Peripheral
`Interventions
`
`Frank J. Criado, MD
`Eric P. Wilson, MD
`Eric Wellons, MD
`Omran Abul-Khoudoud, MD
`Hari Gnanasekeram, MD
`
`Section editor:
`Zvonimir Krajcer, MD
`
`Presented at the Texas
`Heart® Institute’s
`symposium on Peripheral
`Interventions for the
`Cardiovascular Specialist,
`held on 4-5 November 1999,
`at the Marriott Medical
`Center Hotel, Houston,
`Texas
`
`Key words: Aortic aneu-
`rysm, abdominal; blood
`vessel prosthesis
`implantation; catheter-
`ization/methods; clinical
`trials, phase II; iliac
`aneurysm; prosthesis
`design; stents
`
`From: Center for Vascular
`Intervention, Division of
`Vascular Surgery, The Union
`Memorial Hospital/MedStar
`Health, Baltimore, Maryland
`
`Address for reprints:
`Frank J. Criado, MD,
`3333 North Calvert Street,
`Suite 570, Baltimore, MD
`21218
`
`© 2000 by the Texas Heart ®
`Institute, Houston
`
`Early Experience
`with the Talent™
`Stent-Graft System
`for Endoluminal Repair of Abdominal Aortic Aneurysms
`
`E
`
`ndoluminal grafting for treatment of aortic aneurysms is the most exciting
`topic in vascular surgery today. It is anticipated that at least half of all aneu-
`rysms in the infrarenal abdominal and descending thoracic aorta will be re-
`paired endovascularly in the near future.
`Endovascular grafting procedures require a combination of surgical maneuvers
`and refined interventional skills. They are often difficult, and involve catheter tech-
`niques and imaging requirements that are not readily available in most vascular sur-
`gery practices today. Collaboration between surgeons and interventionists is often
`necessary and, occasionally, is mandated by the investigational protocol.
`The most significant technological achievement to date has been the develop-
`ment of the modular, fully supported, bifurcated stent-graft (Fig. 1).1,2 This device
`incorporates 2 features that are currently viewed as critical components of endovas-
`cular graft technology: 1) modular design—which joins 2 or more sections of the
`stent-graft within the aorto-iliac lumen—optimizes deployment and exclusion by
`enabling the addition of extensions both cephalad and caudad; and 2) full-length
`support achieves the columnar strength that is necessary for stability and integrity,
`preserving normal channel flow even when placed across tortuous vessels. Another
`design feature that has recently become the focus of attention is suprarenal fixation
`of the uncovered stent at its proximal end, which enables secure attachment to a
`segment of the aorta less prone to progressive dilatation.3
`In September 1999, 2 stent-graft devices for the exclusion of abdominal aortic
`aneurysms received approval from the Food and Drug Administration: the Ancure®
`device (Guidant; Indianapolis, Ind) (Fig. 2), which is an early-design balloon-
`expandable, 1-piece bifurcated stent-graft; and the AneuRx ™ device (Medtronic
`AVE; Santa Rosa, Calif), a self-expanding, modular-design, fully supported bifur-
`cated stent-graft. Additionally, several other stent-grafts are now under clinical inves-
`tigation, including the Vanguard™ (Boston Scientific Corp; Natick, Mass) (Fig. 3),
`Talent™ (World Medical, a division of Medtronic Vascular; Sunrise, Fla), Bifurcated
`EXCLUDER Endoprosthesis (W.L. Gore & Associates; Sunnyvale, Calif) (Fig. 4), and
`Zenith™ (Cook Inc.; Bloomington, Ind) (Fig. 5). They are all self-expanding, mod-
`ular-design endoluminal grafts, made of nitinol or stainless steel stents covered by a
`Dacron or polytetrafluoroethylene (PTFE) fabric. A somewhat different design is
`being developed by Cordis Endovascular (Cordis Corporation, a Johnson & John-
`son company; Warren, NJ): this is a bilateral, aortoiliac endoluminal graft configu-
`ration that may be deployed percutaneously, given its low-profile (13 F) delivery
`system. A clinical trial is set to begin in mid-2000.
`Endoluminal repair of aneurysms in the descending thoracic aorta is another area
`under active investigation at this time.4 Designers of the Talent™, AneuRx™, and
`EXCLUDER devices have developed endoluminal grafts configured for placement in
`the thoracic aorta (distal to the aortic arch branches). Some forms of aortic dissec-
`tion5 and traumatic rupture are also being managed with endovascular approaches,
`but available information is only preliminary at this time; a much larger clinical ex-
`perience with longer follow-up will be necessary before a definitive view can be
`attained concerning the performance of these endoluminal grafts for treatment of
`aneurysmal and nonaneurysmal thoracic aortic diseases. It is our impression today
`that stent-graft repair of descending thoracic aortic aneurysms will rapidly become a
`
`128
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`
`Volume 27, Number 2, 2000
`
`MEDTRONIC 1040
`
`

