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Jeffrey Solomon, MD, MBA, S. William Stavropoulos, MD,

Richard Shlansky-Goldberg, MD, and Lucas Buchanan, MBA

AdvAnced Procedures in

interventionAl rAdiology

AORTIC ANEURYSM STENT GRAFTS

1. What is the basic composition of a stent graft?

A stent graft is composed of a metallic stent structure covered by a medical-grade fabric. The stents are typically

made from stainless steel or nitinol (nickel titanium alloy), and the fabric is either Dacron (polyester) or expanded

polytetrafluoroethylene (ePTFE). A stent graft comes compressed and loaded in a delivery catheter. Stent graft designs

include straight tubes and bifurcated “pant leg” designs to accommodate the iliac branch. Bifurcated designs can either

be unibody (one piece) or modular (multiple pieces).

2. What are the prevalence, incidence, demographics, and risk factors for abdominal

aortic aneurysms (AAAs)?

The prevalence of AAA in the United States is estimated at 1 million to 1.5 million, and more than 75% of these are

asymptomatic. There are more than 200,000 new diagnoses and more than 15,000 rupture deaths annually (13th

leading cause of death). The prevalence is higher in older men with risk factors (4.5%) and lower in older women

with risk factors (1%). The main risk factors for AAAs include male gender and age older than 65, smoking history,

atherosclerosis, hypertension, and family history.

3. What is the natural history of AAA, and when is intervention indicated?

Aneurysms grow over time. Matrix metalloproteinases and their inhibitors result in the loss of aortic wall structural

integrity, which leads to AAA formation and expansion. The rate of growth is 1 to 4 mm per year for aneurysms less than

4 cm in diameter, 4 to 5 mm per year for aneurysms 4 to 6 cm, and 7 to 8 mm per year for aneurysms greater than

6 cm. Intervention is typically indicated when the aneurysm reaches 5.5 cm, although many clinicians treat at the 5-cm

threshold. The risk of rupture increases as the aneurysm grows: greater than 5 cm = 20% eventual, 4% annual; greater

than 6 cm = 40% eventual, 7% annual; greater than 7 cm = 50% eventual, 20% annual. Given that aneurysms grow,

studies are ongoing to determine the benefit of earlier intervention when aneurysm diameters are smaller, and patients

are relatively healthier.

4. How are most AAAs detected, and what is the role of screening programs?

Symptomatic aneurysms manifest with back, abdominal, buttock, groin, testicular, or leg pain. Most AAAs are

asymptomatic, however. AAAs can be easily detected via a simple ultrasound (US) study, which has been shown to

be cost-effective in targeted, high-risk patients. If aneurysms rupture, the mortality rate is greater than 85%, and the

morbidity rate and cost are significant for patients who survive. Elective repair of aneurysms is associated with low

rates of mortality and morbidity, so aneurysmal disease is well suited to screening. Many hospitals and private, mobile

screening companies offer aneurysm screening, often in conjunction with screening for other conditions such as

peripheral and carotid arterial disease. The U.S. Congress passed the SAAAVE Act (Screen Abdominal Aortic Aneurysms

Very Efficiently) in late 2005. Medicare-funded AAA screening is limited to male ever-smokers and to men and women

with a positive family history of AAA.

5. In general, when is endovascular aneurysm repair (EVAR) favored over open repair?

EVAR is preferred over operative repair when the surgical operative risk is higher because of comorbidities and older

age. Endovascular repair has been shown in studies to have lower short-term rates of death and complications, but

the survival curves merge in the long-term. Generally, open repair is preferred for younger, healthier patients, in whom

longer term durability is a primary concern. EVAR versus open repair is essentially a matter of proper patient selection

based on physiologic and anatomic risk factors, and is often a matter of patient preference for less invasive therapy.

6. Describe briefly the traditional open surgical repair of AAA.

With the patient under general anesthesia, a vascular surgeon makes an incision in the abdominal wall and exposes the

aorta and the aneurysm. The incision is either down the center of the abdomen from immediately below the sternum

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to below the umbilicus or across the abdomen from underneath the left arm across to the center of the abdomen and

down to below the umbilicus. Clamps are placed above and below the aneurysm to arrest blood flow; the surgeon then

butterflies the aneurysm and removes blood clots and plaque. A surgical tube graft is sewn to the healthy sections of the

aorta connecting both ends of the aorta together. The clamps are removed, the wall of the aneurysm is wrapped around

the graft, and the incision is closed. Recovery from AAA surgery is typically 7 to 10 days.

