endovascular - sicve · of medtronic’s endovascular newsletter interesting and relevant. your...

Endovascular NewsletterNews & TechNologies augusT 2008

edition 2

104endovascular repair

complex aaa iliac anatomies

17Thoracic stent grafts

16New endo technologies

Medtronic Newsletter_desfin2.ind1 1 26/8/08 15:04:41

S E L E C T IONN AT U R A L

EndurantAAA Stent Graft System

LATIN NAME:

Rex Graft Stenti(Stent Graft King)

HABITAT:

Abdominal aortic oraorto-iliac aneurysms.Highly adaptable,bred to survive and succeedin challenging environments.Thrives in complicated situations.

ENDURANTAAA Stent Graft System

NATU RA L S E L E C T ION

©20

08M

edtr

onic

,Inc

.All

right

sre

serv

ed.

UC

2009

0063

0EE

UC200900630EEMed_endurant_ad3_aw_A0800.qxd:Layout 1 31/7/08 10:54 Page 1


W elcome to the second edition of Medtronic’s Endovascular Newsletter.

Over the past two decades, less invasive treatments for cardiovascular disease have begun outpacing the traditional surgical approaches. This trend has led to therapy innovations through collaboration across various cardiac and vascular specialties worldwide. Furthermore, the development of new treatments for cardiovascular disease has led many specialised physicians to seek additional training and acquire new skills.

In view of Medtronic’s long history of expertise in both cardiac surgery and vascular disciplines, Medtronic CardioVascular is well positioned to respond to this changing environment by enabling physicians to provide a broad range of therapy options to their patients. Our goal in the CardioVascular business is to better respond to the increasing demand for minimally invasive and catheter-based solutions for cardiovascular disorders, while continuing to serve our customers and patients who need traditional approaches to cardiac surgery and vascular care.

Medtronic’s Endovascular Innovations business is dedicated to innovation through collaboration. We envision a world in which all patients at risk of aortic or peripheral vascular disease receive proper education, detection and an endovascular treatment. Our employees are passionate about delivering innovative and quality products in a timely manner to the clinicians and patients who need them. We are partnering with health care systems around the world to increase screening and disease awareness, and are pursuing advanced technologies to expand patient applicability so that more patients can have access to endovascular aortic repair.

Experience remains the foundation of

our innovations in endovascular therapy. Our next generation Endurant abdominal and Valiant II thoracic stent graft systems, which have been designed for improved deliverability and conformability, represent our latest innovative contributions to this exciting field. Combined with the Talent stent graft systems, Medtronic will soon offer AAA and Valiant thoracic endovascular physicians in Europe new options for their EVAR procedures.

Continuing to focus on our solid aortic device pipeline and leveraging our strong foundational history, we will strive to maintain your trust in our market leadership over the next five years through our dedication and commitment to developing current markets, downsizing devices to reduce access issues, and pursuing advanced technologies. The clinical benefit of endovascular repair for clinicians and patients to treat aortic disease is compelling. Medtronic is dedicated to helping physicians hone their skills and to keeping them informed about new and emerging technologies. The education team is available for physicians to continue their development of interventional skills.

We hope you find this second edition of Medtronic’s Endovascular Newsletter interesting and relevant. Your feedback would be much appreciated. Email comments to the editor at [email protected].

Tony semedoVP and general Manager, Medtronic endovascular

Endovascular Access complex aaa iliac anatomies

aortic stent-graft implantation through percutaneous approach

case report: Facilitated iliac access for endovascular repair

Conformability

collapse issues

importance of device comfortability in the thoracic aorta

Technology / Product News

New endovascular technologies to reconstruct aortic arch in situ

Performance of thoracic stent grafts in high aortic-arch angulation

ud endurant aaa stent graft clinical trial update

improvement to minimally invasive treatment

ud endovascular education continuum

Cost Effectiveness health technology assessment of eVaR

Clinical Update endovascular treatment of aortic dissections – virtue registry

Start Notewelcome to the second endovascular Newsletter

�CoNTENTS

mANAgiNg EdiTor Kathi hall ArT dirECTor alan Paton dESigN dirECTor Matthew williams PiCTUrE EdiTor Nicola Duffy PiCTUrE rESEArChEr Miguel lamas ACCoUNT dirECTor Rob sawyer ProdUCTioN CoNTrollEr sara BearmanArTWorkEr Ricky Fox

PriNTEr chevalier

CovEr PhoTogrAPh: science Picture library

mEdTroNiC EdiToriAl boArd Jean-luc MontoulieuJulien BaissatNathalie Da eiraguilia stefanigreg MciffFiona Pattiselanno

uc200805114ee

Medtronic internationalRoute du Molliauch-11�1 TolochenazswitzerlandTel: +41 21 802 7000Fax: +41 21 802 7900

ENdovASCUlAr NEWSlETTEr is published by story worldwide, 15b st george’s Mews, london Nw1 8Xe Tel: 020 7449 1500

while every effort is made to ensure the accuracy of the information contained in endovascular Newsletter, no responsibility can be accepted for errors or omissions. information is correct at time of going to press.

For distribution only in markets in which Medtronic endovascular products have been approved. Not for distribution in the usa or Japan.

© Medtronic, inc. all rights reserved. Printed in the uK 08/08

Features

4

7

10

12

14

16

17

18

19

20

22

24

S E L E C T IONN AT U R A L

EndurantAAA Stent Graft System

LATIN NAME:

Rex Graft Stenti(Stent Graft King)

HABITAT:

Abdominal aortic oraorto-iliac aneurysms.Highly adaptable,bred to survive and succeedin challenging environments.Thrives in complicated situations.



©20

08M

edtr

onic

,Inc

.All

right

sre

serv

ed.

UC

2009

0063

0EE

UC200900630EEMed_endurant_ad3_aw_A0800.qxd:Layout 1 31/7/08 10:54 Page 1


4ENdovASCUlAr ACCESS

the utmost importance to perform pre-dilatation. Treatment requires a percutaneous transluminal angioplasty (PTA) to be performed, but stent placement must be avoided.

The treatment option for overcoming the problem of enlarged, elongated and kinked iliac vessels (figure 2a and 2b) necessitates working with specific guide wires, especially the super-stiff type such as the Back-up Meier guidewire1. Embolisation of potential branch vessels responsible for Type II endoleaks, an adequate prosthesis design and careful post-dilatation of the prosthesis (figure 3) will provide optimal stent graft patency in the iliac arteries.

The different treatment options available for these challenges are

Specific iliac anatomies can present a challenge when doctors are contemplating

undertaking a minimally invasive endovascular aneurysm repair (EVAR). But most such problems can be resolved by following the recommendations presented here.

Patients requiring abdominal aortic aneurysm (AAA) repair present with varying anatomies in terms of the iliac diameter, or ectasia of the pelvic arteries, and this can be challenging if they are being considered for an EVAR procedure, where anatomical details of the aorta play a critical part in the decision to go ahead. An ectatic common iliac artery, iliac stenosis, or elongated and kinked iliac vessels are particularly difficult to handle. But even in these cases, there are ways of achieving the overall goal of patent and durable limb fixation.

In the first instance, there needs to be a careful assessment of the potential problem before carrying out an EVAR procedure. For example, where it is the iliac diameter, or ectasia of the pelvic arteries that present difficulties, there must be a sufficient sealing zone of 15 mm or more of landing in the external iliac artery in order to proceed with EVAR.

If diagnostic imaging using computed tomography, magnetic resonance imaging or a diagnostic intra-arterial angiogram shows an iliac stenosis (figure 1), it is of

bY STEFAN mÜllEr-hÜlSbECk, mddepartment of diagnostic and interventional radiology/Neuroradiology, Academic hospitals, Flensburg, germany

dealing with complex AAA iliac anatomies

2A1

2b


indicates the likely outcome of endovascular AAA repair. The best results will be obtained in a very, very easy iliac anatomy, which means a sufficient iliac diameter with no occlusive disease, no iliac angles and with a sufficient landing zone. The higher the severity score, the more difficult and the more problematic the outcome might be in terms of iliac fixation, and there may well be post-repair problems later.

To avoid such post-repair problems, it is extremely important that the iliac fixation and the columnar strength should have the ability to prevent migration. It has also been pointed out that iliac fixation plays an important role in preventing migration5. The Talent AAA Stent Graft combines suprarenal and infrarenal fixation


shown in figure 4, using Talent AAA stent grafts.

However, as the results of the EVAR 1 and 2 trials show2, there is a risk of iliac complications, in particular the problem of graft thrombosis, which then necessitates secondary intervention3. This constitutes a real issue, especially if challenging iliac anatomy in terms of kinking, ectasia or stenosis has not been sufficiently recognised. What must be taken into account here is that, following repair, a challenging iliac anatomy might result in Type I, Type II or Type III endoleak, and possibly in graft stenosis leading to secondary intervention or potentially open conversion.

