CLINICAL RESEARCH STUDIES
Remodeling of proximal neck angulation after
endovascular aneurysm repair
Hiroyuki Ishibashi, MD,aTsuneo Ishiguchi, MD,bTakashi Ohta, MD,aIkuo Sugimoto, MD,a
Tetsuya Yamada, MD,aMasao Tadakoshi, MD,aNoriyuki Hida, MD,aand
Yuki Orimoto, MD,aNagakute, Aichi, Japan
Objective: This study investigated the remodeling of proximal neck (PN) angulations of abdominal aortic aneurysms
(AAAs) after endovascular aneurysm repair (EVAR).
Methods: A 64-row multidetector computed tomography scan of AAAs treated with EVAR was reviewed, and the PN
angulation was measured on a volume-rendered three-dimensional image. The computed tomography scan was examined
preoperatively, after EVAR at 1 week, 1 month, 6 months, 1 year, 1.5 years, 2 years, and then yearly. The study enrolled
78 patients, comprising 54 Zenith devices (Cook Medical, Bloomington, Ind) and 24 Excluder devices (W. L. Gore and
Associates, Flagstaff, Ariz).
Results: PN angulation was 50° ? 20° preoperatively, and after EVAR was 36° ? 14° at 1 week, 32° ? 14° at 1 year, and
28° ? 13° at 3 years. PN angulations <60° (n ? 70, 77%) were 41° ? 13° preoperatively, 31° ? 12° 1 week after EVAR,
28° ? 12° at 1 year, and 26° ? 13° after 3 years. An angulation >60° (n ? 18, 23%) was 78° ? 14° preoperatively,
51° ? 11° 1 week after EVAR, 44° ? 11° at 1 year, and 40° ? 12° after 3 years. The greater the preoperative PN
angulation, the greater its reduction immediately after EVAR (r ? .72, P < .001). The diameter shrinkage of AAAs with
a PN angulation >60° was 3 ? 6 mm after 1 year; a significantly smaller shrinkage than with a PN angulation <60°
(7 ? 7 mm, P < .05). AAAs with a PN angulation >60° had a larger angulation reduction and a smaller diameter
shrinkage after the EVAR procedure. The PN angulation of the 54 AAAs treated by Zenith was 49° ? 22° preoperatively,
34° ? 14° 1 week after EVAR, and 25° ? 13° after 3 years. The corresponding angulation of the 24 AAAs treated by
Excluder devices was 52° ? 17°, 41° ? 14°, and 38° ? 9°, respectively. The PN angulation reduction of Zenith and
Excluder was similar 1 week after the EVAR procedure. Unlike Excluder, however, the PN angulation in Zenith
continued to reduce for a long period at a slow pace. There were no significant correlations between PN angulation
reduction and diameter change and between PN length and diameter change (P ? .86 and .18, respectively).
Conclusions: Although the instructions for use of most commercially available stent grafts provide for a PN angulation of
<60°, PN angulation was not a major issue in a midterm follow-up of AAAs with adequate PN length for patients in this
series who received a Zenith or Excluder graft. (J Vasc Surg 2012;56:1201-5.)
Endovascular aneurysm repair (EVAR) for anatomi-
cally suitable abdominal aortic aneurysms (AAAs) has be-
come a standard procedure for high-risk patients with a
suitable anatomy as an alternative to traditional open sur-
gery.1,2Recently, long-term follow-up assessments of
EVAR have been reported.3,4EVAR has several advantages
over traditional open surgery in appropriately selected pa-
tients.5,6However, a hostile proximal neck (PN), including
severe angulation, short neck, and reverse funnel neck, is
still considered a major anatomic limitation for EVAR.
Several investigators have reported that severe angulation
of the PN affected the outcomes of EVAR, including type
Ia endoleak and migration.7-9
In the instructions for use (IFU) of most commercially
available stent grafts, PN angulation is limited to ?60°.
With increasing surgical experience and the introduction of
newer stent graft devices, a number of AAAs with a highly
angulated neck beyond the IFU scope treated by stent
grafts is increasing. Nevertheless, it is still not clear whether
it is safe to perform EVAR for AAAs with such a severely
like with its use, and what the long-term outcomes are. The
present study investigated changes of PN angulation after
EVAR procedures and its remodeling over a midterm
From November 2006 to September 2011, 161 pa-
tients underwent EVAR in our hospital. We conducted
From the Departments of Vascular Surgeryaand Radiology,bAichi Medical
Author conflict of interest: none.