`

`popular approach, given the extensive nature of con-
`ventional surgical treatment and the severe morbidi-
`ty associated with it.
`The Talent ™ AAA
`Stent-Graft System
`The Talent™ stent-graft is a modular, self-expanding
`prosthesis (Fig. 6) designed for endoluminal exclu-
`sion of aortic aneurysms. It consists of a series of ser-
`pentine nitinol stents embedded into woven Dacron
`fabric. The stents are spaced discontinuously along a
`full-length nitinol spine. The delivery system is a co-
`axial sheath with pusher rod and a compliant poly-
`urethane balloon used to maximize attachment to the
`vascular wall and ensure full expansion throughout
`the length of the device. The outer diameter of the
`delivery system (containing the main section) ranges
`from 22 to 25 F (Table I). The more recently devel-
`oped thinner Dacron fabric (Talent Low Profile Sys-
`tem, or LPS™) has significantly reduced the outer
`diameter (Table II). For most AAA patients today, a
`22-F system is used.
`Salient features of the Talent device include the
`proximal bare spring (uncovered nitinol stent) (Fig.
`7) and custom-manufacturing to fit a wide range of
`aorto-iliac sizes and configurations, as determined
`preoperatively by computed-tomographic (CT) im-
`aging and angiography (Table III).
`
`Device Implantation Techniques
`The methods and technical principles described here
`are drawn from the senior author’s (FJC’s) personal
`experience with over 120 implants. Naturally, the
`opinion and advice of many investigators worldwide
`(who together have performed over 5,000 implants)
`and of Medtronic’s engineering and technical team
`have had significant influence in the conception of
`these approaches.
`The intervention often commences with percuta-
`neous catheterization of the left brachial artery and
`placement of a 5-F sheath, as it has been found to be
`of great help during several steps of the implantation
`procedure (Table IV). After the guidewire has been
`steered along the correct pathway, the pigtail catheter
`is introduced and then “parked” in the proximal ab-
`dominal aorta, at the level of T12. Our own enthusi-
`asm notwithstanding, most investigators prefer to use
`the brachial artery approach selectively, perhaps in
`less than 10% of procedures.
`Systemic anticoagulation is induced with heparin,
`given intravenously in amounts adequate to prolong
`activated clotting time (ACT) to 300 to 400 seconds.
`The ACT is monitored and is maintained at this level
`throughout the implantation procedure by adminis-
`tering additional heparin as needed every 15 to 20
`minutes.
`
`Fig. 1 Modular, bifurcated, fully supported stent-graft.
`
`Fig. 2 Ancure® stent-graft device.
`
`Texas Heart Institute Journal
`
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`
`

`

`Fig. 4 Bifurcated EXCLUDER Endoprosthesis.
`
`Fig. 3 Vanguard ™ stent-graft device.
`
`Bilateral vertical groin incisions are made to surgi-
`cally expose the full length of the common femoral
`artery (CFA) from the inguinal ligament to the femo-
`ral bifurcation.
`An Amplatz Super Stiff ™ (Boston Scientific) or
`Lunderquist (Cook) 0.035-inch guidewire, 260 cm in
`length, is inserted transfemorally by the exchange
`
`Fig. 5 Zenith™ stent-graft device.
`
`130
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`Volume 27, Number 2, 2000
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`