Medtronic’s TalentTM AAA Stent Graft with the Xcelerant® Delivery System may be an answer in some difficult cases. For example, figure 5A and 5B shows a patient suffering from mild infrarenal aneurysm and dilatated common iliac artery on both sides. It was not possible to perform a sufficient graft fixation in the left common iliac artery. Instead, the left internal iliac artery was embolised with coils to obtain a sufficient sealing zone in the external iliac artery on the left side and to rule out retrograde flow into the left common iliac artery from a Type II endoleak.

Physicians using the EVAR approach in challenging cases may find that some recent design changes are helpful. For instance,

it is of the utmost importance to use the best Nitinol (nickel-titanium) memory materials. Now, with the Talent prosthesis, the risk of corrosion and strut fracture has been reduced, as the Nitinol it contains is chemically treated (figure 6a). In addition, the connecting bars have been moved from the lateral to the medial position, so preventing the risk of kinking even in elongated or curved anatomy (figure 6b). This means that the improved conformability of the Talent™ Stent Graft should result in a decreased risk of kinking and thrombosis.

Limb fixation plays a role in preventing migration, through the anatomic factor severity score4.This severity score of 0, absent; 1, mild; 2, moderate; and 3, severe,

4

3

5b5A


and sealing with longitudinal columnar support and iliac fixation and seal. Secure iliac fixation minimises the risk of migration, even in the presence of suboptimal aortic neck anatomy. The iliac fixation must be extended to cover the entire common iliac artery to the iliac bifurcation, as this has been proved to prevent endograft migration.

In some cases, prophylactic treatment of limbs at risk of thrombosis is important also, by means of a bare metal stent, and doctors should not hesitate to use this additional procedural step. If a nosed or a kinked limb is found, this should be corrected immediately during the EVAR procedure.

In summary, iliac artery anatomy and disease is one of the most common limitations to EVAR. In challenging cases, the first set of recommendations is that for successful access and delivery of the device there must be least one external iliac artery of a diameter of up to 8 mm. The common iliac arteries should be free of aneurysmal dilatation or marked ectasia, which means a diameter of more than 20 mm. And there should be a landing zone of 15 mm or even more for distal endograft limb fixation.

The second set of recommendations concerns focal iliac stenoses. These are best managed by angioplasty at the time of stent-graft intervention. It may become necessary to place a self-expanding stent within the endograft at the site of narrowing, or even to use a balloon-expandable stent. Persistent stenosis of the limb from extrinsic compression or angulation must be treated aggressively in order to avoid limb thrombosis and the need for secondary procedures. Iliac/femoral angioplasty and stenting should not be performed ahead of time – in other words, before the stent-graft procedure – as the iliac/femoral stent might interfere with the transluminal tracking of the endograft delivery system. Back-up Meier wire should be used to straighten tortuous iliac/femoral access pathways.

In conclusion, it is important to realise that not every case is suitable for an EVAR procedure,

even with evolved technology. To achieve limb patency and durable fixation, the iliac anatomy must first be carefully evaluated. However, if an EVAR procedure is indicated and the decision to perform has been made, one must remain constantly mindful of the iliac anatomy. The limbs can be fixed either by additional stent graft or by additional PTA and, if necessary, by balloon-expandable or self-expanding stents.

Medtronic recommends referring to the IFU of its TalentTM AAA Stent Graft System with the Xcelerant® Hydro Delivery System for correct product use. The opinion and experience expressed by Stefan Müller-Hülsbeck are under his sole responsibility.

Produced under an educational grant from Medtronic CardioVascular.

�ENdovASCUlAr ACCESS

contact stefan Müller-hülsbeck, MD, Department of Diagnostic and interventional Radiology/Neurora-diology, academic hospitals Flensburg, of university hospital schleswig-holstein, Knuthstrasse 1, 249�9 Flensburg, germany

references

1. Boston scientific.

2. eVaR trial partici-pants. endovascular aneurysm repair versus open repair in patients with abdominal aortic aneurysm (eVaR trial 1): randomised controlled trial. lancet 2005; ��5: 2179-8�.

�. Bron lc et al. secondary interventions and mortality following endovascular aortic aneurysm repair: device-specific results from the uK eVaR trials. eur J Vasc surg 2007 sep;�4(�):281-290.

4. chaikof el et al. identifying and grading factors that modify the outcome of endovascular aortic aneurysm repair. J Vasc surg 2002 May;�5(5):10�1-10��.

5. heikinnen M et al. The importance of iliac fixation in the prevention of stent graft migration. J Vasc surg 200�;4 (�):11�0-11�7.

Figure �a: chemical treatment of nitinol – reduce corrosion and risk of fracture

Figure �b: connecting bar moved from lateral to medial position – improve conformability, decrease risk of kinking and thrombosis

Before after

Before after



Endovascular techniques that are used to treat aortic aneurysms have evolved since

the 1990s. Different types of devices have been used and we are, presently, at the third or even fourth generation of endoprostheses, both for the abdominal and thoracic aorta. The devices themselves have improved, as has the profile of their delivery system; however, reduction of French size of the delivery systems remains difficult.

Common complications of all endovascular techniques are those at vascular access with the appearance of haematoma and haemorrhages (requiring transfusions), arteriovenous fistulas, false aneurysms, or infections. Closure devices have been developed, not only to reduce the number of vascular access complications, but also to reduce the time necessary for compression of the puncture point (especially for patients under antiplatelet drugs or anticoagulant drugs for coronary procedures).

Devices with a collagen plug or sutures have long been marketed. More recently, systems using nitinol rings have been introduced. Most of these devices are suitable for access sites of 6 F to 8 F. The Prostar “XL 10”1 allows closing access sites of 8 F and 10 F with a fairly complex but ingenious system of four needles

puncturing the arterial wall, allowing for two polyester threads to be introduced and to make two sutures.

This system has been in use since 1999 for access sites above 10 F, and one study has already reported their efficacy with introducers of 24 F2. Several articles on this topic can be found in the published work.

The aim of this article is mainly

to describe our personal suggestions and tips and tricks of the percutaneous access whenever you use introducers above 18 F. We also include a short review of the published work and our personal experience.

Tips and tricksPercutaneous closure is becoming a key step in endovascular treatment. Unlike closure systems that are used for access sites of 6 F to 8 F, the access closure for 18 F introducers is undertaken in two steps. We first use the preclosure technique by inserting the closure device before the implantation of the stent graft.

We then tighten the knots and close the access site.

Arterial puncture must be done with all necessary care. The common femoral artery should be punctured on the femoral head. If necessary, fluoroscopy can help secure the puncture site. This technique can be especially useful with patients who are obese. The artery must not be transfixed and the punctured segment must not be uniformly calcified. The vascular access site should be assessed by ultrasound or better by a CT scan, which is now routinely done for any patient with aortic disease and for potential candidates for stent graft. Presence of an aneurysm or circumferential calcifications is considered relative and/or absolute contraindications for using this technique. However, presence of posterior calcification is not a contraindication. If a small aneurysm is present, the closure can be attempted with care, to avoid pulling too hard on the threads of the suture.

Once the puncture has been made, we advise starting with a 5 F introducer and then using an 8 F introducer. The puncture hole must be progressively predilated to reach 22–24 F. At 8 F, a first “Prostar XL 10”¹ is implanted while enlarging the subcutaneous tissues. Needles are removed once evidence of good

“Closure devices have been developed to reduce the number of vascular complications”

bY JEAN-PAUl bErEgi, md, Phd department of radiology and Cardiac and vascular imagery,

hôpital Cardiologique, ChrU de lille, France

Aortic stent-graft implantation through

percutaneous approach



thread placement is noted (ie blood flow inside the plastic tube).

introduction of a “Prostar Xl 10” closure deviceCheck if the four needles are visible at the time of withdrawal. The needles must not be pulled too much to keep the option of pushing them into the hub. In case of doubt and if the four needles are impossible to extract, the device should be replaced by a new one. The suture threads are inserted with the cross marker on the delivery system positioned towards the patient’s head. As soon as the threads are properly pulled, match them (one green and one white) making two short ends placed towards the patient’s head and two long ends towards the patient’s feet, gripping them with a clamp. These threads should be placed on the patient’s right side. Pulling of a needle –preparation of the needleA classic 0·035 guidewire is reintroduced for insertion of the second “Prostar XL 10”1 which is placed at 45° in relation to the first. The cross marker on the delivery system must be oriented either to the left or right in relation to the initial axis. Again, remove the needles and check whether the four needles are visible. Match them (one green and one white) making two short ends placed towards the patient’s head and two long ends towards the patient’s feet, gripping them with a clamp. These threads should be placed on the patient’s left side.

The next step is to insert a 10 F or 12 F introducer on the guidewire. We prefer to use a 12 F in case a dilatation balloon would be used during stent-graft placement.Introduce into the aorta a stiff Lunderquist3 or Back-up Meyer4

guidewire of 2·60 or 3 m protected by the pigtail. Remove the pigtail and the introducer. Continue the dilation with 16 F, 18 F, 20 F, 22 or 24 F, or even 26 F dilatators if necessary. Then introduce and deploy the stent graft.

