Peripheral Vasculature in Health and Disease 2, Venous Aspects

Question 1

Describe veins

Answer 1

• Three layers
• Thin walled
• Large expandable lumen
• Not so circular
• Low pressure
• Valves

Question 2

Describe small vein tributaries

Answer 2

Veins in the hand and foot, kidneys, brain, eye

Question 3

Describe medium veins

Answer 3

Mesenteric, renal, femoral, popliteal, tibial, subclavian, brachial

Question 4

Describe large veins

Answer 4

Vena cava, great veins in chest, iliac

Question 5

How can blood drain by many routes?

Answer 5

• Many anastomoses

- Collateral circulation can compensate for occlusion of the main system in almost all circumstances

Question 6

Describe how venous return works

Answer 6

• Muscle pumps
• Thoracic pump action during respiration
• Gravity- lying down
• Right heart function
• Requires functioning competent valves

Question 7

Describe the venous reservoir

Answer 7

-High capacitance system
-64% of the total systemic circulation is within the veins
=18% in large veins
=21% in large venous networks such as liver, bone marrow
=25% in venules and medium sized veins

Question 8

What is venous insufficiency?

Answer 8

• Failure of the muscle pump (typically calf muscle)- immobility, dependency, fixed ankle, loss of muscle mass
• Failure of valves
• Both

Question 9

How are the normal Starling forces disrupted in venous hypertension?

Answer 9

Affects blood pressure- 35 mmHg in arterial end vs 25 mmHg in venule end (should be 16) due to high venous pressure

Question 10

Describe venous hypertension

Answer 10

• Hemosiderin straining
• Swollen legs
• Itchy, fragile skin
• “Gaiter” distribution (shin pad)
• Risk of ulceration

Question 11

What is the treatment for venous hypertension?

Answer 11

• Emollient to stop skin cracks
• Compression (bandages, wraps, stockings)
• Elevate and mobilise

Question 12

What does valve failure lead to?

Answer 12

• Superficial veins= Varicose veins

- Deep veins= venous hypertension

Question 13

What is the treatment for valve failure?

Answer 13

• Superficial veins= endothermal ablation, surgical removal, foam sclerotherapy, adhesive occlusion, compression
• Deep veins= compression

Question 14

How does Virchow’s Triad link to venous thrombosis?

Answer 14

• Coagulopathy (blood)
• Stasis/ turbulence (flow)
• Endothelial abnormality (wall)

Question 15

Where does Deep Venous Thrombosis occur?

Answer 15

Typically pelvic/ leg veins but can be axillary/ subclavian upper limb DVT

Question 16

What are the risk factors for DVT?

Answer 16

Over 60
Overweight
Smoker
Previous DVT
Contraceptive pill
Cancer
Heart failure

Question 17

What is Phlegmasia and Venous Gangrene?

Answer 17

Rare, often with underlying cancer, thrombolysis
results from extensive thrombotic occlusion (blockage by a thrombus) of the major and the collateral veins of an extremity

Question 18

How is DVT managed?

Answer 18

Anticoagulation
Standard management
Recannalisation can occur
Valve damage allows reflux
Not a major issue if calf vein DVT
Problem if iliac vein
Post thrombolytic limb syndrome

Question 19

Describe superficial thrombophlebitis

Answer 19

Minor trauma
Usually underlying varicose veins
Symptomatic treatment
Heparin to stop propagation
Consider treating varicose vein

Question 20

Describe the porto-systemic venous system

Answer 20

• Mesenteric or portal venous drainage is via the liver before the heart
• Systemic circulation is returned to the heart directly
• The two circulation systems combine a number of points

Question 21

What is Porto-systemic venous anastomosis?

Answer 21

In liver disease the portal system fails to drain and porta; hypertension develops
Blood is therefore diverted into systemic venous system
collateral communication between the portal and the systemic venous system

Question 22

What dilated systemic veins are caused by portal hypertension?

Answer 22

Oesophageal varices

Caput Medusa

Question 23

How can veins be summarised?

Answer 23

• Veins are low pressure and rely on valves to ensure drainage
• Venous insufficiency can be failure of muscle pump or valves or both
• Venous thrombosis is determined by Virchow’s triad
• The portal venous system has anastomoses with the systemic venous system

Question 24

Describe the lymphatic system

Answer 24

• Three layers- adventia, media, intima
• Capillary structure
• Valves like veins
• Many anastomoses
• Drain to lymph nodes
• Ultimately drain to thoracic duct
• Thoracic duct empties to left subclavian vein

Question 25

What is lymphoedema?

Answer 25

Blocked lymphatic channels= interstitial fluid accumulates

Question 26

What is the worldwide most common cause of lymphoedema?

Answer 26

Filariasis- parasitic disease caused by roundworms and their larvae

Question 27

What is the treatment for lymphoedema?

Answer 27

• Compression
• Skin care
• Exercise
• Manual lymphatic drainage- specialised massage technique
• Rarely surgery to debulk, liposuction or connecting lymph channel to veins

Question 28

How can lymphatics be summarised?

Answer 28

• Low pressure, mesh-like system
• Valves like veins
• Drain into lymph nodes, then thoracic duct, the left subclavian vein
• Lymphoedema occurs when drainage obstructed

Question 29

How does simple oedema occur?

Answer 29

• Oncotic pressure is the colloid osmotic pressure induced by protein in the blood plasma
• Low protein (albumin) states lead to limb swelling and oedema

Question 30

What are the causes of reduced oncotic pressure?

Answer 30

• Liver failure
• Renal disease= low protein, too much water
• Malnutrition- kwashiorkor (severe protein deficiency)

Question 31

Describe inflammation

Answer 31

• Vasodilation a arteriole level
• Opening pre-capillary sphincter
• More permeable capillaries
• Swollen, hot tissue

Question 32

Describe lower limb cellulitis

Answer 32

Hot swollen leg
Tissue oedema
Chronic cellulitis= lymphatic obstruction

Question 33

Describe right ventricular failure

Answer 33

• Central venous pressure rises
• Peripheral venous pressure rises
• Increased interstitial fluid
• Oedema