Early experience with the SLF (Spiral Laminar Flow) AV Access Graft

Inston N1 , Hofmann WJ2 .
1 Department of Renal Surgery, Queen Elizabeth Hospital, University Hospitals Birmingham, Birmingham, UK
2 Department for Vascular Surgery, Feldkirch General Hospital, Feldkirch, Austria
In Abstracts from VAS 8th International Congress, April 25-27, 2013 Prague, Czech Republic. J Vasc Access 2013; 14(1): 43

Background

Arteriovenous grafts for dialysis are associated with a high incidence of outflow stenosis requiring re-intervention and increased risk of failure. (more…)

A new choice for vascular access: Spiral Flow AV Graft

Cetingok U
Department of Cardiovascular Surgery, Kavaklidere Umut Hospital, Ankara, Turkey
In Abstracts from VAS 8th International Congress, April 25-27, 2013 Prague, Czech Republic. J Vasc Access 2013; 14(1): 36-37

Background

The most commonly used grafts for vascular access are the polytetraflouroethylene (PTFE) grafts. Different types of PTFE grafts are used in the vascular access applications for a long time. (more…)

Vascular Flow Technology: Another run of the mill graft or a breakthrough technology? Experience and perspective from a European centre.

Prim. Univ.-Doz. Dr. Wolfgang J. Hofmann
Department of Vascular Surgery, Landeskrankenhaus (LKH) Feldkirch, Austria
Presented at the 35th Charing Cross International Symposium, 7th April, 2013, London, UK

Background

The AV access strategy at LKH Feldkirch focusses primarily on utilising native fistula and Duplex mapping of the upper extremity is undertaken to identify the most appropriate of the following approaches: (more…)

Vascular Flow Technology: Another run-of-the-mill graft or a breakthrough technology? Experience and perspective from a US centre

Presented at the 35th Charing Cross International Symposium, London, UK 7 April 2013. Hosam El Sayed, MD, Assistant Professor of Cardiovascular Surgery. Methodist DeBakey Heart and Vascular Center, Houston, Texas, USA.

Patients and methods

From January, 2012 – February, 2013, 19 Spiral Flow™ AV Access Grafts (Vascular Flow Technologies Ltd) were placed in 18 patients. The mean age was 60 years (range 42-84 years); 37% (7) were male. Patients presented with the following comorbidities: six diabetes (32%); 17 hypertension (90%); five CAD (26%); four CHF (21%); five CVA (26%); six PVD (32%). Grafts were implanted as: 11 upper arm; two forearm; five femoral; and one chest wall.

Results

The mean follow-up was six months. There are 11 grafts (58%) still in use. Three grafts (15%) were removed for infection; two grafts thrombosed (10%); two grafts were ligated for severe steal (10%). There were two grafts with seroma (10%), but they remained functional. There were three wound complications (15%) and three arm swelling (15%). One graft was ligated (5%). There were no pseudoaneurysms. Two patients died with functioning grafts.

Overall patency results are as follows:

PrimaryPrimary assistedSecondary
90% ± 9%90% ± 9%100% ± 0%

Conclusion

The early results are encouraging and tend to be better compared to standard straight ePTFE and heparin bonded grafts. This might be explained on the basis of improved haemodynamics created by the spiral laminar flow.

Mid-Term Results of the Spiral Flow PV Grafts

Poster at the 15th Turkish Vascular Society Congress, October 2011 Dr Çetingök, Corum Hospital, Corum, Turkey

Patients and Methods

47 patients implanted from June 2009 to August 2011 with a mean follow-up period of 14 months. Mean age at operation was 67 (41 to 89) years and 6% were female. 77% were stage IIb and 23% stage III Fontaine Classification.

73 implantations were performed (a number of patients received more than one graft), 45% of patients received above knee (AK) procedures and 55% received a below knee (BK) procedure.

Results

Five grafts thrombosed (7%) and were all successfully thrombolysed to fully restore patency. There was one patient death unrelated to the graft.

At 14 months mean follow-up primary patency is 93% and secondary is 98%.

Is the structure of the vessel wall a generator of Spiral Flow? A Cadaveric histological study

Heire P1, Wilton J1, Jacques S1,Marie Y2, Jones R3 Inston, N2
1 Department of Anatomy, School of Immunity and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
2 Department of Renal Surgery, Queen Elizabeth Hospital, University Hospitals Birmingham, Birmingham. UK
3 Department of Radiology, Queen Elizabeth Hospital, University Hospitals Birmingham, Birmingham. UK
In Abstracts from VAS 8th International Congress, April 25-27, 2013 Prague, Czech Republic. J Vasc Access 2013; 14(1): 5

Background

In healthy individuals flow patterns in the arterial tree have a spiral vector (Spiral laminar flow, SLF) which is attributed to the eccentric myocardial action and the spiral nature of the aortic arch. (more…)

Hemodynamic differences in the outflow of access vascular grafts

Kokkalis E1, Hoskins PR2, Corner GA3, Doull AJ1, Stonebridge PA1, Houston JG1
1 Cardiovascular and Diabetes Medicine, 2 Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK, 3 Medical Physics, Ninewells Hospital and Medical School, Dundee, UK
In Abstracts from VAS 8th International Congress, April 25-27, 2013 Prague, Czech Republic. J Vasc Access 2013; 14(1): 47

Background

Access vascular (AV) prostheses are commonly used for haemodialysis. Their low patency rates remain a challenge with restenosis in the distal anastomosis being the main reason of failure. (more…)

Haemodynamic effects of spiral ePTFE prosthesis compared with standard arteriovenous graft in a carotid to jugular vein porcine mode

J Vasc Access. 2011 Jul-Sep;12(3):224-30. doi: 10.5301/JVA.2010.6097 Jahrome OK, Hoefer I, Houston GJ, Stonebridge PA, Blankestijn PJ, Moll FL, de Borst GJ.

Introduction

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 colour 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.

Conclusion

This porcine model is robust and allows haemodynamic flow assessment up to 14 days post-implantation. 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.