http://pvs.sagepub.comand Endovascular Therapy

Perspectives in Vascular Surgery

DOI: 10.1177/153100350401600214 2004; 16; 135 Perspect Vasc Surg Endovasc Ther

Amy B. Reed, Geza Mozes, Michele Carmo, James C. Andrews, Thanila A. Macedo and Peter Gloviczki Misplacement of the Stent-Graft?

Renal Artery Coverage During Endovascular Aortic Aneurysm Repair: Proximal Migration or

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Perspectives in Vascular Surgery and Endovascular Therapy Volume 16, Number 2, 2004

Focus on [ndovascular Technique

Renal Artery Coverage During EndovascularAortic Aneurysm Repair: Proximal Migration or

Misplacement of the Stent-Graft?Amy B. Reed, MD, Geza Mozes, MD, PhD,t Michele Carmo, MD,t James C. Andrews,MD,t Thanila A. Macedo MD,t and Peter Gloviczki, MD,1 Cincinnati, OH andRochester, MN

Partial or complete coverage of the renal arteries by the stent-graft during endovascularabdominal aortic aneurysm repair is a serious problem. We present two cases with this compli-cation; both were successfully managed using renal artery stents. To minimize the risk ofrenal artery coverage, completion aortography with good visualization of the renal arteries isrecommended. Even a slight increase in serum creatinine after endovascular abdominal aorticaneurysm repair can be a sign of renal artery coverage due to early proximal migration or

misplacement during deployment. Computed tomographic scan with and without intravenouscontrast is recommended to establish the right diagnosis. Early stenting of the renal arteriesis usually possible and associated with an excellent prognosis.

Key words: Renal artery stenosis, abdominal aortic aneurysm, stent-graft.

IntroductionEndovascular abdominal aortic aneurysm repair(EVAR) has been shown to be successful withgood early and mid-term results in selected pa-tients.' The Achilles heel of EVAR is the seal be-tween the stent graft and the proximal aneurysm

Pers Vasc Surg Endovasc Ther 16:135-140, 2004.From the Division of Vascular Surgery, University of Cincinnati,Cincinnati, Ohio, and tDivision of Vascular Surgery and tDepart-ment of Radiology, Gonda Vascular Center, Mayo Clinic, Roches-ter, Minnesota.Correspondence: Peter Gloviczki, MD, Professor of Surgery andChair, Division of Vascular Surgery; Director, Gonda VascularCenter, Mayo Clinic, Rochester, MN, E-mail: gloviczki.peter@mayo.edu.©2004 Westminster Publications, Inc., 708 Glen Cove Avenue,Glen Head, NY 11545, USA.

neck. Both proximal sealing and fixation of theendograft depend on the length, diameter, andangulation of the aneurysm neck. Although prox-imal fixation can be supported by transrenalstruts, aortic penetration with barbs, or by thecolumnar strength of the device, proximal sealingdepends solely on the apposition between thestent-graft and the aneurysm neck.2

The US Food and Drug Administration's(FDA) selection criteria for approved infrarenalendografts includes a proximal neck with a mini-mum length of 15 mm.1 In many patients the en-tire length of the aneurysm neck is necessary toprovide durable seal. The infrarenal aortic seg-ment is relatively resistant to degeneration; there-fore, it is advisable to place the stent-graft asclose as possible to the renal arteries, even if theneck is longer then 15 mm.

Accidental coverage of the renal artery ostia isthus a potential problem associated with EVAR.

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However, proper initial placement of the mainbody of the stent-graft may be followed by subse-quent proximal migration with depoyment of ad-ditional modular components. We present twoEVAR cases; both were complicated by acciden-tal renal artery coverage by the fabric of the stent-graft. Both patients were successfully treated withrenal artery stenting.

Case 1A 77-year-old man with an asymptomatic, en-larging abdominal aortic aneurysm (AAA) pre-sented for evaluation for elective repair. His med-ical history was remarkable for hypertension, sta-ble coronary artery disease, and hyperlipidemia.Physical examination revealed an obese patientwith normal arterial pulses. His aortic aneurysmwas not palpable. Laboratory study results in-cluded a serum creatinine level of 1.3 mg/dL.Computed tomography (CT) confirmed a 5.3-cmAAA with a neck 25 mm in diameter and 15 mmin length. Aortography showed dilated commoniliac arteries measuring 20 mm on the right and18 mm on the left.

