Long-Term Outcome After Aortic Endovascular Repair:The Sydney Experience

By James May

Background: Since the inception of endovascular aortic aneurysm repair there has been concern about

the unknown long-term outcome following this method of repair. Aim: The purpose of this study is

to present the outcome of patients with abdominal aortic aneurysms (AAAs) who were treated by

endovascular repair between 5 and 11 years ago. Methods: Between May 1992 and November 1997,

190 patients (175 males 15 females, mean age 72 years) were treated at the Royal Prince Alfred

Hospital. Overall, 1 of 3 patients were considered to have comorbidities that precluded open repair.

Endoprostheses used were first generation in two thirds of patients and second generation in one

third of patients. Results: Eight patients (4.2%) died in the perioperative period. Endovascular repair

failed in 20 patients (10.5%) who required conversion to open repair. Secondary conversion at a

subsequent operation was necessary in 25 patients with rupture (n � 10), persistent endoleak (n �11), endotension (n � 2), and inadvertent covering of the renal arteries by their prostheses (n � 2).

Eight of the 20 patients presenting with rupture survived conversion to open repair. A long-term study

of morphological changes in the proximal neck after endovascular AAA repair revealed a high

probability (0.943 at 7 years) of no enlargement. Patients alive with successfully excluded AAA for 5–6,

6–7, 7–8, 8–9 year intervals of time, number 51, 36, 25, and 15, respectively. Conclusion: Considering

that one third of patients were unfit for open repair and two thirds were treated with first generation

prostheses, these results support the continued use of the endovascular method to treat AAA.

© 2003 Elsevier Inc. All rights reserved.

THE AUTHOR HAS BEEN asked to write thisarticle on the basis of early experience. The

first endovascular repair of an abdominal aorticaneurysm (AAA) was performed in Buenos Airesin July 1990, and the first AAA repair in Sydneywas performed in May 1992. The revised versionof Standardized Reporting Practices for Endovas-cular AAA1 repair defines long term as proceduresthat were performed 5 or more years previously.The experience of endovascular AAA repair at theauthor’s institution before November 1977 is pre-sented.

HISTORICAL PERSPECTIVE

Endovascular treatment of patients with aorticaneurysm is not a new concept. As early as 1864,Moore is credited by Keen2 with the introductionof large masses of intraluminal wire into an aneu-rysm in an attempt to precipitate thrombosis. Inpreantibiotic days, the majority of aneurysms weresyphilitic in origin and saccular in morphology(Fig 1), which made them more amenable to treat-ment by wiring than the fusiform variety seentoday. Saccular, syphilitic aneurysms were ex-tremely painful and associated with a poorer prog-nosis than the current fusiform ones. Approxi-mately 90% of patients with syphilitic aneurysmsdied within one year from the onset of symptoms.3

This rather desperate scenario explains why sur-

geons were prepared to offer the procedure ofwiring of aneurysms and why patients were pre-pared to accept this unreliable form of treatment(Fig 2).

In 1879, Corradi modified the wiring process bypassing an electric current along an insulated wirein an attempt to induce thrombosis.2 In 1915, Colt,while working as a house surgeon in London,developed a self-expanding wire umbrella thatcould be introduced via a trocar into an aneurysm(Fig 3).4 The loading capsule and delivery systemhad many similarities with current endovascularsystems. Blakemore and King5 revived the use ofwiring in 1938. Electrothermic coagulation of aor-tic aneurysm by wiring was used until 1953 whengraft replacement of aneurysms was introduced.

The relatively high morbidity and mortality ratesfor graft replacement of aortic aneurysms, partic-ularly in high-risk patients, maintained the interestof researchers in developing an endovascular

From the Department of Surgery, University of Sydney,Australia.

Address reprint requests to James May, MD, MS, FRACS,FACS, Department of Surgery, University of Sydney DO6, NewSouth Wales 2006, Australia.