Reprint requests: Hiroyuki Ishibashi, MD, Department of Vascular Surgery,
Aichi Medical University Hospital, Nagakute, Aichi 480-1195, Japan
The editors and reviewers of this article have no relevant financial relation-
ships to disclose per the JVS policy that requires reviewers to decline
review of any manuscript for which they may have a conflict of interest.
Copyright © 2012 by the Society for Vascular Surgery.
computed tomography (CT) scan examinations preopera-
tively and after EVAR at 1 week, 1 month, 6 months, 1
year, 1.5 years, 2 years, and then yearly thereafter. With
these inclusion criteria, 78 patients with ?1 year of
follow-up were reviewed. Among these patients, 54 were
treated with a Zenith AAA endovascular graft (Cook Med-
ical, Bloomington, Ind) and 24 with an Excluder endo-
prosthesis (W. L. Gore and Associates, Flagstaff, Ariz). The
study excluded EVAR with the Powerlink (Endologix,
Irvine, Calif), Zenith Flex, and a chimney graft. In the
present study, PN remodeling was analyzed only from
the morphology of the AAA; therefore, patient risk
factors were not analyzed.
The deployment procedure nearly always followed the
or Lunderquist Extra Stiff (Cook Medical, Bjaeverskov,
Denmark). In the Zenith procedure, the stent graft was
carefully placed just distal to the lower renal artery, with no
special relation to the location of a stent junction to the PN
angulation. In the Excluder procedure for an angulated
half-deployment of a trunk-ipsilateral leg down to a con-
tralateral limb gate, the trunk was pushed up to fit the PN.
Imaging with contrast medium was captured preoper-
atively with a 64-row multidetector CT scan (Aquilion,
Toshiba Medical Systems, Tochigi, Japan) and after EVAR
for follow-up, unless the AAA was re-enlarged or a signifi-
cant endoleak persisted. The maximum minor diameter in
all axial slices was measured, and a volume-rendered three-
by an Aquarius Workstation (TeraRecon, Foster City,
Calif). The maximum PN angulation between the infrare-
nal PN and the aneurysm sac was measured by rotating the
3D image (Fig 1, A and B). With the plain CT scan, used
after a 6-month follow-up or thereafter, a 3D image of the
stents was reconstructed in the same way, and the PN
angulation was measured in an identically rotated view. In
the present study, only morphology of the PN (length and
angulation) was analyzed, so the calcification or mural
thrombus of the PN was not analyzed.
Relationships between PN angulation and operative
outcomes were analyzed, including postoperative diameter
shrinkage and remodeling of the PN angulation after the
EVAR procedure. Values were compared by Student t-test
and are expressed as mean ? standard deviation. Statistical
significance was assumed at P ? .05. Correlations between
the two groups were analyzed by StatMate (GraphPad, San
Diego, Calkf) with Excel 2004 software (Microsoft, Red-
The IFU for PN length for the stent grafts were strictly
maintained during the EVAR procedures, so the rate of the
EVAR procedure for total AAA surgeries during the same
period was 56% (161 of 285). The preoperative PN length
was 31 ? 11 mm (range, 11-62 mm). Type II endoleaks
were found in 19 patients (24%) at discharge with the CT
scan 1 week after the EVAR procedure, but no type I, III,
or IV endoleaks were documented. The aneurysm diame-
ters were 53 ? 7 mm preoperatively, 52 ? 8 mm 1 month
after EVAR, 50 ? 9 mm at 6 months, 47 ? 11 mm at 1
year, 45 ? 12 mm at 2 years, and 42 ? 13 mm at 3 years.
Fig 1. A, Proximal neck (PN) angulation measurement before endovascular aneurysm repair (EVAR) was 95°(*). B,
Proximal neck angulation was reduced to 65° (**) at 1 week after EVAR.
JOURNAL OF VASCULAR SURGERY
1202 Ishibashi et al
The diameter decreased with time after the EVAR proce-
PN angulations were 50° ? 20° preoperatively and
were 36° ? 14° at 1 week after EVAR, 36° ? 14° at 1
month, 33° ? 14° at 6 months, 32° ? 14° at 1 year, 29° ?
14° at 2 years, and 28° ? 13° at 3 years (Fig 2). Preopera-
tively, 18 patients (23%) exhibited a PN angulation ?60°.
PN angulations ?60° (n ? 60) were 41° ? 13° preopera-
tively, 31° ? 12° at 1 week after EVAR, 31° ? 12° at 1
month, 29° ? 12° at 6 months, 28° ? 12° at 1 year, 27° ?
