Aortic dissection and aneurysm Flashcards by Jack Molyneux

What is meant by an aneurysm?

A permanent, localised dilatation of an artery of more than 50% of its normal diameter

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What is the normal aortic diameter and at what size is an aortic aneurysm classified?

Normal diameter = 1.2 - 2cm
Aneurysm = >3cm

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What are the 2 types of aneurysm?

True aneurysm
false aneurysm

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What is meant by a true aneurysm?

An aneurysm in which all 3 wall layers are involved, so the artery ‘balloons’ at one distinct point

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What is meant by a false aneurysm?

An aneurysm in which there is a defect in the artery wall and only 1 layer balloons out of the side of the artery

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What can usually be found in the extra space of an aneurysm?

A platelet-rich thrombus caused by collagen exposure

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What is the suspected pathogenesis of Abdominal Aortic Aneurysm?

Though it is not fully known, it is thought that it is due to abnormal regulation of elastin and collagen proteins in the aortic wall by enzymatic agents (Metallo-proteins)

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What are some of the risk factors for Abdominal Aortic Aneurysm (AAA)?

Age - Risk increases with age
Sex - M:F = 6:1
Genetic - Male family members
Smoking
Hypertension
Atherosclerosis

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What percentage of AAAs are asymptomatic?

75%

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What are some of the common methods of screening for Abdominal Aortic Aneurysms (AAA)?

Ultrasound
CT scan

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What are some common screening methods for AAA?

Ultrasound
CT scanning

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What are the uses of ultrasound in AAA scanning?

It allows for screening and surveillance
It can give the AP diameter (Anterior - Posterior)
It can show involvement of the iliac arteries

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What are the uses of CT scans in AAA?

It can give the aneurysm morphology, such as shape, size and iliac involvement
It allows for management planning

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What occurs in an AAA rupture?

The blood is first, briefly contained in the retroperitoneum, before erupting into the rest of the abdominal cavity

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At what point should intervention be started in AAA?

Evidence recommends repair of asymptomatic AAA when it reaches an AP diameter of 5.5cm, or when it becomes symptomatic

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What are some common symptoms of AAA?

Rupture
Trashing
Pain

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What is meant by trashing?

Micro-emboli moving down towards the feet due to breaking apart of the blood clot found in the aneurysm

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What are the 2 classes of repair of AAA?

Elective aneurysm repair - prophylactic
Emergency aneurysm repair - Due to risk to life

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What are the 2 types of treatment for AAA?

Open repair
EVAR = EndoVascular Aneurysm Repair

What are the advantages and disadvantages of EVAR

It is not possible in 25% of people
It has a lower mortality risk (1-2%) than open repair
It has a much faster recovery time (7-10 days) than open repair
It requires on-going follow ups and investigations

What are the advantages and disadvantages of open repair?

It is possible in most people
It has a greater mortality risk (3-4%) than EVAR
It has a much longer recovery time (8-9 months) than EVAR

What is involved in the EndoVascular Aneurysm Repair (EVAR) procedure?

Local anaesthetic is applied
Percutaneous access in the groin allows passing of a stent up through the femoral artery
This is X-ray guided
The stent is then opened via balloon
The stent is modular so comes in many parts
This provides a stronger, narrower tube for blood to pass through

What is involved in the open repair procedure?

General anaesthetic is required
A laparotomy is given (Incision to access abdominal cavity)
Aorta and iliac arteries are clamped to prevent exsanguination
Dacron grafting used where the old wall of the aneurysm is removed and a new wall is grafted around the aorta

What are some of the complications of EVAR?

Stent misplacement may lead to the stent covering the renal arteries or internal iliac arteries
Endoleak - blood flow out of the stent and into the aneurysm sac
Stent migration and dislocation - Pieces of the stent can move apart from each other

What are some complications of of open repair?

Myocardial infarction cerebrovascular accident Pneumonia Wound infection UTI Graft infection Pulmonary Embolism Renal failure mesenteric ischaemia (No blood to intestines) Lower limb ischaemia Trash foot Erectile dysfunction Death

What tests are performed to check fitness for intervention?

Cardiac assessment - Echo/Ejection function Respiratory assessment - Pulmonary Function Cardiopulmonary exercise test (CPX) Renal assessment Vascular assessment Anaesthetic assessment End of Bed test

What is involved in surveillance for AAA?

When a patient has an aneurysm between 3 and 5.5cm, they are put under surveillance which allows them to receive regular ultrasound testing

Who can be screened for AAA?

Only males over 65 can be screened via ultrasound, for AAA Females are at a lower risk of getting AAA, but are at higher risk of death once it has developed

What are the 3 types of Acute Aortic Syndromes?

Penetrating Aortic Ulcer (PAU) Intra Mural Haematoma (IMH) Aortic Dissection

What is a Penetrating Aortic Ulcer?

A hole in the intimal layer f the aortic wall that allows blood to move into the wall as an ulcer

What is an intra mural haematoma?

A Penetrating Aortic Ulcer in which the outer edge becomes disrupted, allowing blood to pass out of the aorta, through the ulcer

What is an aortic dissection?

Necrosis of the medial layer allows medial degeneration. A tear in the intima layer allows blood to move into the media layer and propagate, forming a flap between the true lumen and false lumen

What is meant by transmural bleeding?

Bleeding between the layers and eventually through the tunica adventitia

Where can propagation of an aortic dissection move to?

The aortic arch The aortic valve The coronary arteries The mesenteric and renal arteries The iliac arteries and down the limb

What allows a person to be predisposed to aortic dissection?

- Family history due to gene mutations such as Fibrillin-1 and Transforming growth factor ß1 - Connective tissue disorders such as Ehlers Danlos syndrome, Marfans syndrome and Loeys dietz syndrome - Trauma, including iatrogenic trauma

How are aortic dissections usually classified?

Stanford classification (Type A and Type B)

What is meant by a Type A aortic dissection?

A dissection that is proximal and affects the ascending aorta and arch of the aorta central to the left subclavian artery This is a cardiothoracic emergency!

What is meant by a Type B aortic dissection?

A dissection that is distal and affects anywhere distal to the left subclavian artery, including the thoracic and abdominal aorta This requires vascular surgery

What are the risks of propagation of the dissection flap?

Acute aortic valve regurgitation Myocardial infarction Cardiac tamponade Stroke Upper limb ischaemia Lower limb ischaemia Mesenteric ischaemia Spinal ischaemia (Paraplegia)

What are the main symptoms of Aortic dissection?

- Acute excruciating pain (tearing pain between the scapulae - Chest pain - Back pain - Abdominal pain - Syncope - Pulse deficits - Hypotension/shock - Visceral ischaemia - Renal ischaemia - Limb ischaemia - Recurrent pain - Spinal cord ischaemia (Paraplegia)

How is an aortic dissection diagnosed?

Via a CT scan from aortic arch to the femoral arteries, showing the full anatomy involved, the full extent of the dissection and perfusion to the limbs

What is the purpose of treatment of aortic dissection?

To prevent progression and rupture

What are the 2 main forms of treatment?

Blood pressure management Surgery

What is the aim for blood pressure lowering treatment?

To reduce the aortic wall stress and reduce the force of left ventricular ejection The target systolic blood pressure is around 100-120mmHg with a heart rate below 60bpm

What are the 2 forms of surgery available for aortic dissection?

Thoracic EndoVascular Repair - Stent graft Open Repair

What are the risks of surgical intervention for aortic dissection?

30-40% mortality risk 10% stroke risk 2% spinal cord ischaemia (Paraplegia)

When are follow-up examinations performed after surgical intervention?

3, 6 and 12 months