Once the stent graft has been implanted, full attention is needed to complete the closure. You will need to tie the four knots without tangling them while pushing them down. The stent graft sheath is removed while leaving the guidewire in place. Blood flow and bleeding is left to wash any blood clots that might have formed in the iliac area. The access site is closed by pulling on the short strands that are positioned on the right and around which the knots have been made.

In most cases, two sutures are enough to close an access site of 24 or 26 F. If the access site is closed with the first two sutures, the guidewire is removed and the femoral access site is closed with the other two sutures. If bleeding persists, the last two sutures should be closed. Normally the bleeding stops, but a slight compression of 2-3 minutes can be necessary. The guidewire is then removed. If heavy bleeding occurs, insert another “Prostar XL 10”¹ system. Alternatively, bring down the previous “Prostar XL 10”¹ threads to achieve the haemostasis at the

puncture point5. Finally if the suture threads are pulled too hard, the arterial wall might rupture, requiring surgical conversion.

For a successful outcome, all the above-mentioned conditions have to be met and an attempt must be made to avoid surgical conversions as far as possible. Generally, two closure systems are used for 16 or 18 F. Two effective sutures are normally sufficient to close a 22–24 F size, but keeping a second system is advisable as a backup if a problem happens with a knot on the first system.

results from the published workIn 2006, Starnes6 and colleagues published a full retrospective review of the published work on percutaneous closure for a total of 728 accesses with a success rate of 90%. Starnes’ own success rate was 94% with an experience of 79 sites. The problems mentioned in this article and those arising during the use of this device are related to patients who are obese or the use of devices above 20 F. Obesity is certainly a problem in regards to the length of the device available to us. The device must be introduced and the subcutaneous tissues well dilated to reach the common femoral artery. The trick includes lifting the abdominal apron properly with elastoplasts.

Another article from Dosluoglu HH7 and colleagues reports 80% technical success for 17 patients treated for infrarenal abdominal aortic aneurysm. The last and most interesting article from Lee WA8 and

Figure 1 Figure 2



1. abbott laboratories.

2. endovascular suture versus cut down for endovascular aneurysm repair: a prospective randomized pilot study, Torsello et al. J Vasc surg. 200�;�8(1):78–82).

�. cook.

4. Boston scientific.

5. gore.

�. Totally percutaneous aortic aneurysm repair: experience and prudence. starnes et al. J Vasc surg. 200�;4�:270–�.

7. Total percutaneous endovascular repair of abdominal aortic aneurysms using Perclose Proglide closure devices. Dosluoglu hh et al. J endovasc Ther. 2007;14: 184–8.

8. Total percutaneous access for endovascular aortic aneurysm repair (“Preclose” technique). lee wa et al. J Vasc surg. 2007;45: 1095–10.

references

colleagues reports an experience with 279 femoral accesses of 12 to 24 F with an initial success of 94%. It also reports problems in the use of the devices if holes larger than 18 F are to be closed. It reported a benefit over the overall procedure time, but the cost was similar to that for surgical opening. The published work emphasises the correlation between the learning curve gained and the reduction in open conversion. It is clear that the percutaneous approach, like all the other interventional techniques, requires a learning curve. However, we must not balk at the initial hurdles, but look into seeking appropriate training to keep the problems that we may face to a minimum.

Personal resultsIn our centre, in agreement with vascular surgeons, we started undertaking percutaneous approach in 1999. At the beginning, 29 patients with high risks of bleeding benefited from closure by “Prostar XL 10”¹. One patient required an 8 F introducer, three a 10 F introducer, ten a 12 F introducer and five an 18 F introducer. The indications requiring the use of a closure system were aortic dilatation, insertion of a covered stent, extension of endoprosthesis, difficulties in maintaining decubitus, or after fibrinolysis. Once experience was

“The medtronic Xcelerant delivery System has a flexible and trackable middle member that facilitates tracking through tortuous anatomy during endovascular access”

gained, we used these devices for thoracic stent grafts whose delivery systems were in the range of 22–25 F sizes.

The use of these devices was not limited to one pathology but was relevant to patients with aortic dissection, aneurysm or isthmic rupture.

These closures were initially used for the deployment of aortic and iliac extensions (access site 12–20 F). Forty patients in total, including 27 thoracic indications and 13 abdominal extensions, were studied. Two “Prostar XL 10”¹ devices were systematically used when the hole was larger than 12 F. Our initial success rate was 91% for thoracic stents and 96% in total. All patients were reviewed at six months by echo Doppler. We found no false aneurysm or stenosis. The stent graft was directly introduced over the stiff guidewire into the vascular access without the need for a sheath or additional protection.

The Medtronic Xcelerant delivery system has a flexible and trackable middle member that facilitates tracking through tortuous anatomy during endovascular access.

So far, we have undertaken 373 closures by “Prostar XL 10”¹ on 297 patients, with the access sites larger than 12 F. In 1999, our success rate was less than 85%, reaching 100% in 2002. Since then, there has been no surgical conversion. Our present practice is to systematically start with a femoral access site whether for a thoracic or abdominal stent graft. This procedure can be undertaken either by a surgeon or an interventionalist.

Medtronic recommends referring to the IFU of its Valiant® Thoracic stent graft with the Xcelerant® delivery system for correct product use. The opinion and experience expressed by Jean-Paul Beregi are under his sole responsibility.


the renal arteries to just proximal to the internal iliac arteries. An angiogram of the suprarenal aorta was then undertaken to obtain a roadmap of the proximal and distal landing zones.

A 0·035 stiff guidewire (Amplatz or Lunderquist) was passed through the left external iliac sheath, resulting in a reduction of the iliac tortuosity. The Talent™ AAA stent graft with Xcelerant® Hydro Delivery System was inserted

1A

1b 1C

Figure 1: a: 7.0cm aaa missingB: left hypogastric aneurysm c: Kinking of iliac arteries

iliofemoral access for endovascular AAA repair can present challenges for the

vascular interventionalist. Vessel tortuosity, size and presence of calcification can precipitate adverse events and can be the reason to exclude a patient for an endovascular AAA repair. Murray and colleagues1 reported that 13% of patients in the EUROSTAR registry had complications of iliac access, which was a leading cause of primary conversion. Herein we present a case of an abdominal aneurysm with associated iliac vessel disease showing several of these challenges and how an innovative hydrophilic-coated delivery system facilitated vascular assess and stent-graft delivery and deployment.

The patient was a 73-year-old man with a medical history of arterial hypertension and diabetes mellitus type 2, bilateral renal cysts and chronic renal failure. The patient was 3 months post right carotid TEA and presented for treatment of an abdominal aortic aneurysm. A CT scan of the aorta and iliac vessels showed an abdominal aortic aneurysm measuring 7·0 cm with a 3·8 cm aneurysm of the left hypogastric artery and severe tortuosity in the right iliac (figures 1a, b and c).

After induction of general anesthesia, bilateral femoral cut down was undertaken and 5 F 10 cm sheaths introduced into femoral arteries. A pigtail catheter

was placed via left brachial artery for angiographic control during the procedure. An aortogram was undertaken, showing the iliac morphology (figures 2a and b)

The left external iliac artery was chosen as the insertion site for the bifurcated stent graft since it showed the least amount of tortuosity and calcification. Selective angiography was done to confirm the landmarks for stent-graft deployment at the level of

Facilitated iliac access for Endovascular repair with use of the Talent™ AAA stent graft with the Xcelerant® hydro delivery System bY diErk SChEiNErT, md, Phd Park-hospital and University of leipzig-heartcenter, leipzig, germany

10ENdovASCUlAr ACCESS: CASE rEPorT


over the guidewire. A saline-soaked sponge was applied to the delivery system to activate the hydrophilic coating as the delivery system was inserted into the arteriotomy (figure 3a).

Activation of the hydrophilic coating at the time of insertion of the delivery system, rather than at the time of flushing the lumen, allows for easier handling of the delivery system. The Xcelerant® Hydro Delivery System was advanced over the guidewire without difficulty and tracked through the iliac vasculature without incidence. A 26 mm x 170 mm Talent AAA bifurcated stent graft was positioned appropriately under fluoroscopic guidance and deployed at the level of the renal arteries.

The right groin was then accessed via a 10 F sheath and a guidewire advanced into the aneurysm. Successful cannulation of the contralateral limb opening was gained. The sheath was removed and the 14 mm x 90 mm Talent contralateral limb on the Xcelerant® Hydro Delivery System was then advanced over the guidewire, activated with a saline-soaked sponge, and successfully deployed within the bifurcated device. Importantly,

when attempting to advance the 10 F sheath there was significant difficulty in navigating the tortuous right iliac artery, but there was no difficulty at all when the 18 F Xcelerant® Hydro Delivery System limb was advanced.

