How secure is the anastomosis between the proximal and distal body components of a fenestrated stent-graft?
OBJECTIVE
To examine the longitudinal migratory force required to cause disconnection of the bifurcated distal body component from the tubular proximal body of a fenestrated stent-graft.


METHODS
Using a previously reported mathematical model distal distraction forces were calculated prior to performing in vitro pullout testing. The top end of the proximal body and the iliac limbs of the distal body were attached to the grips of a tensile tester via plastic sealing plugs and pneumatic clamps. Channels within the plugs allowed pressurisation of the inside of the stent-graft. Pullout tests were conducted in the vertical plane. Force and displacement data were recorded and tests repeated 8 times at room temperature with the stent-grafts either dry or wet and unpressurized, at 100 mmHg or at 120 mmHg.


RESULTS
The median maximum pullout force was 2.9 N (2.6-4.1) when dry, 3.9 N (3.5-5.4) when wet and unpressurized, 6.3 N (4.8-8.3) when wet and pressurized at 100 mmHg and 6.5 N (4.8-7.2) when wet and pressurized at 120 mmHg. There was a significant difference between pressurized and unpressurized conditions (P < 0.01).


CONCLUSIONS
The force required to distract the distal bifurcated component of a fenestrated stent graft is much lower than the reported proximal fixation strength of both a standard and fenestrated Zenith stent graft. Although this helps protect the fenestrated proximal body from the effects of longitudinal migration forces in vivo the current strength of the body overlap zone may actually be unnecessarily weak and requires careful surveillance in follow up.
Regional Vascular Unit, 8c Link, Royal Liverpool University Hospital, Liverpool L7 8XP, UK. scurrj@hotmail.com
J R H
JR
Scurr
R G
RG
McWilliams
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TV
How
D000714:Anastomosis, Surgical; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation*; D057867:Endoleak / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology; D057510:Endovascular Procedures / Q000009:adverse effects* / Q000295:instrumentation*; D019544:Equipment Failure Analysis; D005548:Foreign-Body Migration / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology; D006439:Hemodynamics; D006801:Humans; D008422:Materials Testing; D008955:Models, Cardiovascular; D011312:Pressure; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D015607:Stents; D013314:Stress, Mechanical; D013718:Tensile Strength