The 7th International Symposium on Critical Issues in Endovascular Grafting

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Held on 31st January and 1st February at Groningen University Hospital, in the very north of Holland, the International Symposium on Critical Issues in Endovascular Grafting is the most important European meeting of the year for leaders in aortic endografting. The meeting of experts in endografting has been held annually since aortic endografts were first developed. The nearest international airport to Groningen is two and a half hours away by train, sometimes requiring changes of train because of the weather, so anyone travelling to the meeting needed to make some efforts to get there. Bad weather, snow blizzards, made travelling even more arduous, but nearly everyone who registered showed up. Jean-Pierre Becquemin did not participate to give his talk on secondary reinterventions after EVAR entitled “The good, the bad or the ugly. This was due to a strike in French hospitals according to Eric Verhoeven. Meanwhile, Sir Peter Bell and John Anderson could not attend for personal reasons. The faculty was still very strong with internationally renowned speakers with backgrounds in vascular surgery, cardiothoracic surgery and interventional radiology.

Altogether 255 specialists, mainly vascular surgeons, attended the 7th International Symposium on Critical Issues in Endovascular Grafting, somewhat more than the first meeting of its kind held in Nottingham in which there were only about 70 people, according to Brian Hopkinson. Groningen University was the latest of four centres to participate in organising this meeting. Previously, it has been held only in Nottingham, Malm̦, and Leiden. Last year it had been planned that the meeting would take place in Malm̦ once more, but this was cancelled, like many other international congresses and symposia that were too close in the calendar to the fateful September 11th bombing of the World Trade Centre. Krassi Ivancev, interventional radiology chief in Malm̦, will bring the meeting back to Sweden once more next year, and it has already been decided that the following year it will be held in Frankfurt and organised by Wolf Stelter’s vascular department.

In the meeting international experts, with the most significant experience in endografting, often gained from constant involvement in this activity for almost a decade, discuss the critical issues in endografting. The best available, most up-to-date information and data are used in presentations, and discussions that follow are in depth. Most importantly, consensus reached has a large bearing on what happens in endografting throughout the world over the year that follows the meeting. What direction will endografting take following this most recent meeting? A decade on in endografting from its introduction, data from early generation devices show the pattern of success or failure, depending on how one wishes to look at it. Nearly all of the experts at the meeting are convinced that endovascular exclusion of aneurysms is a viable alternative to aortic surgery and only a few believe they should continue with caution. Is it that they have got used to the occasional catastrophic device failure? Is it that they know more about the causes of failure? Or is it more because they are able to put the value of this emerging technology into perspective, realising it strengths and weaknesses?

The President of the meeting, Eric Verhoeven, opened the meeting on time with the lecture theatre lacking very few of the registered participants. He thanked key faculty members who had travelled far from other continents in order to attend, namely: Mike Dake, Frank Criado, Frank Veith, and Hugh Beebe from the US, and Michael-Lawrence Brown and Geoff White from Australia. In January, in the US, at Barry Katzen’s meeting many people where referring to this meeting as the Cook meeting, mainly because many of the faculty are major users of Cook’s Zenith stent graft. Another observation that could have been made is many attending also participate in the Eurostar registry. Cook was not on the radar screen when the first meeting was held. In the early days it could well have been referred to as the Vanguard meeting because early on most Eurostar registry participants were Boston Scientific’s Vanguard users and then AneuRx users (now AVE Medtronic).

Importantly there have been many stent graft devices developed for clinical use and several versions of single brand named devices have appeared in the short history of this technology. This was indeed the cause of some embarrassing moments where a question mark hung over what constituted a second-generation device. Gore had its supporters too: in thoracic devices it was Peter Taylor and in abdominal it was Mario Lachat. The issue of what constituted a second or third generation device was questioned after Simon Parvin referred to different generation devices. It appeared Simon Parvin thought his series of procedures with AneuRx showed that AneuRx was prone to migration and had been improved upon by later generation devices that have hooks and barbs. Frans Moll of Nieuwegien, The Netherlands, contested that, and rightly so – all devices have been steadily changed over the years and AneuRx is not the same device today as it was right at the beginning. Indeed Ancure, manufactured by Guidant, which has hooks, has been around a long time. In fact all devices have been upgraded to overcome defects. On another note Simon Parvin questioned the big difference in procedural outcome between his results with AneuRx stent-grafts and those of others, such as Frans Moll. Are Frans Moll’s data too good to be true? Frans Moll argued in the panel discussion session that Simon Parvin had got the proximal neck oversizing of AneuRx wrong. Simon Parvin accepted that he had not oversized enough in his initial procedures but that he had corrected this later on but the migrations still occurred. One has to compare like with like and Simon Parvin did own up to having only greater than 5.5cm abdominal aneurysms in his patient series following the findings of the small aneurysm trial in the UK which demonstrated that only abdominal aneurysms above 5.5 cm should be operated on. Frans Moll’s data include patients with aneurysms smaller than 5.5cm.Industry’s involvement in the symposium

The symposium had four major sponsors: Cook, Gore, Cordis and Medtronic. Edwards Lifesciences and Vascutek (now owned by Terumo) were also sponsors and took part in the exhibition. Endologix, Anson Medical and Boston Scientific sponsored the event but did not participate in the exhibition. Companies sponsoring but not involved in stent graft development included Amersham, GE Medical Systems and Philips. Commercial managers of Gore and Cordis made presentations (P. Mackin for Medtronic, Elisabeth Hoff for Gore, Dezso Farkas for Cordis and D. Hartley for Cook). From them we learned what the industry has in store for AAA treatment and thoracic aneurysm and dissection exclusion.

