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presence of iliac artery occlusions, tortuousaortic anatomy or

a very steeply angled renal artery, the brachial approach can

be used (see chapter 7). A 6F sheath is inserted into the

femoral artery. The author favours the used of a long (typi-

cally 35 cm) sheath, although some others use guiding cath-

eters. A preshaped catheter is then used to access the renal

artery. One of the simplest to use is the Sos Omni (Angio-

dynamics), whichis ofavery similar in shape tothe Simmons

catheter, but has a soft tip which can be reformed in the

abdominal aorta, obviating the need to reform it in the aortic

arch. If theSos Omni isunsuccessful, which israre, the author

will generally use a Cobra 2 (Cordis) catheter. The catheter is

used in combination with a guidewire to cross the lesion.

A hydrophilic guidewire such as a Terumo (Terumo Corp)

can be very helpful, especially in lesions that are difﬁcult to

cross, although many would also use the soft-tipped Bentson

(Cook) guidewire. Having crossed the lesion, heparin and an

antispasmodic drug are administered. The author uses 3,000

unitsof heparin and300 lgof isosorbidedinitraterespectively.

With the catheter across the stenosis, the guidewire is

changed to a specialist guidewire such as the Jindo (Cordis).

This has a short tapered ﬂoppy tip (4 cm long, 0.022

diameter). The wire then increases rapidly in diameter along

its length to reach 0.035

. The guidewire itself is very stiff,

providing good support for the angioplasty balloon. The

atraumatic nature of the tip is very important, as it can then

be placed in a cortical branch without signiﬁcant danger of

causing spasm. An angioplasty balloon is then introduced

over the guidewire and angioplasty is performed. Balloons

are not oversized, but should instead be of the same

diameter as the artery distal to the stenosis. The exception to

this is where there is signiﬁcant post-stenotic dilation,

necessitating slight undersizing of the balloon. Typical

balloon diameters will vary between 5 and 7 mm, with

females generally requiring smaller balloons. Loin pain

with balloon inﬂation is common, but should not be severe.

The latter should be considered a warning of impending

vessel rupture and dilation should be stopped and a smaller

balloon should be used. After dilation the balloon is

removed, the guidewire is left in place and a check angio-

gram is performed through the long sheath or guiding

catheter. If there has been a complication or further dilation

is required, access has thus been maintained to allow

additional intervention. The presence of stenoses at vessel

bifurcations, which are more common in FMD, may require

the use of ‘‘kissing’’ balloons, or additional guidewires to

protect side branches. Such lesions are relatively unusual

with atherosclerosis, but may be encountered, especially

where there is an early bifurcation of the renal artery.

4.2 Renal Stenting

In many respects insertion of renal artery stents is per-

formed in a similar way to renal angioplasty. However,

stents are normally inserted at the ostium of the renal artery

because they are used for the treatment of atheromatous

disease. It is therefore essential to have a clear idea of the

exact location of the ostium to facilitate accurate stent

placement. While it is possible to perform ﬂush aortography

in a number of projections to achieve this, it does poten-

tially involve a signiﬁcant contrast load even before com-

mencement of the stent procedure. In our institution, almost

all of the patients requiring real arterial intervention for

ARAS have had cross-sectional imaging using either CTA

or MRA for diagnosis. It is therefore our practice to refer to

the cross-sectional imaging to determine the obliquity

required to optimally image the ostium of the target vessel.

A single ﬂush aortogram is then performed at that angula-

tion for conﬁrmation.

There are no reported adverse consequences associated

with leaving the stent projecting 2 mm or so into the aorta.

Positioning the stent in this manner ensures that the entire

lesion is stented and avoids aortic plaque from causing

residual or recurrent stenosis.

Prior to stent insertion it is of value to predilate the

stenosis with a 4 mm balloon to ease the passage of the

stent across the stenosis (Fig. 2). Although many

Fig. 2 a Selective renal

arteriogram in a patient with a

single kidney who was

experiencing episodes of ﬂash

pulmonary oedema. The stenosis

is severe and at the ostium. This

required predilation with a 4 mm

balloon to allow passage of the

stent; b Flush aortography via the

long 6F sheath after stent

deployment. The stent is ideally

placed, projecting approximately

2 mm into the aorta. Published

with kind permission of Ó

Elsevier, 2006. All Rights

Reserved

124 M. G. Cowling

https://t.me/med1917

recommend the use of a guiding catheter, modern long

sheaths also perform very well. Use of either allows angi-

ograms to be performed while ﬁnally positioning the stent

prior to deployment. Many systems have been reduced in

diameter and now allow the use of 6F sheaths, and 0.018

systems using even smaller sheaths and catheter are also

available. It may occasionally prove necessary to perform

renal arterial intervention from a brachial approach, for

example when femoral access is not possible, the aorta is

excessively tortuous or if the renal arteries are sharply

angulated inferiorly (Fig. 3).