© 2003 Elsevier Inc. All rights reserved.0895-7967/03/1602-0001$30.00/0doi:10.1016/S0895-7967(03)00005-X

123Seminars in Vascular Surgery, Vol 16, No 2 (June), 2003: pp 123-128

method of repair. Balko et al6 can probably becredited with the first reported experimental use ofa stent-graft combination for the treatment of anartificial aneurysm. In their experiments, a novelform of nitinol Z-stent was combined with a sleeveof polyurethane and tested in a sheep model ofaortic aneurysm. The first radiographically guidedaortic graft implantation in animals was reported in1987 by Lawrence et al,7 who used a chain ofstainless steel Gianturco Z-stents (Cook, Indianap-olis, IN) within a tube of woven polyester. The firstinvestigator to use a balloon expandable stent toanchor an intraluminal graft was Parodi.8-10 How-ever, not until 1991 did Parodi et al11 report thefirst clinical use in humans of transfemoral, endo-vascular grafting to exclude aortic aneurysms.Their concept was the use of balloon-expandable,vascular stents to replace sutures and secure theproximal and distal ends of a fabric graft within thelumen of the aorta.

METHODS

One hundred ninety patients underwent primary endovascu-lar repair of true AAA at the Royal Prince Alfred Hospitalbetween May 1992 and November 1997. There were 175 menand 15 women with a mean age of 72 years. Initially operationswere limited to those patients considered to be unfit for con-

ventional open repair. Overall one of 3 of patients were con-sidered to have comorbidities that precluded open repair.

Endovascular Protheses

Before September 1993, in the absence of commerciallyproduced prostheses, a modification of the prostheses reportedby Parodi11 (Fig 4) was constructed in the operating room andused clinically in patients with AAA. A graft attachment device(GAD) was also developed at Sydney University by White andYu12 during this time. Endovascular aneurysm repair withmaterials currently used in vascular surgery was approved bythe Institutional Review Board and informed consent obtainedfrom the patients. To overcome problems associated with thelarge balloon required with these balloon expandable devices,13

a technique involving a combination of endoluminal and ex-traluminal aortofemoral grafts was reported.14 First- and sec-ond-generation commercially produced prostheses were used asthey became available (Table 1).

The configuration of the prostheses was tube in 56 andnontube (bifurcated and taped aortoiliac) in 134. Criteria for theendovascular technique was a proximal neck of length 1.5 cm orgreater and iliac arteries allowing sheath access to the aorta.

RESULTS

Eight patients (4.2%) died in the perioperativeperiod. Seven of these 8 patients were at high riskand were considered unfit for conventional openrepair. The deaths in these 7 patients were relatedto the following procedures: cardiac death afteroperation for lower limb ischemic complications(n � 3), renal failure as a result of contrast load(n � 2), inadvertent covering of renal arteries (n �

Fig 1. Clinical characteristics of syphilitic and atheroscle-

rotic aneurysms. (Modified from Bahnson HT: Considerations

in the excision of aortic aneurysms. Ann Surg 138:377-382,

1953 with permission).

Fig 2. Postmortem specimen of abdominal aortic aneu-

rysm that had been treated previously by intravascular wire

to encourage thrombosis. By courtesy of Dr John Walsh.

124 JAMES MAY

1), and cardiac death after operation for balloonrupture of the aorta (n � 1). The one death thatoccurred in a patient at good risk was caused bysigmoid volvulus 3 weeks after endoluminal repair.

Endoluminal repair failed in 20 patients (10.5%)who required primary conversion to open repair atthe original operation. Secondary conversion toopen repair was necessary in 25 patients. Ten ofthese were urgent with ruptured AAA, whereas 11had persistent endoleak. Of the remaining 4 pa-

tients who required secondary conversion, 2 had anincreasing AAA diameter, but exhaustive and re-peated investigation failed to show an endoleak.Two had inadvertent covering of the renal arteriesby their prostheses. There were 2 deaths aftersecondary conversion, both in patients with rup-ture. Supplementary endoluminal repair was un-dertaken for persistent endoleak on 15 occasions in12 patients (secondary, n � 12; tertiary, n � 2; andquaternary, n � 1). Further intervention was nec-essary for lower limb ischemia in 24 patients. In 18patients, the ischemia was acute and occurred inthe perioperative period, and in 6 patients, it waschronic and resulted in claudication. Interventionalprocedures for acute and chronic ischemia are

Fig 3. Colt’s apparatus for wiring aneurysms (reprinted with permission4).

Fig 4. Modified Parodi endograft shows the components

(balloon, stent, and fabric) packaged in the delivery catheter.

Table 1. Prostheses Used for Endoluminal Aortic

Aneurysm Repair 1992-1997

Classification Prosthesis No.

