The hybrid vascular ePTFE graft is proposed as an alternative for difficult hemodialysis access cases. It combines an ePTFE graft with a covered nitinol stent to create a sutureless venous anastomosis. This is aimed at improving graft patency by reducing intimal hyperplasia. The initial experience with the hybrid graft shows it can be used safely and effectively to establish access in complex patients with few alternative options. Further studies are still needed to determine if it provides long term patency results superior to other grafts.

1. The Hybrid Vascular ePTFE Graft
as an Alternative for Hemodialysis
Access
Joseph J. Naoum, MD, FACS
Assistant Professor of Surgery
Lebanese American University
Vascular & Endovascular Surgery
University Medical Center Rizk Hospital
Beirut, Lebanon
Joseph.naoum@umcrh.com
+96176933937

2. BACKGROUND
• Native arteriovenous fistulas (AVF) are the first
option for dialysis access creation.
– However, not all patients have adequate veins for the
creation of autologous access.
• With the recent trend of an increasing
hemodialysis population with diabetes and
longer survival, the exhaustion of autologous
sites is becoming more prevalent .
– End-stage Renal Disease (ESRD) patients requiring
chronic hemodialysis are increasingly requiring
alternatives for the challenging creation of long-term
arteriovenous (AV) access sites.
Akoh JA. J Vasc Access. 2009 Jul-Sep;10(3):137-47.
Vascular Access 2006 Work Gruup. Am J kideney Dis 2006; 48 (Supp 1);S176-247.
Anaya-Ayala JE, et al. Ann Vasc Surg. 2011 Jan;25(1):108-19.

3. THE PROBLEM
• The poor long-term prognosis of prosthetic grafts
generally results from development of intimal
hyperplasia and consequently stenosis at the
graft-vein or graft-artery anastomosis.
• For instance, a few in vitro studies utilizing
computational fluid dynamics (CFD) have
described the complex hemodynamics of the AVG
anastomosis (in dialysis access).
– This complexity is the result of the connection of the
high pressure, high velocity arterial flow to a low
pressure low velocity venous system. The effect of
the shear forces are primarily a problem of the
standard graft configuration.
Hakim R,et al. Kidney Intl 1998;54:1029-40.
Heise M, et al.J Vasc Surg. 2011 Jun;53(6):1661-7. Epub 2011 Apr 2.
Dixon BS, et al. N Engl J Med. 2009 May 21;360(21):2191-201.
Heise M, et al. Eur J. Vasc Endovasc Surg 2003;26:367-73.
Krueger U, et al. Artif Organs. 2004;28:623-8.

4. Structural graft modifications
• The development of intimal hyperplasia is one
of the culprits for bypass or graft failure.
• Structural modifications of the conduit that
alter the flow hemodynamics at the distal
anastomosis have been introduced.
– The concept hinges on creating laminar flow at
the distal anastomosis, which in turn can
influence and decrease the occurrence of intimal
hyperplasia.
Naoum JJ, et al. MDHVJ 2012, 8(4): 43-6

5. Flow and Shear Stress
Littele S, et al. http://www.goremedical.com/resources/dam/
assets/AQ0560EN1.HVG.STUDY.FLYER.FNL.MR.pdf
Jackson ZS, et al. J Vasc Surg 2001;34(2):300-307.
• In the conventional
end-to-side
anastomosis,
intimal hyperplasia
occurs in part due to
alterations in shear
stress at the toe and
heel of the AVG
anastomosis.

6. Flow and Shear Stress
• The GORE® Hybrid
Vascular Graft altered
the wall shear stress
region at the toe and
the heel of the graft
anastomosis site,
which corresponds to
the development of
intimal hyperplasia in
the conventional end-
to-side anastomosis.
Littele S, et al. http://www.goremedical.com/resources/dam/
assets/AQ0560EN1.HVG.STUDY.FLYER.FNL.MR.pdf
Jackson ZS, et al. J Vasc Surg 2001;34(2):300-307.

7. • Due to the GORE® Hybrid Vascular Grafts occlusion of the venous inflow,
flow remained laminar, where the conventional construct exhibited
irregular flow patterns downstream from the entry site.
– Irregular, oscillating flow patterns have also been identified as a precursor
to the development of intimal hyperplasia and graft occlusion.
• These observations suggest that the GORE® Hybrid Vascular Graft
provides optimized flow characteristics as compared to a conventional
end-to-side anastomosis thus potentially reducing the incidence of
arteriovenous access graft stenosis due to intimal hyperplasia.
Littele S, et al. http://www.goremedical.com/resources/dam/
assets/AQ0560EN1.HVG.STUDY.FLYER.FNL.MR.pdf
Jackson ZS, et al. J Vasc Surg 2001;34(2):300-307.
Ojha M. Circulation Res 1994;74(6):1227-1231

8. The use of covered nitinol stents to salvage
dialysis grafts after multiple failures.
Naoum JJ, et al. Vasc Endovasc Surg 2006;40:275-79

9. Begovac PC, et al. Eur J of Vasc Endovasc Surg
2003;25(5):432-437.
Heparin Bonded Vascular Graft
Control
At 2 hrs
THE IDEA

10. HYBRID ePTFE HEPARIN BONDED GRAFT

11. THE SOLUTION?
• The stent graft component of the hybrid graft has
been proposed to overcome some of the
hemodynamic features that may contribute to
the development of intimal hyperplasia at the
venous anastomosis.
• This is because the laminar flow through the
graft is in line with the host vessel.
– Unlike the conventional end-to-side anastomosis, this
device deploys as a sutureless outflow anastomosis
with a nitinol reinforced stent section which
presumably shields the vessel lumen area most
susceptible to injury and failure.