`

`Table I. Talent™ AAA Stent-Graft System (Standard
`Graft Material)
`
`Aortic Graft Size
`
`Delivery System Size
`
`Bifurcated Grafts
`
`20 mm
`22 to 30 mm
`32 to 36 mm
`
`20 F
`24 F
`25 F
`
`Table II. Talent LPS™ (Low Profile System)
`
`Aortic Graft Size
`
`Delivery System Size
`
`Bifurcated Grafts
`
`Tube Grafts
`
`20 mm
`22 to 30 mm
`32 to 36 mm
`
`8 to 20 mm
`22 to 28 mm
`30 to 36 mm
`38 to 46 mm
`
`20 F
`22 F
`24 F
`
`18 F
`20 F
`22 F
`24 F
`
`Table III. Talent™ AAA Stent-Graft System:
`Sizes and Configurations
`
`Main Section (usable on 14- to 34-mm aortas)
`Proximal neck diameter
`Length
`
`16 to 36 mm
`5 to 12 cm
`
`Iliac Extensions (usable on 8- to 18-mm vessels)
`Diameter
`Length
`
`8 to 20 mm
`5 to 12 cm
`
`The delivery sheath (containing the main body
`and ipsilateral limb of the endoluminal graft) is in-
`troduced over the Super Stiff wire and advanced care-
`fully across the iliac artery into the aorta under
`fluoroscopic monitoring and guidance. We defer
`angiography until after the device has been intro-
`duced to the aorta, so that a single contrast injection
`will likely suffice for both anatomic definition and
`road-mapping. A push-pull wire technique ensures
`proper tension and facilitates transluminal tracking
`of the sheath; loss of wire access or excessive intra-
`luminal advancement into the right side of the heart
`are avoided by the precautions described above. Very
`tortuous (but soft) iliac arteries can be appropriately
`straightened with brachial-femoral (“body floss”) ac-
`cess, for which we prefer to use a 450-cm Glidewire®
`(Boston Scientific). When applying tension, we
`always protect the aortic arch and the left subclavian
`artery with a 5-F catheter over the wire (Fig. 9).
`The sheath is advanced retrograde to the level of
`L1, and a power-injector angiogram is obtained via
`the brachial catheter. The image intensifier is cen-
`tered on L1-L2 in order to center the fluoroscopic
`
`Fig. 6 Talent™ stent-graft device.
`
`technique. The guidewire is advanced to the top of
`the aortic arch, where it is maintained until deploy-
`ment has been completed. To prevent inadvertent
`advancement into the supra-aortic vessels or heart
`chambers, it is useful to have visual control of the
`wire’s position at all times by relating it to an external
`reference point on the table (Fig. 8).
`In preparation for introducing the sheath, a trans-
`verse arteriotomy is made at the site of the puncture.
`If the femoral arteries are thick-walled and diseased,
`longitudinal arteriotomy and subsequent patch re-
`pair may be more appropriate.
`
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`
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`

`Table IV. Uses of Brachial Artery Catheterization
`
`Pre-deployment aortography
`“Puff angio” to aid juxtarenal placement
`Antegrade wire crossing of contralateral leg
`Brachial-femoral access
`Completion aortography
`
`spring and 1st cloth-covered stent (corresponding to
`the 2 uppermost metal segments on fluoroscopy) are
`allowed to self-expand, the entire assembly is gently
`brought down to the juxtarenal position. “Ideal”
`placement consists of transrenal fixation of the bare
`spring, with the top end of the Dacron fabric 2- to 3-
`mm below the origin of the renal arteries. The fluo-
`roscopic road-mapping technique is adequate to
`determine the proper proximal attachment level; if
`desired, a long 20g spinal needle can be inserted
`through the skin of the upper abdomen to mark the
`position of the renal arteries. When in doubt about
`possible coverage of 1 or both renal artery ostia by
`the Dacron fabric, a “puff angiogram” (through the
`brachial catheter) can easily and quickly provide clues
`in regard to whether the device should be pulled
`down to a lower level. Transrenal fixation may not be
`necessary when a long proximal neck is present.
`Once a satisfactory proximal level of attachment
`(“landing”) has been achieved, the outer sheath is
`retracted fully to allow expansion of the rest of the
`device. Next, the balloon is inflated sequentially, all
`along the length of the body and the ipsilateral limb,
`to ensure proper expansion and embedding. Blood
`pressure control is not necessary during deployment
`of a self-expanding stent-graft.
`Following removal of the delivery system, a long 9-
`F sheath with a radiopaque tip is placed (over the
`wire) through the arteriotomy to obtain a (limited)
`reflux angiogram that visualizes the adequacy of seal
`and the level of placement of the iliac limb. If these
`are satisfactory, the guidewire is removed, and the
`arteriotomy is repaired with interrupted sutures to
`quickly reestablish blood flow to the lower extremity.
`Inadequacies in the iliac-limb landing may be cor-
`rected by further balloon dilation, or by the addition
`of an iliac extension graft.
`Access across the short leg is easily and quickly
`achieved from the top by passing a 300- to 450-cm
`long, 0.035-inch guidewire through the left brachial
`catheter. The wire is advanced antegrade into the an-
`eurysm and out the iliac artery, down to the exposed
`common femoral artery. It can be extracted directly
`through the arteriotomy, or captured intraluminally
`with a goose-neck snare. Alternative access techniques
`can be used. Most investigators prefer the retrograde
`or contralateral (“over the top”) approach for this ma-
`
`Fig. 7 Note the bare spring (uncovered nitinol stent ) at the
`top end of the Talent™ stent-graft.
`
`field on the juxtarenal aortic segment and thereby
`minimize parallax.
`Deployment of the device is effected by gradually
`withdrawing the outer sheath as the pusher rod is
`held frozen in place. We strongly recommend that de-
`ployment begin above the renal arteries. Once the bare
`
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`

