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44 Patient Selection forEndovascular AAA Repair

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24. Han Y, Zhang S, Zhang J, Ji C, Eckstein HH.Outcomes of endovascular abdominal aortic aneurysm repair in octogenarians: meta-analysis and systematic review. Eur J Vasc Endovasc Surg. 2017;54:454–63.

25. Kumar M, Long GW, Major M, Gates E, Studzinski DM, Callahan RE, Brown OW, Welsh RJ.Predictors of mortality in nonagenarians undergoing abdominal aortic aneurysm repair: analysis of the National Surgical Quality Improvement Program dataset. J Vasc Surg. 2022;75:1223–33.

26. Prendes CF, Dayama A, Panneton JM, Stana J, Rantner B, Álvarez Marcos F, Mani K, Wanhainen A, Tsilimparis N. Endovascular aortic repair in nonagenarian patients. J Am Coll Cardiol. 2021;77:1891–9.

27. Tang Y, Chen J, Huang K, Luo D, Liang P, Feng M, Chai W, Fung E, Lan HY, Xu A.The incidence, risk factors and in-hospital mortality of acute kidney injury in patients after abdominal aortic aneurysm repair surgery. BMC Nephrol. 2017;18:184.

28. Brown LC, Epstein D, Manca A, Beard JD, Powell JT, Greenhalgh RM. The UK endovascular aneurysm repair (EVAR) trials: design, methodology and progress. Eur J Vasc Endovasc Surg. 2004;27:372–81.

29. EVAR Trial Participants. Endovascular aneurysm repair and outcome in patients unt for open repair of abdominal aortic aneurysm (EVAR trial 2): randomised controlled trial. Lancet. 2005;365(9478):2187–92.

30. 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. 2010;362:1872–80.

31. De Martino RR, Brooke BS, Robinson W, Schanzer A, Indes JE, Wallaert JB, etal. Designation as “unt for open repair” is associated with poor outcomes after endovascular aortic aneurysm repair. Circ Cardiovasc Qual Outcomes. 2013;6:575–81.

32. United Kingdom EVAR Trial Investigators, Greenhalgh RM, Brown LC, Kwong GP, Powell JT, Thompson SG, Epstein D.Endovascular repair of aortic aneurysm in patients physically ineligible for open repair the United Kingdom EVAR trial investigators. Endovascular repair of aortic aneurysm in patients physically ineligible for open repair. N Engl J Med. 2010;10:1056.

33. Pane B, Spinella G, Signori A, Musio D, Perfumo MG, Lucertini G, etal. Early and long-term outcomes after open or endovascular repair for abdominal aortic aneurysms in high-risk patients. J Cardiovasc Surg (Torino). 2014;55:257–63.

34. Sobocinski J, Maurel B, Delsart P, d’Elia P, Guillou M, Maioli F, etal. Should we modify our indications after the EVAR-2 trial conclusions? Ann Vasc Surg. 2011;25:590–7.

35. Timaran CH, Veith FJ, Rosero EB, Modrall JG, Arko FR, Clagett GP, etal. Endovascular aortic aneurysm repair in patients with the highest risk and in-hospital mortality in the United States. Arch Surg. 2007;142:520–4.

36. Bush RL, Johnson ML, Hedayati N, Henderson WG, Lin PH, Lumsden AB. Performance of endovascular aortic aneurysm repair in high-risk patients: results from the Veterans Affairs National Surgical Quality Improvement Program. J Vasc Surg. 2007;45:227–33.

37. Lim S, Halandras PM, Park T, Lee Y, Crisostomo P, Hershberger R, Aulivola B, Cho JS.Outcomes of endovascular abdominal aortic aneurysm repair in high-risk patients. J Vasc Surg. 2015;61:862–8.

38. Kontopodis N, Galanakis N, Charalambous S, Matsagkas M, Giannoukas AD, Tsetis D, Ioannou CV, Antoniou GA. Editor’s choice—endovascular aneurysm repair in high risk patients: a systematic review and meta-analysis. Eur J Vasc Endovasc Surg. 2022;64:461–74.

39. Truijers M, Resch T, Van Den Berg JC, Blankensteijn JD, Lonn L.Endovascular aneurysm repair: state-of-art imaging techniques for preoperative planning and surveillance. J Cardiovasc Surg (Torino). 2009;50:423–38.