Iliac extensions were placed in both iliacs to insure coverage to the hypogastric arteries. The completion angiography showed good stent graft placement and successful exclusion of the aneurysm (figure 4).

discussionThis case, which was presented live at the LINC 2008 congress, shows several unique challenges faced by physicians attempting to treat abdominal aortic aneurysms with concomitant iliac disease by endovascular approaches. Use of the Talent™ AAA stent graft with the Xcelerant® Hydro Delivery System facilitated vascular access and stent-graft delivery in severely diseased iliac vessels. The hydrophilic coating reduces the friction between the delivery catheter and the vessel, providing easier navigation through tight and tortuous iliac arteries. The low, 22 F profile and option of sheathless access also enhances delivery of the stent graft. Awareness of

these issues and access to the full range of endovascular ancillary equipment, particularly the Xcelerant® Hydro Delivery System, allowed successful management of this patient with a minimally invasive approach.

Medtronic recommends referring to the IFU on its Talent AAA stent graft system with the Xcelerant® Hydro Delivery System for correct product use. The opinion and experience expressed by Dierk Scheinert are under his sole responsibility.

Figure 2:a: Pre-operative angiogramB: inter-operative fluoro

Figure �:a: insertion of hydro Delivery systemB: hydro advancement

Figure 4:completion angiogram

2A

1. Murray et al. J endovasc Ther. 200�;1�:754–7�1.

2b

3A 3b 4

11CASE rEPorT

references


Collapse issues are related to anatomic and endograft design factors bY viNCENT riAmbAU, md, PhdProf and Chief of vascular Surgery divisionThorax institute, hospital Clinic University of barcelona

o ver the past decade, thoracic endografting has become a highly attractive

alternative to treat thoracic aorta pathology. Besides classic aneurysm, different pathologies affecting thoracic aorta can be fixed by endograft technology. Degenerative aortic aneurysms, acute and chronic dissections, penetrating ulcers, intramural haematomas and blunt trauma can be treated with this less-invasive approach. Nevertheless, some technical and crucial issues are still restricting the widespread use of thoracic stent grafts. Conformability in the arch anatomy, especially in the inner curvature, is not easy to achieve for most of the current endografts.

Also in the arch, accurate and controlled deployment is still a concern. Present thoracic endografts are loaded in fairly large delivery systems that restrict their access through tortuous and calcified anatomies. Additionally,

endograft should be designed according to the different pathological scenarios and to the branched areas of the thoracic aorta. Finally, endograft durability remains a chronic concern when stent-graft technology is involved. Focusing on the arch conformability issue, a potentially devastating adverse event has been presented at several congresses and events: stent-graft collapse. Stent-graft collapses have been reported in recent peer-review studies (see Table I)1–8. This complication can lead to major morbidity and mortality. In these series, two deaths and other major ischaemic complications and related secondary procedures are reported. Nevertheless, the true incidence of thoracic stent graft collapse is unknown. Gore estimated a 0·3% event rate or 48 collapses worldwide for 16 000 TAG implants (Gore’s Dear Doctor letter, FDA MAUDE database). But if we analyse the incidence

12secTioN TiTle

12coNFoRMaBiliTy

according pathologies, trauma and dissection would show higher rates.

Collapse issues are correlated to many causes, including, but not limited to, endograft design and anatomical characteristics. Looking at reported cases, endograft collapse is mainly related to trauma and dissection lesions. Collapsed stent grafts were deployed mostly in the distal arch. Three different commercial endografts have been implicated: Gore Tag, Cook Zenith and LeMaitreEndofit devices.

Substantial stent-graft protrusion into the lumen of the aorta (poor apposition in the inner curvature) is the most common radiological finding before collapse. Stent fractures can be identified in explanted specimens probably as a consequence of gross movements of the protruding part. Extreme oversizing has been

related to collapse, but only in less than half the reported collapse cases. A recent small study tried to identify anatomic factors associated with acute Excluder TAG endograft collapse. Curiously, they found that the distal aortic diameter and minimum intragraft aortic diameter predicted collapse2. A larger study is necessary to find statistical anatomical predicting factors for collapse. The natural history of collapse is not fully understood. This complication can appear in the early postoperative period or within the first months of the implantation.

Secondary endovascular repair is an option to fix the collapse problem. Ballooning often fails, so large balloon-expandable stents can be of help in some cases. Placement of proximal aortic extensions, with or without consequent aortic trunks transposition, allows a

looking at reported cases, endograft collapse is mainly related to trauma and dissection lesions. Collapsed stent grafts were deployed mostly in the distal arch.


reported cases in peer-review publicationsArticle

Tehrani 200� gore Trauma 20% isthmus N/a N/a

idu 2005 gore Trauma �7% DTa � Months survived

Mestres Jun 0� gore Trauma 18% isthmus � Months survived

Neschis March 07 gore Trauma None DTa N/a N/a

hinchliffe aug 07 gore aeF (fistula) 17% arch 2 Months Died

hinchliffe aug 07 cook Pseudo - aneurysm �0% arch 10 Days Died

hinchliffe aug 07 gore Trauma �0% DTa 1 Month Renal Failure

Bowel Resection & Paraparesis

hinchliffe aug 07 gore Trauma 11% arch 1 week survived

hinchliffe aug 07 gore Pseudo - aneurysm 15% arch � Months small Proximal endoleak Type i

hinchliffe aug 07 gore Trauma 24% DTa � Days survived

hinchliffe aug 07 gore Trauma 40% arch 20 Days ischaemic left arm

steinbauer March 0� gore Type B Dissection 12% DTa 2 Months survived

steinbauer March 0� gore Trauma 17% DTa N/a survived

Muhs 2007 gore Trauma >iFu arch N/a survived




Muhs 2007 gore Type B Dissection >iFu arch N/a survived


Melissano 2004 endofit Taa ? DTa 2 weeks survived

go 2008 gore Trauma 1�% isthmus 5 Months survived

indication oversizing Collapsed After Procedure outcomelocation

1�secTioN TiTle

1�CliNiCAl STUdY

better apposition in the minor curvature of the arch and can be an alternative solution. When endovascular approach is not feasible, open conversion should be undertaken to solve the complication.

As in other specialties of medicine, prevention is better than treatment. Proximal stent-graft deployment in the horizontal segment of the arch provides a better conformability. The selection of stent grafts with better flexibility, conformability and radial force to treat arch pathology is also a good preventive action. Use of stent grafts with proximal bare stents allows a good lining and apposition of the second row of stents. In fact, collapse problems have not been reported with this type of endografts (Medtronic Talent Thoracic, Medtronic Valiant, Bolton Relay). (* Internal R&A files) Appropriate stent-graft oversize, according to the current IFU (10–20%), is also recommended.

Fortunately, collapse is somehow a rare event and can be prevented with appropriated device selection. It is related to challenging anatomy and endograft design. In other words, angulated landing zone, extreme oversize with infolding, protrusion in to the aortic lumen (lack of

Contact Vincent Riambau, MD, PhDProf and chief of Vascular surgery Division Thorax institute, hospital clinic, university of Barcelona

apposition), stent graft with low radial force and lack of proximal bare stent are predicting factors of collapse.

Patient and endograft selections remain crucial for a successful thoracic endografting. Further technical and design developments are needed to allow a safe and effective treatment of the aortic arch pathology. New thoracic-arch devices should be more flexible to perform better in the minor curvature and with permanent attachment mechanism.

The opinion and experience expressed by Vincent Riambau are under his sole responsibility.

1. hinchliffe RJ et al. observations on the Failure of stent-grafts in the aortic arch. eur J Vas endovasc surg. 2007;�4:451–�. 2. Muhs Be et al. anatomic factors associated with the acute endo-graft collapse after gore Tag treatment of thoracic aortic dissection or traumatic rupture. J Vasc surg. 2007;45:�55-�1. �. Neschis Dg et al. Twenty consecutive cases

of endograft repair of traumatic aortic disruption: lessons learned. J Vasc surg. 2007;45:487–92. 4. Tehrani hy et al. endovascular Repair of Thoracic aortic Tears. ann Thorac surg. 200�;82:87�–8. 5. idu MM et al. collapse of a stent-graft Following Treatment of a Trau-matic Thoracic aortic Rupture. J endovas Ther. 2005;12:50�-507. �. steinbauer Mg et al. endovascular repair of proximal endograft collapse after treatment for thoracic aortic disease. J Vasc surg. 200�;4�:�09-12. 7. Mestres g et al. symptomatic collapse of a thoracic aorta endoprosthe-sis. J Vasc surg. 200�;4�:1270–�. 8. Melissano g et al. Disappointing results with a new commercially avail-able thoracic endograft. J Vasc surg. 2004;�9:124-�0. 9. Barbato MR et al. Thoracic endovascular aortic repair for traumatic aortic transaction, JVs. 2007;0�:049.

references


Figure 1

Early experience with the use of endovascular procedures in the thoracic aorta has

affected clinical practice, and such procedures are becoming established as primary treatment for simple and complex disorders involving both the distal arch and descending thoracic aorta.

