PH6

taneous transvesical retrieval of foreign bodies pen­etrating rhe urethra.] Ural 1999;161(3),915-916.

47. Franzoni DF, Deeter RM. Percutaneous vesicolitho­tomy: an alternative to open bladder surgery in pa­tients with an impassable or surgically ablated ure­rhra.] Ural 1999;162,777-778.

48. Wollin TA, Singal RK, Whelan T, Dicecco R, RazviHA, Denstedt jD. Percutaneous suprapubic cysto­lithotripsy for treatment of large bladder calculi. jEndaural 1999;13(0);739-744.

49. Santarosa RP, Hensle 1W, Shabsigh R. Percutancoustransvesical ureteroscopy for removal of distal ureteralstone in reimplanted ureter. Urology 1993;42(3):313--­316.

50. Rozenblit GN, Del Guercio LR, Rundback ]H,Poplausky MR, Lebovics E. Peritoneal-urinary drain­age for treatment of refraclOry ascites: a pilar study[see comments).]VIR 1998;9(6);998-1005.

Aneurysmal Disease

Thursday, March 8, 200110:00 a.m.-12:00 p.m.Moderator: David M. Williams, MD

10,00 a.m.

Current Status of Aortic Stent-GraftsChet Rees, MDBaylor University Medical Center

Dallas, Texas

The held of aortic stent-grafr placement is evolving at aremarkable rate, driven by a powerful combination ofpatient preference, market forces, and three determinedmedical subspeciallies. At the same time, the pace istempered by the FDA, based on well-grounded concernsover the long-tenn results and durability of these de­vices. Getting to market with a new device involves anarduous process, and staying on the market requiresdiligence. As a result, there are many patients who wantstent-grafts and many doctors who want to utilize them

more extensively, however, at this time in the UnitedStates, only two devices are commercially available andone is currentJy on back-order. A large supply of deviceswith a wide spectrum of complementary characteristicsis available to only a few centers with large experienceand active involvement in multiple device trials. It ap­pears, however I that such things represent mere srulTI­bling blocks to the inevitable proliferation of available

devices and their use.

BackgroundRisk of rupture increases sharply when the ancurysm isgreater than 5 cm. Ideally, aneurysms are repaired elec­tively when between 5 and 6 cm in diameter, or ~6 cm

if serious medical comorbidities exist (1). Medical man­agement includes control of HTN and smoking cessa­tion. At this time, the indications for endografting aregenerally the same as those established for conventionalsurgery, although as the teclmology and skills advance,and the long-tcrm results become more proven, theremay be a shift toward treatment of smaller aneurysms(2).

Current Candidates, Anatomic and ClinicaJIdeal anatomic characteristics include: An aortic neckwith a length of at least 15 mm (to include a reverse taper

of no more than 2 mm), a diameter of 26 mm or less, andwithout mural thrombus; an aortic angle of 60 degrees orless; iliac vessels without severe tortuosity; external iliacarteries with diameters of 8 mm or more, or 6-8 mmwithout significant calcifkation or irregularity due toplaque; common iliac arteries without aneurysm or ec­tasia (diameter 8-12 mm) in the non-excluded portionsand with clean landing zones of at least 10 mm in length;and absence of indispensable branches arising from theaneurysm. These limits are rough gUidelines, are depen­dent on device and operator experience, and many in­teract with each other (eg, iliac tortuosity and diameter),

but are useful as generalizations to loosely define theideal characteristics in late 2000.

Many patients without these characteristics may stillundergo successful endografting, but with increased dif­ficulty and risk. Examples include: Straight, smooth, clot­free aortic necks with lengths of 10-15 mm (or possiblyeven shorter with suprarenal fixation), aortic necks withdiameters>26 mm using devices with larger cuff sizes(with some concern that these larger necks may be morelikely to expand over time and lose their seall15]); aorticangles >60 degrees if the aortic neck is otherwise idealand a kink-resistant device is used; highly tortuous iliacvessels in the absence of smal1-caliber issues or exten­sive disease (especially calcific); common iliac aneu­rysms of 20 mm diameter or less in the nonexcludedportion; extensive common iliac aneurysmal disease re­quiring exclusion of thc common and internal iliac ar­teries if the contralateral internal iliac artery may remainpatent, and accepting a significant incidence (200/0-30%)of hip/buttock claudication; and extensive unilateral iliacocclusive disease using aortomonoiliac graft with fem­fern crossover technique. Approximately 40°/0-600/0 ofpatients with AAA are eligible for stent-grafts anatomi­cally, by rough estimate at the current time. Highernumbers are sometimes quoted at individual sites, butthe effects of a selection bias caused by endograft can­didate referml patterns is difficult lO sort out. Although asmall percentage of patients are anatomically eligible fortube grafting, concerns about potential delayed loss ofdistal attachment caused by a high incidence of distalaortic expansion lead most investigators to utilize bifur­