4.3 Intervention in Renal Transplants

Although technically similar in many ways to angioplasty

or stenting in native kidneys, the management of transplant

renal artery stenosis involves some important differences.

Cadaveric transplants are generally anastomosed to the

recipient external iliac artery because it is possible to obtain

the full length of the renal artery as well as a patch of donor

aorta. Live related transplants have a shorter artery, and as

such are usually anastomosed to the recipient internal iliac

artery. Thus, as a general rule, it is usual to approach a

cadaveric transplant ipsilaterally, whereas treatment of a

live related transplant will normally involve a contralateral

approach, crossing the aortic bifurcation to access the origin

of the internal iliac artery (Fig. 4).

5 Results

The results of percutaneous treatment for renal artery ste-

nosis can be looked at in terms of the pathology being

treated and subdivided into technical success and clinical

outcome. The latter is clearly very important, as however

successful a procedure is technically, if there is no associ-

ated clinical beneﬁt the entire procedure is rendered

pointless. It is also important to consider the complications.

5.1 Fibromuscular Dysplasia

The technical success for angioplasty in FMD has been

reported as 91% in a review of 10 series involving 90

patients (Flechner 1984). The technical results also appear

to be durable, with a predicted 10-year patency rate of 87%

being reported (Tegtmeyer et al. 1991). More recent,

although admittedly smaller, studies have demonstrated

similar results (Birrer et al. 2002; Surowiec et al. 2003).

Clinical success has also been reported as excellent, with a

cure rate of 25–85% for hypertension reported. In a further

13–60%, improvement in hypertension control is to be

expected (Tegtmeyer et al. 1996).

More recently (Trinquart et al. 2010) have published a

meta-analysis looking at 47 angioplasty studies (1,616

patients) and 23 surgery studies (1,014 patients). They

Fig. 3 a In this patient with a severe stenosis affecting a single left

kidney, a femoral approach was not possible because the right external

iliac and left common iliac arteries were occluded. A 90 cm long 6F

sheath was positioned in the upper abdominal aorta, and a Headhunter

catheter used to select the left renal artery; b There was a good

technical result after stent insertion, and the patient’s episodes of ﬂash

pulmonary oedema resolved. Unfortunately, she developed a false

aneurysm of the brachial artery, but this was successfully managed by

thrombin injection

Management of Renal and Visceral Arterial Stenoses 125

https://t.me/med1917

found that across all of the studies the combined cure rate of

angioplasty for hypertension was 45.7% (95% CI

39.8–51.7%). While this was not quite as good as surgery

(57.5, 95% CI 53.0–62.0%) the data are not randomised, so

it is difﬁcult to draw ﬁrm conclusions. Improvement or cure

was seen in 86.4% (95% CI 83.2–89.3%).The published

data therefore supports the use of percutaneous angioplasty

in the treatment for hypertension caused by renal artery

stenosis due to FMD. In addition, should a stenosis recur, it

is usually straightforward to perform a further dilation.

5.2 Atheromatous Renal Artery Stenosis

Technical success of angioplasty for ARAS is generally

held to be disappointing. The majority of atheromatous

renal artery lesions are ostial, and early reports suggested

technical failure rates as high as 80% (Cicuto et al. 1981;

Sos et al. 1983). This ﬁgure contrasts with success rates of

75–100% for truncal lesions. Although more recent reports

give better results for technical success (Hoffman et al.

1998), they are still poor. The immediate technical results of

renal artery stenting are, in contrast, excellent, with success

rates in excess of 90% reported (Dorros et al. 1995; van de

Ven et al. 1995). Such promising data led van de Ven et al.

to undertake a randomised trial of renal artery angioplasty

versus stenting (van de Ven et al. 1999). They randomised

84 patients (42 to angioplasty and 43 to stenting) and fol-

lowed them for 6 months. Primary success was 57% for

angioplasty and 88% for stenting. Primary patency at

6 months was 29% for angioplasty and 75% for stenting.

Restenosis after a successful primary procedure occurred in

48% of the angioplasty group and 14% of the stent group.