As experience with thoracic endografting grows, the range of cases in major centres is becoming increasingly challenging, present-ing even hybrid approaches to arch and thoraco-abdominal aneurysms, management of ruptured thoracic aorta and lesions with unfavour-able anatomy1. Major challenges associated with endovascular pro-cedures with the first generation of endografts ranged from a relative rigidity and considerable size of the delivery system, to the failure of thoracic endografts to conform tightly to the anatomy of the aortic arch. As a consequence, non-con-formity of grafts might lead to graft instability, endoleak, procedural failure and post-operative failures.

importance of device comfortability in the thoracic aorta bY ChriSToPh A. NiENAbEr, ProF. dr. mEd.

head of Cardiology, University of rostock, germany

14CoNFormAbiliTY

Nonetheless, challenges of providing conformability and fixation in the aortic arch and thoracic aorta are substantial, given the spiralling motion of the thoracic aorta with each ventricular contraction (figure 1). The complex thoracic aortic anatomy deserves special attention. When looking at thoracic endovascular repair, one should keep an open eye, since fundamental differences exist between thoracic-endograft procedures and abdominal-endograft procedures.

When looking into the real meaning of device conformability, one’s view is blurred; we generally tend to refer to the three-dimensional aspect of thoracic stent graft – namely, its capacity to adapt to the tortuosity of the thoracic aorta geometry through a flexible design, thus ensuring both low segmental aortic wall stress and device kink resistance. However, the capacity of a thoracic stent graft to appose tightly to the aortic wall not only ensures

an effective sealing and fixation, thus avoiding endoleaks and migration, but it ultimately provides graft stability and overall successful endovascular repair with aortic remodelling. Conformability is therefore the combined effect of adaptability to the thoracic aorta’s anatomy and good aortic wall apposition (figure 2).

Presently, sealing, fixation and aortic wall apposition are often achieved through stent-graft oversizing. Choosing too small a stent-graft diameter can cause endoleak or migration, whereas excessive oversizing can lead to infolding of the graft or local trauma, including retrograde progression of dissection2. Experimental work has shown that oversizing and the stent-graft infolding were both significantly related to the grade of endoleak; moreover, balloon expansion was not helpful to abolish such endoleaks. In selected cases, bare metal stents can be used to provide additional sealing force. With increased angulation, oversizing will cause even greater infolding of any stent graft with low radial force; only highly flexible, compliant stent graft of proper proximal and distal diameter will avoid this effect3.

Proximal landing zone angulation is probably a significant risk factor for endoleak or even stent-graft collapse especially when located in the aortic isthmus or in steep angulations. Sufficient anchoring and a landing zone of 15–20 mm is required to ensure good sealing of the proximal anchoring zone of the stent graft.


Figure 2

However, a stiff stent graft with long segmental design can not easily conform and offer good wall apposition, particularly in the inner curvature of the proximal landing zone. This notion is particularly true in young, post-traumatic and dissected patients.

To overcome issues related to short necks and avoid bird-beaking appearance of the stent on immediate aortograms, the standard practice is to extend landing zone by covering the left subclavian artery. The distance between the left LSA and the primary entry tear is usually shorter in patients with an endoleak than in those without an endoleak. Usually Type I endoleaks need additional stent-graft deployment for sealing or spot coiling, or eventually conversion to open surgery; reports of stent grafts have shown spontaneous thrombosis of the thoracic false lumen without any further treatment despite initial endoleaks4,5. The duration of self-resolution ranges from one week to eight months.

Once implanted, the device is subject to extrinsic forces imposed by the geometry of the tortuous aorta and its cyclic dimensional changes, and the effect of continuous high blood pressure. Mechanical failure of the stent graft can occur, such as metallic fracture, fabric wear, and suture breakage. A stent graft with a design that adapts to the varying shapes of the thoracic aorta can certainly help to reduce the overall stress applied and thus reduce its mechanical failure. Major features such as proximal flexibility, kink resistance and active radial force are therefore to be expected in a stent-graft developed for the thoracic aorta.

The opinion and experience expressed by Christoph Nienaber are under his sole responsibility.

*Produced with educational grant from Medtronic Cardiovascular

1. ishimaru s. endog-rafting of the aortic arch. J. endovasc Ther 2004; 11:�2-71.

2. Fattori R et al. exten-sion of dissection in stent-graft treatment of type B aortic dissec-tion: lessons learned from endovascular experience. J endovas Ther. 2005:12:�0�-�11.

�. idu MM et al. col-lapse of a stent-graft following treat-ment of a traumatic thoracic aortic rupture. J endovasc. Ther. 2005;12:50�-507.

4. leopre V et al. endograft therapy for diseases of the descending thoracic aorta: results in 4� high risk patients. J endovasc Ther 9:829-8�7, 2002.

5. shimono T et al. Transluminal stent-graft placements for the treatments of acute onset and chronic aortic dissections. cir-culation 10�:1241-1247, 2002 (suppl).

15CoNFormAbiliTY

references


Valiant stent graft with conduits in pig aortic arch during necropsy

�D fluorographic reconstruction of Valiant stent graft with conduits

explanted Valiant stent graft with conduits from pig aorta

New endovascular technologies to reconstruct aortic arch in situRetrograde fenestration of Valiant stent grafts and conduit implantation during cerebral circulatory support promises to improve fixation and enable endovascular repair of aortic arch

bY FUrUzAN NUmAN* ANd mEdTroNiC CArdiovASCUlAr r&d

operations to repair aortic arch aneurysms and acute

dissections are one of the most complex in cardiovascular surgery. Despite improvements in open surgical techniques, 30-day mortality is still high1,2. Hybrid procedures, combining supraaortic trunk surgery and endovascular repair have been recently introduced and seem promising, but are still technically challenging, with reported 30-day mortality between 7% and 20%3,4. Many schemes for endovascular repair of the arch have been introduced by several investigators, but results have not been reproducible. High rates of neurological morbidity that were observed in some studies are probably attributable to manipulation of the arch. A set of new endovascular techniques is in development for complete aortic-arch repair by retrograde fenestration and conduit implantation during cerebral circulatory support.

When a stent graft is deployed with fixation and sealing proximal to the great vessels branching from the thoracic aorta, the ostia of these branch vessels is covered by the device. Variations in anatomy preclude a branched stent graft with a fixed design of conduits to the branch vessels. Retrograde fenestration in situ creates a hole in the graft fabric which is adjacent to the ostium of the branch vessel to be perfused, using prototype devices introduced retrograde from carotid or left subclavian arteriotomies. The centering needle

dilator device consists of a compliant balloon to maintain axial position in the branch vessel and a concentric pushable needle and dilator to provide a controlled 3 mm puncture. A superior alternative requiring less force is a radio frequency plasma electrode device that is advanced through a steerable guiding catheter and produces a controlled plasma discharge at its tip to produce a 3 mm hole with fused edges. After either of these techniques is used, an 8–12 mm peripheral covered stent or stent graft (e.g. iCast, Viabahn and Jostent) is deployed in the fenestration to create conduits between the graft lumen and the proximal segments of the great vessels. Peripheral angioplasty balloons and spherical occlusion balloons are used to dilate the initial holes, and create flared seals and fixation of the covered stents with the stent grafts.

The in-situ fenestration and conduit placement techniques have been successfully implemented in several cadaver and animal experiments. In five 70 kg pigs, right femoral to right carotid bypass circuit was established to support cerebral circulation, and Valiant stent grafts were deployed to extend across the aortic arch, covering the ostia of the brachiocephalic trunk and the left subclavian artery. In-situ fenestration and arch reconstruction with covered stents was undertaken successfully, and the animals survived all the procedures unremarkably before being euthanised. Fluorographic

1�TEChNologY/ProdUCT NEWS

three-dimensional reconstruction and necropsy showed that secure fixation and sealing of the conduits was achieved in all cases.

Fewer surgical and endovascular manipulation skills will be necessary in the techniques described here, than in other arch reconstruction procedures requiring full or partial sternotomy5,6 bypass surgery of supraaortic vessels with very large carotid introducers7, or extensive catheter manipulations of custom multibranched stent grafts8. Early estimations of the total in-situ fenestration procedure time suggest a likely 2–3 hour procedure. Furthermore, the bilateral cannulation and clamping during bypass can, in theory, reduce the embolic risk. The puncture devices and conduits described here require introducer sheaths of 8–12F. Prototypes under development include novel conduit designs and a radio-frequency plasma electrode catheter that is capable of creating full-size circular fenestrations with fused edges. In-vitro and in-vivo testing of the conduit stent graft junction is underway to establish clinical robustness of this promising technology for minimally-invasive aortic arch repair.

* Chief of Interventional Radiology, Cerrahpasa Medical Faculty, Istanbul

Medtronic recommends referring to the IFU of its Valiant® Thoracic stent graft.

1. crawford es, craw-ford Jl, safi hJ et al. Thoracoabdominal aortic aneurysms: preoperative and intraoperative factors determining immediate and long-term results of operations in �05 patients. J Vasc surg. 198�;�:�89-404.

2. svensson lg, crawford es, hess KR, coselli Js, safi hJ. experience with 1509 patients undergoing thora-coabdominal aortic operations. J Vasc surg. 199�;17:�57-�8; discussion ��8-70.

