Aortic dysfunction Flashcards by James Reilly

What is normal diameter of aorta

2cm

increases with age

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Define aneurysm

Permanent dilation of the artery to TWICE the normal diameter

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Difference between a true aneurysm and false aneurysm

True - abnormal dilatation that involve all layers of arterial wall
False (pseudoaneurysm) - involves the collection of blood in the OUTER LAYER ONLY (ADVENTITIA) which communicates with the lumen e.g. after trauma from a femoral artery puncture

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What arteries are generally involved in a True Aneurysm

Abdominal aorta (most common)
Iliac, popliteal and femoral arteries
Thoracic aorta
(abdominal aneurysms are classified as abdominal or thoracic)

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Do abdominal aortic aneurysms (AAA) most commonly occur above or below the renal arteries

Below

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AAA: epidemiology

Incidence increases with age
Present in 5% of population >60
More common in men

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Abdominal aneurysms are classified as an aortic diameter exceeding what?

3cm

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Causes/Risk factors of AAAs

Often no specific identifiable causes
• Severe atherosclerotic damage
• Family history
• Tobacco smoking
• Male
• Increasing age
• Hypertension
• COPD
• Trauma
• Hyperlipidaemia

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AAA: Pathophysiology

Degradation of the elastic lamellae resulting in leukocyte infiltrate causing
enhanced proteolysis and smooth muscle cell loss.
The dilatation affects ALL THREE LAYERS of the vascular tunic (if it doesnt then it’s a pseudoaneurysm).

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Unruptured AAA clinical presentation

Often asymptomatic and only picked up via a routing abdominal examination or plain X-ray
Pain in abdomen, back, loin or groin
Pulsatile abdominal swelling (less pronounced)

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Ruptured AAA: clinical presentation

Intermittent or continuous abdominal pain (radiates to the back, iliac fossa’s or groin)
Pulsatile abdominal swelling (more pronounced)
Collapse
Hypotension
Tachycardia
Profound anaemia
Sudden death

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What increases chance of rupturing an AAA

Increased BP
Female
Smoker
Strong family history

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AAA Differential diagnosis

GI bleed
Ischaemic bowel
MSK pain
Perforated GI ulcer
Pyelonephritis
Appendicitis

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AAA Diagnosis

Abdominal ultrasound - can assess aorta to degree of 3mm

CT and/or MRI angiography scans

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AAA Treatment

Small aneurysms below 5.5cm are generally just monitored
Treat underlying causes
Modify risk factors e.g. smoking and diet
Vigorous BP control
Lowering of lipid in blood
Surgery

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What surgery could be done for a symptomatic AAA patient

Open surgical repair

Endovascular repair - stent inserted via femoral or iliac arteries

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What is normal size of mid-descending thoracic aorta?

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26-28mm

What patients are more prone to ascending thoracic aorta aneurysm

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Marfan syndrome

Hypertension

What patients are more prone to descending or arch thoracic aorta aneurysms

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Secondary to atherosclerosis

sometimes Syphilis

Causes of Thoracic Aorta Aneurysm

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STRONG GENETIC LINK - in some families it appears to be an autosomal dominant trait
Connective tissue disorders e.g. Marfan’s syndrome
Weight lifting, cocaine and amphetamine use - perhaps due to the large rise in BP when undertaking these activities
Aortic dissection

Risk factors of Thoracic Aorta Aneurysm

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Hypertension
Increasing age
Smoking
Bicuspid or unicuspid aortic valves
Atherosclerosis
COPD
Renal failure
Previous aortic aneurysm repair

Pathophysiology of Thoracic Aorta Aneurysm

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Inflammation, proteolysis and reduced survival of the smooth muscle cells in the aortic wall.
Once the aorta reaches a crucial diameter (around 6cm in the ascending and
7cm in the descending) it loses all distensibility so that a rise in BP to around
200mmHg can exceed the arterial wall strength and may trigger dissection
or rupture.

