title: Neovascularization in acute venous thrombosis.
abstract: OBJECTIVE
  The aim of this study was to describe the phenomenon of arteriovenous fistula (AVF) formation in venous thrombus.
  
  
  METHODS
  Patients referred to the vascular laboratory for evaluation for deep venous thrombosis were included. Duplex ultrasound scanning was used to detect flow within the thrombus. The flow patterns and the resistivity index were obtained in the veins above/proximal and below/distal to the thrombus, in the adjacent arteries, and within the perivenous vessels. Patients with trauma, hemodialysis access, endovenous ablation, known AVF, or inflammatory conditions were excluded.
  
  
  RESULTS
  There were 22 patients with AVF flow in thrombosed veins. Deep veins were involved in 15 cases and superficial veins in the remainder. Perivenous vessels feeding the AVF in the thrombus could be clearly identified in 16 patients (19 vein segments). In 21 of 22 patients, multiple flow channels were present throughout the involved thrombosed vein segment. These flow channels were isolated to a single vein segment. They measured <4 cm in length in 19 cases and were more extensive in the remaining three. Reflux within the vein segment was identified in 13 cases. Local symptoms that could be attributed to the arterialization of thrombosed veins occurred in four cases, and none of the patients manifested systemic symptoms. The flow within the thrombus had high end-diastolic velocities with a mean resistivity index of 0.48 (SD, 0.08), which is typical of a fistula flow pattern. The flow in the main arteries was unaffected.
  
  
  CONCLUSIONS
  Neovessels were found with AVF flow in thrombi of superficial and deep veins. They had variable length and multiple flow channels, with inflow from perivenous arteries. The flow in the adjacent main arteries was not affected, and no systemic symptoms were detected. The exact etiology and natural history of this phenomenon are not known, and its clinical significance is unclear.
authors.affiliation: Department of Surgery, Loyola University Medical Center, USA. nlabrop@yahoo.com
authors.forename: Nicos
authors.initials: N
authors.lastname: Labropoulos
authors.forename: Ahmad F
authors.initials: AF
authors.lastname: Bhatti
authors.forename: Salomon
authors.initials: S
authors.lastname: Amaral
authors.forename: Luis
authors.initials: L
authors.lastname: Leon
authors.forename: Marc
authors.initials: M
authors.lastname: Borge
authors.forename: Heron
authors.initials: H
authors.lastname: Rodriguez
authors.forename: Peter
authors.initials: P
authors.lastname: Kalman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001164:Arteriovenous Fistula / Q000000981:diagnostic imaging / Q000209:etiology*; D001783:Blood Flow Velocity; D005260:Female; D006801:Humans; D007866:Leg / Q000098:blood supply; D008297:Male; D008875:Middle Aged; D009389:Neovascularization, Pathologic / Q000000981:diagnostic imaging / Q000209:etiology*; D018616:Ultrasonography, Doppler, Duplex; D020246:Venous Thrombosis / Q000150:complications* / Q000000981:diagnostic imaging