�. czerny M, gottardi R, Zimpfer D, schoder M et al. Mid-term results of supraaor-tic transpositions for extended endovas-cular repair of aortic arch pathologies. eur J cardiothorac surg. 2007;�1:�2�-27.

4. schumacher h, Von Tengg-Kobligk h, ostovic M et al. hybrid aortic procedures for endoluminal arch replacement in thoracic aneurysms and type B dissec-tions. J cardiovasc surg. (Torino) 200�;47:509-17.

5. greenberg RK, haddad F, svensson l et al. hybrid ap-proaches to Thoracic aortic aneurysms: The Role of en-dovascular elephant Trunk comple-tion. circulation. 2005;112:2�19-2�.

�. Bergeron P, Mangi-alardi N, costa P et al. great Vessel Management for endovascular exclu-sion of aortic arch aneurysms and Dissections. eur J Vasc endovasc surg. 200�;�2:�8-45.

7. chuter Ta, schneider DB. endovascular Repair of the aortic arch, Perspect Vasc surg endovasc Ther. 2007;19;188.

8. inoue K, hosokawa h, iwase T et al. aortic arch reconstruction by transluminally placed endovascular branched stent graft. circulation. 1999; 100 (suppl ii): ii-�1�-ii-�21.

references


Performance of thoracic stent grafts in high aortic-arch

angulation and oversizing in human cadaver aortas

bY lUdoviC CANAUd, dr department of Thoracic and vascular Surgery,

hôpital Arnaud de villeneuve, ChU montpellier, France

background: Successful thoracic endovascular repair needs adequate graft fixation

to avoid migration, endoleaks and collapse. At the department of thoracic vascular surgery in Montpellier, we assessed fixation of four commercially available thoracic stent grafts as a function of aortic-arch angulation and oversizing.

Methods: Experiments were done with 15 human thoracic cadaveric aortas. We assessed

four commercial stent grafts: TAG (Gore); Zenith TX (Cook); Valiant (Medtronic) and Relay (Bolton). A bench test model with pulsatile flow was devised to improve stent-graft anchorage as a function of proximal landing zone angles from 70° to 140° (length of the proximal landing zone: 2 cm) and oversizing (4·8% to 36·8%). The intraluminal lip length was measured as a function of proximal landing zone angulation during static and dynamic tests; we also investigated stent-graft collapse.

Results: We started to observe a lack of the prosthesis “body” apposition with Zenith graft above 70° proximal landing zone angulation from 1 to 7·5 mm (p<0·001). Lack of the proximal anchorage system (bare spring for the Relay device and of the scalloped flares of the TAG device) apposition was begun to be observed with Relay graft above 80° proximal landing zone angulation from 1 to 7 mm and 90° proximal landing zone angulation with TAG graft from 1 to 6 mm and was greater with Relay than with TAG (p=0·009); but the prosthesis “body” of these devices was always well apposed. With the Valiant device, the prosthesis “body” and bare spring were always in contact with the aortic wall. As the stent-graft oversizing increased, the lack of device wall apposition for the TAG, Zenith TX, and Relay devices was also increased (p<0·01). No collapse was observed during static and dynamic tests, but the lack of device wall apposition of Zenith TX caused a haemodynamically significant stenosis with a blood-pressure decrease from 300/150 to 250/120 mmHg.Conclusions: In this specific situation of severe aortic arch angulation, stent grafts with hooks do not improve stent-graft fixation. Major implications of stent-graft design to provide a secure proximal anchorage seem to be the radial force and the presence of a proximal open stent segment.

The opinion and experience expressed by Ludovic Canaud are under his sole responsibility.

Figure: Proximal anchorage of the different stent grafts at 140° angulation (clockwise from top left): Medtronic Valiant; Zenith TX2; Relay, Bolton; gore Tag

17TechNology/PRoDucT News


Prof. Verhagen Rotterdam The NetherlandsProf. Moll utrecht The NetherlandsDr. cuypers eindhoven The NetherlandsProf. gelkerken enschede The NetherlandsProf. Torsello Münster germanyProf. eckstein Munich germanyDr. Florek Dresden germanyProf. scheinert leipzig germanyProf. Debus hamburg germany

within �0 days of implant (technical success) and up to 12 months1. Type i and Type iii endoleaks2. loss of device integrity �. graft infection, thrombosis or occlusion4. conversion to open surgical repair5. aneurysm rupture�. secondary endovascular procedure related to the endurant stent graft (implant)

after �0 days of implant up to 12 months:7. aneurysm expansion8. stent graft Migration 9. late mortality10. stent graft patency

Table 1: Participating centres

Table 2: secondary endpoints

include technical success (table 2), aneurysm expansion, stent-graft migration, late mortality and stent-graft patency at 30 days and within the 12 months after implant. The analysis of the results will be undertaken on an intention-to-treat basis. Forty patients were enrolled into two groups depending on the angulation of the proximal aortic neck. Thirty-four patients had an infrarenal angulation less than 60°, and six had an infrarenal angulation between 60° and 75°.

At the Charing Cross Symposium in London, Prof. Hence Verhagen – Chief of Vascular Surgery at the Erasmus Medical Centre in Rotterdam and Principal Investigator of the Endurant Clinical Trial – presented his initial experience with the Endurant stent graft system in the trial. He mentioned that results from the interim analysis on the first eight patients treated with the device were very encouraging: “[The] Endurant [stent graft] will offer physicians expanded options to treat AAA patients thanks to the high conformability of the stent graft, the low crossing profile and precise deployment provided by the new delivery system”.

medtronic is proud to announce that the enrolment of patients in

the Endurant AAA stent graft first-in-man clinical trial was completed in April 2008. The enrolled patients will be followed up for 30 days to obtain endpoint data. Thereafter, statistical analysis will be undertaken and the final report written to support CE marking. While the remaining 30-day follow-up data is being gathered and analysis is being done, the participating centres continue to enrol patients under an amended protocol to generate data from an additional 40 patients to support reimbursement requirements for several EU countries.

The Endurant AAA stent graft is Medtronic’s next generation AAA device that is expected to be commercialised in Western Europe later this year. It is aimed at broadening AAA stent-graft treatment to a wider range of patients. The Endurant stent graft is made of materials with over 10 years of proven clinical use. It provides a short proximal sealing because of an M-shaped stent proximal covered stent and a high conformability to the aorta and iliac arteries. The device comes with a delivery system based on the Xcelerant® Delivery System technology. It offers a smaller crossing profile than the Talent AAA stent graft.

The Endurant first-in-man clinical trial is a prospective, non-randomised trial that is being undertaken in ten hospitals in The Netherlands and Germany (table 1). The objective is to show safety and effectiveness of the Endurant stent graft system in the treatment of infrarenal aortic or aorto-iliac AAA. The primary effectiveness endpoint is the delivery and deployment success of the stent graft during the initial implant procedure; the primary safety endpoint is clinical success within 30 days of the implant procedure. Secondary endpoints

Endurant™ AAA stent graft clinical trial updatebY JUliEN bAiSSAT medtronic international Trading Sàrl, Tolochenaz, Switzerland

18CliNiCAl TriAl UPdATE

The Endurant stent graft is currently under investigation and is not commercially available.


Hospital and University of Leipzig-Heartcenter, Germany, and the leader of the first team worldwide to implant the device with the new delivery system. “It will simplify the procedure for endovascular interventionalists in treating patients whose iliac arteries are difficult to navigate when they are small and tortuous.”

The Xcelerant Hydro Delivery System represents the seventh generation of innovation for the Talent AAA stent graft, which was introduced in Europe in April 1998. In bench testing, the Xcelerant Hydro Delivery System generated a 99% reduction in friction compared with the previous delivery system, which does not have the hydrophilic coating. Hydrophilic means affinity for water; because water is a major component of blood, the hydrophilic coating is designed to ease the delivery system’s passage through the artery.

The Xcelerant Hydro Delivery System features an integrated sheath that contributes to the system’s low-profile characteristics, which are intended to enable excellent tracking and access through small vessels.

Medtronic has been seen as an innovator and market leader in the endovascular-stent-graft industry

Continuing its record of innovation in endovascular therapies for aortic

aneurysms, Medtronic launched the Talent™ AAA stent graft on the new Xcelerant® Hydro Delivery System in early March in the European market. This technology features a hydrophilic coating that is designed to aid navigation of the device through tight and tortuous arteries by reducing friction with the artery wall.

Between 5% and 15% of patients are estimated to be excluded from EVAR because of limited iliac access that can be characterised by a small external iliac diameter, iliac tortuosity or iliac artery occlusive disease. Studies have also indicated that difficulties with vascular access are the leading cause for conversion in EVAR patients. The Xcelerant Hydro Delivery System with increased lubricity and enhanced deliverability is aimed at facilitating stent-graft treatment in patients with difficult access.“The Xcelerant Hydro Delivery System is a significant innovation that will make endovascular repair (EVAR) using the Talent Stent Graft a treatment option for more patients with abdominal aortic aneurysms,” said Dr. Dierk Scheinert, MD, PhD, of Park-

for more than a decade, as evidenced by more implants than any other company. Its long history includes more than 130,000 patients treated with aortic stent grafts, dating back to 1995.