Twelve of the angioplasty group underwent stent insertion

due to either primary or late failure of angioplasty. An

intention to treat analysis showed no difference in the

clinical results of the two groups. A cost-effectiveness

analysis was also performed, and the authors conclude that

although the clinical outcomes of angioplasty followed by

rescue stenting are similar to those of primary stenting,

primary stenting is more cost-effective.

Although in technical terms the choice between angio-

plasty and stenting now seems clear, data regarding the

clinical outcomes of treatment of ARAS are far less certain.

A great deal of effort has been put into trying to establish

whether treatment of ARAS is beneﬁcial in the management

of hypertension. In reality it is unrealistic to expect much

effect on hypertension in elderly patients with atheroma-

tous, non-compliant vessels. In addition, up to 32% of

patients receiving best medical therapy have been reported

to show spontaneous improvement in their hypertension

(Brawn and Ramsey 1987). It is generally acknowledged

that modern hypertensive agents are even more efﬁcacious

than at the time of that study, and it may therefore be the

case that hypertension is now more easily managed. It is

therefore not justiﬁed to treat every hypertensive patient

who has ARAS with renal artery stenting. However, there

probably is a place for treating patients who have uncon-

trollable hypertension requiring maximal doses of multiple

agents. The logic behind this is that even if the outcome is

to improve control despite needing the same number of

agents, this is a worthwhile gain clinically. The problem is

that one does not know the outcome of the procedure until

after it has been performed.

With regard to renal function, the picture is far from

clear. The simplistic view that renal impairment in ARAS is

due to impaired blood ﬂow, and should therefore be treat-

able by revascularisation, is clearly untrue. The situation is

far more complex, with other factors being involved, not

least progressive and irreversible renal damage occurring

over a period of time prior to diagnosis and treatment. There

is some evidence that renal stenting may be of value in a

proportion of patients with impaired renal function and

ARAS. Improved renal function is generally taken as rep-

resenting a greater than 20% reduction in serum creatinine,

stable function a less than 20% increase or decrease and

worsened renal function a greater than 20% increase. There

is not, however, a linear relationship between serum creat-

inine and glomerular ﬁltration rate (GFR). It has therefore

been advocated that reciprocal creatinine plots should be

used instead (Harden et al. 1997). These authors showed

that the mean rate of decline in renal function was signiﬁ-

cantly reduced by stenting. Thus, although renal function

continued to deteriorate in some patients, the rate was

slower, potentially delaying the onset of dialysis. A study

looking at outcomes after renal angioplasty (Hoffman et al.

1998) showed that for that patient group angioplasty had no

overall effect on renal function. Therefore, despite the

anatomically superior results of stenting, there is seemingly

little difference with regard to the effect on function, as

most recently shown by the Dutch group (van de Ven et al.

1999) in their randomised study.

More recently, the ASTRAL (The ASTRAL Trial

Investigators 2009) and STAR trials have been published

(Bax et al. 2009). Both trials sought to determine whether

renal artery stenting is beneﬁcial in terms of renal function

on follow-up. Both trials showed that there was no beneﬁt in

terms of renal function in performing renal revascularisation

when compared to best medical therapy alone. In the case of

the ASTRAL study, this seems to have been taken by many

to indicate that renal stenting should not be undertaken at all,

or at least very rarely, and the study has been highly criti-

cised. Such criticism seems largely to be based on a mis-

understanding of the purpose of the study. It was designed to

look at those patients about whom there was genuine

uncertainty about whether they would beneﬁt from renal

126 M. G. Cowling

https://t.me/med1917

revascularisation. Therefore, patients for whom renal artery

stenting was deﬁnitely indicated were not included.

ASTRAL has therefore reduced the level of uncertainty

about how to manage a signiﬁcant number of patients with

ARAS. The STAR trial reached similar conclusions on a

much smaller number of patients, but has the signiﬁcant

limitation that 50% of the patients recruited had been mis-

diagnosed as having RAS on non-invasive imaging.

6 Complications

There is no agreed reporting standard for complications in

renal revascularisation. Mossand Hamilton (2000)undertook

an analysis of a total of 24 studies of both renal angioplasty

and stenting. They divided complications into major (renal

insufﬁciency, renal artery occlusion, renal artery damage

including rupture, etc.) and minor (temporary renal insufﬁ-

ciency, retroperitoneal haematoma, groin complications,

etc.). They found that major complications occurred in 7.8%

and minor complications occurred in 7.0%. The complication

rates were similar between the stent and the angioplasty

groups, with the only exception being the 6.4% rate of stent

misplacement. There is relatively little difference in com-

plication rates between the angioplasty and stenting groups.