14° at 2 years, 26° ? 13° at 3 years, and the PN angulation
reduction was 14° ? 12° (Fig 3). PN angulations ?60°
(n ? 18) were 78° ? 14° preoperatively, 51° ? 11° at 1
week after EVAR, 51° ? 11° at 1 month, 46° ? 11° at 6
months, 44° ? 11° at 1 year, 41° ? 11° at 2 years, 40° ?
12° at 3 years, and the PN angulation reduction was 35° ?
14°. The PN angulations in both groups were markedly
reduced immediately after the EVAR procedure, and PN
angulation ?60° evidenced a much greater reduction.
Both subsequently reduced slowly with time after the
EVAR procedure. The greater the preoperative PN angu-
lation, the greater its reduction just after the EVAR (r ?
.72, P ? .001; Fig 4).
Diameter shrinkage 1 year after EVAR was 3 ? 6 mm
for the PN angulations ?60° and 7 ? 7 mm for those
?60°; the former were significantly smaller than the latter
(P ? .05). However, PN length of AAAs with PN angula-
tion ?60° was 27 ? 12 mm and was 32 ? 11 mm for PN
angulation ?60°; the difference between the two groups
was marginally significant (P ? .07).
Proximal cuffs were placed in three of 24 Excluder
grafts and in zero of 54 in Zenith grafts (P ? .044). Palmaz
XL stent (Cordis, Bridgewater, NJ) was placed in six of 24
Excluder grafts (one patient received both) and in three of
54 in Zenith grafts (P ? .044). In AAAs treated by Zenith,
at 1 week after EVAR, 34° ? 14° at 1 month, 31° ? 13° at
6 months, 30° ? 14° at 1 year, 26° ? 14° at 2 years, and
25° ? 13° at 3 years, with a PN angulation reduction of
was 52° ? 17° preoperatively, 41° ? 14° at 1 week after
EVAR, 41° ? 14° at 1 month, 38° ? 14° at 6 months,
37° ? 14° at 1 year, 35° ? 16° at 2 years, 38° ? 9° at 3
years, with a PN angulation reduction of 15 ? 15°. In
AAAs treated by Zenith, PN angulation reduction contin-
5). The diameter of AAAs treated by Zenith was 53 ? 8
??????? ???? ???? ???????????? ??????
Fig 2. Proximal neck (PN) angulation after endovascular aneu-
rysm repair (EVAR) reduced greatly immediately after the proce-
dure and subsequently reduced slowly and gradually long term.
Mean data are shown with the standard deviation (error bars). Pre,
PNPN angle > 60˚
PN angle ≤ 60˚
pre1 wk 1 mo 3 mo 6 mo1 y1.5 y 2 y 3 y
Fig 3. Proximal neck (PN) angulation after endovascular aneu-
rysm repair (EVAR) in PN angulation ?60° (dashed line) and in
angulation ?60° (solid line). PN angulations in both groups
reduced greatly immediately after the endovascular procedure, and
PN angulation ?60° had much greater reduction. Mean data are
shown with the standard deviation (error bars). Pre, Preoperative.
Fig 4. Relationship between preoperative proximal neck (PN)
angulation and its reduction after endovascular aneurysm repair
(EVAR). The greater the preoperative PN angulation, the greater
its reduction. The X axis denotes preoperative PN angulation and
the Y axis its reduction after endovascular repair.
JOURNAL OF VASCULAR SURGERY
Volume 56, Number 5
Ishibashi et al 1203
mm preoperatively, and its reduction was 6 ? 7 mm at 1
year. The corresponding measurements for Excluder were
52 ? 6 and 5 ? 8 mm, respectively. There were no
significant differences between the two stent grafts (P ?
.93; Fig 6).
In the most angulated (115°) and short-necked (11-
mm) AAA that was treated by Zenith, the left renal artery
was occluded by the upward moving of a stent graft by the
rekinking of the stretched neck after removing a stiff guide-
wire. Another patient with an AAA with a 15-mm-long and
90° angulated neck developed a type Ia endoleak 1.5 years
after the EVAR procedure with a Zenith. Its diameter
increased from 69 to 74 mm; therefore, a Palmaz XL stent
was deployed to seal the endoleak. In all the other patients,
no problems occurred due to an angulated neck. Aneurysm
diameter shrank ?5 mm in 38 of 78 patients (48%), and 36
(46%) were within the 5-mm change. An increase in the
diameter of ?5 mm was found in four patients; three of
them had a PN angulation ?60°. There were no significant
correlations between the PN angulation reduction and
diameter change and between the PN length and diameter
change (data not shown; P ? .86 and .18, respectively).
