CVS 16 - Peripheral AV disease Flashcards
What 2 parts is the lower limb venous system split into?
In which direction does blood flow
1) Superficial veins - within subcutaneous tissue
2) Deep veins - underneath the deep fascia (AKA: femoral vein)
- Blood moves from superficial to deep only
Describe the course of veins in the lower limb. Which of these are superficial?
1) External iliac vein becomes femoral vein
- The deep femoral and long saphenous (superficial) branches off the femoral vein.
2) Femoral vein becomes popliteal vein
- Short saphenous vein (superficial) branches off the popliteal vein
3) Popliteal vein becomes the anterior tibial, posterior tibial + peroneal veins
What is the calf muscle pump + what does it do?
- Called the “peripheral heart”. Soleus and gastrocnemius muscles push blood against gravity towards the heart by opening veins.
What are varicose veins + how do they occur?
What are the associated symptoms?
What are the risk factors?
- Valves ineffective + blood movement is slow or reversed (often in saphenous veins). Walls of the veins weaken + varicosities develop, veins become tortuous + twisted.
- Leg cramps + pain, ankle swelling, haemorrhage from damaged veins.
- Age, family history, female, standing a-lot occupation.
How does chronic venous insufficiency occur?
How does it present?
- Reflux +/or obstruction leading to venous hypertension.
- 50% of people get this within 10 years of a DVT
- Lipodermatosclerosis (thickening of fat layer under skin). brawny oedema + venous ulceration.
How does venous eczema and ulceration present?
- Chronic + painful ulcers develop around hard nodular areas, e.g: medial malleolus - a result of venous hypertension.
- Chronic, itchy red + swollen - leads to lipodermatosclerosis.
Why does the calf muscle pump sometimes fail?
Who is at risk of this?
What are the consequences + how is it treated?
- Under-use of calf muscles (plantarflexion in walking)
- Injured, immobile or obese people
- Retrograde flow of blood in deep vein incompetence
- Blood flows from deep to superficial veins in superficial vein incompetence.
- Ligation + vein stripping (stops retrograde flow + improves ulceration).
How is arterial + venous thrombosis caused?
- Arterial thrombosis = atheroma, platelets activated and aggregate to form plaque.
- Venous thrombosis = stasis + another factor (trauma, medication, inflammatory conditions etc) rich in fibrin.
What is deep vein thrombosis (DVT)?
What are the symptoms?
Why does it occur?
- Clotting of blood in a deep vein, commonly the calf. Inflammatory response follows thrombosis.
- Calf tenderness, warmth, distended + visible superficial veins.
- Due to stasis (no calf muscle pump), i.e.: before + after surgery, after trauma, pregnancy etc.
- Has fatal consequences (pulmonary embolism if clot breaks away).
Describe 2 alternative routes of blood flow + explain why they are there.
1) Collateral circulation - physiological design to limit incidence of acute ischaemia - e.g.: in the knee when we flex/bend the joint (genicular arteries)
2) Collateral circulation - adaptive response to stenosis of a major vessel over a period of months or years - e.g.: in the heart.
How may acute limb ischaemia occur + what are the signs?
- Via Afib or sudden rupture of atherosclerotic plaque, leading to acute occlusion.
- The 6P’s - pain, pallor, perishing with cold, pulseless, paraestheia + paralysis.
What does chronic peripheral arterial disease lead to?
How is it managed?
What diagnostic tool is used for peripheral arterial disease?
- Intermittent claudication (cramping pain induced by exercise) caused by atherosclerosis (like stable angina). Pain goes away upon rest.
- Management = exercise, smoking cessation, anti-platelet drugs etc.
- Ankle-Brachial Index (ABI) - divide ankle systolic by brachial diastolic. <0.9 indicated peripheral arterial disease.
What can peripheral vascular disease progress into?
What are the symptoms associated with this?
- Progression into critical limb ischaemia.
- Rest pain (like unstable angina), untreated will lead to ulceration and gangrene. Strong pain relief needed.
Where are the 4 lower limb pulses located?
1) Femoral pulse - mid inguinal point midway between anterior superior iliac spine + pubic symphysis.
2) Popliteal pulse - deep in the popliteal fossa
3) Dorsalis pedis pulse - lateral to extensor hallucis longus tendon
4) Posterior tibial pulse - behind the medial malleolus
How is doppler ultrasonography used to estimate flow + velocity of blood?
- Echoes produced from moving blood detected and computed into flow direction + velocity.
- Velocity increases through stenosis which can be measured using Doppler.