Medtronic recommends referring to the IFU on its Talent AAA stent graft system with the Xcelerant® Hydro Delivery System for correct product use.

19ProdUCT NEWS

medtronic introduces improvement to minimally invasive treatment of

aortic aneurysms in Europehydrophilic coating on Talent™ AAA stent graft aids navigation of medical device

through tight and tortuous arteries


Endovascular stent grafting requires quite an intense learning curve and a

continuous development in interventional skills and patient management. Summarised in a publication of Lobato in 2002, we know that endovascular success started to overcome its failures with the introduction of commercially available devices and dedicated training courses.

My experience with endovascular therapy started in 1997 at St Franziskus Hospital in Münster (Germany) with the first devices’ generations. After the initial wave of enthusiasm, some endovascular practitioners became sceptical about the effectiveness of the endovascular therapy mainly because of the non-promising mid/long-term results of the first generations of stent grafts1. However, my personal experience of the results of therapy convinced me that with some key adjustments, EVAR was promising.

In 2003, my hospital became an endovascular training centre for AAA EVAR in partnership with Medtronic. I wanted to ensure the development of a promising treatment by sharing my experience and learning curve with other physicians. I was convinced that good results could come only from long-lasting experience and a learning curve on EVAR therapy, as well as patient selection, in connection with technical improvements and improved stent-graft durability.

My decision to work with Medtronic was based on their long-established partnership with endovascular physicians and the common aim to develop tailored educational solutions to meet the different educational needs

of endovascular practitioners. The fact that the company has made physician training and education a primary focus and has continuously been innovating to strengthen the content and increase the variety of its educational programmes was also key in my decision to develop an advanced training programme for AAA EVAR.

Originally, the AAA EVAR sessions were meant for a German-speaking audience and were opportunities to share experience and learn from each other. Live cases offered the opportunities to share practical recommendations and suggestions of how to minimise the complications and improve the effectiveness of the endovascular therapy.

From this preliminary and informal approach, in collaboration with Medtronic Training and Education Department, my partners and colleagues – Dr. J. Tessarek and Dr. T. Umscheid – and I developed an advanced training module for physicians who already have some good AAA EVAR experience (more than 50 cases) and wish to learn more about challenging and borderline cases, tips and tricks for success (from appropriate planning to the intraoperative troubleshooting technique) and how to manage complications.

Since Münster is a referral centre for the region, it offers us the opportunity and the challenge to treat very difficult and sometimes borderline AAA cases. Thus the training attendees have the unique opportunity to be exposed to these challenging cases and to see how they can be approached with successful outcomes.

Percutaneous approach techniques are also an important part of the training programme since most of our AAA procedures are undertaken with this interventional technique.

At the St. Franziskus Hospital, all the endovascular procedures (AAA and TEVAR) are done in the endovascular suite which is equipped with the latest imaging technologies facilitating the treatment of challenging cases. In a normal training session, we schedule three to four Talent AAA live cases; therefore efficient service and excellent imaging equipment are essential. During the theoretical part of the training we share our solutions and suggestions for complications and complex cases in an open discussion.

The format is the standard Medtronic academia programme of a one-and-a-half day intense training with a small group of delegates to facilitate the interaction and exchange of experience, in an informal environment and with a practical approach.

Since 2006, we opened the course to non-German speaking physicians. In fact, I believe that in these five years of collaboration with Medtronic, I have seen more than 200 physicians in my institution. In addition to this collaboration with Medtronic, I am used to hosting physicians from abroad who are interested in internships for 6–12 months and who are willing to learn endovascular therapy.

The organisation of this educational activity requires a great deal of time and dedication, but I enjoy it very much. Medtronic is a trustworthy partner who assists a great deal

in the organisation of these courses. The secret of such successful programmes lies in the strong collaboration and partnership between Medtronic Educational Department and the training centre directors.

medtronic commits to endovascular education continuumMy experience with MedtronicbY giovANNi TorSEllo, md, Phdhead of vascular Surgery, St Fransiskus hospital, münster, germany

20TrAiNiNg


Course Place date

Training courses available until december 2008

TeVaR - Beginner/intermediate english/French lille, France 29-�0 sep 2008aaa eVaR- Beginner/intermediate english utrecht, The Netherlands 29-�0 sep 2008aaa eVaR- Beginner/intermediate english utrecht, The Netherlands 27-28 oct 2008aaa eVaR - Beginner/intermediate english Flensburg, germany 4-5 Nov 2008TeVaR - Beginner/intermediate english/French lille, France 8-9 Dec 2008aaa eVaR- Beginner/intermediate english/german Münster, germany 12 Dec 2008

language

if you are interested in attending one of the Advanced AAA EvAr training courses in münster, please contact your local medtronic vascular representative or medtronic Endovascular training and education department, valkenhuizerlaan 16, 6466 Nl kerkrade, The Netherlands.Ph +31455668779Fax +31455668022

left: lobato et al, JVs 2002

21TrAiNiNg


Technological innovation has yielded truly remarkable advances in health care

during the past three decades, improving health-care delivery and patient outcomes; however, it is also accompanied by burgeoning health-care costs.

Health Technology Assessment (HTA) has an increasing role in determining which medical technologies are made available to patients. HTA involves a wide-ranging assessment of the effect of a technology on patients, carers, the health service and society as a whole. The International Network of Agencies for Health Technology Assessment (INAHTA) defines HTA as: “The systematic evaluation of properties, effects and/or impacts of health care technology. It may address the direct, intended consequences of technologies as well as their indirect, unintended consequences. Its main purpose is to inform technology-related policymaking in health care. HTA is conducted by interdisciplinary groups using explicit analytical frameworks drawing from a variety of methods.”

HTA contributes in many ways to improving the quality of health care, especially supporting development and updating a wide range of standards, guidelines, and other health-care policies. From a policy context, HTA is mainly applied by health-care payers in decisions about the coverage or reimbursement of new technologies. HTA is seen as a tool to help health-care decision makers to identify which interventions offer the best “value for money” and prioritise their investments accordingly.

Assessment of cost-effectiveness has developed a more prominent role for HTAs, with two parallel streams of applied work: that based on randomised trials and that centred on decision

analytic models. Trials and models are not alternative methods for economic evaluation but have different roles in the assessment process and are therefore complementary: the purpose of randomised trials is to estimate particular parameters associated with a disease and/or the effects of a health-care intervention. However, the purpose of models is not to predict the result of an ideal pragmatic trial (or observational study) but to inform decision making by indicating the most cost-effective management option on the basis of best available data at a particular timepoint. Models should therefore combine information existing at the time the decision has to be made.

Cost-effectiveness modelling can be applied to any health intervention, including pharmaceuticals, medical devices, diagnostics and surgical procedures. However, cost-effectiveness analysis for new technologies is fraught with difficulties and especially challenging when undertaken for medical devices. Medical devices are indeed fast-changing technologies and their development is characterised by a constant flow of incremental product improvements. Accordingly, the life cycle of a specific type or variation of a device is often as short as 18–24 months, which is substantially less than compared with that of pharmaceuticals. This also means that by the time results of clinical trials are published, new generations of devices have already been launched and interventionalists have gained additional experience in 1) planning and selection of the appropriate treatment option/device, 2) undertaking the intervention/accessing the lesion and deployment of the device and

3) designing better suited follow-up protocols. All these elements are crucial for successful and/or better outcomes and therefore improved cost-effectiveness.

Therefore, in the case of EVAR, it is important to keep in mind that randomised controlled studies like EVAR-1, EVAR-2 and DREAM were initiated in 1999, and that contemporary datasets (for instance the field study reported by Bowen and colleagues in their HTA for the Ontario Ministry of Health and Long-term Care) have shown that present clinical practice differs from the results of the above-mentioned randomised controlled trials.

The long-term cost-effectiveness model comparing EVAR with open repair published by Epstein and colleagues in the British Journal of Surgery and primarily based on the results of the EVAR-1 trial, concludes that “EVAR is unlikely to be cost-effective on the basis of existing devices, costs and evidence”. The investigators, however, recognise that “several factors add uncertainty to the present modeling exercise” and that “there are plausible scenarios under which EVAR might be cost-effective... This will be informed by continued follow-up of patients in the EVAR trials. Endografts must be developed that will reduce the need for reintervention and surveillance, obviating the need for annual CT.”