40. Picel AC, Kansal N.Essentials of endovascular abdominal aortic aneurysm repair imaging: preprocedural assessment. AJR Am J Roentgenol. 2014;203:W347–57.

41. Saida T, Mori K, Sato F, etal. Prospective intraindividual comparison of unenhanced magnetic resonance imaging vs contrastenhanced computed tomography for the planning of endovascular abdominal aortic aneurysm repair. J Vasc Surg. 2012;55:679–87.

42. Keefer A, Hislop S, Singh MJ, Gillespie D, Illig KA.The inuence of aneurysm size on anatomic suitability for endovascular repair. J Vasc Surg. 2010;52:873–87.

43. Brinster CJ, Sternbergh WC III. Endovascular aneurysm repair technique. In: Sidawy AN, Perler BA, editors. Rutherford’s vascular and endovascular therapy, 9th ed. Philadelphia. 2019. pp.930–942.

44. Bastos Gonçalves F, Verhagen HJ, Chinsakchai K, et al. The inuence of neck thrombus on clinical outcome and aneurysm morphology after endovascular aneurysm repair. J Vasc Surg. 2012;56:36–44.

45. Yaoguo Y, Zhong C, Lei K, Yaowen X.Treatment of complex aortic aneurysms with fenestrated endografts and chimney stent repair: systematic review and meta-analysis. Vascular. 2017;25:92–100.

46. Linsen MA, Jongkind V, Nio D, Hoksbergen AW, Wisselink W.Pararenal aortic aneurysm repair using fenestrated endografts. J Vasc Surg. 2012;56:238–46.

47. Caradu C, Ammollo RP, Dari L, Wanhainen A, Van Herzeele I, Bellmunt-Montoya S, Ducasse E, Bérard X.Management of inammatory aortic aneurysms—a scoping review. Eur J Vasc Endovasc Surg. 2023;65(4):493–502. S1078-5884(23)00005-9.

48. Lobato AC, Camacho-Lobato L.The sandwich technique to treat complex aortoiliac or isolated iliac aneurysms: results of midterm follow-up. J Vasc Surg. 2013;57:26S–34S.

49. DeRubertis BG, Quinones-Baldrich WJ, Greenberg JI, Jimenez JC, Lee JT. Results of a doublebarrel technique with commercially available devices for hypogastric preservation during aortoiliac endovascular abdominal aortic aneurysm repair. J Vasc Surg. 2012;56:1252–9.

50. Bosanquet DC, Wilcox C, Whitehurst L, Cox A, Williams IM, Twine CP, British Society of Endovascular Therapy (BSET). Systematic review and meta-analysis of the effect of internal iliac artery exclusion for patients undergoing EVAR. Eur J Vasc Endovasc Surg. 2017;53:534–48.

51. Papazoglou KO, Sfyroeras GS, Zambas N, Konstantinidis K, Kakkos SK, Mitka M.Outcomes of endovascular aneurysm repair with selective internal iliac artery coverage without coil embolization. J Vasc Surg. 2012;56:298–303.

52. Puech-Leão P.Banding of the common iliac artery: an expedient in endoluminal correction of aortoiliac aneurysms. J Vasc Surg. 2000;32:1232–4.

53. Faries PL, Morrissey N, Burks JA, Gravereaux E, Kerstein MD, Teodorescu VJ, etal. Internal iliac artery revascularization as an adjunct to endovascular repair of aortoiliac aneurysms. J Vasc Surg. 2001;34:892–9.

54. Parodi JC, Ferreira M.Relocation of the iliac artery bifurcation to facilitate endoluminal treatment of abdominal aortic aneurysms. J Endovasc Surg. 1999;6:342–7.

55. Kritpracha B, Pigott JP, Russell TE, Corbey MJ, Whalen RC, DiSalle RS, etal. Bell-bottom aortoiliac endografts: an alternative that preserves pelvic blood ow. J Vasc Surg. 2002;35:874–81.

56. Kotsis T, Tsanis A, Sfyroeras G, Lioupis C, Moulakakis K, Georgakis P. Endovascular exclusion of symptomatic bilateral common iliac artery aneurysms with preservation of an aneurysmal internal iliac artery via a reverse-U stent-graft. J Endovasc Ther. 2006;13:158–63.

57. Sfyroeras GS, Koutsias S, Karathanos C, Stamoulis K, Giannoukas AD.Colonic ischemia after endovascular exclusion of an aortoiliac aneurysm using an iliac branch device. Vasc Endovasc Surg. 2010;44:597–600.

