Aortic dissection and aneurysm Flashcards
What is meant by an aneurysm?
A permanent, localised dilatation of an artery of more than 50% of its normal diameter
What is the normal aortic diameter and at what size is an aortic aneurysm classified?
Normal diameter = 1.2 - 2cm
Aneurysm = >3cm
What are the 2 types of aneurysm?
True aneurysm
false aneurysm
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
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
What can usually be found in the extra space of an aneurysm?
A platelet-rich thrombus caused by collagen exposure
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)
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
What percentage of AAAs are asymptomatic?
75%
What are some of the common methods of screening for Abdominal Aortic Aneurysms (AAA)?
Ultrasound
CT scan
What are some common screening methods for AAA?
Ultrasound
CT scanning
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
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
What occurs in an AAA rupture?
The blood is first, briefly contained in the retroperitoneum, before erupting into the rest of the abdominal cavity
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
What are some common symptoms of AAA?
Rupture
Trashing
Pain
What is meant by trashing?
Micro-emboli moving down towards the feet due to breaking apart of the blood clot found in the aneurysm
What are the 2 classes of repair of AAA?
Elective aneurysm repair - prophylactic
Emergency aneurysm repair - Due to risk to life
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
