EndoVascular Aneurysm Repair
What is an EVAR?
An endovascular aneurysm repair (EVAR) is a minimally invasive procedure treating, and thereby preventing rupture of, an abdominal aortic aneurysm (AAA) (see figure 1). Typically, a stentgraft is passed into the aneurysmal aorta via a puncture in the groin artery. Once in the correct position, the stent is deployed and fixed in position. It works like the inner tubing of a tyre that effectively takes the pressure off the aneurysmal wall, reducing the risk of its rupture. Aortic stentgrafts are usually modular devices that allow for the construction of bifurcated reconstructions so that both legs are kept in circulation (see figure 2 & figure 3). Depending on the anatomy, aorto-uni-iliac endovascular reconstructions may be used, which mostly need to be completed by a cross over bypass graft in the groin in order to keep both legs adequately perfused.
Why is this operation being offered?
Endovascular aneurysm repair is a prophylactic procedure; the aim is to prevent rupture of the aortic aneurysm which mostly leads to fatal internal bleeding. The risk of rupture of any aneurysm is related to its maximum size. Below 5cm maximum diameter, the risk of rupture is very small (
What happens before the operation?
Before you undergo an EVAR a number of essential investigations and assessments are performed to assess the suitability of your aortic anatomy for endovascular repair as well as your overall fitness to undergo major arterial surgery. These may include: •Blood tests •CT angiography •Cardiac Echocardiogram •Cardiopulmonary exercise test •Chest X-ray •ECG Once the decision has been made to proceed to EVAR, an admission date will be agreed between yourself and your surgeon. A pre-admission visit may be required to complete paperwork and undertake blood tests or other allied tests required prior to undergoing a general anaesthetic. Please bring all your medications to your pre-admission review.
What happens on the day of admission?
Your surgeon will visit you to find out if you have any additional questions. You will also be visited by your anaesthetist. Please do not stop any of your normal medications unless specifically instructed to by your surgeon. If you smoke, we strongly encourage you to stop as soon as possible to reduce the risk of peri-operative complications.
What happens during the operation?
The majority of EVAR cases are performed under general anaesthesia (with you asleep). Occasionally the procedure may be performed under a spinal anaesthetic where an injection into your back numbs you from the waist down for the duration of the procedure or even under local anaesthetic. You will usually have a tube (catheter) inserted into your bladder to drain your urine. This facilitates accurate assessment of your hydration status during and immediately after the operation. Occasionally the anaesthetist will decide to insert a small tube into an artery in your wrist to enable accurate measurement of your blood pressure during your operation. Once the necessary monitoring equipment has been connected your surgeon will start the operation. At Circulation Clinic we undertake all EVAR procedures as a joint case with two of our consultants operating together. This reduces the time taken to perform the operation. We strongly believe this improves our patient’s outcomes and reduces the risk of a variety of potential complications including heart attacks, kidney failure, respiratory complications and infection rates. Through small transverse incisions the surgeons will expose the femoral artery in both groins. The femoral artery is punctured, and a wire is advanced through the puncture hole into the aorta. Over this wire the stentgraft components are manoeuvred into place and deployed under X-ray image guidance. Occasionally an adjunct procedure is required to ensure exclusion of the aneurysm e.g. for an endoleak (see below). The wounds are repaired in layers with stitches.
What are the potential risks?
