title: Finite element analysis of uncommonly large renal arteriovenous malformation--adjacent renal cyst complex.
abstract: BACKGROUND
  Renal arteriovenous malformation (RAVM) represents abnormal communication between the intrarenal arterial and venous system. The purpose of this study was to investigate hemodynamics and biomechanics quantities which may influence the instability of RAVM and imply clinical complications.
  
  
  METHODS
  A detailed 3D reconstruction of RAVM was obtained from the patient CT scans, aortic inlet flow was measured by color-flow Doppler ultrasound, while material characteristics were adopted from the literature. A numerical finite element analysis (FEA) of the blood flow was performed by solving the governing equations for the viscous incompressible flow. The physical quantities calculated at the systolic and diastolic peak moment were velocity, pressure, shear stress and drag forces.
  
  
  RESULTS
  We reported a case of a 50-year-old patient with a large RAVM and adjacent renal cyst, who unsuccessfully underwent two attempts of embolization that resulted in the consequent nephrectomy. FEA showed that the cyst had a very low pressure intensity and velocity field (with unstable flow in diastolic peak). For both systolic and diastolic moments, increased values of wall shear stress were found on the places with intensive wall calcification. Unusually high values of drag force which would likely explain the presence of pressure in the cystic formation were found on the infero-medial side where the cyst wall was the thinnest and where the flow streamlines converged.
  
  
  CONCLUSIONS
  FEA showed that the hemodynamics of the cyst-RAVM complex was unstable making it prone to rupture. Clinically established diagnosis of imminent rupture together with unfavorable hemodynamics of the lesion consequently made additional attempts of embolization risky and unsuccessful leading to total nephrectomy.
authors: Faculty of Engineering, University of Kragujevac, Sestre Janjic 6, Kragujevac, Serbia; Bioengineering Research and Development Center Kragujevac, Prvoslava Stojanovica 6, 34000 Kragujevac, Serbia.
authors: Arso M
authors: AM
authors: Vukicevic
authors: Medical Faculty, University of Novi Sad, Hajduk Veljkova 3, Novi Sad, Serbia; Institute of Cardiovascular Diseases Vojvodina, Put doktora Goldmana 4, Sremska Kamenica, Serbia.
authors: Lazar U
authors: LU
authors: Velicki
authors: Faculty of Engineering, University of Kragujevac, Sestre Janjic 6, Kragujevac, Serbia.
authors: Gordana R
authors: GR
authors: Jovicic
authors: Faculty of Engineering, University of Kragujevac, Sestre Janjic 6, Kragujevac, Serbia.
authors: Nebojsa
authors: N
authors: Jovicic
authors: Department of Urology, Clinic of Urology and Nephrology, Clinical Centre "Kragujevac", Zmaj Jovina 30, Kragujevac, Serbia.
authors: Miroslav M
authors: MM
authors: Stojadinovic
authors: Faculty of Engineering, University of Kragujevac, Sestre Janjic 6, Kragujevac, Serbia; Bioengineering Research and Development Center Kragujevac, Prvoslava Stojanovica 6, 34000 Kragujevac, Serbia. Electronic address: fica@kg.ac.rs.
authors: Nenad D
authors: ND
authors: Filipovic
mesh_terms: D000792:Angiography; D001165:Arteriovenous Malformations / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology* / Q000628:therapy; D004621:Embolization, Therapeutic; D020342:Finite Element Analysis; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007668:Kidney / Q000098:blood supply / Q000000981:diagnostic imaging / Q000473:pathology; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D012077:Renal Artery / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000473:pathology; D014057:Tomography, X-Ray Computed
keywords: Finite element analysis; Hemodynamics; Instability; Modeling; Renal arteriovenous malformation