Since the Thoracic Masterclass at Guys in London early last year, many surgeons doing thoracic aortic procedures have been asking Gore to have Gore’s Excluder thoracic stent graft returned to the market. These surgeons, including Eric Verhoeven, consider that there is sometimes no alternative to this relatively less invasive procedure because surgery would result in very high mortality. Eric Verhoeven has been asking for these devices for compassionate cases. Gore only allows these devices to be used in cases where there has already been an Excluder implanted before the embargo was initiated by Gore.

Excluder on track to be relaunched

Elisabeth Hoff told the audience that the longitudinal spline stent of the Excluder thoracic stent graft had been shown to fracture and that it had affected the integrity of the graft. She said Gore was committed to relaunching this device among other things because the person who hired her at Gore had himself died of a ruptured thoracic dissection. She told the audience that the Excluder thoracic stent graft would be available again at the end of 2003 or beginning of 2004. In the exhibition area, Gore personnel talked to Vascular News and mentioned that for Gore this device had to be right before they would relaunch it, and that Gore had always, since its inception, prided itself on quality. Gore Excluder thoracic stent graft devices should only be used if there is a problem with an Excluder thoracic stent graft device that has already been implanted but which is failing.

How regularly should patients with stent grafts be followed-up?

The issue of how surgeons should follow patients that have been given stent grafts emerged several times. Whether there should be more or less follow-up in the short or long term was questioned. Thomas Umshied who works with Wolf Stelter in Frankfurt Hoechst gave a presentation on whether some patients should be given stent grafts and then forgotten. Patrick Peeters made the point that patients are not followed up after conventional graft surgery. Martin Malina of Malm̦, showed that a steady practice of 100 AAA stent graft procedures per year could soon develop more than 500 follow-up cases per annum after five years.

Side branch AAA and thoracic aneurysm devices

The notion of using side branches in stent grafts in the aorta has been around for a long time. Willem Wisselink of the AMC in Amsterdam gained the first patent covering this technology in the late 1990s after he returned from working in the US. So far his devices have not been used in human subjects but animal trials are advanced. Cook has already launched fenestrated stent grafts for use in human subjects, and a presentation, which was meant to be given by John Anderson of Australia, was given by Eric Verhoeven in John’s absence. This was the first serious discussion about fenestrated devices in Europe since their trial launch in Europe almost a year ago. Very accurate deployment technique is required to deploy the limbs through the fenestrations of the main body of the aortic device.

Side branches give much greater fixation

One major advantage of fenestrated stent grafts is that they allow much higher resistance to aortic blood flow. It had been shown earlier that all of the current stent grafts available commercially have only a few newtons resistance force to flow. Sutured surgical vascular grafts have a resistance, which is an order or magnitude higher in resistance according to experiments carried out on cadaver by Malm̦ University. Fenestrated stent grafts have a resistance that lies midway between the dislodgement forces required for bifurcated stent grafts (even those with hooks and barbs) and sutured grafts. It was stated that the downward force from the blood flow in the aorta is already quite close to the displacement force required to dislodge stent grafts. What keeps them in place in many cases is the body strength of the devices, which is given exclusively by the stents used and the configuration and fixation of the bifurcated iliac legs in the iliac arteries or iliac end in the case of aorto-iliac uni-body devices. These devices and sutured grafts do not have much tissue in-growth from the aorta after the repair. Hajo van Bockel, speaking about biological healing as an alternative solution for fixation said that grafts could be manufactured in such a way that tissue in-growth would be more likely. Although not the only way, external skirting on the graft body would give this, and this was apparent on one home made device illustrated in one presentation given at the meeting.

The presentations on pressure measurements in the excluded aneurysm sac and their importance showed that this subject probably needs more work. Percutaneous needle devices (not the only method of reading pressure in the sac) give different readings depending on their size and it apparently matters exactly where in the sac the measurement is taken. These talks given by Michel Visser of Leiden and Bj̦rn Sonnesson of Malm̦ referred to elegant studies of intra-sac pressure measurement. It is clear how pressure measurements can be carried out. It is less clear how valuable they are in assessing risk of sac rupture.

The social events were very well attended with 250 people visiting the Groningen Museum for a cultural tour, followed by the symposium dinner. More than 100 people joined the Saturday night pub-crawl after the symposium closed. This lasted until six o’clock Sunday morning.

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