Vascular Flashcards
Effect of age on arteries:
Arteries have properties to allow circulation propagation - as you get older these properties are lost, calcification occurs and vessels become less elastic = disease
proximal =
towards heart
distal =
away from heart
antegrade flow =
away from heart
retrograde flow =
towards heart
arteries and veins have 3 layers
intima, media, adventitia
intima
inner layer of vessel
vascular endothelium - provides lubrication
media
middle layer of vessel
made of elastin, collagen, layers of smooth muscle
provides elasticity
adventitia
outer layer of vessel
strong thick collagen layers with some elastin
fixes arteries in place
vein walls
walls are thin and very elastic
media and adventitia are less well-defined
distal veins have…
valves
the trunk or portal venous system do not have…
valves
How big are arterioles? What are walls made of? What do they do?
<1mm diameter
smooth muscle
control flow to distal capillary beds
Aorta =
The main artery that comes out of heart - main blood vessel that supplies body with blood (oxygen).
It runs straight down the centre of the body – sits just in front of spine, slightly to the left.
Ascending aorta
comes straight out of heart and into the aortic arch
Abdominal aorta splits into…
bifurcates into left and rigth common iliac arteries (at the level of the belly button to supply both legs with blood)
the thoracic aorta becomes the abdominal aorta at the level of the…
diaphragm
Abdominal aorta can be further divided into…
suprarenal = above kidney
Infrarenal aorta = below the renal arteries which supply blood to the kidneys
The abdominal aorta
Continuation of the descending thoracic aorta
Supplies all of the abdominal organs and the under surface of the diaphragm and parts of the abdominal wall. Its terminal goes on to supply the pelvis and lower limbs
the normal diameter of the abdominal aorta =
<2cm in diameter
Ultrasound: vein vs artery
arteries have thicker more muscular walls than veins
veins are easily compressed
central venous structures will fluctuate in size with respiration
Definition of an aneurysm:
An abnormal dilatation of a blood vessel by more than 50% of its normal diameter.
What diameter is considered an AAA?
> 3cm
When is an AAA at risk of rupture?
> 5.5cm
If AAA ruptures…
causes massive internal haemorrhage = patient needs urgent 2-week wait referral to vascular surgery to discuss elective repair
What is the cause of AAA?
atherosclerosis
What are the risk factors for AAA?
smoking is biggest risk factor
age
males at higher risk
PAD/CAD
family history
hypertension
high cholesterol
connective tissue disorders
diabetes is protective - slower AAA growth
Pathophysiology of AAA:
dilation/swelling of the aortic wall causes gradual weakening due to inflammation, oxidative stress, proteolysis and biochemical wall stress = loss of structural integrity due to reduced structural proteins (elastin + collagen)
there are 3 types of AAA
fusiform = bulges out on all sides
saccular = bulges only on 1 side
pseudoaneurysm = outer layer of aortic wall becomes dilated
Symptoms of AAA:
normal no symtoms until rupture
back pain, abdominal pain, low blood pressure, tachycardia, collapse or pulsatile abdominal mass
National Abdominal Aortic Aneurysm Screening Programme:
Men aged 65 and over
uses abdominal ultrasound scan
two anterier posterior measurements are taken (longitudinal + transverse)
Measure aorta in peak systole due to slight changes in diameter during the cardiac cycle
inner-to-inner measurements of diameter used for consistency
<3 = no anyrsuym
3-4.4 = annual survallence
4.5-5.4 = 3 monthly survallance
>5.5 = intervention
B mode =
brightness mode = grey scale 2D image
Curvy linear probe =
lower frequency = better penetration at depth at expense of resolution
Advantages of Ultrasound in AAA surveillance:
- Non-invasive
- Safe – no ionizing radiation
- Quick
- Accurate
- Reproducible – can show increases in AAA over time
- High patient acceptance – just cold jelly on skin
Limitations of Ultrasound in AAA surveillance:
obesity - aorta sitting deeper
excess bowel gas can cause acoustic shadowing (ultrasound can not pass through gas)
variation of aortic diameters with the cardiac cycle
no visualisation of the thoracic aorta
inter-operator and intra-operator variability
When is intervention used for an AAA?
- Asymptomatic and 5.5 cm or larger
- Symptomatic AAA
- Asymptomatic, larger than 4.0 cm and has grown by more than 1 cm in 1 year
Types of AAA intervention:
open surgery (invasive, higher risk and longer recovery so only used when appropriate)
endovascular aneurysm repair (EVAR) = used when comorbidities or anesthetic risk = uses catheter and stent graft
EVAR has risk of..