Preprocedural Planning

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andMeasurements forEVAR

TheodosiosBisdas

Background

The endovascular repair (EVAR) of non-complex infrarenal abdominal aortic aneurysms (AAA) is the standard of care in the majority of health systems worldwide [1]. At present, there is a plethora of endovascular devices with different characteristics and features; however, the principles of planning and measurement remain the same [2]. It is crucial for the nal outcome that the physician is able to make his/her own measurements and select the most appropriate device. The rule of “6Ps” (prior proper plan- ning prevents poor performance) reects that the preoperative planning is equally important to the intervention itself. In this chapter, we present the basic principles of planning and measurements which can be applied to all standard AAAs and devices.

Preoperative Clinical Assessment

The rst important step is to assess the clinical status of the patient. The examination includes palpation of the abdomen and the peripheral pulses, measurement of the ankle-brachial index, duplex ultrasound of both carotid and popliteal arteries, and exclusion of any skin infection at the level of the groin.

Assessment oftheComputed Tomography Angiography (CTA): Drawing oftheAneurysm

The CTA should be maximum 6months old, at least 1mm in thickness, and should cover the renovisceral segment up to the proximal part of the supercial femoral artery at both sides. During the rst brief assessment, the physician looks for possible co-existing aneurysms in the aorta (e.g., visceral arteries) or other pathological ndings from the scanned area. The next step is to upload the CTA in a dedicated software for EVAR (e.g., Endosize, 3Mensio) or to perform the measurements manually through OsiriX or RadiAnt DICOM Viewer. After the upload, we strongly recommend drawing the AAA on a sheet of paper (Fig.45.1), which will include all important details for both patient and CTA. Such details are:

1. Name of the patient, date of birth

2. Date of CTA, thickness

3. Morphology of the AAA, all relevant diameters and

lengths

4. All relevant anatomic characteristics, which can cause

problems during the intervention (e.g., patchplasty of the common femoral artery, hostile abdomen, calcication, stenosis, femoral bifurcation above the inguinal ligament, dissection of the arteries, stenosis of the renal arteries, inferior mesenteric artery with >3mm diameter)

T. Bisdas (*) Clinic for Vascular Surgery, Athens Medical Center, Athens, Greece

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Fig. 45.1 Example of drawing an infrarenal aortic aneurysm on a sheet of paper and all relevant information needed for a successful endovascular aortic repair

Creating theCenterline: Step-by-Step Measurement

During the measurements, it is crucial to create automatically or manually the centerline. The centerline essentially represents the position of the stiff guidewire through which the device will be delivered. It is obvious that two centerlines should be created, one for each iliac axis and one for the abdominal aorta. In case of angulated infrarenal neck and/or elongated iliac arteries, any calculation of the lengths will be wrong with the risk of a poor nal outcome or the need for more devices (Fig.45.2).

After the creation of the centerline, the physician should

follow the next steps:

Step 1: The rst measurement is the diameter of the infra-

renal aorta just below the lowest renal artery. It is important

Fig. 45.2 Measurement of the aneurysm length by (a) adding the length of each slide of a CT angiography and (b) using the centerline

to mention which is the lowest renal artery in your drawing. Moreover, you have to assess from which view you will see precisely the origin of the lowest renal artery and the least parallax of the proximal markers. This calculation will lead to lower administration of contrast agent and use of radiation. However, it is feasible mainly in dedicated software for EVAR planning. According to the instructions for use (IFU), you have to measure the diameter of the aorta 15–20mm below the lowest renal artery. We recommend measuring the aorta at three different points, level of the lowest renal artery, 10mm below it, and 20mm below it, and selecting the diameter of the device according to the rst two diameters. The main reason for this strategy is that the proximal sealing of the stent graft is based mainly on the rst stent of the devices which is 10 mm in length in the majority of the EVAR devices. In specic cases of hostile proximal neck (bulged, reversed tapered, tapered), the diameter of the aorta at 20mm should be taken into consideration for the diameter of the EVAR device. In such cases, the operator should know that the implantation might be outside the IFUs and inform the patient accordingly.

All manufacturers recommend 20% oversizing of the EVAR device and we strongly agree with this recommendation. However, in angulated necks, the centerline does not always represent the real position of the guidewire during the

LL L

−

LL L

=−−or

LL L

−

45 Preprocedural Planning andMeasurements forEVAR

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485

gate through the common femoral artery, and thus the physician has to change the entry site of the main body. This maneuver will facilitate the cannulation of the contralateral limb having the sac at the opposite site of the gate.