7. Name some findings on preprocedure imaging of AAA that would preclude a patient

from EVAR.

A major preclusion is proximal neck complexity or lack of a suitable landing zone just below the renal arteries to ensure

fixation and seal of the stent graft. A short neck is defined as less than 10 cm from immediately below the renal arteries

to the beginning of the aneurysmal zone. An angulated neck is defined as greater than 45 degrees from immediately

below the renal arteries to the beginning of the aneurysmal zone. A wide neck is greater than 32 mm. A neck that

flares immediately below the renal arteries or an aneurysm that extends into and above the renal arteries (juxtarenal)

would also preclude safe landing of a stent graft. Another contraindication is complex iliac arteries. The arteries may

be tortuous or calcified, precluding passage of the delivery catheter, or they may be aneurysmal in which case it may

be difficult to achieve fixation and seal of the iliac “legs” of a bifurcated stent graft. Lower profile delivery systems,

branched and fenestrated grafts, and more flexible and conformable designs are under development to attempt to solve

some of these contraindications to EVAR.

8. What is an endoleak? What are the different types of endoleak, and how are they

treated?

An endoleak is persistent blood flow into the aneurysmal sac after placement of a stent graft. A type I endoleak results

from poor attachment to the vessel wall. It can be caused by poor apposition of the stent graft to the aortic or iliac

wall, often owing to tortuosity, angulation, or disease (e.g., thrombus or calcification). Stent graft undersizing and aortic

neck dilation are also causes of type I leaks. Type I leaks are typically treated with balloon dilation or the placement of

an additional stent graft or balloon-expandable stent. Type II endoleaks are not caused by the graft itself, but rather by

retrograde flow into the sac from collateral arterial branches such as lumbar arteries or the inferior mesenteric artery.

Type II endoleaks sometimes resolve spontaneously or are monitored to see if they contribute to sac expansion or

pressurization. If intervention is indicated, they are treated using coils or embolic glues. Type III endoleaks are caused

by modular disconnections of stent graft pieces or by graft or metal fatigue causing tears in the fabric. This type of

endoleak was more common in the early days of EVAR, but is now decreasing in incidence because of more durable

designs and more overlap of stent graft pieces in the initial procedure. Type IV endoleaks are transgraft endoleaks

caused by fabric porosity or microabrasion caused by graft or metal fatigue. Type III and type IV endoleaks are treated by

placement of additional stent graft pieces or through open repair.

9. What kind of follow-up imaging do patients treated with EVAR undergo?

Patients require lifelong imaging surveillance to monitor for endoleak, aneurysm expansion, and graft integrity. Imaging

follow-up after EVAR is usually performed by periodic contrast-enhanced computed tomography (CT) scans. The typical

regimen is a baseline CT study at 1 month, with a follow-up study at 6 months and annually thereafter. To reduce the

need for expensive, radiation-exposing serial CT scans, some experts advocate for follow-up via color flow duplex US

scanning in the absence of endoleak and no clinical suspicions based on anatomy.

10. What are some of the complications related to EVAR?

Complications of EVAR include endoleak, continued enlargement or pressurization of the aneurysm sac without

endoleak, delayed aneurysm rupture, graft migration, graft limb occlusion, graft infection, stent-graft structural

breakdown, and groin or access complications.

Key Points: Abdominal Aortic Aneurysm

1. AAA is an asymptomatic but often fatal disease when rupture occurs; AAAs must be detected, monitored, and

treated. Intervention is typically indicated when the aneurysm reaches 5.5 cm, although many clinicians treat

at the 5-cm threshold. The main risk factors for AAAs include male gender and age older than 65, smoking

history, atherosclerosis, hypertension, and family history.

2. There are two primary treatment options for AAAs: EVAR and surgical repair. Endovascular repair is preferred

over operative repair when the surgical operative risk is higher because of comorbidities and older age. Open

repair is preferred for younger, healthier patients, in whom longer term durability is a primary concern.

3. The advantages of EVAR are that it is less invasive than open surgery, has a lower surgical morbidity and

mortality rate, and reduces the length of postoperative hospital stays. EVAR complications include endoleak,

continued enlargement or pressurization of the aneurysm sac without endoleak, delayed aneurysm rupture,

graft migration, graft limb occlusion, graft infection, stent-graft structural breakdown, and groin or access

complications.