A 28 x 16 mm bifurcated AneuRx(Medtronic, Sunnyvale, Calif) stent-graft wasplaced with a right iliac extension cuff withoutdifficulty. The graft was deployed just distal to

Figure 1. Case 1: Computed tomographic scan 2 daysafter endovascular aortic aneurysm repair in a 77-year-old man shows the AneuRx graft at the level of the renalarteries, suggesting high placement.

the renal arteries. An intraoperative aortogramconfirmed the presence of a small type II en-doleak; however, final visualization of therenal arteries was suboptimal.

The patient's serum creatinine level increasedto 1.8 mg/dL on the first postoperative day, but itrecovered spontaneously in 3 days. A CT scan be-fore discharge showed that the stent-graft par-tially covered the orifices of both renal arteries

A

B

Figure 2 A and B. Case 1: Postoperative aortogram inthe same patient shows partial bilateral obstruction ofthe main renal arteries by the aortic stent-graft (A).Selective right renal artery angiogram shows coverage ofmost of the orifice of the right renal artery by the aorticstent-graft (B).

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Reed et a] Renal Artery Coverage During EVAR 137

(Figure 1). Duplex ultrasonography (DUS), how-ever, suggested patent renal arteries, though theproximal segments of both renals were not wellvisualized. The patient was discharged and wasinstructed to recheck renal function at home withhis primary care physician.

Two weeks later the patient presented withfatigue and a serum creatinine level of 5.4 mg/dL.DUS showed bilateral high-grade renal arterystenosis. Selective renal arteriograms revealedthat the renal arteries were partially covered bythe upper margin of the stent-graft (Figures 2Aand B). Balloon expandable 6-mm Palmaz stents(Cordis/Johnson & Johnson, New Brunswick, NJ)were deployed in both renal arteries proximally.The stents displaced the AneuRx graft distally asthey were expanded with the balloon. No he-modialysis was required and the patient was dis-charged in 4 days with a serum creatinine levelof 1.8 mg/dL.

Figure 3. Case 1. Follow-up computed tomographicangiography with three-dimensional reconstructiondemonstrates a functioning endograft and patent renalartery stents 3 years after endovascular abdominal aorticaneurysm repair and bilateral renal artery stenting.

Three years later, the patient is doing wellwith a serum creatinine level of 1.2 mg/dL. CT-angiography demonstrates a functioning endo-graft without migration, or endoleak; the renalartery stents were patent without evidence ofstenosis (Figure 3). The AAA diameter decreasedfrom 5.3 to 4.7 cm.

Case 2

A 72-year-old man presented with a 4.9-cmasymptomatic AAA. The aneurysm had increasedby 4 mm in the last 12 months, and the patientwas concerned that it would rupture. His med-ical history included hypertension, hyperlipi-demia, former tobacco abuse (120 packs peryear), lobectomy for bronchogenic carcinoma,and photodynamic therapy for tracheal cancer,with no clinical signs of recurrences. Physical ex-amination revealed obesity, full peripheral puls-es, and a pulsating abdominal mass. His serumcreatinine level was 1.1 mg/dL. CT-angiographyshowed a 4.9-cm AAA with a 3-cm-long neck of25 mm in diameter.

Following left hypogastric artery emboliza-tion a bifurcated AneuRx stent-graft (26 x 15mm) was placed with bilateral iliac extensions.Completion aortography confirmed AAA exclu-sion with no endoleak and patent renal arteries(Figure 4). On postoperative day 1 his serum cre-atinine level was 1.3 mg/dL, but routine abdom-inal CT scan demonstrated partial coverage ofboth renal artery ostia (Figure 5).

The patient underwent bilateral balloon ex-pandable renal artery stent (6-mm Palmaz)placement. The procedure was successful, withsmall dissection in the left renal artery, withoutany significant stenosis (Figure 6). He was anti-coagulated with intravenous heparin.

