Arteries and Veins Flashcards
What are the functions of arteries
- providing oxygen and nutrients to organs
- correct speed of flow (autoregulation)
- correct pressure (vital for perfusion)
How do arteries regulate blood pressure
Arteries can change calibre resulting in adequate pressure.
What does blood pressure depend on
Cardiac output and peripheral resistance.
What happens to surrounding tissues when blood pressure increases
Fluid leaks out into the surrounding tissues.
What happens to the blood when the fluid leaks out into the tissues due to high pressure
There will be an increase protein content in the blood when it reaches the venous system.
How does the hydrostatic and osmotic pressure system work across capillaries
Hydrostatic pressure causes fluid to leak out of capillaries. This pressure is greatest at the arterial end and lowest at the venule end. Osmotic pressure counterbalances this and holds blood in the blood vessel.
What happens in primary lymphedema
The person is born with fewer lymphatic vessels so is less able to return fluid back to the blood.
What happens in secondary lymphedema
The inability to return fluid back to the blood is due to an another factor.
What are three indirect methods of measuring arterial function
Organ function, oximetry, TcPO2 (transcutaneous partial pressure of oxygen)
What are three direct methods of measuring arterial function
Shygmomanometer, direct puncture and imaging.
How do you measure kidney function
Testing the urine.
What are some lifestyle factors which cause degeneration of arteries
- smoking
- age
- diabetes
What could be a consequence of the degeneration of arteries
They can dilate and become aneurysmic. The aneurysm could then rupture.
In what circumstances can blood vessels become damaged
Degenerative disease, occlusive disease, inflammatory disease, iatrogenic injury, trauma
What are examples of degenerative diseases that can damage arteries
Arterial aneurysms, traumatic aneurysms, false aneurysms, mycotic aneurysms, ehlers-danlos syndrome, marfans syndrome.
How may a traumatic aneurysm occur
A seatbelt may crush the aorta in a car crash and cause a traumatic aneurysm.
What is a false aneurysm (pseudoaneurysm)
This does not involve the artery itself. If the artery has a small hole, blood can leak out and create a cavity. The cavity pulsates and gives the impression of being aneurysmic.
At what diameter does the risk of rupture of an aneurysm become high
Between 5 and 6 cm.
How do you repair an aortic aneurysm
Using an aortic graft which is inserted using open surgery. This does not degenerate unless it becomes infected.
In which gender are aortic aneurysms more common
Male
What is claudication
Claudication can result from peripheral vascular disease. This is where there is not enough blood supply to the legs and the person cannot walk properly. Often people need to stop to allow blood flow to the legs.
How can claudication be compensated for
Collateral circulation
What is used to treat peripheral vascular disease
Antiplatelets, lipid lowering drugs, control of blood pressure and smoking cessation.
What is vasculitis
Inflammation of the blood vessels
What is the most common form of vasculitis
Rheumatoid arthritis.
What is used to treat vasculitis
Steroids
Other than vasculitis, what are two other examplesinflammatory disease affecting the blood vessels
Takayasus and diabetes,
What type of drug use can result in blood vessel damage
Intra-arterial drug use.
What are the functions of veins
They return oxygen and nutrient depleted blood back to the heart. They also act as a reservior.
What fraction of blood volume is in the venous system
2/3 blood volume
What type of flow occurs in veins - active or passive
Passive
What are venae comitantes
Veins which are wrapped around arteries.
What is an example of an artery which has lots of venae comitantes
The popliteal artery in the leg.
What is the function of venae comitantes
To warm up the blood as it returns to the heart.
What are three important features of the structure of veins
- thin wall
- they distend
- they have valves
What is the significance of the fact that veins distend
It means they can be used in bypass surgery as they are able to cope with arterial pressure.
What is the function of valves in veins
To spread the pressure in the vein so that the venous column is divided into shorter segments and the pressure does not all collect at the bottom.
What is the purpose of Doppler imaging for taking venous measurements
It allows the direction of blood flow to be visualised so that reflux in the valves can be detected.
What is plethysmography
A method of venous measurement which allows assessment of change in volume.
How does ultrasound mapping work in venous assessment
Veins should compress easily on ultrasound. if they do not, this means there may be a clot present in the vein.
What is venography
It is a method where dye is injected into the veins and allows the blood flow through the veins to be visualised. it is similar to angiography.
What can go wrong in the veins
Venous hypertension or venous obstruction
What are the causes of venous hypertension
- right heart failure
- deep vein incompetence
- superficial vein incompetence
What is deep vein incompetence
it is where a thrombus which had formed in the deep veins dissolves and damages the valves.
What are the causes of venous obstruction
Deep venous thrombosis and mechanical obstruction
What causes deep vein thrombosis
Any one of Virchow’s triad (stasis, hypercoagulability and endothelial damage)
What is an example of a cause of mechanical venous obstruction
A cancerous tumour causing pressure on the vein and subsequent obstruction.
What occurs to the jugular vein in right heart failure
It distends.
What condition can superficial venous incompetence lead to
Varicose veins
What is a tell-tale sign of varicose veins
Discolouration of the ankles.
What happens to cause varicose veins
There is increased pressure of blood at the ankles due to the lack of competence of the venous valves. There is leakage of fluid from he blood and the pressure increases further. Blood can also leak out and collect at the ankles leading to discolouration.
In what circumstances does ulceration occur
When the area is so nutritionally deplete that healing cannot occur.
What is used to treat varicose veins
Surgical procedures.
How is open surgery to treat varicose veins performed
A cut is made in the groin and the saphenous vein is disconnected. The varicose vein is then pulled out.
What is the name of the surgical procedure to remove a vein
Phlebectomy
How does foam sclerotherapy work as a treatment for varicose veins
Foam is created and injected into the vein to irritate it and cause it to close up.
What is the disadvantage of foam sclerotherapy
Discolouration
What is the current most commonly used procedure for treatment of varicose veins
Radiofrequency ablation
How does radiofrequency ablation for treatment of varicose veins work
A catheter is inserted into the vein and the vein is treated with heat until it closes off. The vein hardens.
How does endovenous laser treatment for varicose veins work
A fibre-optic laser is inserted into the diseased vein. Laser energy causes the vein to collapse so it becomes harmless fibrous tissue.
How does vein glue work in the treatment of varicose veins
Glue is injected into the vein through a catheter. The catheter is withdrawn and the glue hardens. The vein is sealed.
Which is more of a problem to deal with - arterial bleeding or venous bleeding
Venous bleeding
What are the most common causes of venous bleeding
Trauma and iatrogenic
In which veins does the worst bleeding occur
The vena cava and pelvic veins
What happens in phlegmasia
In this condition, blood van enter the leg through the arterial system but cannot get out again
How is phlegmasia treated
Blood needs to be compressed out of the leg so the leg needs to be elevated
What is the end result of phlegmasia if left untreated
Venous gangrene.
What happens if there is a blockage in the superior vena cava
Large venous collaterals form in compensation to try and get blood back to the heart. This causes very high pressure in the veins.
What diseases of the veins can occur
- varicose veins
- blocked iliac vein leading to phlegmasia and gangrene
- blocked superior vena cava
- neck engorgement
- haemorrhoids
- caput medusa
What lifestyle factor can cause venous disease
Intravenous drug use
What factors can cause venous disease
- intravenous drug use
- trauma
- iatrogenic injury