With modern equipment and endovascular techniques, it is

often possible to successfully treat complications. Thus, for

example, should renal arterial rupture occur, it can be man-

aged by inserting a balloon expandable stent graft. If arterial

thrombosis occurs, often this can be managed by thrombol-

ysis. If the artery is occluded by dissection (Fig. 5)becauseit

has been difﬁcult to cross it can often be treated endovascu-

larly. It may, however, prove necessary to undertake emer-

gency surgical repair to effect reperfusion. In the ASTRAL

trial there were 31 serious complications in the 280 patients in

the revascularisation group, of whom two died.

The most common complication, reduction or loss of

renal function, can be multifactorial. Contrast-induced

nephropathy will often recover over a week to 10 days,

though in patients with pre-existing renal impairment,

serum creatinine may not return to its pretreatment level.

Cholesterol embolisation may also occur; this is generally

not reversible, and if severe may be fatal.

Restenosis is the most important late complication.

When it occurs in patients who have had angioplasty for

FMD it is almost always possible to manage with further

angioplasty. Restenosis after angioplasty for ostial ARAS is

so frequent that primary stenting is justiﬁed on cost-effec-

tiveness grounds (van de Ven et al. 1999), and so strictly

should be a thing of the past. However, there is an incidence

of in stent restenosis of 6–12%. This can be managed either

by angioplasty or by placement of a further stent. Neither

strategy is perfect, and there is currently no evidence to

support one over the other.

7 Management of Visceral Artery

Stenoses

Mesenteric ischaemia is a relatively rare entity. It may be

acute or chronic, but it is the latter that generally comes

to the attention of Interventional Radiologists. The rarity

Fig. 4 a Transfemoral

arteriogram of a cadaveric renal

transplant in the right iliac fossa,

obtained using an ipsilateral

approach. Note a diffuse 90%

stenosis of the proximal

transplant artery. b This was

treated by angioplasty for graft

dysfunction, with a good

technical and clinical result

Management of Renal and Visceral Arterial Stenoses 127

https://t.me/med1917

of mesenteric ischaemia is explained by the presence of

three arteries supplying the gut combined with a rich

collateral supply. Thus it is generally accepted that at

least two of the vessels need to be affected before

symptoms occur. In the author’s experience, this has

generally involved occlusion of two vessels with a ste-

nosis of the third. There is usually evidence of vascular

disease elsewhere, and there is often quite severe aortic

involvement.

The diagnosis is generally made quite late, with the

patient having undergone multiple investigations for

weight loss and, frequently, post-prandial abdominal pain.

They may also experience diarrhoea, nausea and vomiting.

Latterly we have found CT angiography to be an invalu-

able tool in establishing the diagnosis. Although MRA

may be equally useful in identifying stenotic or occlusive

disease, CTA gives a much clearer depiction of vessel wall

calciﬁcation. This gives an indication of how good the

response to endovascular therapy may be, and also allows

decisions regarding which vessel to treat to be made

prospectively.

8 Indications for Treatment

If the patient has classical symptoms with vessel involve-

ment as described above, a good response to treatment is

highly likely. Other patients whose symptoms are less

typical may eventually be treated because there seems to be

no other option. However, treatment results in this group are

often disappointing. Endovascular treatment is only indi-

cated for intrinsic disease of the mesenteric vessels, which

for practical purposes is always due to atheroma although

FMD occasionally described. Extrinsic compression does

not respond to angioplasty, and at present there is no evi-

dence as to whether stents will fair any better in this setting.

9 Technique

The author uses essentially an identical technique to that

employed for renal revascularisation. Although a brachial

approach has certain potential advantages because of the

caudal angulation of the visceral vessels, with modern

guidewires, long sheaths and guiding catheters the femoral

approach is often feasible. It is probably most often a matter

of operator preference (Fig. 6).

There are no randomised data on whether angioplasty

or stenting is most suitable for this indication. Several

studies have suggested no difference when angioplasty is

used for treatment of ostial or non-ostial lesions of vis-

ceral vessels (Allen et al. 1996; Matsumoto et al. 1995).

However, the numbers of cases published in the literature

are inevitably small. Since there is no likelihood of ran-

domised data ever becoming available on this matter, it

would seem reasonable to look at the renal arterial data.

Ostial stenoses of the visceral vessels are caused by aortic

atheroma, in a very similar way to ostial stenoses of the

renal arteries. Thus, based on the Dutch randomised trial

(van de Ven et al. 1999) the response to angioplasty

might be expected to be less than that for stenting.