The remainder of his hospital course wascomplicated by a groin hematoma that requiredsurgical evacuation, and by urinary retention andurinary tract infection. His serum creatinine levelrose to a maximum of 1.8 mg/dL, but returned to1.5 mg/dL at the end of thel2-day hospitaliza-tion. He was discharged without further compli-cations. Three years later, his kidney function re-mains stable; however, he has not returned forimaging studies in our institution.

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Discussion

Renal complications after EVAR are not uncom-mon, but coverage of the renal arteries by thestent-graft that requires a secondary procedureis a rare event. A MEDLINE review of the Englishlanguage literature revealed only one case reporton accidental renal artery coverage5; reports onlarge series of EVAR, however, included cases

with this complication.6'9Renal complications during and after EVAR

include contrast nephropathy, thrombo- oratheroembolism, coverage of the renal arteriesduring placement of the proximal graft, or prox-imal migration of a correctly placed stent-graft.Contrast nephropathy and minor renal infarc-tions secondary to embolic events are usually as-sociated with limited impairment of kidney func-tion and manifested only by a temporary increasein the serum creatinine level.

Figure 4. Case 2. Intraoperative completion aortogramin a 72-year-old man after endovascular abdominal aorticaneurysm repair shows patent renal arteries.

However, major embolic events and acciden-tal coverage of the renal arteries, in particular,are associated with a high risk of permanent lossof kidney function. Any intraluminal device, suchas an aortic stent-graft with transrenal fixationthat is placed proximal to the renal artery, car-ries the potential to dislodge atherosclerotic de-bris or thrombus into the renal circulation.Careful selection and handling of guidewires andcatheters can help to reduce this risk, howeversome manipulation around the renal arteries isan unavoidable part of EVAR.

EVAR can be performed with stent-grafts byusing either trans- or infrarenal proximal fixa-tion. Regardless of the device, the fabric-coveredsegment of the stent-graft has to be placed asclose to the ostium of the more distal renal arteryas possible to maximize the surface for infrarenalsealing. Transrenal fixation requires partial cov-erage of the renal artery by the struts of barestents, but not by any graft material.

Controversy exists about the effect of cross-ing stents on renal artery circulation. In a retro-spective comparison of endografts with transre-nal fixation to those with infrarenal fixation only,transrenal fixation was associated with a trendfor higher incidence of small renal infarcts, butwith no short- or mid-term impairment of renal

Figure 5. Case 2: A ccomputed tomographic scan ob-tained one day after endovascular abdominal aorticaneurysm repair confirmed bilateral partial coverage ofthe renal artery ostia.

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Reed, et a] Renal Artery Coverage During EVAR 139

function.3 Similarly, in a study that included 99patients with Vanguard (Boston Scien-tific Corp.,Natick, Mass), Talent (Medtronic, Sunnyvale,Calif), Excluder (Gore and Assoc, Flagstaff, Ariz),Corvita (Boston Scientific Corp), AneuRx,Lifepath (Baxter Healthcare, Irvine, Calif), andZenith (Cook Inc., Bloomington, Indiana) devices,renal infarction rate was 8.7% in 69 renal arterieswith bare stents extending through the ostium,and 5.6% in the 124 arteries with infrarenal fixa-tion alone.4

In large clinical series of EVAR, renal arterycoverage is reported to occur with less than 1%frequency. In 128 patients treated with theAneuRx device, one suprarenal deployment oc-curred, which was corrected with intraoperativerepositioning of the fully deployed endograft.6Neither accidental renal artery coverage nor anysecondary interventions for renal complicationswere reported in two other series of 179 and 239EVAR with a variety of different endografts.7,8 Inanother series, homemade and Talent-LPS tran-srenal devices were used in 192 patients andrenal artery coverage by the graft material wasreported only in 2 cases. Unfortunately, bothcases resulted in kidney infarction and permanentrise in serum creatinine.9

The two potential explanations for how renalartery coverage occurs are (1) coverage is acci-dental due to misplacement of the stent-graft and(2) proximal migration of the correctly placedstent-graft may occur during placement of addi-

Figure 6. Case 2: An angiogram following bilateralrenal artery stent placement shows widely patent renalarteries, renal stents and aortic stent-graft.

tional limbs to the main body of the graft.Tortuosity of the stent-graft may store elastic en-ergy, which can move the whole device upwardsin case of suboptimal fixation due to laminatedthrombus or a short neck.

