Diseases of Thoracic Aorta

4 sections of the thoracic aorta

aortic root - root of valsalva

• starts at level of aortic valve until sinotubular junction

ascending aorta

• starts at level of sinotubular junction and ends at origin of brachiocephalic artery

aortic arch

• starts at origin of brachiocephalic until just after left subclavian artery

descending aorta

• starts after the origin of left subclavian artery and the diaphragm

basic histology of the aorta

internal elastic lamina - layer that separates intima and media

tunica intima - inner

tunica media - middle

tunica adventitia - outer

tunica intima

layer of endothelial cells

subendothelial layer = collagen and elastic fibres

separated from tunica media by internal elastic lamina

tunica media

smooth muscle cells

secrete elastin in form of sheets/lamellae

tunica adventitia

thin connective tissue layer

collagen and elastic fibres

collagen prevents elastic tubes from stretching beyond their physiological limit during systole

atherosclerosis risk factors

hypertension

age

diabetes

hypercholesterolaemia

smoking

family history

male

what can atherosclerosis lead to

stroke

MI

peripheral vascular disease

aneurysm

definition of aneurysm

a localised enlargement of an artery caused by a weakening of the vessel wall

types of aneurysm

true aneurysm

• fusiform

• saccular

false aneurysm

true aneurysm characteristics

weakness and dilation of vessel wall

involves all 3 layers

• saccular one side - looks like a little sac

• fusiform both sides

what are true aneurysms associated with

hypertension

atherosclerosis

smoking

bicuspid aortic valve

collagen abnormalities - MARFANS

infection

trauma

false aneurysm characteristics

rupture of wall of aorta with haematoma contained by thin adventitia or surrounding soft tissue

aetiology of false aneurysm

trauma

iatrogenic

inflammation - endocarditis with septal emboli

aneurysm site classification

ascending aorta aneurysm

aortic arch aneurysm

descending aorta aneurysm

abdominal aorta aneurysm

signs and symptoms of thoracic aneurysms

mostly asymptomatic

but can have symptoms

• SOB - associated aortic regurgitation

• dysphagia and hoarseness

• back pain

• symptoms of dissection

• palpable mass

symptoms of aneurysm dissection

sharp sudden pain radiating to back between shoulder blades

hypotension

investigations for thoracic aneurysm

CXR - widened mediastinum

echo - assess aortic root size and aortic valve

CT angiogram of aorta - diagnostic tool

MRI - diagnostic and follow up

what is an aortic dissection

tear in the inner wall of the aorta (media)

• blood forces walls apart

• can be acute which is a medical emergency

• can be chronic dissection

aetiology of dissection

hypertension

atherosclerosis

marfans

bicuspid aortic valve

trauma

histology of aortic dissection

cystic medial necrosis

• replacement of media layer with muco-polysaccharide cysts which replace the smooth muscles in the elastin that is normally in the media layer

• causes weakness and necrosis of the media making a tear in the artery more likely

DeBakey classification of aortic dissection

- type I

originates in ascending aorta, propagates at least to the aortic arch and often beyond it distally

DeBakey classification of aortic dissection

- type II

originates and is confined to ascending aorta

DeBakey classification of aortic dissection

- type III

originates in descending aorta and extends distally down the aorta or rarely retrograde into aortic arch and ascending aorta

Stanford classification of aortic dissection

- type A

all dissections involving ascending aorta regardless of site of origin

Stanford classification of aortic dissection

- type B

all dissections not involving ascending aorta

clinical presentation of aortic dissection

chest pain - inter scapular - severe and sudden

collapse due to tamponade, acute aortic regurgitation, external rupture

stroke - involvement of carotids

examination findings of aortic dissection

reduced or absent peripheral pulses

hyper or hypotension

BP mismatch between sides

soft early diastolic murmur (aortic regurg)

pulmonary oedema

signs of cerebral vascular accident

investigation for aortic dissection

ECG - ST elevation/ischaemia indication of coronary involvement

CXR - widened mediastinum

transthoracic ECHO - examine aortic root

CT angiogram aorta - confirm diagnosis

type A dissection treatment

BP control

• beta blocker

• IVI nitrate

• CCB

• IVI sodium nitroprusside

emergency surgery

type B dissection treatment

BP control

• beta blocker

• IVI nitrate

• CCB

• IVI sodium nitroprusside - careful can cause cyanide poisoning

percutaneous (end-vascular) intervention (PCI)

what congenital conditions predispose to aneurysm

bicuspid aortic valve

coarctation of aorta

marfans

how does bicuspid aortic valve occur

leaflets of aortic valve have fused together

• most common congenital abnormality

• associated with coarctation of aorta

• reduced tensile strength in aorta

what is aortic coarctation

narrowing of the aorta below left subclavian artery due to ductus arteriosus inserts

3 types of aortic coarctation

pre-ductal

• can be life threatening if severe narrowing

ductal

post-ductal

• hypertension on upper extremities

• weak pulses in lower limbs

• associated with rib notching

signs of aortic coarctation

cold legs

poor leg pulses

radio-radial delay - before left subclavian artery

right radial-femoral delay - before left subclavian artery

right AND left radial-femoral delay - after left subclavian artery

heart failure and failure to thrive in infants

hypertension and CV complication on adults

diagnosis of coarctation of aorta

CT or MRI

CXR - rib notching

Treatment of coarctation of the aorta

PCI

surgical correction

what is Marfan's syndrome

connective tissue disorder with a multi system manifestation caused by a mutation in the fibrillin one gene

cardiac manifestations of Marfan's

aortic/mitral valve prolapse or regurgitation