`neuver. Recently, the latter has become the authors’
`preferred approach.
`A catheter (or long sheath) is used to exchange the
`brachial-femoral access wire for an Amplatz Super
`Stiff guidewire to deliver and deploy the contralater-
`al limb; or, as we prefer, the contralateral limb can
`be introduced over the brachial-femoral wire. A 300-
`cm or longer guidewire is required for the latter. A
`limited retrograde hand-injection angiogram is per-
`formed (in the same manner as described above) to
`verify iliac attachment.
`A final antegrade aortogram is obtained to ascertain
`that a satisfactory technical result has been achieved
`(without endoleak) and to document intact renal ar-
`tery flow. The femoral arteriotomy is then repaired
`and lower-extremity circulation is re-established.
`Femoral incisions are closed in routine manner
`after reversal of the heparin effect with protamine
`sulfate. The left brachial sheath is removed when the
`ACT is less than 180 seconds, and hemostasis is ob-
`tained by manual compression of the artery against
`the humerus for 20 minutes.
`Problem Solving. Problem prevention comes 1st
`and is achieved mainly through precise preoperative
`evaluation that yields accurate measurements and
`leads to proper planning. Both CT imaging and con-
`trast biplane angiography are used for this purpose.
`We feel strongly about the desirability of obtaining
`diagnostic aortography (in addition to CT imaging)
`whenever possible. Diameter oversizing (4-mm top
`end, 2-mm distal ends) and modularity are the best
`friends of the AAA interventionist. The follow-
`ing guidelines are critical: “diameter oversize” at the
`proximal (mainly) and distal attachment sites; and
`“length undersize” whenever in doubt (modular
`grafts can always be extended).
`Iliac artery tortuosity is a common cause of techni-
`cal failure during endoluminal repair of AAA. In the
`absence of severe calcific disease, straightening the
`access vessel is possible and quite effective. Use of a
`Super Stiff wire is thought to be mandatory in every
`case.
`Problems posed by the aneurysm’s neck are most
`often the result of short length or of angulation.
`Aortic aneurysms with proximal necks as short as
`0.7 to 1.0 cm can be repaired with the Talent system
`through transrenal or suprarenal fixation as described,
`although this circumstance is less than ideal and car-
`ries a greater risk of failure. Diameter oversizing of
`4 to 6 mm at the top end is important to maximize
`sealing in such cases. Aggressive ballooning is another
`critical component of this procedure, especially when
`using grafts that are more than 15% oversized. Angu-
`lations of less than 60 degrees are manageable, but tilt-
`ing of the upper segment of the device can cause less
`predictable (less controllable) placement at the juxta-
`
`Fig. 8 “External control” of Super Stiff ™ transfemoral
`guidewire.
`
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`
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`

`

`renal position (Fig. 10). A proximal cuff may need to
`be added; indeed such a cuff should always be avail-
`able when embarking upon any AAA implantation,
`no matter how straightforward the procedure may
`seem.
`Extension of the graft with distal landing at the
`external iliac artery is used to bypass a frankly an-
`eurysmal or very large common iliac artery. In such
`instances, it is advisable to occlude the ipsilateral in-
`ternal iliac artery to avoid subsequent reflux and
`endoleak. Percutaneous coil embolization is most
`conveniently done as a preliminary outpatient proce-
`dure a few days before exclusion of the aneurysm. On
`occasion, bilateral internal iliac artery occlusion
`becomes necessary: we feel strongly that this should
`be done as 2 separate, staged interventions prior to
`repair of the AAA. We have not thus far seen any
`ischemic complication from internal iliac artery
`occlusion, either unilateral or bilateral, and only a
`handful of patients have developed severe buttock
`claudication. However, it must be emphasized that
`the decision to occlude the internal iliac artery
`should be judicious and dictated by a conservative
`attitude towards preservation of hypogastric flow.
`On occasion, aorto-uni-iliac endoluminal grafting
`is the best technical approach. This implies the need
`both for exclusion of the contralateral common iliac
`artery and for a crossover femoro-femoral bypass to
`
`Fig. 10 A short, angulated neck can tilt the device and cause a
`proximal endoleak at the time of deployment.
`
`revascularize the contralateral lower extremity. This
`situation is likely to require use of an iliac conduit for
`access and device deployment (Fig. 11A). The syn-
`thetic conduit thus becomes: 1) the site of distal land-
`ing of the endoluminal graft’s iliac limb; and 2) the
`source of inflow for the crossover bypass (Fig. 11B).
`Additionally, a similar (but temporary) femoral side-
`graft constitutes a good access option for those occa-
`sional patients who present with heavily scarred groins
`wherein it is difficult to obtain a segment of femoral
`artery that is long enough for proper control during
`deployment.
`As we have said above, “aggressive ballooning” is felt
`to be an important part of the Talent AAA procedure.
`However, caution must be exercised to avoid danger-
`ous over-dilation at the iliac artery level, especially
`when the compliant balloon is inflated partly inside
`the native iliac artery (outside the graft).
`
`A
`
`B
`
`Fig. 9 Tortuous iliac artery (A) can be straightened by tensing
`a brachial-femoral guidewire (B).
`
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`

