Robbins 9th ed - Chapter 11 - Blood Vessels - Aneurysm and Dissection (1)

Question 1

Define a “true aneurysm”.

Answer 1

This is an area of an artery that has a widened lumen due to stretched arterial wall. The area is enclosed by intact arterial wall components, and all blood remains in the vascular space.

Question 2

Define a “false aneurysm”.

Answer 2

This is an extravascular haematoma that communicates with the intravascular space. The entire thickness of the arterial wall has been punctured.

Question 3

Define a “dissection”.

Answer 3

This is when there is a defect in the intima, leading to blood accumulation in between the intima and the media (an intramural haematoma). The media and adventitia remain intact.

Question 4

Define a “Berry aneurysm”.

Answer 4

This is a spherical dilatation (a type of saccular aneurysm) due to congenital wall weakness, most common in the Circle of Willis.

Question 5

Define a “saccular aneurysm”

Answer 5

Large spherical dilation up to 20cm diameter often partially filled with thrombus. Generally occur secondary to atherosclerosis. “Berry aneurysm” is another term often used interchangeably with “saccular aneurysm”.

Question 6

Define a “fusiform aneurysm”

Answer 6

This is cylindrical dilatation, rather than an out-pouching. Most commonly seen in the aorta. Generally occurs secondary to atherosclerosis.

Question 7

What is the most common cause of an abdominal aortic aneurysm? What is a secondary risk factor?

Answer 7

Atherosclerosis. A secondary risk factor is FHx.

Question 8

What is the most common cause of an ascending aortic aneurysm?

Answer 8

Hypertension.

Question 9

Apart from atherosclerosis and FHx, name a few other risk factors for developing aortic aneurysms.

Answer 9

HT, Smoking, Age >50, Syphilis, Trauma, Vasculitis, Connective tissue disorders such as Marfan’s or Ehlers-Danlos, Infection (mycotic aneurysms)

Question 10

Describe the epidemiology of abdominal aortic aneurysms.

Answer 10

Much more common in men. Incidence rises with increasing age and smoking. Incidence is less than 5% of men over 60.

Question 11

What is the classic location for an abdominal aortic aneurysm?

Answer 11

Between the renal arteries and the common iliacs.

Question 12

Name four dangerous potential outcomes of an abdominal aortic aneurysm.

Answer 12

1) Rupture, and haemorrhage into intraperitoneal cavity or retroperitoneal tissues.
2) Occlusion of a branch of the aorta, by direct pressure or by thrombus
3) Thrombus formation and embolization
4) Compression of an adjacent structure – ureter, vertebrae.

Question 13

What is the risk of rupture of an abdominal aortic aneurysm that is <4cm in diameter?

Answer 13

Almost zero per year

Question 14

What is the risk of rupture of an abdominal aortic aneurysm that is 4-5cm in diameter?

Answer 14

1% per year.

Question 15

What is the risk of rupture of an abdominal aortic aneurysm that is 5-6cm in diameter?

Answer 15

11% per year.

Question 16

What is the risk of rupture of an abdominal aortic aneurysm that is larger than 6cm diameter?

Answer 16

25% per year.

Question 17

Describe a few details about thoracic aortic aneurysms.

Answer 17

They are uncommon. They can be secondary to HT, Marfan’s, or tertiary syphilis. Dissection is rare due to scarring.

Question 18

What is the most common cause of aortic dissection?

Answer 18

Hypertension (90% of cases).

Question 19

Epidemiology of aortic dissection: name two population groups.

Answer 19

1) Men aged 40-60 with pre-existing hypertension

2) Younger patients with Marfan’s or other connective tissue disorders

Question 20

What causes the initial intimal tear and the beginnings of an intramural thrombus formation?

Answer 20

This is usually not known.

Question 21

What is a Type A dissection? What is a Type B? Which is more common? Which is more dangerous?

Answer 21

Type A (being both more common and more dangerous) involves the ascending aorta. Type B does not involve the ascending aorta.

Question 22

What is a DeBakey Type I dissection?

Answer 22

Type I is when both the ascending and descending aortas are involved.

Question 23

What is a DeBakey Type II dissection?

Answer 23

Type II is when only the ascending, but not the descending, aorta is involved.

Question 24

What is a DeBakey Type III dissection?

Answer 24

Type III is when only the descending, but not the ascending, aorta is involved.

Question 25

Name three potential dangerous outcomes of an aortic dissection.

Answer 25

1) Rupture through the adventitia, into the peritoneum, pericardium or pleural space
2) Extension into arterial branches resulting in occlusion
3) Retrograde extension resulting in disruption of aortic valve