Vascular Pathology

Question 1

What are the mechanisms of oedema formation?

Answer 1

1. Increased hydrostatic pressure - increased BP r decreased venous return
2. Decreased oncotic pressure - e.g. hypoproteinaemia (hypoalbuminaemia)
3. Increased vascular permeability - inflammation or immunogenic
4. Decreased lympathic drainage

Question 2

How can increased hydrostatic pressure cause oedema?

Answer 2

• Water +/- blood leaves BV
• BP decreases
• Kidneys stimulated to secrete renin
• Renin causes liver to produce angiotensin
• Angiotensin causes BV to constrict and BP increases
• Increases hydrostatic pressure
• Potentiates oedema

Question 3

How can normal circulation be disrupted pathologically?

Answer 3

• Rupture - arterial, aortic (horses)
• Torsion - twisted vessels, veins collapse, tissue congestion, infarction/necrosis
• Vascular thickening
• Vasculitis - leakage from loose vessel wall, hypoxia, anoxia
• Thrombosis - inappropriate haemostasis

Question 4

Define:

1. Aneurysm
2. Dissecting aneurysm
3. Emphyema

Answer 4

1. Aneurysm - thinning and dilation of blood vessel wall
2. Dissecting aneurysm - split in vessel wall causing weakening
3. Emphyema - accumulation of pus in body cavity

Question 5

Define arterioscelerosis

Answer 5

Hardening and thickening of arteries due to old age and high BP. Proliferation of medial smooth muscle and fibrosis of intima, +/- mineralisation

Question 6

Define atherosclerosis

Answer 6

Specific thickening of vessel walls due to depressed lipid metabolism. Fibro-fatty plaques accumulate in vessel wall causing occlusion. Endothelial damage leads to thrombus formation.

*Dogs with hypothyroidism*

Question 7

Define phlebitis and arteritis

Answer 7

• Phlebitis - inflammation of veins
• Arteritis - inflammation of arteries

Question 8

Define thrombus. Give examples of arterial and venous thrombi

Answer 8

• Thrombus - solid mass in BV when normal haemostasis is disrupted
• Arterial - saddle thrombus in cats (HCM - over birfurcation of iliac arteries)
• Venous - vena caval syndrome, iatrogenic (catheterisation)

Question 9

Describe the pathology of lymphatic disease

Answer 9

• Lesions are similar to those found in BV
• Lymphangiectasis - dilation of lymphatics in GI wall
• Rupture - thorax (thoracic duct; cyclothorax), abdomen (cisterna chyli; chylous ascites)
• Lymphangitis - systemic infection or idiopathic