S11) The Peripheral Arterial and Venous Systems Flashcards

1
Q

Describe the role of the calf muscles in blood circulation in the limbs

A
  • The veins in the lower limb have valves which permit unidirectional blood flow
  • When the calf muscles contract, the deep veins are compressed and blood flows upwards
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2
Q

Briefly describe the role of perforating veins in the lower limb

A
  • When the muscles relax, blood is “sucked” into the deep veins via the perforating veins from the superficial veins
  • The valves in the perforating veins only allow unidirectional blood flow
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3
Q

Describe the pathology of the perforating veins of the lower limb

A

Varicosities result when the valves in the perforating veins become incompetent or diseased

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4
Q

What are varicose veins?

A

Varicose veins are tortuous, twisted, or lengthened veins

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5
Q

Describe the pathophysiology of varicose veins

A

The vein wall is inherently weak in varicose veins, which leads to dilatation and separation of valve cusps so that they become incompetent

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6
Q

What are the symptoms of varicose veins?

A

Occur along the vein itself (trunk varices):

  • Heaviness
  • Tension
  • Aching
  • Itching
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7
Q

What are the 5 complications of varicose veins resulting from venous hypertension due to calf muscle pump failure?

A
  • Oedema
  • Skin pigmentation
  • Varicose eczema
  • Lipodermatosclerosis
  • Venous ulceration
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8
Q

What are the complications of varicose veins resulting from the vein itself?

A
  • Haemorrhage
  • Thrombophlebitis
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9
Q

What is thrombophlebitis?

A

Thrombophlebitis is an inflammatory process that causes a venous thrombosis to form, commonly in the legs:

  • Superficial thrombophlebitis
  • Deep vein thrombosis
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10
Q

What are the causes of calf muscle pump failure?

A
  • Failure of calf muscle contraction – immobility, obesity, reduced movement
  • Deep vein incompetence
  • Superficial vein incompetence (volume overload)
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11
Q

What is the pathophysiology of thrombosis?

A

Virchow’s triad:

  • Changes in the lining of the vessel wall
  • Changes in the flow of blood
  • Changes in the constituents of blood
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12
Q

In terms of Virchow’s triad, what is the most important factor in the pathophysiology of arterial thrombosis?

A

Changes in the lining of the vessel wall

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13
Q

In terms of Virchow’s triad, what is the most important factor in the pathophysiology of venous thrombosis?

A

Changes in the flow of blood

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14
Q

Does stasis lead to thrombosis?

A

Stasis + another provocateur (trauma, oral contraceptive pill, dehydration, cancer)

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15
Q

Distinguish between arterial and venous thrombosis in response to bleeding

A
  • Arterial thrombosis in response to bleeding involves vasoconstriction, platelets, extrinsic and then intrinsic pathways, hence arterial thrombi are platelet rich
  • Venous thrombosis in response to bleeding involves venoconstriction, intrinsic then extrinsic pathways, hence, venous thrombi are fibrin rich
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16
Q

What is a deep vein thrombosis?

A
  • A deep vein thrombosis is the formation of a thrombus within a deep vein, most commonly the deep calf veins
  • It produces an inflammatory response (calor, dolor, rubor, tumor, functio laesa)
17
Q

What are the symptoms of DVT?

A
  • Pain (cannot walk)
  • Swelling
  • Blue-red skin discolouration
18
Q

What are the signs of DVT?

A
  • Calf tenderness
  • Skin warmth & discolouration
  • Distended, warm superficial veins
  • Oedema
  • Pyrexia
19
Q

What is the association between surgery and DVT?

A
  • Immobility prior to surgery
  • No calf muscle pump during surgery
  • Immobility after surgery
  • Surgery is trauma (body’s response → prothrombotic state)
20
Q

What is the fatal consequence of DVT?

A

Pulmonary embolism

21
Q

What is peripheral arterial disease?

A

Peripheral arterial disease is a common condition, in which a build-up of fatty deposits in the arteries restricts blood supply to leg muscles

22
Q

What are the two types of peripheral arterial disease?

A
  • Acute limb ischaemia
  • Chronic limb ischaemia
23
Q

Describe the pathophysiology of acute limb ischaemia

A
  • The limb goes from a normal blood supply to greatly impaired blood supply over a period of minutes (sudden onset)
  • No chance for collateral vessel development (weeks/months)
24
Q

What are the commonest causes of acute limb ischaemia?

A
  • Embolism (from heart / abdominal aortic aneurysm)
  • Trauma
25
Q

What are the 6 signs & symptoms of acute limb ischaemia?

A
  • Pain
  • Paralysis
  • Paraesthesia
  • Pallor
  • Pulselessness
  • Perishing cold
26
Q

What are the consequences of acute limb ischaemia?

A
  • If not reversed within 6 hours the limb cannot be recovered
  • If not amputated the patient will die (hyperkalemia)
27
Q

What are the clinical features of chronic peripheral arterial disease?

A
  • Intermittent claudication (equivalent to stable angina)
  • Rest pain (equivalent to unstable angina)
  • Ulceration/gangrene (equivalent to myocardial infarction)
28
Q

What is claudication?

A

Claudication is pain in the muscles of the lower limb elicited by walking / exercise

29
Q

Where can you feel the femoral pulse?

A

The femoral pulse can be palpated at the mid-inguinal point

30
Q

Where can you feel the popliteal pulse?

A

Popliteal pulse is palpated deep in the popliteal fossa (difficult to feel)

31
Q

Where can you feel the dorsalis pedis pulse?

A

Dorsalis pedis pulse can be palpated just lateral to extensor hallucis longus tendon

32
Q

Where can you feel the posterior tibial pulse?

A

The posterior tibial pulse can be palpated posterior to the medial malleolus

33
Q

Describe normal lower limb circulation

A
  • No symptoms
  • Full set of lower limb pulses
34
Q

Describe aortoiliac occlusion

A
  • Bilateral buttock, thigh and calf claudication
  • Absent lower limb pulses
  • Rare
35
Q

Describe common iliac occlusion (unilateral)

A
  • Right buttock, thigh and calf claudication
  • Absent right lower limb pulses
  • Not so common
36
Q

Describe common femoral occlusion (unilateral)

A
  • Right thigh and calf claudication
  • Absent right lower limb pulses
  • Not so common
37
Q

Describe superficial femoral artery occlusion (unilateral)

A
  • Right calf claudication
  • Femoral pulse present, absent popliteal and pedal pulses
  • Commonest finding in patients with claudication
38
Q

What is rest pain?

A
  • Rest pain is pain in the foot that comes on when the patient goes to bed and is relieved by hanging the foot out of the bed
  • The ischaemia is so severe that at rest the foot skin, muscles, bones are ischaemic at rest, if left untreated then will progress to gangrene/ulceration
39
Q

What are the clinical features of critical ischaemia?

A
  • Rest pain (equivalent to unstable angina)
  • Ulceration/gangrene (equivalent to myocardial infarction)