Aneurysms

Question 1

Definition of aneurysms

Answer 1

localised abnormal dilation of a blood vessel or heart

can be saccular or fusiform

Question 2

True vs false aneurysms

Answer 2

• true aneurysm - intact attenuated vessel/heart wall

- false aneurysm - defect in vessel wall with extravascular hematoma that communicates with the intravascular space

Question 3

Causes of aneurysms (7)

Answer 3

1. Atherosclerosis
2. Tertiary syphilis
3. Cystic medial necrosis (dissecting)
4. Polyarteritis nodosa
5. Trauma
6. Congenital defect (berry)
7. Infections

Question 4

Pathogenesis of aneurysms

Answer 4

1. Weakening of vessel wall
   - Loss of elasticity & contractility due to deficiency in media
   - Poor intrinsic quality of vascular wall connective tissue
   - Collagen degradation by local inflammation

Question 5

Effects of aneurysms

Answer 5

1. Pressure on surrounding structures
2. Thromboembolism - disruption of laminar flow
3. Occlusion of branch vessels - ischemia
4. Rupture with haemorrhage
5. Cardiac disease - in thoracic aortic aneurysm - dilation of aortic valve - aortic insufficiency

Question 6

Features of berry aneurysms

Answer 6

• small berry-like saccular aneurysms in the Circle of Willis, 90% in ant circulation
• found in 2% of population, multiple in 20-30%
• rupture - subarachnoid hemorrhage
• idiopathic w associated genetic & predisposing factors

Question 7

Features of dissecting aneurysm

Answer 7

• blood enters arterial wall, splays apart laminar planes of media to form a blood filled channel within the vessel wall, dissects between its layers
• found in 40-60y men w htn (90%), young patients w connective tissue abnormalities affecting the aorta (eg Marfan’s) or due to iatrogenic factors (surgery, catheterisation)

Question 8

Pathogenesis of aortic dissection

Answer 8

1. Intimal tear/rupture of vasa vasorum
2. Hemorrhage occurs in between middle & outer third of media
3. Tear is usually in the ascending aorta, may dissect retrograde towards heart of distally
4. May rupture internally (back into intima) or externally (into adventitia, bleed into mediastinum, thoracic/abdo cavities, pericardial sac)

Question 9

Clinical features of aortic dissection

Answer 9

• sudden onset of excruciating pain

- usually from ant chest, radiating to back b/w scapulae, moves downwards as dissection progresses

Question 10

Effects of aortic dissection (3)

Answer 10

1. Bleeding/rupture into pericardial (cardiac tamponade), pleural or peritoneal cavities - death
2. Aortic valve insufficiency (retrograde dissection)
3. Extension into aorta branches - vascular obstruction & ischemia eg MI