Although some workers suggest that the pathology is

different and that angioplasty with selective stenting is a

better policy, we shall never know for sure. Pragmati-

cally, therefore, the author has adopted the policy of

primary stenting for ostial visceral artery stenosis. Non-

Fig. 5 a Pre treatment arteriogram in patient with an ulcerated plaque

causing a 70% stenosis of the left renal artery. Treatment was being

undertaken because of a rise in serum creatinine after administration of

an ACE inhibitor. b Despite careful guidewire manipulation, vessel

dissection occurred, causing complete occlusion of the vessel. c Using

an angled Terumo guidewire it proved possible to cross the occluded

segment and perform and angioplasty to reopen the vessel. The post

angioplasty appearance was so good that a stent was not used

128 M. G. Cowling

https://t.me/med1917

ostial lesions are still treated by angioplasty, with stent

insertion reserved for angioplasty failures such as elastic

recoil or ﬂow limiting dissection.

10 Results

The number of series published on this subject is growing.

However, many of the publications concern series of 10–25

patients and are not randomised. Earlier series from the late

1980s to mid-1990s reported technical success rates for

angioplasty of between 79 and 95% (Odurney et al. 1988;

Simonetti et al. 1992; Matsumoto et al. 1995; Allen et al.

1996). More recent series (Sharafuddin et al. 2003; Abu-

Rahma et al. 2003; Chahi et al. 2004; Resch et al. 2005)

have technical success rates of between 94 and 100%. These

series, which include a mixture of angioplasty and stenting,

therefore show a trend towards slightly better technical

results. It is difﬁcult to speculate as to the reasons for this,

but it may in part be due to improvements in the equipment

available, and also the availability of stents. A more recent

study which reports the outcomes showed similar results,

with an immediate technical success rate of 93% (Fioole

et al. 2010). Complete symptom relief was seen in 78% of

patients, with 12% requiring open revascularisation due to

failure of percutaneous intervention.

Recurrent symptoms due to restenosis remain a problem,

with between 21 and 39% requiring reintervention. Although

the long-term results are inferior to those of surgery, they do

illustrate that endovascular techniques offer a reasonable

alternative in patients with intestinal ischaemia who are unﬁt

for open revascularisation. An increasing number of patients

fall into this category as our population ages.

11 Complications

It is difﬁcult to be certain about complication rates in this

situation. All of the series are relatively small, and there

is almost certainly a degree of under reporting. Periop-

erative mortality of up to 5.8% has been reported, but this

represents a single patient in only one of the series cited

(Resch et al. 2005). Vessel dissection is clearly a wor-

rying possibility, but in most cases successful manage-

ment by stenting should be expected. Although

embolisation to the gut is a theoretical possibility, reports

would suggest that it rarely causes any clinically impor-

tant problems.

12 Conclusion

Percutaneous renal revascularisation has become an

accepted procedure for certain clinical indications. These

include uncontrolled hypertension, especially when caused

by FMD, ﬂash pulmonary oedema and deteriorating renal

function. There is evidence from one trial that it is more

cost-effective to treat ARAS by primary stenting. How-

ever, with easier access to non-invasive imaging, it is

becoming clear that RAS is a common problem in our

ageing population. Although criticised for their method-

ology the ASTRAL and STAR trials both indicate that

Fig. 6 a Flush aortography in 58

year old lady with a 1 year

history of abdominal pain after

meals and 25kg weight loss. It

conﬁrms the ﬁndings of a

previous CTA, which had shown

occlusion of the coeliac axis and

SMA, with a severe stenosis at

the origin of the IMA. b Despite

the angulation of the vessel, it

proved possible to predilate the

origin with a 3mm angioplasty

balloon and insert a 5mm

diameter balloon expandable

stent. It was not possible to fully

expand the stent, so there was a

residual stenosis of around 30%.

However, the lumen achieved

was sufﬁcient to bring about

resolution of symptoms

Management of Renal and Visceral Arterial Stenoses 129

https://t.me/med1917

there is no advantage for renal revascularisation over best

medical therapy in preventing deteriorating renal function

in patients with ARAS with no additional indication for

stent insertion.

Stenosis of visceral arteries causing clinical symptoms is

rare, but can be managed by percutaneous techniques. It is

unlikely that there will ever be deﬁnitive data available

concerning whether angioplasty or stenting is superior.