cated systems for most patients when possible OS).Although stent-grafts are being increasingly used for

the treatment of excellent operative candidates, this re-

mains controversial in view of the absence of significantlong-term results. Early on the learning curve, such treat­ment may actually have more short-term complicationsthan conventional surgery in experienced hands. Con­servative operators recommend conventional surgery forlow-risk candidates and patients with long life expect­ancies (3). It is generally agreed that higher-risk patientsand patients with "hostile abdomens" are best treated bystent-grafts. Despite an early study of the use of stent­grafts to treat acutely ruptured aortoiliac aneurysms inwhich six of eight patients survived, stent-grafts are notused to treat acute ruptures except in very specializedcases, as a result of the uncertainty of achieving com­plete occlusion and concerns about the long-term stabil­ity of current devices that can be readily available in a"one size fits all" fashion (4). Mycotic AAA should un­dergo open surgery, except in highly unusual circum­stances, as reported in thoracic aneurysms (5).

PreproceduralVVorkupImaging studies vary among institutions and operatorpreference and experience. The studies are adequate ifthe anatomic parameters can be assessed with accuracy.Helical CT is almost universally used as the primaryscreening and measurement tool, and may be a stand­alone modality in straightforward cases, or at centersexperienced with good 3D reconstruction software andmeasurement tools, and extensive implantation experi­ence. CT is superior to catheter angiography for assess­ment of clot in attachment sites, vessel diameters, preciseaneurysm transition sites, and extent of calcification.Catheter angiography is reqUired at Some point, butfrequently some experienced operators will reserve ituntil the time of implant. Many very experienced insti­tutions will perform preprocedural catheter angiographyon all patients. Certainly, this is recommended in all earlycases for any operator or institution. Preimplantationembolization of an internal iliac artery can be ideallyperformed at the time of angiography in cases wheregraft extension to the external· iliac artery is planned. Itcan be difficult to assess distance from renal artelY tointernal iliac artery on CT, and this is best done with amultiple-marker catheter at angiography. If this is notperformed until the time of implantation, a larger inven­tory of graft lengths may be necessary. IVUS can be usedto accurately assess vessel diameters and length fromrenal to internal iliac artery, but does not seem to addsignificant information to a careful CT and catheter­based length assessment.

Follow-UpBecause of the conundrum of endoleaks, stent-graftsrequire extensive imaging surveillance. The concepts ofendoleaks and pressurization or "endotension" are ex­ceedingly important topics, and are therefore the sub­jects of a separate plenary presentation and discussedelsewhere in thiS handout book, so they will not bediscussed here.

Commercial DevicesTwo basic categories of stent-graft design exist. First, theAncure (Guidant, Indianapolis, IN) arose from the con­cept that stent-grafts should ideally mimic standard sur­gical repair, with hooks instead of sutures, and absenceof a fully supported skeleton. Other devices were devel­oped upon the strategy of optimum utilization of cathe­ter-based techniques in which the device is constructedwithin the aorta from modular components, with a fullysupporting skeleton. The Ancure is limited with regardto sheath size and rather cumbersome implantation, butit is believed by some that they will demonstrate dura­bility and ability to respond to late aneurysm remodelingwith less device failure, ultimately providing superiorlong-term performance (6).

Currently, two devices are approved for use in theUnited States: the Ancure, and the AneuR.;{ (Medtronic,Minneapolis, MN). The Ancure is a single piece bodywith Elgiloy (Elgiloy Limited Partnerships, Elgin, IL) alloystents at the ends only, with relatively long hooks thatextend beyond the ends of the graft to act as attachmentsites. It has no supporting metal along the body. TheAneuRx resembles the majority of other stent-grafts, inthat it is fully supported by a metal skeleton, and has amodular design. Its nitinol frame is on the outside of thegraft material (exoskeleton), and it does not have anybarbs or exposed metal beyond the margins of the graft.

Other qualities that differentiate these and severalother unapproved devices include graft material, metalcomposition, extension of metal beyond the graft mate­rial, which if long enough, may permit suprarenal fixa­tion, intmducer caliber, balloon versus self-expandingdeSign, and maximum cuff diameters. The Table sum­marizes some of the following qualities.

