupture. However, relying only on aneurysm size means excessively simplifying a more complicated reality. Aneurysms emerge in areas of the vascular wall exposed to high wall shear stress. The direction in which blood flows once an aneurysm forms depends on aspects such as neck diameter, its angle with respect to the parent artery, the parent vessel caliber, the caliber or the angle of efferent vessels, and aneurysm shape. The progression and rupture of aneurysms have been associated with zones of the aneurysm wall exposed to both high and low wall shear stresses. Advances in this challenging and growing field are intended to predict more precisely the risk of rupture of aneurysms and to better understand the mechanisms of origin and growth of aneurysms.
authors.affiliation: Department of Neurosurgery, University Hospital "12 de Octubre", Complutense, University of Madrid, Madrid, Spain. Electronic address: pablommunarriz@gmail.com.
authors.forename: Pablo M
authors.initials: PM
authors.lastname: Munarriz
authors.affiliation: Department of Neurosurgery, University Hospital "12 de Octubre", Complutense, University of Madrid, Madrid, Spain.
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Gómez
authors.affiliation: Department of Neurosurgery, University Hospital "12 de Octubre", Complutense, University of Madrid, Madrid, Spain.
authors.forename: Igor
authors.initials: I
authors.lastname: Paredes
authors.affiliation: Department of Neurosurgery, University Hospital "12 de Octubre", Complutense, University of Madrid, Madrid, Spain.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Castaño-Leon
authors.affiliation: Department of Neurosurgery, University Hospital "12 de Octubre", Complutense, University of Madrid, Madrid, Spain.
authors.forename: Santiago
authors.initials: S
authors.lastname: Cepeda
authors.affiliation: Department of Neurosurgery, University Hospital "12 de Octubre", Complutense, University of Madrid, Madrid, Spain.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Lagares
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity; D001810:Blood Volume; D002536:Cerebral Arteries / Q000503:physiopathology*; D002560:Cerebrovascular Circulation; D006439:Hemodynamics; D006801:Humans; D002532:Intracranial Aneurysm / Q000503:physiopathology*; D008955:Models, Cardiovascular
keywords: Cerebral aneurysm; Computational fluid dynamics; Hemodynamics; Rupture; Wall shear stress; Wall tension