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11. What are the major studies that have looked at the outcomes of EVAR?

The major randomized controlled studies include (1) the Dutch Randomized Endovascular Aneurysm Management

(DREAM) trial, (2) the EVAR versus open repair in patients with abdominal aortic aneurysm randomised controlled trial

(EVAR trial 1), and (3) the EVAR and outcome in patients unfit for open repair of abdominal aortic aneurysm randomised

controlled trial (EVAR trial 2). Major registry data include the European EUROSTAR database, the U.S.-based Lifeline

Registry of Endovascular Aneurysm Repair, and the Medicare matched cohort data published in the New England

Journal of Medicine. Short-term and long-term data from Investigational Device Exemption (IDE) studies from all U.S.

Food and Drug Administration (FDA)–approved stent grafts are available at the respective manufacturers’ websites.

12. What are the results of the major EVAR studies?

The EVAR 1 trial showed a 3% lower initial mortality for EVAR, with a persistent reduction in aneurysm-related death

at 4 years. Improvement in overall late survival was not shown. Similarly, the DREAM trial observed an initial mortality

advantage for EVAR, but overall 1-year survival was equivalent in both groups. The EVAR 2 trial did not show a survival

advantage of EVAR with respect to nonoperative management, although the design of this trial has been heavily debated.

The Medicare matched cohort study concluded that, compared with open repair, endovascular repair of AAA is associated

with lower short-term rates of death and complications. The survival advantage was more durable among older patients.

In the Lifeline Registry, patients receiving endovascular grafts were older and had more cardiac comorbidities compared

with surgical controls (e.g., open repair), but there was no difference in the primary end points of all-cause mortality,

AAA death, or aneurysm rupture between the endovascular graft and surgical control groups up to 3 years.

13. What devices are currently commercially available in the United States for EVAR, and

how do they differ?

Current FDA-approved devices include the Cook Zenith, the Endologix Powerlink, the Gore Excluder, the Medtronic

AneuRx, and the Medtronic Talent. Except for the unibody Powerlink platform, all platforms are modular in design.

Each manufacturer offers a slightly different range of widths and lengths, including tapered and flared iliac extensions.

The Zenith and the Excluder are equipped with tiny hooks or barbs to aid in fixation of the graft to the aortic wall.

Some stent grafts are suprarenal, meaning they have uncovered stent structures that extend across and above the renal

arteries. The Zenith and the Talent are suprarenal stent grafts. The AneuRx and the Excluder are infrarenal stent grafts.

The Powerlink offers infrarenal and suprarenal aortic cuffs and is the only graft that is designed to “sit” on the iliac

bifurcation. All stent grafts are self-expanding, but each has a different delivery catheter and actuator mechanism.

14. What advantages will future generations of stent grafts have over ones that are

currently available?

Currently approved stent grafts have catheter delivery profiles ranging from 20 to 24 Fr. New designs currently in clinical

trials have profiles ranging from 14 to 18 Fr, which would decrease access complications and significantly improve

the ability to treat patients (especially women) with complex and narrow iliac arteries, for which EVAR is currently

contraindicated. Patients with complex proximal aortic necks and juxtarenal aneurysms would benefit from branched

and fenestrated grafts that permit endovascular repair, while preserving renal patency. More durable fixation methods

(e.g., endostapling) and more flexible stent graft designs would expand the applicability of EVAR further.

15. What are advantages of EVAR over traditional surgical repair?

The advantages of EVAR are that it is less invasive than open surgery, has a lower surgical morbidity and mortality rate,

and reduces the length of postoperative hospital stays. The disadvantages of EVAR are the initial cost of the devices, the

need for lifelong follow-up imaging, and the question of long-term durability.

TRANSARTERIAL CHEMOEMBOLIZATION

16. What is meant by transarterial chemoembolization (TACE)?

TACE is a procedure that involves blocking (embolizing) the blood supply to a tumor and injecting chemotherapeutic

drugs directly into the artery that feeds the tumor. A catheter is placed in the femoral artery and used to select the

hepatic artery. The catheter in the hepatic artery is used for delivery of the embolic agent and drug delivery. The catheter

is removed immediately after treatment.