ResultsAs experience is gained, and stent-grafts have developedfrom "home-made" devices constructed from availablematerials, to single piece devices, to modular devices,there has been an accompanying increase in initial suc­cess and a decrease in surgical conversion rates (7). Withcareful case selection at experienced centers using mod­ular devices, current urgent conversion rates due to de­vice migration, coverage of renal vessels, vascular rup­ture or severe injury due to manipulation, thrombosiS, orfailure of graft deployment, can be very isolated events.Failure to complete the implantation is most conunonlydue to diseased or tortuous access vessels, and may notrequire urgent conversion. Device caliber and stiffness,and ease of use are important considerations regardingrisk of conversion.

Short-term benefits of stent-graft relative to open sur­gery are dramatic, and include reduced anesthesia re­quirements, physiologic stress, and blood loss; all impor­tant considerations in the elderly and poor operativecandidates (8). The ICU is rarely utilized, patients ambu­late the following day, and hospitalization is reducedfrom 6-10 days to 2-3 days. 30-day mortality is variable

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CostsStent-grafts are expensive ($10,400), and accounted for52% of total inpatient costs (2). Costs were higher thanopen surgeI)' ($19,985 vs $12,546).

among series, and depends most importantly on riskcategoI)' of the patients. With specific regard to 30-daymortality, the benefits of stent-grafts over surgeI)' areclear for high-risk patients, but diminish for low-riskpatients. Complications have significantly reduced withexperience. In 116 high-risk patients, many receivingcustom-made devices and aortomonoiliac devices, 30­day rates of mortality, major morbidity, and minor mor­bidity dropped from 3.4%,20.7%, and 12% to 0%,3.4%,and 3.4% when comparing the first to the second 58patients (4).

In the Eurostar registI)' of 1554 patients at 56 Euro­pean sites with implants form 1994-1999, systemic com­plications were the most common adverse events duringthe first month, and were associated with advanced age,impaired cardiac status, and poor general medical con­dition (3). Failure to complete the procedure occurredin 39 patients, device or procedure related complicationsin 149 patients, and arterial complications in 51 patients.

eed for adjuvant surgical procedures was a significantrisk factor for death and failure to complete procedure.2.6% died within 30 days. EndoJeaks were present in

16% at completion of procedure, and in 9% at 1 month.Management of endoleaks is discussed in a separate

presentation. Briefly, rates of late surgical conversioncaused by persistent endoleaks are low, but may in­crease as follow-up durations increase. In a retrospectiveworldwide review of 669 patients undergoing EVf (nowGuidant) repair between 1993-1997, 3% underwent im­mediate open conversion, and 4% required explantationlater, from 1-40 months (9). Of the 27 late conversions,20 were caused by persistent endoleaks, three werecaused by aneUlysm rupture, three caused by graft oc­clusion, one was caused by graft migration, and one wascaused by aortic dissection.

The results of a prospective, nonrandomized, multi­center trial of the AneuRx device (Medtronic) withshorter follow-ups than the above study, were reportedby Zarins et al (0). 190 patients with stent-grafts werecompared to 60 undergeing open surgeI)'. All patientswere operative candidates. There were no significantdifferences in operative mortality rdtes or combinedmorbidity/mortality rates, although morbidity was lowerfor stent-grafts (12% vs 23%, P < .05). Periproceduralendoleak rate was 21%, but was 9% at 1 month. Primarypatency at 6 months was 97% for stent-grafts and 98% forsurgeI)'. Stent-grafts migrated in three patients resultingin endoleaks, repaired with extender cuffs. There wereno conversions or aneuI)'sm ruptures, during the 1 yearfollow-up.

Conversion rates increase as follow-up increases, andthe results at this time can still be viewed as preliminaI)'for endografts in general.

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The FutureAs always, the future is uncertain, but great efforts arebeing made in certain directions. The driving forcestoward utilization are so strong, and potential profits formanufacturers so great, that considerable progress isinevitable. Introducer profile will hopefully continue todecrease, permitting percutaneous approach someday.Devices that can be placed across major vessels andmaintain patency are already under investigation, andcould potentially broaden the anatomic inclusion criteriaconsiderably (11). Improved ability to resist distonion,kinking, or torsion over time is developing. A mecha­nism for dealing with continued aortic neck expansion isneeded. Improved device designs may potentially re­duce type I endoleaks, but type II endoleak preventionand treatment remains an important area of research.

