37. Aortic Disease Flashcards
What are the 3 branches of the aorta?
- brachiocephalic artery (splits into right common carotid artery and right subclavian artery)
- left common carotid artery
- left subclavian artery
What is found within the aortic root?
- sinotubular junction
- right and left coronary ostrium
- right and left sinus of valsalva (give rise to coronary arteries; there are 3: one anterior (gives rise to right coronary artery) and two posterior; left posterior gives rise to left coronary artery and right posterior doesn’t give rise to any vessels)
What are 3 layers of the aorta?
- tunica intima
- tunica media
- tunica adventitia
What makes up tunica intima?
- layer of endothelial cells
- subendothelial layer made of collages and elastic fibres
- internal elastic membrane separates it from tunica media
What makes up tunica media?
- smooth muscle cells
- secrete elastin in the form of sheets or lameliae
What makes up tunica adventitia?
- thin connective tissue layer
- collagen fibres and elastic fibres
- the collagen in the adventitia prevents elastic arteries from stretching beyond their physiological limits during systole
When does atherosclerosis begin?
in early childhood
What are risk factors for atherosclerosis?
- hypertension
- hypercholesterolaemia
- smoking
- diabetes (and its control)
- family history
- male>female (relative protection in females until menopause)
Describe the stages of atherosclerotic plaque. (6)
- foam cells
- fatty streak
- intermediate lesion
- atheroma
- fibrous plaque
- complication lesion/ rupture
What is atherosclerosis the leading cause of? (3)
- stroke
- MI
- aneurysm
Define aneursm.
A localised enlargement of an artery caused by a weakening of the vessel wall
What are 4 different types of aneurysms?
- Saccular (true aneurysm)
- fusiform (true aneurysm)
- false aneurysm
- dissecting aneurysm
What does a saccular aneurysm look like?
- have a characteristic rounded shape
- true aneurysm involves the formation of the aneurysm sac from the arterial wall with at least one unbroken layer
What does a fusiform aneurysm look like?
- spindle shaped aneurysm
- true aneurysm involves the formation of the aneurysm sac from the arterial wall with at least one unbroken layer
What does a false aneurysm look like?
- usually caused by trauma
- the wall of the blood vessel is ruptured and blood escapes into surrounding tissues and forms a clot.
- because of pressure within the clot arising from the heart’s contractions, the clot often pulsates against the examiner’s hand as does a true aneurysm.
What does a dissecting aneurysm look like?
one resulting from hemorrhage that causes lengthwise splitting of the arterial wall, producing a tear in the inner wall (intima) and establishing communication with the lumen of the vessel. It usually affects the thoracic aorta but can also occur in other large arteries
What determines whether an aneurysm is true or false?
the layers involved
What is a true aneurysm? What is it associated with? (7)
- weakness and dilation of wall in ALL 3 layers
- associated with: hypertension, atherosclerosis, smoking, colagen abnormalities, Marfan’s cystic medal necrosis, trauma or infection (mycocic/ syphillis)
What infection is the most common to cause an aneurysm?
syphillis
What is a false aneurysm? What is it associated with?
- rupture of aortic wall with the haemorrhage either contained in the adventitial layers or by surrounding tissue
- third layer is still intact
- associated with:
- inflammation (e.g. endocarditis with septic emboli)
- trauma
- iatrogenic (caused by illness)
What can be felt/ examined with false aneurysms? (3)
- thrills
- bruits
- pulsatile mass
What does false aneurysm put the body at risk of? (2)
- ischaemia
2. rupture
What are the common aortic aneurysm sites? (4)
- in ascending aorta
- aortic arch aneurysm
- descending aorta aneurysm
- abdominal aorta aneurysm
What are signs and symptoms of aortic aneurysm based on?
based on location of the aneurysm
Are most aneurysms symptomatic?