17. What types of hepatic malignancies can be treated with TACE?

TACE is most often used for liver tumors. The most common tumors treated with chemoembolization are hepatocellular

carcinomas (HCC) and metastatic lesions from colon cancer. Other tumors include metastatic hepatic lesions from

carcinoid tumors and other neuroendocrine tumors, breast cancer, islet cell tumors of pancreas, ocular melanomas, and

sarcomas. Benign tumors such as adenomas can also be treated with chemoembolization.

18. What is a typical mixture used to perform TACE?

There is no standard mixture of chemotherapy drugs or embolic agents that is widely used for TACE.

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19. What is the purpose of ethiodized oil (Ethiodol) in the TACE mixture?

Ethiodol is used during TACE because it is selectively retained by tumor cells and is radiopaque and can be seen under

fluoroscopy during chemoembolization.

20. What types of patients should be considered candidates for TACE?

TACE is a liver-directed therapy for liver tumors. It works best in HCC when the tumor has not spread to extrahepatic

sites. The best therapy for HCC is often liver transplantation. TACE is used to control HCC while the patient is on the

transplant list awaiting a liver transplantation. For patients who are not transplant candidates, TACE offers a noncurative

treatment for HCC. For metastatic lesions to the liver, TACE is best used when disease outside the liver is well controlled,

and the metastatic lesions to the liver represent the biggest threat to the patient’s health.

21. How are patients followed after TACE, and when is retreatment indicated?

Patients are generally admitted 1 night in the hospital after TACE. Patients receive a post-TACE CT or magnetic

resonance imaging (MRI) examination and are seen in an outpatient interventional radiology clinic 1 month after TACE.

Additional clinic visits and imaging with MRI or CT of the liver are done every 3 months to evaluate the success or failure

of the procedure. Retreatment can be done and is usually indicated if follow-up imaging shows new masses in the liver

or recurrent disease at the site of the treated tumor.

22. What is the typical imaging and work-up required before TACE?

Before TACE, patients are seen in the interventional radiology clinic, and a full history and physical examination are

performed. MRI is done within 1 month of the planned TACE. Within 1 week of the procedure, blood work is performed

that should include complete blood count, international normalized ration (INR), creatinine levels, and liver function tests.

23. What is postembolization syndrome?

Nearly all patients get postembolization syndrome after TACE. This condition includes low-grade fever, nausea, abdominal

pain, and fatigue. It is worst in the first 24 to 48 hours after the procedure and usually resolves 1 week after TACE.

24. What medications are patients typically treated with after TACE?

After TACE, patients are given powerful antibiotics to lessen the chance of infection and intravenous medications to

control nausea and pain while they are in the hospital. When they are sent home, patients receive a 5-day course of an

oral antibiotic (usually amoxicillin and clavulanate potassium [Augmentin]) and oral medications for nausea and pain.

25. What is the major risk factor for hepatic abscess formation secondary to TACE?

Hepatic abscess is always mentioned as a risk after TACE, but the risk increases greatly if the patient does not have a

competent ampulla of Vater. This can occur because of biliary stent placement or because of a biliary bypass procedure

that results in resection of the ampulla. Bacteria from the intestines can colonize the biliary tree if the ampulla is not

patent. A biliary tree that is colonized with bacteria is at an increased risk for abscess formation after TACE.

26. What tumor markers are used to follow HCC? What about metastatic colon cancer?

For HCC, the most reliable tumor marker is alpha fetoprotein. For colon cancer, the tumor marker commonly used is

carcinoembryonic antigen.

27. What laboratory values should be checked when determining candidacy for TACE?

Within 1 week of the procedure, blood work is performed, which should include complete blood count, INR,

creatinine, and liver function tests. If the patient has an elevated INR, bilirubin, aspartate aminotransferase, or alanine

aminotransferase, this may indicate that the patient has some degree of liver failure. Preexisting liver failure increases

the risk of TACE and could be an reason not to perform the procedure.

28. How can the liver tolerate embolization of the hepatic artery without undergoing

infarction?

The liver can tolerate TACE because it receives its blood supply from two sources: the hepatic artery and the portal

vein. Liver tumors derive most of their blood supply from the hepatic artery. The normal portion of the liver gets most of

its blood supply from the portal vein. Before the TACE agents are delivered, an arteriogram is done to confirm patency

of the portal vein. If the portal vein is completely occluded, the risk of liver failure and infarction after TACE increases

significantly. An occluded portal vein may be reason not to perform TACE.

29. What does one look for on follow-up imaging to evaluate the success of a TACE

procedure?