If accidental renal artery coverage is discov-ered, intraoperative correction should be at-tempted even if the endograft has already beenfully deployed. A balloon inflated above the flow-divider of a bifurcated device may help "to grab"the endograft intraluminally and pool it into theinfrarenal position.6 A transfemoral crossoverwire may also be used to reposition the endo-graft.10 Intuitively, these maneuvers are advisableonly for endografts without penetrating proximalbarbs. Renal artery stenting in other cases may bethe only alternative.

Selective catheterization of the lowest renalartery, aortography, and renal arteriography per-formed immediately before deployment, and ob-taining a good quality aortogram at the end of theprocedure are maneuvers which may help to pre-vent or recognize renal artery coverage intraop-eratively. It is imperative to tilt the C-arm of thefluoroscope to the appropriate angle to obtain thebest view of a tortuous or angulated neck duringdeployment of the main body of the graft. Partialrenal artery coverage, however, can be over-looked on fluoroscopic images with suboptimalresolution.5

In both of cases presented here, accidentalcoverage of the renal arteries was discovered onimmediate postoperative CT-scans. In the firstcase, the intraoperative completion aortogramwas suboptimal and filling of the renal arteries bythe contrast medium was interpreted as goodproximal deployment. In the second patient, abetter quality aortogram was more convincingthat immediate coverage of the renal orifices hadnot occurred.

The partial renal artery coverage in both ofthese patients was associated with serum creati-nine increase; in the first case the significance ofthis was under-appreciated owing to the misin-terpretation of a nondiagnostic renal artery ultra-sound. Once diagnosed, the partial renal arterycoverage was treated successfully in both caseswith placement of balloon-expandable renalartery stents.

If there is clinical suspicion for renal arterycoverage, early postoperative CT angiography isour first test of choice. In equivocal cases, how-ever, a low threshold for proceeding with rentalangiography is recommended. Early stenting ofpartially covered renal arteries is usually possible

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and it is associated with excellent long-termpreservation of renal function.

REFERENCES

1. Najibi S, Terramani TT, Weiss VJ, et al: Endovascularaortic aneurysm operations. Arch Surg 137(2):211-216, 2002.

2. Greenberg R, Fairman R, Srivastava S, et al: Endo-vascular grafting in patients with short proximalnecks: An analysis of short-term results. CardiovascSurg 8(5):350-354, 2000.

3. Cayne NS, Rhee SJ, Veith FJ, et al: Does transrenalfixation of aortic endografts impair renal function? JVasc Surg 38(4):639-644, 2003.

4. Kramer SC, Seifarth H, Pamler R, et al: Renal infarc-tion following endovascular aortic aneurysm repair:incidence and clinical consequences. J Endovasc Ther9(1):98-102, 2002.

5. van Dijk LC, van Sambeek MR, Cademartiri F, et al:Partial blockage of the renal artery ostium after stent-graft placement: detection and treatment. J EndovascTher 10(3):684, 2003.

6. Tutein Nolthenius RP, van Herwaarden JA, van denBerg JC, et al: Three year single centre experiencewith the AneuRx aortic stent graft. Eur J VascEndovasc Surg 22(3):257-264, 2001.

7. Conner MS, 3rd, Sternbergh WC, 3rd, Carter G, etal: Secondary procedures after endovascular aorticaneurysm repair. J Vasc Surg 36(5):992-996, 2002.

8. Ohki T, Veith FJ, Shaw P, et al: Increasing incidenceof midterm and long-term complications after en-dovascular graft repair of abdominal aorticaneurysms: a note of caution based on a 9-year ex-perience. Ann Surg 234(3) :323-334; discussion 334-335, 2001.

9. Burks JA Jr, Faries PL, Gravereaux EC, et al: Endo-vascular repair of abdominal aortic aneurysms: stent-graft fixation across the visceral arteries. J Vasc Surg35(1):109-113, 2002.

10. Ruckert RI, Romaniuk P, Rogalla P, et al. A methodfor adjusting a malpositioned bifurcated aortic endo-graft. J Endovasc Surg 5(3):261-265, 1998.

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