12. PREVIOUS EXPERIENCES
• Experimental devices capable to create a sutureless
arterial anastomosis have demonstrated safety and
efficacy in porcine models.
• Some have described the use of modified devices
utilizing a standard Viabahn stent graft (WL Gore,
Flagstaff, AZ) and an ePTFE graft for bypass in
peripheral arterial disease with encouraging initial
technical and clinical outcomes.
• The initial experience with “non-hybrid” heparin
bonded PTFE grafts for dialysis access patients has
resulted in 15 to 20% benefit improved graft patency at
12 months.
Taam SA, et al. J Vasc Surg. 2011 Dec 1. [Epub ahead of print]
Ferretto L, et al Ann Vasc Surg.2011 Oct 21. [Epub ahead of print]
Bonvini S, et al. J Vasc Surg. 2011 Sep;54(3):889-92.

15. Patient selection
• Previous AV Access involving the axilla
– Previous graft anastomosis or a stent in the
venous target at the axilla
– Failed brachial-basilic or brachial-brachial upper
arm transposition arteriovenous fistula
• A target vein < 0.3 cm within the axilla.
• NO option for AVF creation by vein mapping
and exam.

17. PATIENT CHARACTERISTICS
Demographics
No (%) or
Mean ± SD (range)
Patient Total 25 (100)
Age, years 62 ± 14 (29-88)
Men 13 (52)
Women 12(48)
Medical Comorbidities
Diabetes Mellitus 18 (72)
Hypertension 25 (100)
Coronary Artery Disease 10 (40)
Congestive Heart Failure 10 (40)
Myocardial Infarction 2 (8)
COPD 2 (8)
CVA 7 (28)
Hyperlipidemia 12 (48)
PAD 4 (16)

18. OPEN TECHNIQUE

19. Venous access with Stiff Glide wire in the IVC
for support
Wire goes into
the IVC for
support

20. 14 Fr. Split Sheath access into the vein

21. Introduction of the Hybrid Graft over the
wire and through the sheath
Keep forward
pressure as the
split sheath is
removed.
Advance the
stent graft > 2.5
cm into the
vessel.

23. Tunneled Hybrid graft

24. Balloon Angioplasty of the stent graft segment
and venous entry site

25. Venotomy site
Balloon Angioplasty of Viabahn stent graft
segment and venous entrance site
(Usually with a 7 mm Balloon)

26. Low Volume Venogram

27. Completion
Arterial sutured
anastomosis
Venous stent-grafted
outflow segment

28. Completion Fistulogram

29. Two Incisions

30. PERCUTANEOUS TECHNIQUE
YES:
US GUIDED VENOUS
PUNCTURE
NO:
“BLIND” VENOUS
PUNCTURE

31. A WORD OF CAUTION: WATCH THE NERVE
R. Brachial
artery
R. Brachial/Axillary
vein
R. Nerve
Bundle
Nerve
Bundle

32. Wire is in the IVC for
support

34. COMPLETION FISTULOGRAM AND PTA

38. Crossed long segment axillary vein
severe stenosis and PTA with
extravasation
Covered Axillary/subclavian vein
with an 8 mmx10 cm stent graft
Hybrid graft utflow
stent-graft segment
• 7 patients required a stent-
graft extension.
• 2 patients required PTA to
improve venous outflow at
the axillary and/or
subclavian vein.

39. “Percutaneous Venous Access”

40. 12 MONTH Patency rate
Primary Secondary
70 % 92
Predicted

41. Primary Patency
J Vasc Surg, Volume 38(6) December 2003, 1206–1212

42. CONCLUSION
• New graft technologies can be successfully
used to handle clinical and anatomic
challenges with complex dialysis patients.
• The Hybrid graft is a safe and efficacious
alternative for access creation.
– However, further studies will determine whether
this graft provides long term results equivalent or
superior to those achieved with other
prostheses.

43. THANK YOU

45. Steps
• Venous access:
– US guided: Micro-puncture kit with etched needle and a
stiff wire.
• Make a 1 cm incision and use a hemostat to dissect free the
tissues and create a small pocket. Blunt dissection.
– Open exposure: Micro-puncture kit with etched needle
and a stiff wire

46. Steps
– Venogram
• Hybrid graft venous insertion and deployment:
– Place 14 Fr. Sheath over a wire
– Introduce/deploy Hybrid graft (over the wire)

47. Steps
– Low volume venogram and PTA stent graft
segment, especially at venotomy site.
• Arterial segment:
– Tunnel the graft.
– Perform the arterial anastomosis.

48. Steps
• Check function and patency:
– If a thrill is not evident, consider fistulogram
and PTA graft/stent confluence to expand the
graft (that is a transition site with ↓ radial
support).