First generationModified Parodi 10White-Yu 92Endovascular Technologies 17Chuter 1

Second generationStentor Vanguard 56Bard 5Talent 4Baxter 2AneuRx 3

Total 190

125ENDOVASCULAR AAA REPAIR: LONG-TERM OUTCOME

summarized in Table 2. Three patients had periph-eral emboli that were treated with heparin infusion.Hemodialysis after endoluminal repair was neces-sitated in 7 patients, including the 2 patients withinadvertent covering of the renal arteries. Thewound complications comprised lymph leak/lyn-phocele (n � 5), hematoma (n � 4), and infection(n � 3). The infections were staphylococcal andinvolved the subcutaneous tissue but not the un-derlying vessels. Of the 12 patients with woundcomplications, only one with persistent lymph leakrequired a secondary operation. Hospital stay wasprolonged beyond 10 days in 2 patients with infec-tion and lymph leak, respectively.

Long-Term Outcome

The number of patients at risk with a success-fully excluded AAA between 5 and 10 years fromimplantation is shown in Table 3.

Long-term Study of Morphologic Changes in theProximal Neck After Endovascular AAA Repair

A study was undertaken also to documentchanges in diameter of the proximal neck ofAAA in a group of 51 patients who had under-gone endoluminal repair between 5 and 9 yearspreviously.15 Morphologic changes in the prox-imal aortic neck were studied by contrast CTusing the methodology recommended by the Ad

Hoc Committee for Standardized ReportingPractices for Endovascular AAA repair (RevisedVersion).1

The maximum transverse diameter of theproximal neck was measured 1 cm below themost inferior renal artery. A Kaplan Meier anal-ysis was performed showing the proportion ofpatients at risk with a demonstrated enlargementof the neck at each interval of time comparedwith the predischarge computed tomographyscan. A longitudinal study of morphologicchanges in the proximal aortic neck was under-taken also in 28 patients with successful endolu-minal repair who survived 5 years. The KaplanMeier curve showed a probability of no dilationof the proximal neck of 0.943 at 7 years afterendoluminal AAA repair, at which time, 15patients were at risk.

Of 28 patients with a 5-year follow-up afterdischarge, only 2 had increases in the diameterof the proximal neck greater than 2 mm. Theendograft in both patients had undergone migra-tion before any proximal neck dilation (Fig 5).This led to a paradoxical situation in which theaneurysm diminished in size, because there wasno endoleak, and that portion of the proximal

Table 2. Procedures Performed in the Management of

Acute and Chronic Ischemia of the Lower Extremity After

Endoluminal Abdominal Aortic Aneurysm Repair

ProcedureAcute

Ischemia Claudication

Iliofemoral graft 5Femorofemoral graft 4 2Embolectomy 2Endovascular stent alone 2 3Endovascular stent plus

iliofemoral graft 1Endovascular stent plus

femorofemoral graft 1Endovascular stent plus

femoropopliteal graft 1

Table 3. Number of Patients Alive with Successfully

Excluded AAA for Each Interval of Time

Period from implantation (ys)

5-6 6-7 7-8 8-9 9-10

Patients at risk 51 36 25 16 3

Fig 5. Diagram shows sequence of events in one of the 2

similar patients in which the proximal neck enlarged after

endoluminal AAA repair. On the left, migration has left the

long proximal neck uncovered. Three years after operation

(right) the aneurysm sac has shrunk, and the uncovered seg-

ment of the proximal neck has dilated. The covered segment

of the proximal neck remains unchanged (reprinted with per-

mission15).

126 JAMES MAY

neck that was not protected by the endograftenlarged. A paired t test showed that the overallaverage increase of 0.4 mm (SE � 0.3 mm) inthese 28 patients was not statistically significant(P � .23) (Fig 6).

We concluded that there is a high probability(0.943 at 7 years) of no enlargement of theproximal neck of AAA after endoluminal repair.We hypothesize that endografts positioned cor-rectly directly below the renal arteries protectthe proximal neck from dilatation in a mannerthat does not occur after open repair of AAA.

DISCUSSION

One of the most striking features of the earlyexperience with endovascular AAA repair wasthe high incidence (10.5%) of primary conver-sion from endovascular to open repair. Thisresulted from the large diameter and compara-tive inflexibility of the delivery systems and thelearning curve associated with a new technique.

