Diseases of the Thoracic Aorta Flashcards
Features of Tunica Intima
- Layer of endothelial cells
- Subendothelial layer: collagen and elastic fibres
- Separated from tunica media internal elastic membrane
Features of Tunica media
- Smooth muscle cells
- Secrete elastin in the form of sheets, or lamellae
Features of Tunica adventitia
- Thin connective tissue layer
- Collagen fibres and elastic fibres (not lamellae)
- The collagen in the adventitia prevents elastic arteries from stretching beyond their physiological limits during systole
What are risk factors of atherosclerosis?
- Hypertension
- Hypercholesterolaemia
- Smoking
- Diabetes
- Family history
- Male > Female (relative protection in females until menopause)
Atherosclerosis timeline
Foam cells > Fatty streak > Intermediate lesion > Atheroma > Fibrous plaque > Complicated lesion/Rupture
What can atherosclerosis lead to?
- Stroke
- Myocardial infarction
- Aneurysm
What is an Aneurysm?
A localised enlargement of an artery caused by a weakening of the vessel wall
Classification of aneurysms by type
- Saccular aneurysm
- Fusiform aneurysm
- False aneurysm
- Dissecting aneurysm
Saccular and Fusiform are true aneurysms
What are features of a True aneurysm?
- Weakness & dilation of wall
- Involves all 3 layers
What are true aneurysms associated with?
- Hypertension
- Atherosclerosis
- Smoking
- Collagen abnormalities (Marfans’s, cystic medial necrosis)
- Trauma
- Infection (mycotic/syphillis)
What is a False Aneurysm?
Rupture of wall of aorta with the haemotoma either contained by the thin adventitial layer or by the surrounding soft tissue
What does a False aneurysm cause?
- Inflammation (e.g. endocarditis with septic emboli)
- Trauma
- Iatrogenic
- Thrills
- Bruit
- Pulsatile mass
- Ischaemia
- Rupture
Classification of aortic aneurysm by site
- Normal
- Ascending aorta aneurysm
- Aortic arch aneurysm
- Descending aorta aneurysm
- Abdominal aorta aneurysm
Signs and symptoms of Thoracic aneurysms
Asymptomatic
Based on the location of the aneurysm:
- Shortness of breath or even heart failure (AR)
- Dysphagia and hoarseness (ascending aorta, chronic)
- Sharp chest pain radiating to back - between shoulder blades, possible dissection
- Pulsatile mass
- Hypotension
Features of aortic dissection
- Tear in the inner wall of aorta
- Blood forces walls apart
- Acute - medical/surgical emergency
- Chronic
Classification systems of thoracic aortic dissection
DeBakey
- Type I
- Type II
- Type III
Stanford
- Type A: all dissections involving the ascending aorta, regardless of the site of origin.
- Type B: All dissections not involving the ascending aorta.
Features of Dissection
- False lumen can progress in an antegrade or retrograde direction
- May occlude branches (e.g. mesenteric, carotid, renal, spinal)
- Rupture: back into the lumen or externally in to pericardium (tamponade) or mediastinum
- Dilation of ascending aorta may cause acute aortic regurgutation.
Aetiological factors of dissection
- Hypertension
- Atherosclerosis
- Trauma
- Marfan’s syndrome
Histology of dissection
Cystic medial necrosis
Symptoms of aortic dissection
- Tearing, severe chest pain (radiating to back)
- Collapse (tamponade, acute AR, external rupture)
- Beware inferior ST elevation
Examination signs of aortic dissection
- Reduced or absent peripheral pulses (BP mismatch between sides)
- Hypotension/hypertension
- Soft early diastolic mumur (AR)
- Pulmonary oedema
- Chest X-ray usually shows a widened mediastinum
- Diagnosis can be confirmed by echocardiogram or CT scanning
What is the treatment for Type A aortic dissection?
Surgery: prophylactic aortic root surgery
What is the treatment for Type B aortic dissection?
- Meticulous blood pressure control
- Sodium nitroprusside plus beta blocker
Infection and Inflammation affecting the aorta
Infection: Syphyllis
Inflammation: Takayasu’s Arteritis
Features of Takayasu’s Arteritis
- Granulomatous vasculitis
- Females > Males
- Aorta & main branches
- Stenosis, thrombosis, aneurysms, renal artery stenosis, neurological sx
- Steroids
- Surgery
Features of Syphilis
- STD
- Treponema pallidum
- Antibiotics prevent late stages
Signs of Primary and Secondary syphillis
Primary - Chancre
Secondary - Rashes (mainly back rashes)
Tertiary Syphilis without treatment
- Late neuro-syphillis
- Gummatous syphillis
- Cardiac syphillis
Features of congenital aortic aneurysm
- Bicuspid aortic valve
- Marfan’s syndrome
- Coarctation
Features of Bicuspid aortic valve
- Most common congenital abnormality
- 1-2% prevalence
- Prone to stenosis +/- regurgitation
- Associated with coarctation
- Abnormal aorta (reduced tensile strength)
- Prone to aneurysm/dissection
- Monitor with echo/MRI
What occurs during Aortic Coarctation?
Narrowing below the left subclavian artery
What are the 3 shunts in coarctation?
- Ductus arteriosus
- Foramen ovale
- Ductus venosus
Features of Coarctation
- Aortic narrowing close to where Ductus arteriosus inserts (ligamentum arteriosum)
3 Types:
- Pre-ductal: (5% turner’s) can be life-threatening if severe narrowing
- Ductal
- Post-ductal: most common in adults, hypertension in upper extremities, weak pulses in lower limbs
Signs of Coarctation
- Cold legs
- Poor leg pulses
- If before left subclavian artery: Radial, Radial and Right radial-femoral delay
- If after left subclavian artery: no radial-radial delay, right and left radio-femoral delay
Symptoms of coarctation
Infancy (severe)
- Heart failure
- Failure to thrive
Later life
- Hypertension
Imaging for coarctation
- Chest Xray
- CMRI: narrowing distal to the subclvian artery
Features of Marfan’s Syndrome
- Fibrillin 1 gene
- Connective tissue weakness
- Aortic/Mitral valve prolapse - regurgitation
- Skeletal system
- Eyes (cataract, lens dislocation)
- Vascular: aneurysm, dissection
- Lungs (pneumothorax)
- Aneurysm
- Dissection