Step 3: The last step is to measure the diameter and the length of the common iliac arteries. In general, it is suggested to measure the distance up to the iliac bifurcation and to cover it with the iliac limb accordingly. However, this strategy is not always necessary in long common iliac arteries. In any case, the physician should dene a distal landing zone of at least 20mm (in some devices 15mm) and measure the proximal and distal diameter or the common iliac artery. The length and the diameter of the limb will be selected accordingly and always taking into consideration the IFUs of the manufacturer.

The physician should calculate the length of the iliac limb using the following formula:

Fig. 45.3 Diameter of the aorta in angulated neck based on the centerline (red line, 27mm) and the real landing zone of the device (yellow line, 29mm). The device was selected with a diameter of 36mm

intervention. Thus, and according to our experience, our common practice in angulated necks is to perform a 30%

instead of 20% oversizing (Fig.45.3). In any case, we recommend always ordering an aortic extension in angulated necks in case you identify a type Ia endoleak intraoperatively.

Step 2: The next step is to assess the distance between the lowest renal artery and the bifurcation. This measurement is important in order to ensure that the contralateral gate of the bifurcated endograft will open adequately inside the aneurysm sac. Thus, we recommend measuring the distance from the lowest renal artery up to 0.5–1cm above the bifurcation in order to be sure that the contralateral limb will be adequately opened and catheterized during the intervention. During this step, it is important to assess and highlight in your drawing any important anatomic challenges regarding the morphology of the aneurysm sac (Fig.45.1). For instance, opening the contralateral limb in saccular aneurysms may lead to a challenging or even impossible cannulation of the

where L

limblowerRA IliacBif MBTube

length of the iliac limb, L

limb

−

lower RA–Iliac Bif

length between the lowest renal artery and the distal landing point above the iliac bifurcation, and L

length between cra-

MB Tube

nial graft edge and bifurcation of the graft.

In case the company does not include the overlapping zone in the provided length of the limbs (e.g., Zenith Spiral Z, COOK Medical), the formula changes to the following:

where L

limblowerRA IliacBif MBcontralat

limblowerRA IliacBif MBipsilat

length of the iliac limb, L

limb

−

lower RA–Iliac Bif

length between the lowest renal artery and the distal landing point above the iliac bifurcation, and L

MB contralat

cranial graft edge and end of the contralateral limb or L

length between cranial graft edge and end of the ipsilat-

ipsilat

length between

eral limb.

There are a few devices where the iliac leg should not necessarily overlap the total length of the ipsilateral or contralateral limb (in situ measurement). We recommend always using total overlapping length. There are two scenarios where this option is useful: (1) in case of the tortuous iliac arteries where the selected limb is shorter than initially considered and (2) if the required length for the iliac leg is not represented in the available limbs of the manufacturer (e.g., length to cover: 134 mm, available device 124 mm or 156mm in length).

Take-Home Messages

• Draw the aneurysm on a sheet of paper.

• Be aware of all relevant issues (stenosis, tortuosity, dis-

section, thrombus, etc.) that may inuence your interven-

tion—notice all issues in your drawing.

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• Plan your intervention according to the respective IFU of each manufacturer.

• Identify the right landing zone, especially in case of angulated necks.

• Oversize adequately.

• Learn all features and sizes of the endograft you use.

• Start with one endograft until you build your own learning curve.

References

1. Donas KP, Torsello G, Bisdas T.New EVAR devices: pros and cons. J Cardiovasc Surg (Torino). 2012;53(5):559–69.

2. Bisdas T, Weiss K, Eisenack M, Austermann M, Torsello G, Donas KP.Durability of the endurant stent-graft in patients undergoing endovascular abdominal aortic aneurysm. J Vasc Surg. 2014;60(5):1125–31.

