Abdominal aortic aneurysm national pathway

Background

An Abdominal Aortic Aneurysm (AAA) is a dilatation of the main artery in the abdomen which, once it reaches a certain size, may rupture and, without emergency treatment, this is likely to prove fatal. Ideally, AAAs should be detected prior to rupture so that they can be repaired surgically in a planned, elective manner.

Abdominal Aortic Aneurysms (AAA) are currently identified by two different paths. The majority are found incidentally as a consequence of a scan for some other reason, the remainder by the National AAA Screening Programme, where men aged 65 are invited to participate in AAA abdominal ultrasound screening. Those found to have a large AAA (equal to or greater than 5.5cm in AP diameter) are referred urgently to Vascular Services. The AAA Screening Programme, via the Key performance Indicators, dictates that men who are found to have a large AAA are seen and treated within 8 weeks.

The Provision of Vascular Services 2021 document from the Vascular Society of Great Britain and Ireland states that all AAA above threshold, irrespective of how they were detected, should be treated in a similar manner with patients being seen within 2 weeks of diagnosis and being treated within 8 weeks. Previously, due to limited resources for assessment and intervention on AAA, screen-detected aneurysms may have been prioritised over those found incidentally. Currently those patients with an AAA discovered incidentally tend to wait longer for assessment and treatment compared to those with a screen-detected AAA leading to unacceptable inequality.

A single pathway should be established for all patients with aneurysms in Scotland, supported by a dedicated local co-ordinator, an efficient ‘one stop’ pre-operative assessment service, with ‘lifestyle’ advice given at the time of diagnosis, as well as adequate resource for timely operative intervention. For most patients it should be possible to complete this within 8 weeks of diagnosis.

Pathway overview

Click on the image to view a larger version

Triage and review

All patients with an AAA of 5.5cm or above should be actively triaged and seen by a Vascular Specialist within 2 weeks of their diagnostic imaging. At this review, patients can be assessed for their suitability for intervention, informed about the implications of having an AAA and the options for treatment, and be given appropriate lifestyle advice. Cardiovascular risk factors should be addressed, including smoking cessation.

One-stop assessment clinic

Repair of an AAA is a significant intervention and patients require further investigation prior to a decision on treatment being made. As intervention for AAA is time-critical, this assessment process is best delivered in a one stop clinic where patients can undergo CT scanning and appropriate cardiorespiratory assessment, such as cardiopulmonary exercise testing, on the same day. This is time efficient and also more convenient for patients, avoiding repeated out-patient appointments.

There is no gold standard for cardiorespiratory assessment and so locally agreed protocols for investigation should be followed.

Anaesthetic review

Patients undergoing AAA repair should be reviewed by an anaesthetist with an interest in vascular patients. It may be possible to combine this with the one-stop assessment clinic or else this may take place separately.

Some patients will require further investigation following anaesthetic review and local pathways for this should be in place.

Multi-disciplinary team meeting

All patients with an AAA should be discussed at a weekly MDT meeting which should include at least 2 vascular surgeons, 2 interventional radiologists or those with appropriate endovascular experience, and a vascular anaesthetist.

Core members should have attendance recognised in their job plans and there should be equal access for clinicians working at the arterial centre and those working in spoke sites.

Decisions should be documented in the patient’s notes. Some patients will be found to have a complex abdominal or thoraco-abdominal aortic aneurysm and would not be suitable for conventional infrarenal open or endovascular repair. Such patients should be discussed at the Scottish TAA and Complex Aortic Surgery MDT.

Following a decision at the MDT, patients should be reviewed in a timely fashion and treatment options can be discussed and a treatment plan, with a fully informed patient, made.

Intervention

Treatment of an AAA can involve open repair or endovascular repair and is time-critical once it has reached threshold. Repair should be performed in a centre performing sufficient numbers of cases as stated in the Provision of Services for People with Vascular Diseases 2021 document.

Adequate theatre resource, including staff, must be available to treat patients within an acceptable time and, for endovascular aneurysm repair, this should be performed in a hybrid operating theatre. Open surgery to repair an AAA is a significant operation and is associated with recognised morbidity and mortality. Centres performing this should have access to appropriate critical care and renal support services. For endovascular repair, there must be sufficient provision of interventional radiology services with availability of appropriately trained personnel.

Monitoring and clinical governance

To support implementation and ongoing clinical governance units will submit all AAA cases that undergo intervention to the National Vascular Registry. Units should regularly review their outcomes compared to those for the rest of the country.