After TACE, MRI or CT of the abdomen and pelvis is done with intravenous contrast agent. The intravenous contrast

agent causes the tumors to enhance if they are still viable. If a tumor is successfully treated, it is necrotic and does not

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enhance after contrast agent administration on CT or MRI. In patients who have elevated tumor markers, a decrease in

the tumor marker levels would also be an indication of successful TACE.

30. What is radiofrequency ablation (RFA), and how does it work?

RFA is a technique for generating heat in living tissues through alternating electrical currents. The alternating currents

result in agitation of ions and frictional heat, which can result in coagulation necrosis of tissue. This technology has

been applied to the treatment of many conditions, including the treatment of liver, kidney, bone, and lung tumors.

A metal probe can be placed percutaneously in the tumor using US or CT guidance and is attached to the RF machine.

RFA results in tumor death via thermal energy.

31. What characteristics of hepatic lesions are considered treatable by RFA? What are

the characteristics of renal lesions treatable by RFA?

RFA is best done when there are three or fewer tumors to treat in the liver or kidney. Liver or kidney tumors 3 cm or

smaller in size respond best to RFA. Larger tumors can be treated, but results are not as good.

32. What are the imaging characteristics on MRI and CT of a lesion successfully treated

with RFA?

MRI or CT is done with intravenous contrast agent 1 month after RFA to evaluate the success of the treatment.

The intravenous contrast agent causes tumors to enhance if they are still viable. If a tumor is successfully treated,

it is necrotic and does not enhance after contrast agent administration on CT or MRI.

33. How are patients followed after RFA procedures?

Patients usually have CT or MRI performed 1 month after the procedure and then at 3- to 6-month intervals as

determined by the tumor type and institutional protocol.

34. What subset of patients is best treated with RFA of renal lesions?

Currently, RFA is usually reserved for patients who are not surgical candidates because of comorbid medical conditions

or renal insufficiency, or who have refused surgical resection of the kidney mass. As more long-term studies of RFA in

renal masses are done, more patients may be considered candidates for this therapy.

35. What are complications of RFA?

Complications after RFA include bleeding, infection, injury to the organ being treated, and injury to surrounding organs

including bowel.

UTERINE FIBROID EMBOLIZATION

36. What are typical symptoms of uterine fibroids?

Symptoms can be diverse, but may include menorrhagia (abnormal bleeding with menses), dysmenorrhea (painful

menses), and bulk symptoms such as pain and pressure. Other symptoms include infertility, urinary urgency and

incontinence, and constipation.

37. What clinical work-up is required before undergoing uterine fibroid embolization

(UFE)?

Work-up should include a thorough history focusing on the presence of symptoms compatible with uterine fibroids.

A physical examination should be performed directed at evaluating the fibroid uterus. Laboratory evaluation should

include a Pap smear and endometrial biopsy depending on symptoms, complete blood count, creatinine, and

coagulation factors.

38. What imaging is required before UFE?

Cross-sectional imaging is performed before embolization. This can be either US or preferably MRI with contrast

agent. The purpose of imaging is to evaluate fibroid size and location and to determine presence of possible adnexal

disease that may change the management of the patient. Knowledge of the size and location of fibroids is important

because submucosal fibroids are usually associated with bleeding and are at risk for being expelled after embolization.

Large intracavitary fibroids may be a relative contraindication because of the risk of infection.

39. How is a patient followed after undergoing UFE?

Patients are followed closely in the immediate postembolization period to help manage pain. Usually MRI is obtained

3 to 6 months after the procedure to ascertain the degree of fibroid infarction and correlate imaging with changes in

symptoms.

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40. What are the risks associated with UFE?

Aside from the risks that are common to any angiographic procedure, such as bleeding and reaction to contrast agent,

complications associated with UFE include infection or infarction of the uterus that might result in hysterectomy, fibroid

expulsion, and premature menopause.

41. What are the alternatives to UFE?

Medical management consisting of hormonal therapy exists, but most patients presenting for UFE have already failed

this treatment. Myomectomy is an option for patients seeking therapy for infertility. Hysterectomy is an option for

patients with fibroids when pregnancy is not a consideration.

42. How do symptoms typically respond to UFE?

There is a success rate of 85% to 90% in controlling bleeding and bulk symptoms. Urinary symptoms may not respond as well.