The anatomic characteristics of AAAs are presumed to
determine the degree of difficulty and potential technical
vere PN angulation is one of the major factors that directly
affect the safety of the EVAR procedure and also affect
early-term and long-term outcomes after EVAR. Many
studies that previously investigated the influence of PN
angulations on EVAR outcomes have concluded that it
had a direct negative influence on the outcomes after
Several findings were obtained from the present study
regarding the remodeling of PN angulation after EVAR.
The PN angulation reduced greatly immediately after the
EVAR procedure and continued to reduce slowly and
gradually. This slow remodeling of reduction was consid-
ered to be related to post-EVAR shrinkage of the aneurysm
sac. PN angulations ?60°, compared with angulations
?60°, had a greater angulation reduction and a smaller
diameter shrinkage after an EVAR procedure. However,
the PN length of the former was somewhat shorter; thus,
this might have affected the smaller diameter shrinkage.
Only two patients in the present study experienced an
increase in PN angulation during follow-up, and neither
developed a type I endoleak. There was no relationship
between PN angulation and re-enlargement of the sac
diameter after EVAR procedures. We previously reported
that only persistent type II endoleaks had a negative influ-
ence on diameter shrinkage after EVAR,13and other re-
searchers also reported similar results.14,15
Although the IFU of most commercially available stent
grafts provide a PN angulation of ?60°, according to the
results from the present study, PN angulation was not a
major issue in patients with AAAs with an adequate PN
length. Of course, attention should be paid to a short,
severely angulated neck, because such a neck has a risk for
type Ia endoleak or obstruction of a renal artery by the
upward movement of a stent graft after removing a stiff
Zenith and Excluder have two major differences in
their stent graft structure; Zenith is made of woven Dacron
expanded tetrafluoroethylene and does not have a suprare-
nal stent. Although the PN angulation reduction immedi-
ately after the EVAR procedure was similar between the
two stent grafts, unlike Excluder, the PN angulation in
Zenith continued to reduce over a long period at a slow
rigid and strong enough to stretch the PN angulation for a
long period. AAAs treated by Excluder received more ad-
Fig 5. Proximal neck (PN) angulation after endovascular aneurysm
repair (EVAR) in Zenith (solid line) and Excluder (dashed line). PN
angulation reduction after Zenith continued for a longer period at a
slower pace after the endovascular procedure. Mean data are shown
with the standard deviation (error bars). Pre, Preoperative.
Fig 6. Aneurysm diameter after endovascular aneurysm repair
(EVAR) with Zenith (solid line) and Excluder (dashed line). There
was no significant difference between the two stent grafts. Pre,
JOURNAL OF VASCULAR SURGERY
1204 Ishibashi et al
junctive proximal cuffs or Palmaz stents, which might have
affected immediate PN angulation reduction after the
EVAR procedure, but we considered that it did not affect
on subsequent midterm PN angulation reduction. No dif-
ferences were found between the two stent grafts in their
shrinkage of diameter after EVAR.
the suprarenal aorta and the PN of the AAA is also of
interest. Follow-up CT scans in the present study were
done without contrast medium over a long follow-up pe-
riod, unless a significant endoleak persisted or the sac
re-enlarged. Therefore, no trend in the suprarenal aortic
angulation after EVAR was analyzed. Van Keulen et al16
analyzed suprarenal and infrarenal aortic angulations of the
Talent (Medtronic Vascular, Santa Rosa, Calif) and Ex-
cluder and described a large reduction in both angulations
directly after the EVAR procedure and continuing angula-
tion reduction during the first few years after EVAR. They
did not notice any differences between the two stent grafts.
The present study enrolled a relatively small number of
patients, and we could not find any major differences
between the PN angulation and midterm outcomes nor
between the Zenith and Excluder stent grafts. The reasons
a type Ia endoleak over a midterm follow-up and that few
patients with AAAs developed a re-enlarged sac after the
that a PN angulation measured preoperatively is an angu-
lation between the PN and an aneurysmal sac; however, an
angulation measured after EVAR is an angulation of the
stent graft itself placed in the aneurysmal sac. The latter
might be somewhat different from the former: the true
angulation of the AAA. It would nonetheless be interesting
to study whether different types of stent grafts have differ-
ent effects on PN angulations and on long-term outcomes
The PN angulation reduced greatly immediately after
the EVAR procedure and continued to reduce slowly and
gradually. PN angulations ?60°, compared with those
?60°, had a larger angulation reduction and a smaller
diameter shrinkage after the EVAR procedure. The PN
procedure was similar for Zenith and Excluder; however,
unlike Excluder, the PN angulation in Zenith continued to
reduce for a long period at a slow pace.