No, most are asymptomatic and are discovered by chance on echo or chest x ray where dilated aorta will be seen
What are the signs and symptoms of thoracic aortic aneurysms? (8)
- shortness of breath (dyspnoea)
- heart failure
- dysphagia (difficulty swallowing) and hoarseness (ascending aorta, chronic)
- sharp, sudden chest pain radiating to the back (between should blades; possible dissection)
- pulsatile mass
- hypotension (compliance of aorta isn’t good)
- unequal arm pulses
- acute limb ischaemia
What is an aortic dissection?
- tear in the INNER wall of aorta
- blood forces walls apart (at high pressure from l.ventricle)
- acute (medical/surgical emergency) or chronic
What is a Debakey Type 1 thoracic aortic dissection?
Originates in the ascending aorta, propagates at least to the aortic arch and often beyond it distally
What is a Debakey Type 2 thoracic aortic dissection?
Original in and is confined to the ascending aorta
What is a Debakey Type 3 thoracic aortic dissection?
Originates in the descending aorta and extends distally down the aorta or rarely retrograde into the aortic arch and ascending aorta
What is Stanford Type A thoracic aortic dissection?
All dissections involving the ascending aorta regardless of site of origin
What is Stanford Type B thoracic aortic dissection?
All dissections NOT involving the ascending aorta
What is the aetiology for aortic dissection? (4)
- hypertension
- atherosclerosis (weakens layers of aorta)
- trauma
- Marfan’s
What is seen on histology in aortic dissection?
cystic medial necrosis
Describe the pathophysiology of aortic dissection.
- false lumen is created by first layer which is teared and second layer creates the aneurysm
- false lumen can progress in an antegrade or retrograde direction
What branches can aortic dissection occlude? (4)
Branches such as mesenteric, carotid, renal, spinal etc and more!
What can a dissection rupture cause?
Blood backs into the lumen or externally in to the pericardium which causes a temponade or mediastinum
What cardiac condition can be caused as a result of a dilated ascending aorta?
acute aortic regurgitation (which can be present as heart failure)
What are symptoms and signs of aortic dissection?
- tearing, severe chest pain radiating to the back; interscapular or anterior chest
- Collapse (due to temponade, acute aortic regurgitation, external rupture)
- inferior ST elevation
- nausea
- sweating and vomiting
- syncope
What does an aortic dissection involving a coronary artery cause?
myocardial ischaemia (and eventually death)
What does an aortic dissection involving a rupture into a pericardium cause?
acute temponade ( and eventually death)
What is found on examination in aortic dissection patients? (5)
- reduced or absent peripheral pulses (BP mismatch between sides)
- hypotension/ hypertension
- soft early diastolic murmur (aortic regurgitation)
- pulmonary oedema
- chest x ray shows widened mediastinum
What investigations should be done to diagnose an aortic dissection? (4)
- chest x ray
- echo (transthoracic (TTE) or tranoesophageal (TOE)
- cardiac CT
- MRI
What is the treatment for Type A aortic aneurysm? (ascending aorta involved)
Surgery
What is the treatment for Type B aortic aneurysm (not ascending aorta involved)? (3)
- meticulous BP control
- sodium nitroprusside plus beta blocker
- tend to be managed medically through drugs for BP control
What 2 infective and inflammatory infections can lead to aneurysms?
1 infective: syphyllis
2. inflammation: Takayasu’s arteritis
What medication is best avoided in aortic dissection patients?
ACEIs (until involvement of renal arteries has been excluded)
What antihypertensive drug therapy can be used at treatment for type B aneurysms? (3)
- beta blockers
- vasodilators e.g. hydralazine, nitrates and Ca antagonists (nifedipine or amlodipine)
- labetalol (combined alpha and beta blocker)
What type of disease is Takayasu’s arteritis?