It is of interest also to note that 10 patientspresented with rupture after endovascular AAArepair. Eight of these had known type I en-doleaks at the proximal neck. The fact that thesepatients progressed to rupture was in part owing

to a prevailing overly optimistic view at the timethat type I endoleaks would seal spontaneouslyplus the unavailability of aortic cuffs to treatendoleaks at the proximal neck.

It is of interest also to note that 8 of the 10patients presenting with rupture survived con-version to open repair. The following hypothesismay explain this unexpected 80% survival rate.An endoleak allows systemic arterial pressure tobe communicated to the AAA sac as wouldoccur in an untreated aneurysm. The risk ofrupture, therefore, remains the same. When rup-ture occurs, the quantity and rate of blood loss islimited by the cross-sectional area of the en-doleak channel. In an untreated AAA, however,blood loss is limited only by the defect in theruptured sac. We conclude that endoluminalAAA repair complicated by endoleak does notprotect the patient from rupture. There does,however, appear to be a level of protectionafforded by failed endoluminal repair, whichdoes not prevent rupture but enhances survivalafter open operation for rupture, possibly byameliorating the hemodynamic changes associ-ated with the rupture process.

Considering that endovascular repair of AAA

Fig 6. Contrast-enhanced CT after endoluminal AAA repair before discharge (A) and 8 years later (B). The diameter of the

proximal neck remains unchanged (reprinted with permission15).

127ENDOVASCULAR AAA REPAIR: LONG-TERM OUTCOME

is predicated on stability of the proximal neck, it isreassuring to note that enlargement of this segmentof the aorta was rarely observed in long-termfollow-up in both Sydney and Buenos Aires.

ACKNOWLEDGMENT

The endovascular procedures reported were performed by theauthor and colleagues G. H. White, M. S. Stephen, and J. P.Harris, Department of Vascular Surgery.

REFERENCES

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2. Keen WW: Surgery: Its Principles and Practice. Philadel-phia, PA, Saunders, 1921, pp 216-349

3. Kampmeier RH: Saccular aneurysm of the thoracic aorta: Aclinical study of 633 cases. Ann Intern Med 12:624-651, 1938

4. Power D’A: The palliative treatment of aneurysms bywiring with Colt’s apparatus. Br J Surg 9:27, 1921

5. Blakemore AH, King BG: Electrothermic coagulation ofaortic aneurysms. JAMA 111:1821, 1938

6. Balko A, Piasecki GJ, Shah DM, et al: Transfemoralplacement of intraluminal polyurethane prosthesis for abdomi-nal aortic aneurysm. J Surg Res 40:305-309, 1986

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8. Parodi JC, Palmaz JC, Barone HD, et al: Tratemientoendoluminal de los aneurismas de aorta abdominal: Estudioexperimental. in, Capdevila JM (ed): Proceedings of II Conven-cion de Curujanos Vasculares de Habla Hispana. Buenos Aires,Argentina, 1990 pp 122

9. Palmaz JC, Parodi JC, Barone HD, et al: Transluminalbypass of experimental abdominal aortic aneurysm. Presentedat the seventy-sixth Scientific Assembly and Annual Meeting ofRSNA, 1990

10. Parodi JC, Palmaz JC, Barone HD, et al: Transluminalaneurysm bypass: Experimental observations and preliminaryclinical experiences. Presented at International Congress IV.Endovasc Therap Vasc Dis 1991

11. Parodi JC, Palmaz JC, Barone HD: Transfemoral intralu-minal graft implantation for abdominal aortic aneurysm. AnnVasc Surg 5:491-499, 1991

12. White GH, Yu W, May J, et al: A new non-stentedballoon expandable graft for straight or bifurcated endoluminalbypass. J Endovasc Surg 1:16-24, 1994

13. May J, White GH, Yu W, et al: Endoluminal grafting ofabdominal aortic aneurysms: Causes of failure and their pre-vention. J Endovasc Surg 1:44-52, 1994

14. May J, White GH, Yu W, et al: Treatment of complexabdominal aortic aneurysms by a combination of endoluminaland extraluminal aorto-bifemoral grafts. J Vasc Surg 19:924-933, 1994

15. May J, White GH, Ly CN, et al: Endoluminal repair ofabdominal aortic aneurysm prevents enlargement of the proxi-mal neck: A 9-year life table and 5-year longitudinal study. JVasc Surg 37:86-90, 2003

128 JAMES MAY