However, based on data from the renal arteries the author

generally chooses to stent ostial visceral artery stenoses and

angioplasty truncal lesions.

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130 M. G. Cowling

https://t.me/med1917

Endovascular Abdominal Aortic Aneurysm Repair

Andrew England, Micheal Murphy, and Richard G. McWilliams

Contents

1 Introduction.......................................................................... 132

2 Assessment/Indications........................................................ 132

3 Devices................................................................................... 133

4 Planning the Procedure ...................................................... 135

5 Technique.............................................................................. 137

6 Stent-Graft Complications and Surveillance.................... 138

7 Device Variations................................................................. 144

8 Device Improvements .......................................................... 146

9 Evidence ................................................................................ 146

10 Future Developments .......................................................... 148

References...................................................................................... 149

Abstract

Endovascular aortic aneurysm repair (EVAR) is a

minimally-invasive alternative to open repair and offers

lower early mortality rates, reduction in morbidity and

post-procedural stay. Patient suitability for EVAR

requires that the aortic morphology meets anatomical

inclusion criteria. Short, excessively dilated, angulated

and thrombus-lined aortic necks are associated with

suboptimal outcomes. Although early mortality rates are

favourable, EVAR is also associated with a higher

incidence of follow-up complications and reinterventions

compared to open surgery. Endoleaks form the bulk of

these and if device-related increase the risk of aneurysm

rupture. Graft migration, occlusion and structural disin-

tegration have also been reported following EVAR. Even

so, EVAR has now become the dominant treatment

option for asymptomatic AAAs (C 5.5 cm in diameter)

for patients deemed ﬁt for surgery. Such is the enthusiasm

for EVAR that studies have started to report on the

efﬁcacy of EVAR in small or ruptured AAAs. With the

anatomical limitations of many EVAR devices there has

been a drive to develop stent grafts which can extend the

reach of EVAR. Fenestrated and branched stent grafts

provide an alternative option for complex aortic aneu-

rysms. Conventional infrarenal devices have also been

redesigned to incorporate lower proﬁle delivery systems

and cover a wider range of aortic morphologies. Modern

hybrid theatres are the ideal environment to implant these

complex grafts. In many centres annual follow-up by

contrast-enhanced CT has switched to a more cost-

effective combination of ultrasound and abdominal

radiography.

A. England

Royal Liverpool University Hospital, Liverpool, UK

M. Murphy

Victoria University Hospital, Cork, Ireland

R. G. McWilliams (&)

Royal Liverpool & Broadgreen university Hospitals,

Liverpool, UK

e-mail: Richard.McWilliams@rlbuht.nhs.uk

M. G. Cowling (ed.), Vascular Interventional Radiology, Medical Radiology. Diagnostic Imaging,

DOI: 10.1007/174_2012_535, Ó Springer-Verlag Berlin Heidelberg 2012

131

https://t.me/med1917

1 Introduction

For the past two decades minimally-invasive endovascular

aortic aneurysm repair (EVAR) has offered an alternative

treatment option for patients with abdominal aortic aneu-

rysms (AAAs). EVAR was ﬁrst introduced in the Ukraine

and Argentina by Volodos et al. (1988) and Parodi et al.

(1991) and was initially met with great enthusiasm by

radiologists and vascular surgeons alike. The ﬁrst EVAR

devices were crude and often made in the operating theatre

just before deployment. This initial interest led the way for

rapid commercial development of endovascular devices

with increasingly sophisticated deployment systems. Today

EVAR procedures account for the majority of AAA repairs

performed worldwide with commercial income from stent-

graft sales in excess of £600 million per annum (Thompson

2011). With the development and widespread use of aortic

stent-grafts came the need for greater evidence of both

safety and efﬁcacy. The initial anecdotal cases from over

20 years ago were the prelude to a steady progression

through the different levels of scientiﬁc evidence. There are

now over 4,000 publications relating to EVAR in peer-

reviewed journals ranging from case-reports to national

randomised controlled trials and meta-analyses. Four ran-

domised controlled trials have now been published com-

paring EVAR with open surgical repair (OSR); the UK

EVAR 1 Trial (Greenhalgh et al. 2004), the Dutch DREAM

Trial (Prinssen et al. 2004), the US OVER Trial (Lederle

et al. 2009) and the French ACE Trial (Becquemin et al.

2011). The largest of these is the UK EVAR 1 trial (1,082

patients) which reported 30-day mortality data in 2004,

4 year durability data in June 2005 and more recently the

long-term data were published in May 2010. Further trials

are evaluating the role of EVAR in patients with small

aneurysms and those with aneurysm rupture. These results

and their consequences will be considered later in this

chapter.