All surgery is associated with risk. EVAR may be a minimally invasive (key hole) procedure, but it is associated with manipulation of the aorta and is therefore associated with a risk of significant complications. Complications of surgery can broadly be categorised according to when they occur (during the hospital admission - early or following discharge - late) and whether or not they occur at the site of surgery (local) or affect the entire body (systemic). Some possible complications of EVAR include: •Early complications: •Local oWound related - Bleeding - Infection - Wound breakdown - Fluid collection oInjury to surrounding structures - Nerve damage causing numbness, pain or weakness in the leg - Lymphatic leak causing leakage from the wound, collection or leg swelling oGraft complications: - Bleeding or blockage requiring re-operation. - Graft infection (rare) oBlood clot in leg (deep vein thrombosis) oLimb loss (very rare) •Systemic oImplantation Syndrome: Stentgrafts are essentially metallic structures covered in waterproof material. Occasionally the body mounts an inflammatory response to this foreign material much in the same way which a thumb would go red, swell and become hot at the site of a splinter. This, when following an EVAR, is on a larger scale and the patient might experience this as flu-like symptoms; high temperature, night sweats, fatigue etc. This is invariably self-resolving within a couple of weeks; the symptoms treated with over the counter medication such as paracetamol. On very rare occasions the symptoms can last for a couple of months. oHeart related - Heart attack - Irregular heart rhythm oLung related - Pneumonia - fluid on the lungs - Clot on the lung (pulmonary embolus) oKidney related - Kidney failure that may require temporary dialysis oBrain related - stroke •Late complications •Stentgraft blockage: oBlockage of (a limb of) the stentgraft is a rare occurrence. It is seen in 0-5% of EVAR cases. This may be precipitated by stentgraft kinking or narrowing/blockages of blood vessels upstream or downstream of the stentgraft. The indication for treatment depends on the severity of associated symptoms, the physical condition of the patient and the vascular anatomy. If possible, endovascular (key hole) procedures are used to restore blood flow through the graft e.g. angioplasty, although occasionally a surgical bypass operation may have to be carried out. •Endoleak oPersistent blood flow in the aneurysm sac after endovascular repair is defined as an endoleak and is considered a complication of the procedure as the primary objective of endovascular aneurysm repair is to exclude the aneurysm sack from the circulation. Depending on the nature of the endoleak, the persistent blood flow in the aneurysm sac means that the sac may still be pressurised and therefore continues to be at risk of rupture. Endoleaks caused by holes in the graft material, insufficient apposition of the stent graft against the aortic wall or disconnection of overlapping stent graft components require intervention in order to depressurize the aneurysm sac and mitigate the risk of rupture. These endoleaks may be related to, stentgraft material failure, graft migration or progression of aneurysmal disease. Lifelong surveillance is necessary to mitigate the risk associated with these endoleaks, which develop in as many as 20-40% of patients during long term follow-up. Alternatively, retrograde flow of blood through aortic side branches such as the lumbar arteries or the inferior mesenteric artery, into the aneurysm sack are innocuous and do not require any treatment in the majority of cases. All these potential complications are understandably concerning. Rest assured our surgeons make every effort to ensure your risk is reduced to the lowest level possible through our expertise and experience. The overall risk of you suffering from a major complication that either threatens your life or leg is about 2%. When complications do occur, we deal with them rapidly and appropriately.
What happens after the operation?
The majority of patients remain in hospital for one day for monitoring and recuperation. Patients are encouraged to mobilise as soon as possible after the procedure. People should be fully mobile directly after the operation. Throughout the early period of recuperation there will be discomfort at the site of the operation which we treat with pain medication.
What happens when I go home?
Although at the time of discharge we ensure you are safe to go home we ask that there is a responsible adult with you for the first few days following discharge. You will be able to have a shower at 48 hours post-surgery, but we ask you to refrain from bathing until the wounds are fully dry. For the first few weeks post-surgery there is often wound pain and discomfort. You may feel physically exhausted doing relatively minor activity, rest assured this is entirely normal and improves with time. The majority of people are able to return to work within 2 weeks of discharge, but this does depend on the nature of your employment, the type of EVAR operation you have had and how well you recuperate from your surgery. If in any doubt, please wait until you have been reviewed in clinic by your surgeon.
When will I be able to drive?
You are able to drive when you are able to perform an emergency stop and are able to concentrate fully on driving. Overall, we advise you to not drive a car for the first 4 weeks post-surgery or until you have pain free movement of your foot and knee, and are able to stamp your foot on the ground. Different rules apply for different ‘Group’ license holders and we recommend contacting the DVLA and your car insurance company for further advice.
Will I need to see the surgeon again?
We review all EVAR patients in clinic approximately 6 weeks following discharge. All clients who have undergone EVAR surgery are entered into a surveillance programme to help prevent stent graft related complications through early identification of graft migration, stent kinking or endoleak development. The surveillance programme involves annual duplex Doppler ultrasound and X-ray examination of the stentgraft after one year post-surgery. During the first-year surveillance will occur more frequently.
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What should I do next?
If you think you have one of these conditions or any of the described symptoms we recommend you seek medical advice.
For further information or to arrange an appointment at Circulation Clinic
Enquiries: 0345 3690106
Figure 1: Large Infra-renal abdominal aortic aneurysm
Figure 2: Modular EVAR stent successfully treating AAA in figure 1. Overlap zone between modular components (white arrow)
Figure 3: 3D CT reconstruction imaging of fig. 2 EVAR
Figure 4: Model of an AAA demonstrating the position of a bifurcated EVAR stentgraft (black arrow) in relation to the renal and iliac arteries.
Figure 5: Complex Chimney graft reconstructions into right kidney and bowel arteries (white arrows) as part of ChEVAR (chimney augmented endovascular aneurysm repair) for localised AAA.