43. Are there any other indications for UFE other than fibroids?

Uterine embolization can be used to treat bleeding emergencies such as postpartum hemorrhage, uterine atony, and

cervical ectopic pregnancy. Uterine embolization may also be used for other conditions such as adenomyosis; however,

its success may not be as durable as with the treatment of fibroids.

44. What type of embolic is typically used?

Polyvinyl alcohol particles or trisacryl particles (Embosphere) have been shown to have the best success to date for UFE.

Absorbable gelatin sponge (Gelfoam) has been shown to work when treating acute bleeding.

45. Is there a correlation between postprocedure pain and clinical outcomes?

There is no correlation between degree of pain and outcomes. Patients usually return to normal activities in 1 to

2 weeks after UFE.

46. What is a typical analgesia protocol for patients undergoing UFE?

Patients receive ketorolac tromethamine (Toradol), 30 mg intravenously, periprocedure and are managed with fentanyl

(Fentora) and midazolam (Versed) during the procedure. Postprocedure, a patient-controlled analgesia pump with

morphine or hydromorphone (Dilaudid) along with an oral nonsteroidal anti-inflammatory drug (NSAID) is used to

control pain. Some authorities advocate the use of epidurals during hospitalization. Patients are discharged with an oral

narcotic, such as oxycodone with acetaminophen and an NSAID, such as ibuprofen.

47. What are the indications for discharge from the hospital after UFE?

Patients may be discharged when they are able to tolerate oral intake, and pain is controlled with oral medications.

48. Describe the vascular anatomy relevant to UFE.

Although anatomic variations exist, the paired uterine arteries are typically the first branch of the anterior division of

the internal iliac arteries. Embolization is usually performed with the tip of the catheter in the horizontal segment of the

uterine artery that is past the cervical-vaginal branch. The ovarian arteries usually arise from the aorta and can also

supply the uterus. This collateral blood supply is a potential cause for poor clinical response to UFE.

49. What is the risk of premature menopause related to UFE?

The risk is low for patients younger than 45 years old, and the risk increases after this age. The rate of premature

menopause may be 40% in patients older than 51 years.

50. Is pregnancy possible after UFE?

Yes, however, the incidence of placental location abnormalities, such as placenta previa, may be increased. There may

also be a higher rate of miscarriage, but it is uncertain if this is related to a history of UFE or the higher maternal age in

this specific patient population.

B

iBliography

[1] L.J. Leurs, J. Buth, P.L. Harris, J.D. Blankensteijn, Impact of study design on outcome after endovascular abdominal aortic aneurysm

repair: a comparison between the Randomized Controlled DREAM-trial and the Observational EUROSTAR-registry, Eur. J. Vasc. Endovasc.

Surg. 33 (2007) 172–176.

[2] Lifeline Registry of EVAR Publications Committee, Lifeline registry of endovascular aneurysm repair: long-term primary outcome

measures, J. Vasc. Surg. 42 (2005) 1–10.

[3] M.L. Schermerhorn, A.J. O’Malley, A. Jhaveri, et al., Endovascular vs. open repair of abdominal aortic aneurysms in the Medicare

population, N. Engl. J. Med. 358 (2008) 464–474.

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D

ream

T

rial

[1] J.D. Blankensteijn, S.E. de Jong, M. Prinssen, et al., Dutch Randomized Endovascular Aneurysm Management (DREAM) Trial Group: two-

year outcomes after conventional or endovascular repair of abdominal aortic aneurysms, N. Engl. J. Med. 352 (2005) 2398–2405.

[2] M. Prinssen, E.L. Verhoeven, J. Buth, et al., Dutch Randomized Endovascular Aneurysm Management (DREAM)Trial Group: a randomized

trial comparing conventional and endovascular repair of abdominal aortic aneurysms, N. Engl. J. Med. 351 (2004) 1607–1618.

e

var

T

rial

[1] E.V.A.R. trial participants, Endovascular aneurysm repair versus open repair in patients with abdominal aortic aneurysm (EVAR trial 1):

randomised controlled trial, Lancet 365 (2005) 2179–2186.

[2] E.V.A.R. trial participants, Endovascular aneurysm repair and outcome in patients unfit for open repair of abdominal aortic aneurysm (EVAR

trial 2): randomised controlled trial, Lancet 365 (2005) 2187–2192.

[3] R.M. Greenhalgh, L.C. Brown, G.P. Kwong, et al., 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: Randomised controlled trial, Lancet 364 (2004)

843–848.