2 Assessment/Indications

The indications for EVAR vary from centre to centre and

country to country depending upon the sources of funding

and the enthusiasm and experience of the vascular team.

In the UK, practice has generally been governed by data

from the two UK EVAR trials (1 and 2) and recommen-

dations from the National Institute for Health and Clinical

Excellence (NICE). NICE currently recommends that

EVAR is an acceptable treatment option for patients with

unruptured infrarenal AAAs, where surgical intervention is

considered appropriate (NICE 2009). EVAR has also been

used to repair inﬂammatory and mycotic AAAs. Data from

a single systematic review of 1,120 patients with inﬂam-

matory AAAs, concluded that EVAR (n = 121) when

compared to open surgery (n = 999), is associated with a

lower 1 year all-cause mortality (Paravastu et al. 2009).

Reports of the use of EVAR for mycotic aneurysms are

limited to single centre case series. In this instance 30-day

mortalityand 2 year survival rates for EVAR andopen surgery

were similar (5 vs. 4.8%; 83.9 vs. 78.3%) (Kan et al. 2010).

For ruptured AAAs NICE currently recommends that endo-

vasculartreatmentis notrecommendedexcept inthe contextof

research (NICE 2009). However in the US, the Society for

Vascular Surgery (SVS) strongly recommends that emergent

EVAR should be considered for patients with ruptured AAAs,

if anatomically suitable (Chaikof et al. 2009). The SVS

guidelines are based only on moderate evidence and there are

currently three randomised controlled trials recruiting or that

have recently ﬁnished comparing open surgery and EVAR for

AAA rupture.

Many aneurysmsare initially diagnosedon ultrasound (US).

However, cross-sectional imaging is necessary for further

evaluation of the aneurysm morphology when considering

EVAR. Contrast-enhanced multi-detector computed tomogra-

phy (MDCT) is considered the modality of choice in most

centres. The CT should include the entire abdomen from the

level of the diaphragm down to the common femoral arteries.

With the possibility of a coexisting thoracic aneurysm some

centres will routinely include the thoracic aorta within the

imaging volume. MDCT allows high quality thin-slice arterial

phase CT datasets to be acquired which is essential for three-

dimensional reconstructions and precise morphological mea-

surements of the AAA. Conventional angiography is rarely

needed nowadays prior to surgery due to the high quality of

MDCT data. The use of catheter angiography is still

occasionally reported in the further assessment of tortuous and

calciﬁed common iliac arteries inorder to gauge if it is possible

to pass a catheter and stiff guidewire although this is no longer

the practicein the authors’ centre. Magnetic resonance imaging

(MRI) is also used in some centres for aneurysm assessment

(Engellau et al. 2003;Ataretal.2006). Gadolinium-enhanced

angiography is the mainstay of MRI assessment but it is

important that T1- and T2-weighted images are also acquired

and reviewed as these provide vital information on the aneu-

rysm sac and thrombus.

Suitability forEVAR is partially determined by anatomical

criteria and this usually starts with aneurysm diameter.

Aneurysm diameter can be determined from the CT data and

involves the measurement of the maximum diameter which

may bein the anteroposterior,transverseor oblique planes. CT

data should be reconstructed in three dimensions in order to

allowmeasurementsperpendicular tothe longaxis ofthe aorta.

Asymptomatic AAAs are generally not treated unless the

maximum diameter is [5 cm. This criterion is based on data

fromthe UKSmall Aneurysm Trialwhichshowedthatsurgical

132 A. England et al.

https://t.me/med1917

intervention was not justiﬁed for aneurysms \5.5 cm

(UK Small Aneurysm Trial Participants 1998). The diameter

used in the UK Small Aneurysm Trial was based on the AP

diameter recorded at ultrasound. Diameters measured at CT

have been found to be greater (Sprouse et al. 2003), multiple

reasons have been suggested and include the fact that the US

measurements are from the inner aortic wall to inner wall

which will provide smaller measurements, US measurements

are also operator dependent and may have been corrected for

longitudinal angulation. With the C5.5 cm criterion being

based on open surgical repair mortality data, questions have

arisen regarding any extra beneﬁt from treating small aneu-

rysms (\5.5 cm) early with EVAR. Two randomised

controlled trials (CAESAR and PIVOTAL) have compared

early EVAR with surveillance for small AAAs and have

recently reported.

