What is a stent graft?
A stent graft is a metal skeleton (the ‘stent’) sewn (or glued) to one or more fabric tubes (the ‘graft’).
The stent graft comes loaded into a delivery system of similar width to a pen. This allows the stent graft to be inserted through an artery in your groin. The stent graft is positioned using x-rays and deployed using the delivery system, which is then removed.
The aim is to only allow blood to flow within the fabric tube (the ‘graft’) and not into the bulging sac (for an aneurysm) or the ‘false lumen’ (for a dissection). The sac (or false lumen) is no longer under pressure and should shrink with time. This ‘excludes’ the aneurysm/dissection and reduces ruptre risk.
Why might I need a surgical bypass in my neck?
If there is not enough normal aorta below an important artery to your brain (left carotid artery) or your left arm (left subclavian artery), it may be necessary to perform a neck bypass. This allows the thoracic stent graft to be placed closer into the aortic arch.
Planning and manufacture
Most thoracic stent grafts are ‘off the shelf’ and kept in the hospital. Occasionally, the stent graft has to be ‘custom-made’ to fit your aorta. Using measurements from the CT scan, and working with the planning centre, a technical drawing of the custom grafts is made. Your graft will then be made by hand to fit your anatomy.
It will take longer to make a custom-made stent graft. It takes around three months from your scan being sent to the planning centre to the graft being delivered to the hospital.
Thoracic endovascular aortic repair (TEVAR) is a procedure to treat an aneurysm in the upper part of your aorta. The operation can be performed under:
- General anaesthetic – asleep on a ventilator
- Spinal anaesthetic – injection in the back to numb the groin area and legs
- Local anaesthetic – injection to ‘freeze’ both groin areas
After this, there is an incision to first gain access into the arteries before we can put the stent into the aorta. To do this, we usually use arteries in the groins (the ‘common femoral arteries’):
- Surgical incision – this allows the team to see the artery, puncture it under direct vision, and stitch it to repair the hole left once the delivery system is removed.
- Percutaneous – the artery is punctured using ultrasound, a smaller incision, and special devices (like Proglide) to place stitches through the artery wall. Afterwards, the stitches are used to close the hole left in the artery.
Your specialist team will assess you and your arteries on CT to decide the most appropriate method of ‘arterial access’
The stenting procedure is done with the help of x-rays. This allows the team to accurately place the stent in the ideal position to treat your aortic condition.
- A stiff ‘guide wire’ is inserted into the aorta from the groin up into the aortic arch. This wire supports the stent delivery system as it is taken from the groin up into the chest.
- From the other groin (or sometimes the neck or arm), we place a small tube (catheter) into the aorta. This catheter is used to perform an angiogram, where contrast is injected into your arteries whilst taking an x-ray. This injection helps create a detailed map of your arteries because blood vessels do not show up on ordinary x-rays.
- Once we have a map of the arteries, the thoracic aortic stent can be opened up inside the aorta.
- A final angiogram is done to check that the blood is now flowing through the stents and down the aorta rather than around the stent and into the aneurysm or dissection.
It is sometimes necessary to extend the stent further around the aortic arch or down the aorta.
After the procedure
Patients are admitted to the intensive care unit. They are monitored for 24 to 48 hours for signs or symptoms of spinal cord injury or leg ischaemia. They then return to the vascular ward for one to three days (average 2 days).
When on the High Dependency Unit, it is quite common to need some medication to support your blood pressure. This has been shown to reduce your risk of spinal cord ischaemia while the spinal cord blood supply adapts over the two days after surgery. More information on preparing for your surgery, your admission to hospital and recovery afterwards are explained in the information booklet, ‘Coming in for your aortic surgery’.
Possible early complications
Following surgery, 1 in 8 patients will have a complication:
- Spinal cord injury (1-10%) while several techniques are used to minimise the risk of spinal cord injury from surgery, losing the use and sensation in your leg is probably the most devastating complication of a complex aortic stent is a risk. This complication can occur because the blood supply to the spinal cord comes mainly from small arteries from the aorta, so the more arteries (so the greater amount of the aorta) the stent grafts cover, the greater the risk.
- Readmission to hospital within 30 days (14.7%)
- Chest infection or breathing problem (5.9%)
- Return to theatre (3.8%)
- Heart problem (2.9%)
- Paraplegia (2.8%) related to the length of aorta stented. It can occasionally be reversed by the insertion of a ‘spinal drain’
- Death (2.4%) but no deaths reported in NBT (2016-18)
- Kidney problem (<1%)
- Problem with blood supply to leg(s) (<1%)
- Stroke can be caused by wire manipulation in the aortic arch – no strokes reported in NBT (2016-18)
The incisions in the groin may cause problems too:
- Bleeding from or blockage of the artery in the groin
- Burning pain in the thighs due to bruising of nerves
- Wound infection, fluid discharge or ‘lumpiness’
- Clots in the legs or lungs – as with any major surgery, there is a risk of Deep Vein Thrombosis (DVT) or Pulmonary Embolus (PE). Good dental care may reduce the risk of infection.
- Complications of anaesthesia – your anaesthetist will talk to you about these in the pre-operative assessment clinic and on the day of your surgery.
The aneurysm sac can rupture. This is only likely to occur if the aneurysm has started to grow again and it is very rare to need to convert to open surgical repair. Another rare complication is aortoesophageal fistula, where the stent graft erodes into the oesophagus. This can cause life-threatening bleeding.
Aortic graft infection happens in 0.2% of patients:
- It is possible for stent grafts to pick up bugs from the skin at the time of the operation or for bugs to stick to the fabric graft when you have an infection in the blood stream at some later time (e.g. a chest infection).
- These bugs slowly multiply over time and can weaken the aorta or cause a collection of fluid around the graft.
- Such infection can be difficult to diagnose; symptoms can range from feeling tired with flu-like symptoms to being very unwell or bleeding.
- Good dental care may reduce the risk of an aortic graft infection.
- We rarely need to convert to open repair as we can only 100% treat infection by removal of the stent graft.
After a thoracic aortic stent graft, check-ups with CT are advised at least once a year to check:
- The stent graft remains in the correct place
- The stent graft is not blocked, kinked or broken
- The aneurysm sac has not started to grow
- No blood is flowing outside of the stent and into the aneurysm sac – an ‘endoleak’
This is a poor choice of word to use, as there is no actual ‘leak’. What the term actually means is that there is blood is flowing into and out of the aneurysm sac despite the stent graft being there to stop it. This can be through smaller arteries as shown in the picture.
The risk of a serious endoleak leading to aortic rupture is the reason why you are advised to have regular scans after an aortic stent graft.
The Circulation Foundation: www.circulationfoundation.org.uk
The Vascular Society (UK): www.vascularsociety.org.uk
National Institute for Clinical Excellence: www.nice.org.uk
Vascular Society specialists: www.vascularsociety.org.uk/patients/surgeons/default.aspx
North Bristol NHS Trust specialists: www.nbt.nhs.uk/our-services/a-z-services/vascular-services/vascular-services-team
If you or the individual you are caring for need support reading this leaflet please ask a member of staff for advice.
How to contact us:
Vascular clinical nurse specialists: 0117 414 5302/3/4
AAA screening programme: 0117 414 8610
Patient pathway coordinators: 0117 414 0798
© North Bristol NHS Trust. This edition published August 2020. Review due August 2022. NBT003285