Introduction toEndografts

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forInfrarenal AAAs

AndreasM.Lazaris

History

The history of endovascular treatment of aortic aneurysm diseases began about four decades ago. It was May 4, 1985, when a Ukrainian (USSR) cardiovascular surgeon, Professor Nikolai Leontyevich Volodos (Fig.46.1), implanted the rst hand-made endograft into iliac arteries. His patient had presented with lower limb gangrene secondary to multi-level peripheral arterial occlusive disease. The patient was treated by inserting a stent graft into the iliac arteries, followed by a femorotibial venous bypass graft [1]. In March 1987, following extensive preclinical work in models and cadavers, Volodos and his team implanted the rst aortic stent graft in history. The patient had presented with a false aneurysm of the descending thoracic aorta [1]. The patient survived 18 years after the aneurysm exclusion with this rst-ever stent graft. In 1986, Volodos published his rst report about the use of “self-xing synthetic blood vessel endoprosthesis” [2]. It probably did not receive wide acceptance because it was written in Russian. In 1989, Volodos and his colleagues tried to treat an abdominal aortic aneurysm (AAA) with a stent graft using a unibody bifurcated endoprosthesis. Unfortunately, the unsupported contralateral limb twisted, and the endovascular procedure was converted to open surgery [3].

At the same time, Juan Parodi, a vascular surgeon from Argentina, then a clinical fellow at the Cleveland Clinic in Ohio, USA, conceived his idea for a stent graft to treat AAA. Parodi proved that his early concept of stent grafts, based on zigzag stents in combination with polyurethane, was workable in dogs. However, he never published his work [3]. In 1988, when he met Julio Palmaz, and through him obtained the balloon-expandable Palmaz stent, he was able to use the combination of his straight tubular polyester stent graft with a Palmaz stent as a proximal xation to treat his rst patient with an AAA on September 7, 1990, with great success

A. M. Lazaris (*) Vascular Surgery Department, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece

Fig. 46.1 Nicolai Leontievich Volodos was a Soviet and Ukrainian

cardiovascular surgeon and scientist. Volodos developed and introduced the world’s rst endovascular stent graft into clinical practice for treating stenotic and aneurysmal diseases of the arterial system

(Fig.46.2). In 1991, Parodi published the details of the rst ve patients, all treated successfully with straight tubular endografts (Fig.46.3) [4].

Following these two pioneers, the endovascular treatment of aortic aneurysm disease exploded. The concept of stent graft treatment for aortic aneurysms rapidly spread to the USA, Australia, and Europe. Geoff White, Jim May, Michael

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Fig. 46.2 Illustration of the rst custom-made endografts. The surgeons created the endografts on the operating theater’s back table. Balloon-expandable stents anchor the graft onto the aortic wall [4]

A. M. Lazaris

46 Introduction toEndografts forInfrarenal AAAs

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The invention of endovascular aortic repair (EVAR) took place almost in the same period, in multiple locations around the world, on a simultaneous invention concept of invention and discovery, found in other elds of development such as aviation and automotive vehicle manufacturing. Like other elds of medicine, Vascular Surgery owes a great deal to its development in biology and engineering evolution. The growth and expansion of EVAR sprang from a simple common idea of a small group of inventive radiological and surgical visionaries, ourished almost simultaneously in industrial laboratories and hospital operating rooms, and became one of the most signicant discoveries in the history of medicine.

Fig. 46.3 Endovascular grafts composed from commercially available materials, used for the repair of aortic and peripheral artery aneurysms, arterial occlusions, and traumatic vascular injuries [5]

Lawrence-Brown, and David Hartley in Australia contributed signicantly to developing aortic stent grafts and using them to treat patients. In the 1990s, tubular aortic stent grafts were the way to treat patients with aortic aneurysm disease. However, it soon became apparent that common iliac arteries and the abdominal aorta should be part of the treatment option. Thus, the idea of using bifurcated or aorto-uni-iliac endograft systems soon became necessary. Vascular surgeons such as Tim Chutter from the USA and Krassi Ivancev from Sweden proposed their solutions to this concept. The involvement of industry and vascular surgery pioneers inevitably boosted the design and development of the stent- graft philosophy. Cook Inc. (Bloomington, Indiana, USA) was an example, working closely with a signicant number of vascular surgeons, such as Michale Lawrence Brown and David Hartley in Perth (Australia), Krassi Invacev in Malmoe (Sweden), Brian Hopkinson in Nottingham (England), Tim Chutter in Cornell (USA), Wof Stelter in Frankfurt (Germany), and Eric Verhoeven in Groningen (Netherlands). Soon, other companies followed, such as Gore (W.L. Gore & Associates, Incorporated, Flagstaff, Arizona), Medtronic (Medtronic Vascular, Santa Rosa, California), and many others in the following years. Famous worldwide vascular surgeons, well known for their open aortic surgery skills, made a signicant shift in their careers, embracing with enthusiasm the new technology. Frank Veith in NewYork (USA), Edward “Ted” Dietrich in Phoenix (USA), Peter Bell in Leicester (UK), and Roger Greenhalgh in London (UK) were some of them.