Granulomatous vasculitis (inflammation of the aorta and pulmonary arteries)
Is Takayasu’s arteritis more common in males or females?
females
What structures does Takayasu’s arteritis affect?
aorta and its main branches
What does Takayasu’s arteritis cause? (5)
- stenosis/ narrowing
- thrombosis
- aneurysms
- renal artery stenosis
- neurological symptoms
What is the main treatment for Takayasu’s arteritis? (2)
- steroids
2. surgery
What bacteria causes syphilis that can lead to aneurysms?
treponema pallidum
What type of infective disease is syphilis?
an STD
What prevents later stages of syphilis?
antibiotics
What does primary syphilis cause the formation of on the skin?
chancre: painless ulcers (sores) forming approx. 21 days after syphilis exposure
Without treatment, what 3 types of syphilis do 1/3 of patients develop?
- late neuro-syphillis
- gummatous syphilis
- cardiac syphilis
When does cardiac syphilis present itself?
10-30 years post infection
What 2 conditions can cardiac syphilis cause?
- syphilitic aortitis (causing aortic aneurysms)
2. aortic regurgitation
What can cause a congenital aortic aneurysm? (3)
- biscuspid aortic valve
- coarctation of aorta
- Marfan’s syndrome
Why is bicuspid aortic valve so dangerous?
- presents fine at young age and at later stages in life can cause problems
- prone to stenosis and regurgitation
- 1-2% prevalence
What can a bicuspid valve be often associated with?
coarctation of the aorta (but not always)
What does a bicuspid aortic valve lead to?
- abnormal aorta with reduced tensile strength
- aorta more prone to aneurysm or dissection
What are bicuspid aortic valves monitored with? (2)
- echo
- MRI
Where does the tear in aortic dissection occur?
In the intima layer (inner layer) of the aorta
In which two types of aorta can aortic dissection usually happen?
usually in thoracic aorta or abdominal aorta
What happens when a tear occurs in the aorta during a dissection?
- tear forms 2 channels; one where blood continues to travel and one where blood stays still
- If the channel with non-traveling blood gets bigger, it can push on other branches of the aorta. This can narrow the other branches and reduce blood flow through them.
- aortic dissection can also cause abnormal widening and ballooning of the aorta leading to an aneurysm
What 3 shunts exist in a coarctation of aorta?
- ductus arteriosus
- foramen ovale
- ductus venosus
Where does aortic narrowing usually occur in coarctation of the aorta?
Close to where the ductus arteriosus inserts (ligamentum arteriosum; remnant of ductus arteriosis)
What are 3 types of coarctation of aorta?
- pre-ductal
- ductal
- post-ductal
What can pre-ductal coarctation cause? What can it be related to?
- 5% can be related to Turner’s
- can be life threatening of severe narrowing
What does post-ductal coarctation cause?
- most common in adults
- causes hypertension in upper extremities
- weak pulses in lower limbs
- associated with rib-notching (collateral circulation)
What are signs of aortic coarctation? (6)
- cold legs
- poor leg pulses
- hypertension
- headaches
- chest pain
- muscle weakness or leg cramps
If there is coarctation of aorta before l. subclavian artery, what does this cause? (2)
- Radial-radial delay
- right radial -femoral delay only
If there is coarctation of aorta after l.subclavian artery, what does this cause? (2)
- no radial-radial delay
- right AND left radio-femoral delay
What are symptoms of coarctation of aorta in infancy? (4)
More severe
- heart failure
- failure to thrive
- acidosis
- poor perfusion to lower limbs
What are symptoms of coarctation of aorta in later life? (5)
- hypertension
- muscle cramps/ weakness
- nosebleeds and headaches
- possible neurological changes
- cold legs
What gene is associated with Marfan’s? What does it cause
Fibrillin 1 gene; causes muscle weakness
What cardiac symptoms can Marfan’s cause? (3)
- aneurysm
- dissection
- aortic/ mitral valve prolapse or regurgitation
What other symptoms does Marfan’s cause in the eyes, skeletal system and lungs?
- eyes: cataract (clouding in the lens leading to decreased vision) and lens discolouration
- lungs: pneumothorax
- skeletal problems; stature
