title: Hemodynamic effects of spiral ePTFE prosthesis compared with standard arteriovenous graft in a carotid to jugular vein porcine model.
abstract: BACKGROUND
  The primary patency rate of arteriovenous (AV) grafts is limited by distal venous anastomosis stenosis or occlusion due to intimal hyperplasia associated with distal graft turbulence. The normal blood flow in native arteries is spiral laminar flow. Standard vascular grafts do not produce spiral laminar flow at the distal anastomosis. Vascular grafts which induce a spiral laminar flow distally result in lower turbulence, particularly near the vessel wall. This initial study compares the hemodynamic effects of a spiral flow-inducing graft and a standard graft in a new AV carotid to jugular vein crossover graft porcine model.
  
  
  METHODS
  Four spiral flow grafts and 4 control grafts were implanted from the carotid artery to the contralateral jugular vein in 4 pigs. Two animals were terminated after 48 hours and 2 at 14 days. Graft patency was assessed by selective catheter digital angiography, and the flow pattern was assessed by intraoperative flow probe and color Doppler ultrasound (CDU) measurements. The spiral grafts were also assessed at enhanced flow rates using an external roller pump to simulate increased flow rates that may occur during dialysis using a standard dialysis needle cannulation. The method increased the flow rate through the graft by 660 ml/min. The graft distal anastomotic appearances were evaluated by explant histopathology.
  
  
  RESULTS
  All grafts were patent at explantation with no complications. All anastomoses were found to be wide open and showed no significant angiographic stenosis at the distal anastomosis in both spiral and control grafts. CDU examinations showed a spiral flow pattern in the spiral graft and double helix pattern in the control graft. No gross histopathological effects were seen in either spiral or control grafts.
  
  
  CONCLUSIONS
  This porcine model is robust and allows hemodynamic flow assessment up to 14 days postimplantation. The spiral flow-inducing grafts produced and maintained spiral flow at baseline and enhanced flow rates during dialysis needle cannulation, whereas control grafts did not produce spiral flow through the distal anastomosis. There was no deleterious effect of the spiral flow-inducing graft on macroscopic and histological examination. The reducing effect of spiral flow on intima hyperplasia formation will be the subject of further study using the same AV graft model at a longer period of implantation.
authors.affiliation: Department of Vascular Surgery, University Medical Center, Utrecht, The Netherlands.
authors.forename: Ommid K
authors.initials: OK
authors.lastname: Jahrome
authors.forename: Imo
authors.initials: I
authors.lastname: Hoefer
authors.forename: Graeme J
authors.initials: GJ
authors.lastname: Houston
authors.forename: Peter A
authors.initials: PA
authors.lastname: Stonebridge
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Blankestijn
authors.forename: Frans L
authors.initials: FL
authors.lastname: Moll
authors.forename: Gert J
authors.initials: GJ
authors.lastname: de Borst
mesh_terms: D000818:Animals; D001166:Arteriovenous Shunt, Surgical / Q000295:instrumentation*; D001783:Blood Flow Velocity; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation / Q000295:instrumentation*; D002339:Carotid Arteries / Q000000981:diagnostic imaging / Q000601:surgery*; D005260:Female; D006439:Hemodynamics; D007601:Jugular Veins / Q000000981:diagnostic imaging / Q000601:surgery*; D023421:Models, Animal; D010690:Phlebography; D011138:Polytetrafluoroethylene; D011474:Prosthesis Design; D012039:Regional Blood Flow; D013552:Swine; D013997:Time Factors; D018615:Ultrasonography, Doppler, Color; D014654:Vascular Patency
chemical_list: D011138:Polytetrafluoroethylene