The vascular system and stroke - Varicose veins, DVT and leg ulcers Flashcards
What is the gold standard imaging modality for assessing the competence of venous valves
Duplex ultrasound
a) What is a varicocele
b) Describe the presentation
c) Describe the complications
d) Describe the treatment
a) Enlargement of the scrotal veins
b) Often asymptomatic but may cause an ache or heavy feeling within the scrotum
c) Impaired fertility
d) If asymptomatic they require no treatment. If they are causing pain or infertility they can be treated using embolization or surgery. I
a) What is a thrombus?
b) What is it composed of?
a) A thrombus is a mass of normal blood constituents formed inappropriately within the circulation
b) Composed of fibrin and platelets with entrapped red and white blood cells
What are the 3 consequences of thrombus?
- May obstruct lumen of the vessel which it forms
- May form in cardiac chamber or vessel
- May break off, travel in circulation, and obstruct a vessel elsewhere - embolus/thromboembolus
Which process is thrombosis identical to? and define that process.
Haemostasis - a physiological response to injury of blood vessels
The process involved in thrombosis are identical to those involved in haemostasis. Describe the mechanisms of haemostasis.
- Injury to blood vessels leads to loss of the lining endothelial cells, which normally prevent haemostasis
- Exposure of underlying extracellular matrix (collagen), activates platelets forming a primary haemostatic plug
- Coagulation cascade activated
- Thrombin produced, fibrin deposited around fused platelets, producing secondary haemostatic plug
Name the 3 main components of controlled haemostasis
- Endothelial cells
- Platelets
- Coagulation system
a) What are endothelial cells?
b) List 3 properties of endothelial cells and provide 1-2 examples for each property
a) Normal interrupted sheet of cells with anti-thrombotic properties
b)
1. Antiplatelet properties - Prostacyclin and nitric oxide
- Anticoagulant properties - Antithrombin III and thrombomodulin-activated protein C/S
- Profibronyltic properties - tissue plasminogen activator (tPA)
a) What are platelets produced by?
b) How is it activated?
a) Produced by megakarocytes
b) Activated on exposure to sub endothelial extracellular matrix
a) What is the coagulation cascade?
b) Name the 2 pathways
c) What is the common pathway between the two pathways you mentioned above?
a) Cascade of protein converted from inactive pro-enzyme to active enzymes and cofactors
b)
1. Intrinsic pathway - Hageman factor (XII)
- Extrinsic pathway - tissue factor (thromboplastin)
c) Common pathway - Fibrinogen to fibrin
Name the 3 predisposing factors for thrombus information (Virchow’s triad)
- Change in blood flow
- Change in vessel wall
- Change in blood constituents
Name 5 causes of altered blood flow
- Narrowing caused by atherosclerosis
- Aneurysms
- Infarcted myocardium
- AF
- Abdominal cardiac rhythm
- Valvular heart disease
- Stasis
What does the
disruption of laminar flow cause?
- Causes platelets to come into contact with endothelium
- Leads to injury or activation of endothelium
- Impaired removal of pro-coagulant factors/impaired delivery of anti-coagulant factors
Name 3 causes that results in a change of vessel wall
- Endothelial cell injury or activation
- Coronary artery thrombosis
- myocardial infarction
Name 5 reasons for endothelial cell injury or activation
- Ischaemia hypoxia
- Infection of blood vessels
- Physical e.g., atheroma, crushed veins, hypertension
- Chemical e.g., lipids, cigarette toxins
- Immunological deposition of immune complexes
Changes in constituents of blood can be genetic or acquired
a) Provide 2 examples of genetic changes in constituents
b) Provide 5 examples of acquired changes in constituents
a)
1. Antithrombin II deficiency
2. Protein C
b)
1. Tissue damage
2. Pre-operative
3. Malignancy
4. Cigarette smoke
5. Elevated blood lipids
6. Oral contraceptives
Describe the possible fate of thrombus
a) What is an embolism?
b) Name the 5 types of embolism
a) An abnormal mass of undissolved material which is transported from one part of the circulation to another
b)
1. Thrombus
2. Gas - air, nitrogen
3. Fat
4. Tumour
5. Miscellaneous - foreign bodies (drug addicts), amniotic fluid, therapeutic
Name 3 ways that pulmonary thromboembolism may occur
- Saddle embolus
- Smaller emboli in peripheral arterial tree
- Paradoxical embolus
What is a saddle embolus?
Occludes both pulmonary arteries
What is paradoxical embolus?
An embolus that moves through intraatrial (e.g., patent foramen) or inter ventricular cardiac defect to gain access to systemic circulation. Following this, it may lead to an arterial embolus and associated sequelae (DVT like symptoms followed by the development of ALI)
a) Emboli can travel from the left side of heart or aorta will enter the systemic arterial system. What organs can it affect?
b) What is the consequence of this?
c) What is the consequence if the emboli is infected?
a) Brain, kidney, spleen, gut and legs
b) Ischaemia or infarction
c) Infected emboli may give rise pyaemia and absence formation
Air may enter the circulation, known as an air embolus. Give 2 reasons that could lead this to
- During obstetric procedures
- In chest wall injury
a) When do nitrogen embolus’ occur?
b) Describe how this occurs
c) What is this also known as and what organs can it affect?
a) Occurs in deep sea divers on rapid ascent
b) Occurs when nitrogen expands, bubbling out of tissues into the blood to form a painful gas emboli
c)
Decompression sickness (the bends). It can affect the skeletal muscle, brain, heart and lungs