Early experience with the SLF (Spiral Laminar Flow) AV Access Graft
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
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.
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…)
Spiral Laminar Flow Prosthetic Bypass Graft: Bypass Graft: Medium-Term Results From a First-In-Man Structured Registry Study
Background
A number of surgical strategies and graft enhancements have been trialled to improve the performance of prosthetic grafts. (more…)
Vascular Flow Technology: Another run-of-the-mill graft or a breakthrough technology? Experience and perspective from a US centre
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:
| Primary | Primary assisted | Secondary |
|---|---|---|
| 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
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
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
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
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.
Haemodynamic effects of spiral ePTFE prosthesis compared with standard arteriovenous graft in a carotid to jugular vein porcine model
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. (more…)