endoleaks = requires yearly monitoring
AAA open surgery thus has better outcomes long term
Endoleak
complication of EVAR (endovascular aneurysm repair)
blood flows outside of stent but within aneurysm sac
can be better detected using contrast-enhance ultrasound (microbubbles injected into bloodstream)
Thrombus =
blood clot
Blood clots (thrombus) forms due to…
Virchow’s Triad
Virchow’s Triad =
1) blood stasis
2) changes in vessel wall (damage)
3) thrombogenic changes in blood (hypercoagulability)
Blood stasis
free-flowing blood doesn’t clot
blood can get caught in areas and pool
external compression can cause clotting – e.g. tumours/pregnancy/muscle swelling after extreme weight lifting
May-Thurner Syndrome
Left iliac vein is compressed by the right iliac artery = Artery is sitting over top of iliac vein, causing vein compression + repeated strain = blood will clot = DVT
Things that trigger the Virchow’s triad
- major trauma
- congestive heart failure (inefficient pump) = oedema in legs, cooling of blood in reservoirs (veins)
- previous history
- central venous catheters
- hormone therapy
embolus =
detached mass able to travel in a vessel
embolism =
lodging of an embolus
Thrombo-embolism =
blockage by a thrombus that has travelled
Venous Thrombo-Embolic Disease (VTE):
Deep Vein Thrombosis (DVT) – usually in the lower limb
Pulmonary embolism (PE) - Sudden and life-threatening
DVT
Calf is painful, swollen, hot with reddened skin
Vein is non-compressible
Swelling around vein – oedema
Risk factors for Venous Thrombo-Embolic Disease (VTE):
surgery
immobility = sedentary lifestyle, elderly, surgery
age
malignancy
pregnancy
varicose veins (may not be causal)
thrombophilia (blood more likely to clot)
DVT NICE guidelines:
When DVT is suspected, the 2 level DVT Wells score is used to estimate the clinical probability of DVT.
Patients with a likely DVT Wells score (2 points or more):
A proximal leg vein ultrasound scan, with the result available within 4 hours if possible
A D dimer test if the scan result is negative, then offer a repeat proximal leg vein ultrasound scan 6-8 days later.
Why do DVTs need to be treated?
DVT can embolise to lungs = life-threatening
Blood clot in leg causes scaring = venous pooling = venous hypertension = cascade of inflammation = ulcer
Patients can develop Post Thrombotic Syndrome (PTS)
Normally working people are effected = significant impact to NHS costs but also independence/earning potential
Post Thrombotic Syndrome (PTS)
chronic pain and swelling, venous congestion, oedema, ulceration
different than claudication – Claudication is reproducible (same aggravating factor (walking) and same relieving factor (rest). Whilst PTS feels like leg is going to burst.
Management of DVT:
Elevation – gravity to help drainage
Stockings – compress leg to reduce swelling (improved blood flow)
Anticoagulation - thins blood to prevent clot forming (reduces further risk of VT)
Invasive intervention of DVT:
Remove the clot and restore blood flow
- Mechanical thrombectomy
- Thrombolysis infusion via venous catheter
- Angiojet / mechanical assisted lysis / EKOS (endovenous ultrasound-assisted)
Varicose veins:
Effects superficial (surface level) veins
Characterised by enlarged tortuous veins and failure of valves
Causes aching heavy legs
faulty valves
weak walls
failure of calf muscle pump
aetiology of varicose veins?
Unknown
?DVT
?occupational standing
?obesity
Venous Incompetence results in…
venous hypertension
- pigmentation
- ulceration
- lipodermato-sclerosis or woody leg –thickening
- varicose eczema- leaking components – inflame -
- mis-shaping-“inverted champagne bottle”
- swelling
Venous ulceration =
painless
wet/weeping
tissue hardening
hyperpigmentation
arterial ulceration =
painful
necrotic edges
Varicose veins treatment options:
- Endovenous ablation
- Foam Sclerotherapy
- Surgery / Stab avulsions
- Pull vein out of leg
Lower limb vein disease:
DVT
Telangiectasia
Superficial Thrombophlebitis
Kippel-Trenaunay-Weber Syndrome
Telangiectasia =
- SPIDER VEINS
- sun damage
- post radiation
- NOT LIFE THREATENING
- venous hypertension
- chronic flushing
- not treated on NHS? laser?
Superficial Thrombophlebitis =
Superficial vein thrombosis
inflammation of vein caused by clotting
painful in the inflammatory phase
feels like hard lumpy ‘rope’ under skin
episodic
complication of varicose veins
does not usually progress to DVT but can
IV drug use
Kippel-Trenaunay-Weber Syndrome =
- rare congenital condition
- port wine stain
- varicose veins
- hypertrophy of soft tissue and bone locally
- underdeveloped lymph system
Carotid artery stenosis =
the internal carotid artery and vertebral arteries supply the brain
high velocities are associated with stenoses
stenosis can lead to embolisation, TIA and stroke
Stroke can be…
Hemorrhagic (15%) = caused by a burst blood vessel - blood pools in brain, causing a buildup of pressure on the brain.
ischemic (85%) - blood flow is blocked plaque build up, thrombosis (plaque rupture and blood clot formation) or embolism (clot breaks off from somewhere else)
Risk factors for stroke are same as….
PAD