References1. Hallet JW. Management of abdominal aortic aneu­

rysms. Mayo Clin Proc 2000;75:395-9.

2. Ohki T, Veith FJ. Patient selection for endovascularrepair of abdominal aortic aneurysms: changing thethreshold for intelV"ention. Semin Vasc Surg 1999;12:

226-34.

3. Abou-Zamzam AJ, Porter J. Does endovascular graft­ing represent a giant step forward? Semin Vasc Surg1999;210:361-365.

4. Ohki T, Veith F, Sanchez L, et al. Endovascular graftrepair of ruptured aortoiliac aneurysms. J Am ColiSurg 1999;13:328-9.

5. Semba C, Sakai T, Sionim S, et al. Mycotic aneurysmsof the thoracic aOlta: repair with use of endovascularstent-grafts.]VIR 1998;9:33--40.

6. Edwards WH and Naslund TC. Bifurcated devices inthe treatment of abdominal aortic aneurysms: limi­tations and advantages of a single-component bifur­cated prosthesis. Semin Vasc Surg 1999;12:165-9.

7. May J, White GH, YU W, et al. Endovascular graftingfor abdominal aortic aneurysms: changing incidenceand indication for conversion to open operation.Carcliovasc Surg 1998;6:194-7.

8. Thompson J, Boyle J, Thompsonlvl, et al. Card~ovas­

cular and catecholamine responses during endovas­cular and conventional abdominal aortic aneurysmrepair. Eur J Vasc Endovasc Surg 1999;17:326-333.

9. Jacobowitz GR, Lee AM, Riles TS. Immediate and lateexplantation of endovascular aortic grafts: the endo­vascular technologies experience, J Vasc Surg 1999;29:309-16.

10. Zarins CK, White RA, Schwalten D, et al. AneuRxstent graft versus open sugical repair of abdoinalaortic aneurysms; multicenter prospective clinicaltrial. J Vasc Surg 1999;29:292,

11. Iwase T, Inoue K, Sato M, et al. Transluminal repairof an infrarenal aortiiliac aneurysm by a comnination

of bifurcated and branched stent grafts, Cathtet Car­diovasc lntelvent 1999;47:491-4.

12. Sternbergh WC, Money SR. Hospital cost of endo­vascular versus open repair of abdominal aortic an­eurysms: a multicenter sUldy, J Vasc Surg 2000;31:

237-44.

13, BluthJ, LaheifRJ, Early complications and endoleaksafter endovascular abdominal aortic aneurysm re­pair: report of a multicenter study, J Vasc Surg 2000;

31:134-46,

14, ChuteI' TA, ReiJly LM, Faruqi RM, et al. Endovascularaneurysm repair in high-risk patients. J Vasc Surg2000;31: 122-33.

15, MatsumuraJS, Pearce WH. Early coinical results andstudies of aortic aneurysm morphology after endo­vascular repair. Sllfg Clin N Am 1999;79:529-40.

10:20 a.m.

Conflicts of Interest in Clinical TrialsFeatured Speaker: J1!Iarcia E. Angell, MD

Cambridge, Massachusetts

There is growing concern about the financial conflicts ofinterest that abound among clinical investigators andacademic medical centers. Before discussing the issue, Iwill define a financial conflict of interest, because thereis often some confusion on that score. Afinancial conflictof interest is any financial association that would causean investigator to prefer one research outcome to an­other. For example, if an. investigator is comparing de­vice A with device B and owns a large amount of stockin the company that makes device A, he or she willnaturally prefer to find that device A is better than deviceB. That is a conflict of interest.

Note that a conflict of interest is a function of thesituation, not of the investigator's response to that situ­ation. Thus, if our hypothetical investigator finds thatdevice B is better than device A, despite hopes to the

contrary, he or she may swallow the disappointment andrepoft the facts objectively-or not. According to thisdefinition, there is nothing "potential" about a conflict ofinterest. Either it exists or it doesn't. What is potential isthat the conflict will lead to biased work.

Note also that financial conflicts of interest are notinherent to the research enterprise, They're entirely op­tional, unlike the intellectual conflicts of interest towhich they're often compared-such as the desire fordramatic results or to see a favorite hypothesis con­firmed. The latter cannot be eliminated.

At one time, financial associations with private indus­try were largely confined to drug or device companiesawarding grants to academic institutions for research inareas of interest to both of them. In the best institutions,this was done at arm's length. The companies had nopart in designing or analyzing the studies, they did notown the data, and they certainly did not write the papers

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