Aortic stent grafts at Guildford Hospital

What are aortic stent grafts?

An aortic stent graft is a tube-shaped implant used to repair a weakened, bulging section of your aorta, known as an aneurysm, without open surgery. It's placed inside the blood vessel to create a new, reinforced channel for blood to flow through, taking the pressure off the weakened wall.

What conditions does it treat?

Aortic stent grafts are used to treat:

• abdominal aortic aneurysms (AAA), a bulge in the section of the aorta running through your tummy, most commonly below the level of the kidneys
• thoracoabdominal aortic aneurysms (TAAAs), which stretch from around the left collarbone down to the groin and are usually linked to age-related wearing of the aorta, though less common causes include Marfan syndrome, Ehlers-Danlos syndrome and infection
• aneurysms with more complicated shapes, such as a short or awkwardly angled 'neck' between the aneurysm and healthy aorta, using specially designed suprarenal or fenestrated stent grafts

TAAAs in particular tend to affect older people with other health conditions, such as high blood pressure, reduced kidney function or heart or lung disease, and often cause no symptoms until they produce back pain or, without treatment, rupture.

What are the benefits of having an aortic stent graft?

Compared with open surgical repair, stent grafting is less invasive, with shorter operating times, less blood loss, fewer breathing-related complications and a shorter hospital stay. Overall rates of complications and death are also lower than with open surgery, and the treatment costs less overall.

This approach can also make treatment possible for people who wouldn't tolerate a major open operation well because of other health conditions.

Are there different types or approaches?

Standard stent grafts work well for straightforward aneurysm shapes. Around 4 in 10 people, though, have a more complicated aneurysm neck that rules out a standard device, so two specialist designs have been developed:

• suprarenal stent grafts, which add an uncovered section with hooks or barbs above the main graft; this can strengthen fixation by up to 10 times and reduce the chance of the graft moving out of place, though it places stent wires near the kidney arteries
• fenestrated stent grafts, which have openings cut into the fabric so blood can keep flowing to nearby arteries, such as those supplying the kidneys, bowel or liver; these suit short necks under about 10mm

Manufacturers also differ in design details. For example, one device on the market uses an ultra-low-profile delivery system and a customisable three-part structure intended to simplify placement in complex anatomy, while stent grafts more broadly are used across abdominal (EVAR), thoracic (TEVAR) and related sac-anchoring procedures.

What happens before the procedure?

Detailed imaging is used to plan and size the stent graft. This can include CT angiography, MRI, chest X-ray, catheter-based angiography, transoesophageal echocardiography or intravascular ultrasound, depending on how complex your aneurysm is.

Your suitability depends on the shape of your aorta, including the length, angle and diameter of the healthy 'landing zones' above and below the aneurysm, and whether the arteries in your groin and legs can accommodate the delivery device. Your care team will also discuss how you'd cope with open surgery as an alternative, since stent grafting is often considered for people less able to tolerate a major operation.

What happens during the procedure?

The exact steps depend on the type of stent graft used, but generally:

1. Your surgeon accesses your blood vessels, most often through the arteries in your groin.
2. Guided by continuous X-ray imaging, sometimes combined with ultrasound, a catheter carrying the folded stent graft is threaded up to the site of the aneurysm.
3. The stent graft is positioned carefully and released, opening up and fixing against healthy aorta above and below the bulge to create a new, reinforced channel for blood flow.
4. For more complex aneurysms, additional limb pieces are added, or fenestrated or suprarenal sections are lined up with nearby arteries, such as those supplying the kidneys, so blood flow to these organs is preserved.
5. Imaging is repeated to check the graft is sealed and correctly placed before the procedure is completed.

What does recovery look like?

Because a stent graft can move, leak or wear over time, monitoring continues for life rather than stopping after a set period. Scans are typically carried out at 1, 6 and 12 months after the procedure, then at regular intervals afterwards.

CT angiography is the most established way to check the graft's position and look for leaks, but it involves radiation exposure, so ultrasound is increasingly used for routine surveillance instead, with CT reserved for cases where there's a concern about the aneurysm sac enlarging or a possible leak.

If problems are found, such as the graft moving out of place or a leak developing, further treatment, which can include another endovascular procedure or, occasionally, open surgery, may be needed.

What are the risks and complications?

• endoleaks, where blood continues to leak into the aneurysm sac around or through the graft; this is the most common complication, recorded in around 1 in 5 patients in one study of thoracic aneurysm repairs
• the graft moving out of position (migration) over time, which is more likely with large aneurysms and may need a repeat procedure
• rarely, the graft can wear through, or perforate, the aorta wall
• with suprarenal or fenestrated designs, stent wires positioned near the kidney arteries can affect blood flow to the kidneys, so kidney function is monitored closely afterwards
• further treatment, including open surgery, is sometimes needed afterwards to fix a leak, replace a damaged graft or improve fixation.