The landing zones in the infrarenal aorta and iliac

arteries with EVAR are equivalent to the surgical anasto-

moses in a bifurcated surgical prosthesis. However, unlike

the sutured surgical anastomosis, endovascular ‘‘anasto-

moses’’ are currently not sutured. They rely on the radial

force of the sealing stent, the ﬁrst fabric-covered stent, to

achieve a seal and prevent movement (migration). To

achieve this, the infrarenal aortic neck must be parallel and

relatively thrombus free for 15 mm below the most caudal

renal artery according to the instructions for use of most

devices. In addition the neck must not be excessively

angulated and ideally the angle of the neck in relation to the

aneurysm should be\60

. The iliac landing zones, typically

the common iliac arteries, must also be reasonably parallel

and thrombus free. If the common iliac arteries are not

suitable because of their shape or diameter then extension

into the external iliac artery can be considered with endo-

vascular occlusion of the proximal internal iliac artery. This

can be achieved using coils or a vascular plug and is nec-

essary in order to prevent retrograde ﬂow into the aneurysm

sac. Iliac branched stent-grafts (IBDs) can also be implanted

in aneurysmal common iliac arteries and provide the option

of preserving perfusion to the internal iliac artery.

The delivery system for endovascular devices is large

and typically ranges from 16 to 24 F. Delivery is via the

iliac arteries and they must be able to accommodate these

large devices. A 24 F delivery system requires an external

iliac artery diameter of at least 8 mm. Iliac tortuosity can

also be a problem for device delivery, but if these vessels

are not heavily calciﬁed then the curves usually straighten

upon the introduction of a stiff guidewire. Strategies to

manage difﬁcult iliac access include the use of ﬂexible

delivery systems, conduits, ‘cracking and paving’ and

alternative access, e.g. via the carotid artery (Ghosh et al.

2009). The worst scenario is a small, tortuous and calciﬁed

external iliac artery which may contraindicate a transfe-

moral approach to EVAR.

With stringent anatomical requirements for EVAR, one

might expect that all patients treated with EVAR would

meet the manufacturer’s anatomical indications recorded in

their instructions for use (IFU). This has not been the case

and a recent analysis of 10,228 EVAR patients reported that

42 and 69% of patients neither met conservative nor liberal

IFU treatment criteria respectively (Schanzer et al. 2011).

Further analysis revealed that 59% of AAAs were treated

with diameters \5.5 cm and that over time there has been

an increasing trend for treating larger diameter aortic necks

and those with increasing conicity and angulation. Schanzer

et al. also reported that the 5 year post-EVAR sac

enlargement rate (C5 mm) for their series was 41% and was

signiﬁcantly higher in patients who had been treated outside

of the manufacturer’s IFU.

The assessment of preoperative imaging data must

extend beyond an evaluation of the aorta and its branches.

Evaluation of non-aneurysm related imaging ﬁndings is

important. Incidental ﬁndings have been demonstrated in

around 89% of AAA patients on preoperative CT scanning

(Indes et al. 2008). Around 20% of these ﬁndings were

considered clinically signiﬁcant with the majority suggest-

ing malignancy. Such ﬁndings could have an impact on the

decision whether to treat the aneurysm and the timing and

approach of the repair. Either way extra-aortic ﬁndings

warrant a full discussion within a multidisciplinary team

environment. Another factor which also needs to be con-

sidered is the availability of fenestrated and branched stent-

grafts. Traditionally, with only conventional stent-grafts

available for treating infrarenal AAAs, decisions on suit-

ability were relatively straightforward. Now clinicians are

armed with an increased range of endovascular options and

a more thorough morphological assessment of the CT data

must be undertaken.

3 Devices

The endovascular ‘‘stent-graft’’ comprises a metal (stain-

less steel or nitinol) framework covered with an imper-

meable fabric (polytetraﬂuoroethylene or polyster). Most

devices have external hooks or barbs mounted proximally

to aid ﬁxation to the aortic wall. Many devices also have a

proximal section of uncovered device which allows

suprarenal ﬁxation of the device whilst maintaining renal

perfusion. Radial force at the proximal and distal margins

of the device provides the necessary seal to exclude the

aneurysm from the circulation. There are three different

conﬁgurations of stent-graft available for treating AAAs:

tube, bifurcated and aorto-uni-iliac (AUI) grafts. Straight

tube grafts where the proximal and distal attachment sites

are within the aorta were associated with a high incidence

of distal endoleaks and are rarely used nowadays.

Endovascular Abdominal Aortic Aneurysm Repair 133

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