Although IFU of most commercially available stent
grafts provide PN angulation of ?60°, according to the
present results, PN angulation was not a major issue for
AAAs with adequate PN length over the midterm follow-up
for patients in this series who received a Zenith or Excluder
graft. Only one of 18 patients with PN angulation ?60°
developed a type I endoleak and a sac re-enlargement
during follow-up. We wish to emphasize that patients with
PN lengths ?15 mm and with severe angulations may
develop immediate or delayed type I endoleaks.
Conception and design: HI
Analysis and interpretation: HI, TI
Data collection: HI, TI, TY, MD, NH, YO
Writing the article: HI
Critical revision of the article: HI, TI, TO
Final approval of the article: HI, TO, IS
Statistical analysis: HI
Obtained funding: Not applicable
Overall responsibility: HI
1. Greenhalgh RM, Brown LC, Kwong GP, Powell JT, Thompson SG,
EVAR trial participants. Comparison of endovascular aneurysm repair
with open repair in patients with abdominal aortic aneurysm (EVAR
trial 1), 30-day operative mortality results: Randomized controlled trial.
2. Prinssen M,VerhoevenEL,ButhJ,CuypersPW,vanSambeekMR,Balm
R, et al. Dutch randomized endovascular aneurysm (DREAM) Trial
Group. A randomized trial comparing conventional and endovascular
repair of abdominal aortic aneurysms. N Engl J Med 2004;351:1607-18.
3. United Kingdom EVAR Trial Investigators, Greenhalgh RM, Brown
LC, Thompson SG, Epstein D, Sculpher MJ. Endovascular versus open
4. United Kingdom EVAR Trial Investigators, Greenhalgh RM, Brown
LC, Powell JT, Thompson SG, Epstein D. Endovascular repair of aortic
aneurysm in patients physically ineligible for open repair. N Engl J Med
5. EVAR trial participants. Endovascular aneurysm repair versus open
repair in patients with abdominal aortic aneurysm (EVAR trial 1):
randomized controlled trial. Lancet 2005;365:2179-86.
Abdominal aortic aneurysm surgery for octogenarians. Surg Today
7. Sternbergh WC 3rd, Carter G, York JW, Yoselevitz M, Money SR.
Aortic neck angulation predicts adverse outcome with endovascular
abdominal aortic aneurysm repair. J Vasc Surg 2002;35:482-6.
Does hostile neck anatomy preclude successful endovascular aortic
aneurysm repair? J Vasc Surg 2003;38:657-63.
9. Choke E, Munneke G, Morgan R, Belli AM, Loftus I, McFarland R, et al.
Outcomes of endovascular abdominal aortic aneurysm repair in patients
with hostile neck anatomy. Cardiovasc Interv Radiol 2006;29:975-80.
10. Chaikof EL,FillingerMF,MatsumuraJS,RutherfordRB,WhiteGH,Blan-
endovascular aortic aneurysm repair. J Vasc Surg 2002;35:1061-6.
score predicts technical difficulty, early outcomes, and hospital resource utili-
12. Hobo R, Kievit J, Leurs LJ, Buth J, on behalf of the EUROSTAR
Collaborators. Influence of severe infrarenal aortic neck angulation on
complications at the proximal neck following endovascular AAA repair:
A EUROSTAR study. J Endovasc Ther 2007;14:1-11.
Mid-term results of endovascular abdominal aortic aneurysm repair: is it
possible to predict sac shrinkage? Surg Today 2011;41:1605-9.
14. Schlösser FJ, Gusberg RJ, Dardik A, Lin PH, Verhagen HJ, Moll FL, et
Eur J Vasc Endovasc Surg 2009;37:15-22.
antiplatelet therapy on abdominal aortic aneurysm shrinkage after en-
dovascular repair. J Vasc Surg 2011;54:947-51.
16. van Keulen JW, Moll FL, Arts J, Vonken EJ, van Herwaarden JA. Aortic
neck angulations decrease during and after endovascular aneurysm
repair. J Endovasc Ther 2010;17:594-8.
Submitted Jan 14, 2012; accepted Apr 8, 2012.
JOURNAL OF VASCULAR SURGERY
Volume 56, Number 5
Ishibashi et al 1205