Aortic Aneurysm and Dissection

Question 1

Define aneurysm.

Answer 1

• Aneurysm is a full thickness dilatation of an artery by more than 50% of its normal diameter.
  
  • Normal aortic diameter is ~2cm, therefore an aortic aneurysm occurs when the diameter is >3cm.
  • 2-3cm is referred to as ‘ectatic’.
• True aneurysms involve dilatation of all the layers of the arterial wall.
  
  • E.g. atherosclerotic aneurysms.
• False aneurysms do not involve all the layers of the arterial wall.
  
  • E.g. iatrogenic damage to an artery during angioplasty, forming groin haematoma with ongoing arterial flow is a ‘false’ or ‘pseudo’ aneurysm.

Question 2

Describe the different types of aneurysm.

Answer 2

• Aneurysms are usually fusiform, with circumferential dilatation of the artery. Fusiform = most common type.
• However, saccular aneurysms can also form on the side wall of the artery, often because a small “penetrating ulcer” in an atherosclerotic plaque has dilated. They are also at risk of rupture.
• Saccular happens when there is a small ulcer within the atherosclerotic plaque which can dilate and become aneurysm on the side of a vessel wall. Can often be treated by stenting if at risk of rupture.

Question 3

What are the risk factors for aortic aneurysm?

Answer 3

• Age
• Sex
• Hypertension
• FHx
• Smoking
• Not diabetes

Question 4

Describe the natural history of aortic aneurysm?

Answer 4

1. Gradual expansion (~1mm / year)
2. ?Rupture

Question 5

How can aortic aneurysms present?

Answer 5

• Asymptomatic
• Symptomatic - pain, embolus
• Ruptured

Question 6

Describe the aneurysm screening programme.

Answer 6

• All men are invited in the year after they turn 65.
• Abdominal USS to inspect aorta.
• If >3cm, ongoing follow-up or aorta.
• If >5.5cm, referred to surgical clinic for investigation and treatment.
• Targets - 2 weeks from diagnosis to clinic appointment, and 40 days from diagnosis to treatment of aneurysm.

Question 7

Describe the management of an asymptomatic aneurysm (>5.5cm).

Answer 7

• USS - for diagnosis.
• Clinic appointment.
• CT angiogram - to outline anatomy and clarify what options are available.
• Anaesthetic assessment (including at least ECHO and PFTs).
• MDT discussion (anaesthetists, interventional radiologists and surgeons).
• Surgery.

Question 8

Describe symptomatic aortic aneurysms.

Answer 8

• Pain
  
  • Pain or tenderness without evidence of rupture on CT.
• Acute limb ischaemia
  
  • Due to thrombus inside aneurysm embolising distally into lower limbs.
• Inflammatory aneurysms
  
  • May cause pain, and other local symptoms such as hydronephrosis due to ureteric involvement within inflammation.
  • Indications for repair include persistent pain, or local effects on other organs such as hydronephrosis.
• Symptomatic aneurysm is an indication for repair, irrespective of its size.

Question 9

Describe the presentation of a ruptured abdominal aortic aneurysm.

Answer 9

• Mortality and morbidiy is high - have a high index of suspicion.
• Back pain
• Abdominal pain
• Hypotension
• Collapse
• Atypical presentations:
  
  • Left renal angle pain radiating to groin. FIRST PRESENTATION of renal colic in a man >60 - DO NOT MISS THIS.
  • RIF pain
  • Back pain

Question 10

Describe the management of ruptured AAA.

Answer 10

• A, B, C
• Call for help - get senior support pronto and vascular team on board early.
• Oxygen
• IV access - bloods, G&S, major haemorrhage protocol.
• Fluids?
• CT angiogram
• Vascular team will alert theatre and anaesthetics early.
• EVAR
• Open surgical repair

Question 11

Describe permissive hypotension.

Answer 11

• In the setting of intra-abdominal bleeding, hypotension can be helpful.
• If BP is increased rapidly, then this may destabilise retroperitoneal haematoma, and cause bleeding to worsen.
• Aim whilst organising surgery is to perfuse brain - if the patient is orientated and able to talk, the BP is sufficient.
• Transfuse if disorientated and confused.
• Permissive hypotension is used to facilitate resuscitation in the setting of major bleeding. Rapidly infusing fluids to increase BP may destabilise clot and start bleeding again that had slowed or stopped.

Question 12

Describe aortic dissection.

Answer 12

• Tear occurs in the intima, allowing blood to enter the media of the aortic wall.
• This can then propagate proximally and distally, ‘dissecting’ the layers of the wall apart and causing a false lumen or channel to form with blood flowing within the wall.

Question 13

What are the risk factors for aortic dissection?

Answer 13

• Hypertension
• Most common in men aged 65-75.
• Also associated with genetic conditions such as Marfan’s syndrome.

Question 14

Describe the classification of aortic dissection.

Answer 14

• Stanford:
  
  • Type A involves the ascending aortia (+/- descending).
  • Type B involves descending aorta alone.

Question 15

Describe the presentation and complications of type A aortic dissection.

Answer 15

• Affects ascending aorta.
• Presents with sudden onset ‘tearing’ anterior chest pain.
• Cardiac complications include acute mitral regurgitation, MI, cardiac tamponade and stroke (due to extension into carotid arteries).
• Urgent transfer to cardiothoracics for surgical arch replacement if patient is fit - no role for medical management.

Question 16

Describe the presentation, management and complications of type B aortic dissection.

Answer 16

• Presents with sudden onset intracapsular pain.
• Pain control and urgent BP control (aiming BP <110mmHg).
• Joint management vascular surgery and cardiology.
• Indications for surgery: uncontrolled pain, end organ hypoperfusion, ongoing dilatation and dissection despite BP control.
• EVAR management is usually surgical management option.
• Conservative management with BP control usually has a good outcome - requires follow-up to detect future aneurysmal dilatation.
• Often need Labetolol infusion to control BP.