Showcase for innovation

Geoffrey Gilling-Smith (Liverpool, UK) will be speaking on ‘Minimising endograft migration’ (9.20 – 9.30, Sunday 13 April) during the Global Endovascular Forum. He told Vascular News that he intends to use this forum to present “a new concept in endovascular grafting – the balloon endograft”. Gilling-Smith said that his team believe that migration and distortion of the stent graft are the principal causes of late failure after endovascular repair of aortic aneurysm. Without secondary intervention, migration will almost always result in late proximal endoleak, which is associated with a significant risk of rupture and death. Migration also results in distortion of the stent graft and this in turn increases the risk of further migration since it increases the magnitude of the haemodynamic force which tends to displace the graft in a caudal direction. Distortion also increases the stresses on the metal skeleton of the stent, which can fracture and tear the graft fabric.

Gilling-Smith explained, “The balloon endograft addresses both problems. The graft consists of an inner luminal layer, which lines the flow channel and a second outer layer that can expand to line the aneurysm sac. Once the graft is in place, the space between the two layers (the balloon) is filled with a gel that brings the outer surface of the graft into contact with the aneurysm wall. The gel sets to a solid consistency so that the balloon supports the graft, which therefore requires no additional metal or stent to support it. The balloon also prevents any caudal movement of the graft.”

He continued, “An additional benefit of this device is the ability to rapidly seal any tear in the aneurysm wall. It may therefore offer an elegant solution to the problem of ruptured aneurysm.

“We cannot claim all the credit for this concept. Although we have refined the original idea, the concept was first proposed by a retired professor of physics. We are simply developing the idea into a clinically useful tool,” concluded Gilling-Smith.

Conquering total occlusions
Presentations focusing on occlusions include: ‘Acute arterial and venous occlusions: a major paradigm shift’ by Tom Fogarty (9.40 – 9.50, Sunday 13 April).

Acute arterial and venous occlusions in the past have typically required thrombectomy or thrombolytics for a successful outcome. However, mechanical thrombectomy requires operative exposure of the vessel and the use of thrombolytics requires return visits to the angiography suite that are costly. Furthermore, thrombolytics can be associated with bleeding complications and distal embolization. Several novel percutaneous mechanical thrombectomy devices have been developed in an attempt to decrease these complications and limit costs. Forgarty mentions two novel thrombectomy devices from Bacchus Vascular. Early results with these devices in patients with acute arterial and venous occlusions suggest that they are safe and efficacious. The devices appear to minimise the complications associated with thrombolytics by avoiding the prolonged infusion time and decreasing the risk of bleeding complications compared to standard catheter directed thrombolysis.

The use of 3D rotational angiography
During the Global Endovascular Forum, Jos van den Berg of St Antonius Hospital, Nieuwegein, the Netherlands, will give a talk on the use of 3D rotational angiography (11.35 – 11.45, Sunday 13 April).

This precise measuring system is of particular use in carotids for stent and protection device sizing and placement. The unwanted complications of undersizing can be insufficient seal and migration, while oversizing may have deleterious effects on the vessel wall. With normal angiography, without duplex ultrasound, it is difficult to select the correct stent/device size.

According to van den Berg, Philips Medical Systems have now modified the 3D rotational angiography (3D-RA) software to allow the merging of images, enabling vessel wall calcifications and the position of stents to be seen on a 3D-RA image.

Van den Berg said that one area of 3D-RA use that his talk will touch upon is residual stenosis. “What we have seen is that in 10–15% of the 200–300 cases where we have routinely performed duplex ultrasound the day after the procedure, residual stenosis (over 50%) is present. We saw nothing, however, with standard unidirectional angiography.”

3D-RA appears to provide the solution. In 15–20 cases scanned with 3D-RA, the residual stenosis detected by duplex ultrasound performed immediately after the procedure was confirmed. This appears to show that the parameters for ultrasound remain valid when a stent is in place.

The processing time for a primary 3D-RA reconstruction is now down to less than a minute (about 30–40 seconds) and according to van den Berg with the most recent software secondary and tertiary images are also much quicker.

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Fenestrated stent grafts for AAA procedures
During the Global Endovascular Forum, which precedes the Charing Cross International Symposium, Dr Eric Verhoeven of Groningen, the Netherlands, will give two presentations regarding fenestrations. His first presentation will be during the Cook satellite symposium ‘Extending the role of endovascular aortic aneurysm repair’ (12.55 – 13.55, Sunday 13 April) in which he will focus on the technical points. Cook’s Zenith AAA Graft System includes advanced features to improve fixation and reduce the likelihood of stent-graft leakage, which are problems seen with earlier AAA devices.

Additional features include:

Extra holes

Markers around the holes

Orientation markers

Diameter reducing ties

Extra safety lock or trigger wire

Composite system

Additional techniques:

Catheterisation of sidebranches

Use of stents and flaring of those stents

In his second presentation (14.40 – 14.50, Sunday 13 April) Verhoeven will present the experience of the Groningen group. He will also look at the tactic one should use and the risk for endoleaks and occlusions Talking to Vascular News, Verhoeven said: “ I may also discuss our patients’ results and the category of patients that are in my view candidates, from the anatomical point but also from the general point (co-morbidity profile).”

Branch stent graft sytems
Krassi Ivancev (Malmo, Sweden) is to talk on branch stent-graft systems (14.30 – 14.40, Sunday 13 April). Speaking to Vascular News he said, “My intention is to show that we place branched stent grafts in internal iliac arteries in order to preserve flow in the presence of AAA and CIA aneurysms. I will present two of these cases. Also, the other situation in which branched stent-grafts may be helpful is in thoracic aneurysms with very short proximal neck where a branch can be placed in the left subclavian artery and in this way elongate the proximal fixation site. This is also intended to be used in situations with type B dissection starting immediately below the left subclavian artery. I don't think I will have a case of type B dissection but I will certainly have a case on pseudoaneurysm in the aortic arch.”

Venous valves for chronic insufficiency
Frans Moll (Nieuwegein, The Netherlands) will address the subject of venous valves in his talk (16.35 – 16.45, Sunday 13 April). “The point is that there is a great patient group worldwide with venous ulcers – millions and millions of people,” Moll told Vascular News. “It is not a disease that will kill you but it is disabling and it has a large financial impact on countries’ healthcare budgets.” Venous valve surgery is one solution, however, according to Moll it is “quite complicated but is still done in some selected centres”.

Moll explained the work that is ongoing at his centre. “We have been developing a compressible tissue valve with a nitinol frame that is delivered percutanoeusly. We are now looking at the third generation of this venous valve. The second generation has already been tested in man and for venous ulcers it worked. However, we were not satisfied with the second generation because of degeneration of the valve (thrombus on the leaflet of the valve) although two out of five patients were cured.”

“We think that we can improve on this,” said Moll. “The third generation venous valve has been in animal studies over the last two months. Clinical trials are due to start in May in centres across Europe – in Germany, Italy and Holland. The valve will also be placed in patients in the USA (as was the second generation valve).”

According to Moll, this valve may also be of use in areas around the heart, such as the pulmonary artery. It also has potential in other situations, with diameters of 12, 13 and 14mm, but this is for the future.