The need to preserve the normal anatomy led to the development of fenestrations and directional branches. Marcel Goodman in Perth (Australia), Wolf Stelter in Frankfurt (Germany), and Tim Chuter and Roy Greenberg in the USA proposed and implemented fenestrations for splanchnic vessels.

Design andCharacteristics ofAortic Endografts

The evolution of endografts has undergone multiple changes over time. Numerous generations of technological advancements based on physician and engineering feedback have addressed areas of clinical need, improved deliverability, decreased prole, and promoted better conformability to tortuous anatomy. Nevertheless, a similar general philosophy exists for all endografts. Every aortic endograft is comprised of two distinct components: the sheath with the delivery system and the endograft.

Sheath andDelivery System

The sheath is a necessary component of the aortic endograft device, ensuring the device’s safe insertion into the arterial system. In most devices, the endograft and the sheath are combined into one single sheath-endograft unity. An exception to this general concept is the Gore endograft delivered through a separately provided sheath. The delivery system and the endograft are loaded in an over-the-wire fashion and brought into the arterial system.

The sheaths and delivery systems of all modern endograft

devices have some common general characteristics:

1. Hydrophilic coating. The sheath is covered by a hydro- philic cover which reduces the friction resistance. Hydrophilic coating permits easy insertion and removal of the sheath, minimizing the risk of artery spasm.

2. Conical tip. The tip of the sheath is conical, allowing easy and safe insertion into the arterial system.

3. Low prole. First- and second-generation delivery sys- tems were bulky, blunt-ended, and stiff. The advances in engineering allowed the development of narrow delivery systems, reducing the rate of iliac artery trauma, and allowing endovascular treatment in patients with small

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A. M. Lazaris

iliofemoral access arteries, like those with severe calcication or those with iliac vessels of small caliber, for example women.

4. Controlled deployment. Most delivery systems allow a controlled endograft deployment, increasing the accuracy of positioning inside the aorta. The existence of gradual stent-graft-releasing mechanisms in endograft devices accomplishes this.

Endograft

The endograft is usually preloaded in the sheath, except for the Gore device, where the sheath and endograft are distinct components. There is a wide availability of different devices today (Fig.46.4), with plenty of similarities but also some unique differences:

• Endograft coating. Endografts are made of polyester

(Dacron) or polytetrauorethylene (PTFE).

• Metallic skeleton. A metallic frame (skeleton) supports

the endograft. In the rst generations of endografts the skeleton was made of stainless steel, which is rarely used nowadays. Most endografts frames today are made of nitinol, an alloy of nickel and titanium. The skeleton lies either outside the graft (exoskeleton) or, more rarely, inside the graft (endoskeleton), and it is secured on the graft with tiny non-absorbable sutures. The conguration of the skeleton can be either circular or, more often, in a Z-stent fashion.

• Endograft packing. The endograft is packed in a collapsed state inside the sheath of the delivery system. In the Gore device, in contrast to other devices, the endograft is brought as a separate unit; it is collapsed around the delivery system and is inserted into the sheath by the surgeon during the surgical procedure.

• Fixation systems. The xation of the endograft on the healthy proximal aorta is necessary to minimize the possibility of distal migration and is achieved in various ways. On the top end of the endograft there are various types of anchoring adjuncts like hooks, barbs, and anchors that embed into the aortic wall. Fixation is also enhanced by the radial force of the metallic frame produced by the stents of the skeleton (Z-stent or circular). The endograft oversizing, as compared to the size of the native proximal aortic neck, is necessary to achieve an adequate radial force increasing the endograft stabilization on the healthy aortic neck. In some grafts, a longitudinal metallic wire along the endograft enhances the xation of the endograft by increasing its columnar strength. Finally, most endografts carry a line of triangular-shaped are metal stents on their top end, which contributes to the stabilization and xation of the endograft on the suprarenal aorta. A unique idea for endograft stabilization exists in the Endologix AFX Powerlink graft. Its unibody bifurcated design allows the positioning of the endograft over the aortic bifurcation, eliminating the possibility of distal migration.