Clinical presentation of Thoracic Aorta Aneurysm

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-Generally asymptomatic
-May be diagnosed incidentally e.g. on routing CXR or cardiological
investigation or if complicated by dissection, rupture or other complications
- Pain in chest, neck, upper back, mid-back or epigastrium
- Aortic regurgitation
- Fever (if infective cause)
- Symptoms due to compression of local structures
- Acute pain
- Collapse, shock and sudden death
- Cardiac tamponade
- Haemoptysis

Differential diagnosis of Thoracic Aorta Aneurysm

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Thoracic back pain
Arterial ischaemia
Collapse
MI

Diagnosis of Thoracic Aorta Aneurysm

- CT or MRI used for assessment of TAA - Aortography (helpful for assessing the position of the key branches in relation to the aneurysm) - Transoesophageal echocardiography (useful for identifying aortic dissection) - Ultrasound

Treatment of Thoracic Aorta Aneurysm

Ruptured TAA requires urgent immediate surgery Symptomatic TAA's = surgery regardless of size Regular monitoring by CT or MRI every 6 months Rigorous BP control using Beta-blockers e.g. Bisoprolol Smoking cessation Treat underlying cause

Process of aortic dissection

Begins with a tear in the intima (inner wall) Blood then penetrates the diseased medial layer and flows between the layers of aorta Forces layers apart = results in dissection Medical emergency that can lead to death

What is the most common medical emergency affecting the aorta

Aortic dissection

What people are more at risk of aortic dissection

Men more at risk | Most common between ages of 50-70 (<40 is rare)

How can aortic dissection be classified

According to the timing of diagnosis from the origin of symptoms: • Acute - less than 2 weeks • Subacute - 2-8 weeks • Chronic - more than 8 weeks

Causes of aortic dissection

- Inherited - Degenerative - Atherosclerotic - Inflammatory - Trauma e.g. shearing stresses in a road traffic accident (RTA)

Pathophysiology of aortic dissection

Begins with a tear in the intimal lining of the aorta Tear allows a column of blood under prssure to enter the aortic wall, forming a haemotoma that separates the intima and adventitia to create a false lumen. False lumen extends for a variable distance in either direction.

Pathophysiology of aortic dissection: In what directions can the false lumen extend

Anterograde - towards bifurcations | Retrograde - towards the aortic root

Pathophysiology of aortic dissection: What are the most common sites for intimal tears

Within 2-3cm of aortic valve | Distal to left subclavian artery in the descending aorta

Pathophysiology of aortic dissection: Between which layers of the artery does false lumen form

Intima and adventitia

Clinical presentation of aortic dissection

Sudden onset of central chest pain that radiates to the back and down arms (mimics MI) Hypertension Pain is maximal from the onset (but in MI pain gains intensity) Shock and neurological symptoms secondary to loss of blood supply to spinal cord. Aortic regurgitation, coronary ischaemia and cardiac tamponade may develop. Peripheral pulses may be absent. Acute kidney failure, acute lower limb ischaemia or visceral ischaemia

What symptom of MI is mimiced by aortic dissection

Sudden onset of sever and central chest pain that radiates to the back and down the arms. But in MI pain increses from onset, but in aortic dissection the level of pain does not change.

Differential diagnosis of aortic dissection

Acute coronary syndrome, MI, Aortic regurgitation without dissection, MSK pain, pericarditis, cholecystitis, atherosclerotic embolism

Diagnosis of aortic dissection

CXR - widened mediastinum Urgant CT scan, Transoesophageal echocardiography or MRI will confirm the diagnosis

Treatment of aortic dissection

- At least 50% are hypertensive and may require urgent antihypertensive medication to reduce blood pressure to less than 120mmHg - give IV betablockers e.g. IV metoprolol or vasodilators e.g. IV GTN - Adequate analgesia e.g. morphine - Surgery to replace aortic arch - Endovascular intervention with stents - Patients require long term follow-up with CT or MRI

Aortic dysfunction Flashcards

(40 cards)