`A
`
`B
`
`achieved before endovascular grafting becomes stan-
`dard treatment of aneurysms for the majority of pa-
`tients.
`
`Table V. Aortic Stent-Grafts:
`Requirements for Technical Success
`
`Deliverable to target area
`Secure fixation to vessel wall
`Blood-tight seal at all junctions
`
`Table VI. Aortic Stent-Grafts: Optimal Clinical
`Performance (Proposed Goals)
`
`Applicability
`Technical success
`Procedure time
`Blood loss
`Endoleak rate
`30-day mortality
`Length of stay
`Overall costs
`
`>50%
`>90%
`<3 hours
`<500 mL
`<10%
`<3%
`<3 days
`<surgical Rx
`
`References
`
`1. Donayre CE. Intraluminal grafts: current status and future
`perspectives. In: White RA, Fogarty TJ, editors. Peripheral
`endovascular interventions. St. Louis: Mosby-Yearbook,
`1996:364-405.
`2. Criado FJ, editor. Endovascular intervention: basic con-
`cepts and techniques. Armonk, NY: Futura Publishing Co.,
`1999.
`3. Criado FJ, Abul-Khoudoud O, Wellons E, et al. Treatment
`of abdominal aortic aneurysms with the Talent stent-graft
`system: techniques and problem solving. In: Katzen BT
`and Semba CP, editors. Techniques in vascular and inter-
`ventional radiology. Philadelphia: WB Saunders, 1999:
`133-44.
`4. Mitchell RS, Dake MD, Semba CP, Fogarty TJ, Zarins
`CK, Liddell RP, et al. Endovascular stent-graft repair of
`thoracic aortic aneurysms. J Thorac Cardiovasc Surg 1996;
`111:1054-62.
`5. Nienaber CA, Fattori R, Lund G, Dieckmann C, Wolf W,
`von Kodolitsch Y, et al. Nonsurgical reconstruction of tho-
`racic aortic dissection by stent-graft placement. N Engl J
`Med 1999;340:1539-1545.
`
`Fig. 11 A, B Artist’s depiction of iliac conduit technique for
`aneurysm exclusion with aorto-uni-iliac stent-graft system.
`
`Early Results with the Talent™ AAA Device
`The Talent stent-graft system for treatment of AAA
`is an investigational device under an Investigational
`Device Exemption (IDE) protocol approved by the
`Food and Drug Administration for use in the United
`States. Patient enrollment is complete for several
`Phase II studies on both high-risk and low-risk
`cohorts. Information on overall technical and clinical
`results is not yet available. Our own experience at
`Union Memorial Hospital/MedStar Health in Balti-
`more now extends to over 120 patients (as of 31 Oc-
`tober 1999). Early technical results and acute clinical
`outcome can be summarized as follows:
`
`• Talent endoluminal graft applicable in nearly 70%
`of screened AAA patients
`• Overall technical success: 94%
`• 30-day mortality: 2.5%
`• Acute surgical conversion: <1%
`• Average length of hospital stay: 3.5 days
`• Use of ICU: 10%
`• Unable to deliver device during attempted
`implant: 5%
`• Endoleaks
`At procedure or on initial CT scan: 15%
`On 30-day CT scan: 8%
`
`Overview and Conclusions
`
`Endovascular grafting of aortic aneurysms is clearly
`feasible and capable of achieving a high degree of
`technical success. The question of whether it can
`justifiably replace surgical treatment will not be an-
`swerable for several more years, when the results of on-
`going trials and long-term follow-up data become
`available. The essential requirements of a successful
`stent-graft device have been defined (Table V). Opti-
`mal clinical performance (Table VI) will have to be
`
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`Experience with Talent™ Stent-Graft System 135
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`