The UK National Institute for Health and Clinical Excellence (NICE) issued their first interventional procedures guidance on EVAR in 2003, with an update in March 2006, and they now have included EVAR in the next phase of their assessment process under the form of a thorough technology appraisal for which results are expected for November 2008.

health technology assessment of EvArbY PASCAlE brASSEUr, medtronic international Trading Sarl, Tolochenaz, Switzerland

22CoST EFFECTivENESS


NICE is one of the most advanced HTA bodies worldwide; it has a key role in the UK health-care system but its effect is also felt outside the UK as organisations and individual physicians in other countries monitor its conclusions. This is probably due to the fact that, together with its commonwealth sister countries Australia and Canada, the UK was one of the first countries to introduce the formal, organised and systematic use of health economics to inform government decision making. Additionally, amongst academic centres in the UK, the University of York (and more specifically the University of York Centre for Health Economics, CHE) has always been at the forefront of methodological developments for the economic analysis of health care interventions.

Assessment undertaken by NICE can be sometimes be perceived as lengthy and at times controversial, but it is systematically done under a process which is quite unique, through the involvement of all stakeholders at every step.

We therefore hope that CHE, the independent academic centre Assessment Group that is assigned to undertake the assessment of EVAR will not limit their analysis

to the EVAR-1 trial data like they did in their publication (Epstein and colleagues 2007), but will acknowledge that cost-effectiveness analyses applying resource use that reflects clinical practice when the randomised controlled trials were done might not accurately reflect current practice in terms of time in theatre, hospital length of stay and ICU/ITU use, and therefore might overestimate the total cost associated with the procedures in current UK clinical practice. We expect CHE to also carefully consider recently published studies and/or new evidence provided by manufacturers, professional groups and patient/carer associations, showing that clinical practice has continued to evolve over the years, with improved selection of patients who are suitable for the procedure, resulting in lower mortality rates, fewer complications – including fewer conversions to open repair – and reduced number of reinterventions1. The need for secondary interventions in EVAR has indeed decreased over time. This reduction is partly due to better performance during the primary procedure and partly due to a tendency to “over treat” in the past, especially Type II endoleaks.

More recent publications

suggest that EVAR is not more expensive than open repair for elective aneurysm repair, including an average two-and-a-half years of follow-up2, and that EVAR is a cost-effective treatment option in some sub groups of patients3. Finally, the 2008 publication by Schermerhorn and colleagues in the NEJM, comparing EVAR with open repair in the Medicare population, reports that rate reinterventions related to abdominal aortic aneurysm are more common after endovascular repair, but are balanced by an increase in laparotomy-related reinterventions and admissions to hospital after open surgery.

Overall, the chosen model structure by Epstein and colleagues, and incorporation of data resulting from EVAR-1 and, more importantly, from recent articles such as those mentioned above will constitute the right framework for NICE to judge on cost-effectiveness of EVAR.

In the meantime, we at Medtronic remain committed to the further advancement of the endovascular technology by developing new generation devices like Medtronic Talent™ Hydro and Endurant, and by actively contributing to the NICE assessment at every stage of the appraisal process.

references

1. Franks sc et al. systematic review and meta-analysis of 12 years of endovascular abdominal aortic aneurysm repair; ontario hTa, March 2007.

2. Mani et al. similar cost for elective open and endovascular aaa repair in a population-based setting. 2008.

�. hynes et al. a prospective, clinical, economic and quality-of-life analysis comparing endovascular aneurysm repair (eVaR), open repair and best medical treatment in high-risk patients with abdominal aortic aneurysms suitable for eVaR: The irish Patient Trial.

2�


Endovascular repair of the thoracic aorta has become an established treatment

method with a fairly poor evidence base, which is due to a lack of randomised trials that often accompany the introduction of new therapies.

There are good explanations for the lack of randomised data when the clinical outcomes for pathologies with established indications for treatment are compared for endovascular procedures and open thoracic surgery. Case series and registry data suggest that the endovascular procedures offer significantly lower mortality, morbidity and paraplegia rates compared with open thoracic repair of thoracic aneurysms or acute dissections. The lack of randomised trials does, however, pose a problem for endovascular techniques since much of the evidence base consists of small retrospective series and registries

that do not offer sufficient detail to facilitate the subgroup analysis which is mandatory to refine indications for treatment.

As a result of the problems that are encountered with the quality and quantity of the published work, the outcome of endovascular repair for differing indications within the thoracic aorta has become difficult to establish. These challenges are of particular relevance to thoracic aortic dissections because of their differing presentations, differing indications for treatment and varying outcomes, which often reflect the initial presentation. Progress in the treatment of thoracic dissections can only be made by improving the evidence base.

Acute dissections: indications for treatment and areas of uncertaintyPatients with acute type B dissection are generally thought to have robust indications for

Endovascular treatment of aortic dissections - virtue registryan independent multicentric study of patients treated with the Talent thoracic devicebY mATT ThomPSoN, ProF. mEd.St george’s vascular institute, St James Wing, St george’s hospital NhS Trust, london, Uk

24CliNiCAl UPdATE


endovascular therapy if they present with complications (rupture, end organ ischaemia, and impending rupture).

Several series have reported reasonable short-term outcomes in these cohorts, although long-term results are not so well documented, as is the morphological fate of the false lumen over the long term. Several technical details of acute dissection therapy remain unresolved, such as the length of thoracic aorta that should be covered; whether bare-metal stents have a role in stimulating remodelling and reducing paraplegia by limiting the number of intercostals occluded; whether there are any specific outcomes that could be related to graft design (e.g. retrograde type A dissection and proximal fixation methodology); and whether endografts should have differing designs in dissections compared with aneurysms. Robust registry data with careful follow-up of the aortic morphology should be able to provide evidence to define consensus practice. Elucidation of the change in aortic morphology in the thoracic and abdominal aorta that accompanying thoracic endografting for dissections is essential to define long-term management strategies.

Chronic dissections: indications for treatment and areas of uncertaintyIndications for repair of chronic dissections have usually been limited to the onset of complications and an aortic

diameter exceeding 5·5–6·0 cm. Studies surrounding the results of endovascular repair for chronic dissections or those in the subacute phase are particularly poor. Many studies combine acute and chronic dissections and the long-term fate of the aorta in chronic dissections treated endovascularly remains undefined. Anecdotal reports suggest that the false lumen below the stent might continue to expand after treatment and that the rate of repeated intervention is high. This is an area that requires careful documentation to facilitate effective therapy. Again, procedural details need refinement since there is still uncertainty regarding the extent of aorta that should be covered; whether covering the entry tear is sufficient or if all re-entry tears should be treated; and whether aortic remodelling can be predicted by the morphology of the lesion.

The virtue registryThe Virtue study is a prospective single-group clinical registry that is designed to assess the Valiant endograft in the treatment of acute, subacute and chronic type B dissections. The study plans to recruit 100 patients with type B dissection, treated with the Valiant endograft, from 18 European centres. The primary endpoint is procedure, device-related or disease-related mortality at 12 months but, more importantly, patients will be assessed by serial imaging up to 36 months post-

procedure, and the results of CT imaging will be assessed by a core lab. This study will provide reliable data for the morphology of the aorta after endovascular treatment, and in particular might help to define the results of endovascular therapy in subacute and chronic cases.

Fifty six patients are now enrolled in the Virtue registry. At the current run rate, recruitment is expected to be finalised by December 2008.

Medtronic recommends referring to the IFU of its Valiant® Thoracic stent graft. The opinion and experience expressed by Matt Thompson are under his sole responsibility.

25CliNiCAl UPdATE


Notford

istributionintheUSA

.©2008

Medtronic,Inc.Allrightsreserved.PrintedintheUK.

UC200900195EE6/08

Thoracic Stent GraftDesigned to Conform

Valiant®Valiant® Thoracic Stent Graft combines anatomic adaptabilityand good wall apposition.

A New dimension in conformability

Valiant_sww:A0550 MED Valient AD 26/8/08 11:44 Page 1

©2008Medtronic,Inc.Allrightsreserved.UC200900638EE



Laser-cutnitinolstent

Talent™AAAStent Graft:Suprarenalfixation /UniDOCtechnology

Valiant®Stent Graft:Conformability

Xcelerant®Hydro DeliverySystem:Hydrophiliccoating

Resilient:Multifilamentpolyesterfabric

Xcelerant®DeliverySystem:Trackability /FlexibilityEase of use

FROM 1000'S OF DIFFERENT ANATOMIES AND 1000'S OF DIFFERENT

TREATMENT CHALLENGES, A 12 YEAR EVOLUTIONARY CYCLE HAS

PROVIDED A SOLUTION - A SUPER SPECIES OF STENT GRAFT.

IT I S MEDTRON IC ' S U LT IMATE EVOLUT ION . IT I S . . .

E N D U R A N T

E V O L U T I O NA A A S T E N T G R A F T S Y S T E M

UC200900638EEMed_endurant_evo_ad2_aw_A0687.qxd:Layout 1 26/8/08 15:03 Page 1


Over 132,000 EVAR patients treated globally

In partnership with Medtronic, physicians have treated more EVAR patients globally than with anyone else.

© 2007 Medtronic, Inc. Not for distribution or use in the US. Data on file at Medtronic. UC200704581EE

_ _ _p _UC200704581EE_EVAR_sww.qxd:Layout 1 26/8/08 11:54 Page 1


endovascular - sicve · of medtronic’s endovascular newsletter interesting and relevant. your...

Documents