• Endograft repositioning. After the endograft is extracted from the sheath, it cannot be reloaded back on the sheath. However, most modern endografts are repositionable,

Fig. 46.4 Various types of endografts

46 Introduction toEndografts forInfrarenal AAAs

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meaning that the user can reposition the graft inside the arterial system, as long as the endograft remains partially deployed.

• Modular concept. Abdominal aortic endografts are usually modular grafts. They consist of two or three different endograft components that are united inside the human body. An adequate overlap between the adjacent components is necessary to minimize the possibility of blood leakage between them (type III endoleak), An exception to the modular design of most endografts, is the Endologix AFX Powerlink device, which is delivered on a unibody conguration.

• Bifurcated conguration. Abdominal aortic endografts are bifurcated grafts. Aorto-uni-iliac tube grafts are rarely used today in the usual treatment of AAA disease. Aortouni- iliac endografts are used today for specic clinical cases, such as when there is a narrow distal aortic neck or when there is an occlusion of one iliac axis not allowing intraluminal access from both iliac arteries and the accommodation of a bifurcated graft.

• Radiopaque markers. All endografts have x-ray radi- opaque markers on specic positions, such as the top end of the endograft in the graft bifurcation, on the entry gate of the contralateral limb. Radiopaque markers assist graft orientation and correct alignment inside the human body.

• Self-expanding property. Endografts are self-expanding straight after their deployment outside their sheath. Ballooning is usually necessary to improve proximal and distal apposition on the landing zones of the endograft, on the healthy aorta, and on the iliac arteries.

Principles andConcepts ofEndograft Deployment

For the deployment of each different endograft, there are specic steps that need to be followed. These steps are always explained in detail in each endograft instructions for use (IFU). However, certain steps are common in most cases. The typical steps that need to be followed for all endografts are the following:

1. Choice of the iliac axis for the insertion of the main

body’s delivery system. The iliac axis should be wide enough to accommodate the large prole main body device. Additionally, it should be as free of calcication as possible. If both iliac axes are suitable in terms of size for the main body delivery system, it is a prudent choice to prefer the most tortuous iliac artery, and leave the less tortuous iliac artery for the contralateral limb. This way, catheterizing the contralateral gate can be a relatively

easy task. In contrast, when the most tortuous iliac artery is left for the contralateral limb, the catheterization of the contralateral gate of the main body could become a difcult task for both the patient and the performing physician.

2. Access in both femoral arteries. After deciding which iliac axis is suitable for the main body delivery system, access to the femoral arteries follows. Usually, this is done through small incisions on both groins, although the availability of closure devices and the low-prole endografts may occasionally permit percutaneous ultrasoundguided access. Using the Seldinger technique, a standard J wire is inserted into the femoral artery through which the main body will be advanced. The wire is supported by a short 11cm-long, 6 Fr sheath, and it is advanced to the aortic arch and the ascending aorta together with a soft catheter. The same procedure is performed on the contralateral side, which will be used to insert the angiographic catheter.

3. Insertion of the angiographic catheter. A pigtail angiographic catheter or a large bore 8 Fr, 45cm long sheath can be used for the diagnostic angiography. The large bore sheath allows a good-quality angiogram even when done without an injector, simply by manual contrast injection. The angiographic catheter or sheath is advanced at the level of renal arteries orices, usually at the level of L1–L2 vertebrae.

4. Insertion of main body delivery system. Based on the preoperative CT investigation, the main body is inserted over an extra stiff guidewire approximately at the level where it should be, usually between L1 and L2 vertebrae levels.

5. Angiography. From the angiographic catheter or sheath, an angiogram is performed. The patient needs to be as still as possible. This can be accomplished by asking the patient not to breathe if the procedure is performed under local anesthesia or by asking the anesthetist to hold the patient’s breath for a while. To better view the proximal neck, the two renal arteries need to be visualized. This can be achieved by putting the C-arm intensier perpendicular to the aorta onto the area of interest.

6. Deployment of the main body of the endograft. Usually, the ipsilateral limb is partially deployed until the contralateral gate has been cannulated.

7. Catheterization of the contralateral gate. By using a hydrophilic guidewire with a half J tip from the ipsilateral iliac axis, the contralateral gate is catheterized with the support of a catheter. Occasionally, this can prove a timeconsuming task, and the vascular surgeon/interventionist needs to be as patient as possible to complete it. If catheterization is not successful from the iliac axis, other options should be considered such as catheterization from

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