Aneurysms Flashcards
Arterial vs venous system?
venous- low resistance vessels which take deoxygenated blood back to the heart
arterial- carries oxygenated blood from the heart to perfuse all the organs in the body. Much higher pressure
What are the three main layers to the arterial wall?
tunica intima- endothelial cells which are in direct contact with blood flowing in lumen
tunica media - muscular layer made up of smooth muscle cells and connective tissue
tunica externa (adventita)- made up largely of connective tissues and the tiny blood vessels which supply walls of larger arteries also run in this layer.
What is an aneurysm?
increase in diameter of an artery >1.5 times normal
AND
involving all layers of the arterial wall
True vs false vs dissection aneurysm?
TRUE- all layers of arterial wall
(fusiform and saccular)
FALSE- hole in the wall of an artery through which blood escapes and is then contained by the surrounding tissues. Sometimes bounded by adventitia but more often a thin wall is developed from the fibrin/ platelet cross links-which form as part of the clotting cascade.
DISSECTION- tear in the intima-which allows blood to track between the layers of the arterial wall
What are the arteries most affected by true aneurysms?
aorta (ascending, descending and abdominal), iliac arteries and the popliteal arteries.
Less common locations of aneurysms?
aneurysms of visceral arteries (splenic artery and cerebral arteries)
risk factors for aneurysms?
increasing age
male sex
genetics (connective tissue disorders)
Why is diabetes protective for aneurysms?
actions on components like metalloproteins in vessel wall- resulting in stiffer, more rigid arterial walls
Why are aneurysms a worry?
as aneurysms gets larger, the wall gets stretched progressively thinner and wall becomes too weak to contain the pressure- hole forms in arterial wall and allows blood to flow into surrounding tissues.
On cellular level: evidence of inflammation , smooth muscle cell death and degradation of the extracellular matrix.
Mortality rate of rAAA?
high
What does where aneurysm ruptures have to do with outcome?
if aneurysm ruptures posteriorly so can be more tamponaded by surrounding structures.
Parent may present with an episode of severe pain and then appear to stabilise.
if aneurysm ruptures anteriorly into peritoneal cavity then there’s a much higher initial mortality as this is a large space into which blood can pool.
What screening is available for over 65?
abdominal aortic aneurysm screening
What happens if small aneurysm found?
entered into a surveillance program and invited back for further ultra sound scans
What if found to have a large abdominal aortic aneurysm?
referred directly for consultation with vascular surgery
What is the threshold of treatment for an AAA?
5.5 cm
How do non ruptured aortic aneurysms present?
mostly asymptomatic
What is relevant history to ask about patients who need treated for AAA?
medical co-morbidities?
need care?
Describe open AAA repair?
requires laparotomy - cut down middle of stomach
move small bowel aside
cross clamp abdominal aorta above and below aneurysm- usually on abdominal aorta and common iliac arteries
open up aneurysm sac and removes any thrombus
and sew a synthetic graft in to replace the diseased section
Describe endovascular repair?
can be done under local, regional or general anesthetic
involves puncturing both femoral arteries under ultrasound guidance and then placing wires and sheaths into these to deliver stent grafts within the arteries
during procedure- need to use x-rays and dyes to visualise the arteries and allow positioning of stents in correct place
Compare OPEN VS EVAR?
OPEN- higher up-front morbidity and mortality
-good long term outcomes
-no long- term surveillance
EVAR- not all aneurysms are a suitable shape for a stent graft
-long term surveillance and ultrasound after
-higher re- intervention rates
What is the pre- operative repair?
- make him aware of both procedures
-arrange more tests (CT angiogram of aorta) - put him on statin- reduce inflammation in blood vessel walls
What are the tests for assessment and optimization of pre-operative fitness?
ECHO
Pulmonary Function Tests
CardioPulmonaryExercise test (CPEX)
Anaesthetic review
When should a clinical diagnosis of ruptured abdominal aortic aneurysm be considered?
- men aged 50 or over presenting with acute abdominal pain and hypotension should be considered to have rAAA until proven otherwise
-and for women with similar symptoms
What is the initial management of rAAA?
CT angiogram if possible
call necessary people
activate major haemorrhage protocol
arterial blood gas - idea of haemoglobin and lactate
analgesia for pain
