DZ of Aorta Flashcards
normal diameter of ascending aorta
3cm
normal diameter in descending portion
2.5cm
measurement of aorta in abdomen
1.8-2cm
why is the aorta prone to injury
d/t its constant exposure to high pulsatile pressure and shear stress
-more prone than any other vessel
3 layers of the aorta
- intima - thin inner layer
- media - thick middle ayer that give the aorta strength, elasticity, and distensibility
- adventitia - thin outer layer
2 anatomically into two components
- thoracic - within the thorax, above the diaphragm
2. abdominal aorta - section below the diaphragm
three segments of thoracic arota
- ascending
- aortic arch - has great vessels
- descedning aorta
2 segments of ascending aorta
- aortic root: lower segment
- begins at the level or the aortic valve
- supports the aortic valve leaflets
- extends into the sinotubular junction
- area where right and left main coronaries arise - ascending aorta - upper segment
3 vessles that come off the aortic arch
- innominate artery/brachiocephalictrunk
- left CCA
- left subclavian
descending thoracic aorta runs how to the diaphragm
distally
what is the aortic isthmus
point at which the aortic arch joins the descending aorta
-vulnerable to trauma
abdominal aorta extends from the what
from the thoracic aorta at the level of the diaphragm to the bifurcation of the right and left common iliac arteries
2 segments of abdominal aorta
- suprarenal - segment aboe the renal arteries
2. infrarenal - segment below the reanl arteis
aorta as we age
- elasticity and distensibility decreases with age
- these changes occur earlier and more rapidly in men tha women - loss of elasticity is accerelated in pts with HTN, hypercholesterolemia, and CAD
2 dz of the aorta
- aortic aneurysms
- thoracic
- abdominal - aortic dissections
what is an aortic aneurysm
pathologic dilation of the aorta that can occur anywhere along the course of the aorta
-involves all layers of the vessel
2 types of aortic aneursysm
- fusiform - affects the entire cirumference of a segment of a vessel
- saccular - involves only a portion of the circumference (outpouching of a vessel)
classification of aortic aneurysms
determined by locations
- abdominal - below diaphragem
- thoracic - above diaphragem
- thoracolumbar - involves the descending thoracic aorta and abdominal aorta
complications of aortic aneurysms
dissection
acute ruptrue - greatest fear!!
avg growth rate of thoracic aortic aneurysm
- 1-0.2cm/year
- those with marfacns syndrome may expand ast a greater rate
risk of rupture is related to the
size and presence of symptoms
- -2-3% rupture per year when 6.0cm in diameter
- fewer than 1/2 of pts with an acute rupture arrive to the hospital alive
etiology of thoracic aortic aneurysms
- ascending aortic aneurysms - cystic medial necrosis is most common cause
- aortic arch and descending thoracic aneurysms - atherosclerosis is the most common cause
risk factors for thoracic aortic aneurysms
- atherosclerosis
- connective tissue disorders - Marfan’s Ehlers-Danlos syndrome
- HTN
- familial thoracic aortic aneurysm syndromes
- infections - syphilis (rare) TB,
- vasculitis
- traumas
s/s of thoracic aortic aneurysms
most are asymptomatic and found on routine physical exam or chest x ray
-+/- chest and back pain (steady, deep and at times extremely severe
if symptoms are present, they coincide with what?
size and location of aneurysm
- aortic root: CHF, AR
- aortic arch - compress the trachea and/or recurrent laryngeal nerve
- descending - compresses esophagus
imaging for thoracic aortic aneurysms
- CXR - widening of mediastinum, displacement or compression of trachea, calcifications of the outline of the aorta, large aortic knob
- TEE: can assess the proximal ascending aorta and descending thoracic aorta
- CT scan - MODALITY OF CHOICE
- MRII AND AORTOGRAPHY - BOTH SENSITIVE AND SPECIFIC TEST
TX OF THORACIC AORTIC ANEURYSMS
- SURGERY -
- AORTIC ARCH/ASCENDING AORTA:OPEN SURGERY REQUIRED - -DESCENDING - ENDOVASCULAR STENT GRAFTING - MEDICAL MANAGEMENT
indications for surgery in a thoracic aortic aneurysm
- symptomatic pts
- ascending aortic aneurysm >5,5-6cm
descending aortic aneurysm >6.5-7cm
aneurysms that have increased >1.0 cm/year
Marfan’s syndrome pts: ascending aortic aneurysm >5cm
surgical complications of thoracic aortic aneurysm
- higher morbidity and mortality than AAA
- paraplegia (4-10% rate foloowing endovascular repair)
- stroke
medical management of thoracic aortic aneurysms
- indications - asymptomatic pts with aneurysms too small to jusitfy surgery
- beta blockers - decreased mortality and slow the rate of dilation
- ACE-I/ARBs - sutdies showiing these reduce the rate of expansion in pts with Marfans’ syndomre
prognosis of thoracic aortic aneurysms
- survival rate of those not undergoing repair is 20% at 5 eras
- less than 1/2 of the pts with an acute rupture arrive to the hospital alive
what is abdominal aortic aneurysms
defined as an aneurysm measuring >=3.0cm
M>F 4:1-90% of AAA are related to atherosclerosis
90% are infrarenal in location
risk of rupture increases as the size increases 5cm: 5 year risk of rupture if 20-40%
overall mortality from rupture is
80%
approx what % of pts with acute will die b4 receiving med attn
-operative mortality for those reaching hospital is
50%
risk factors for abdominal aortic aneurysms
atherosclerosis - MC
- HTN
- smokoking
- hypercholesterolemia
- PVD
- age m>55 W>70
- male gender
- genetics
s/s of abdominal aortic aneurysms
asymptomatic mostly
- usually found on exam as a palpable, pulsatile nontender mass or seen incidentally on imaging studies ordered for an unrelated issue
- as the aneurysm expands, pts may feel abdominal or lower back pain
- pain may be constant or intermittent and may be brought on by gentle pressure on the aneurysm
- pain is usually a sign of impending rupture and is a medical emergency
dz/imaging for abdominal aortic aneurysm
- pulsatile mass anywhere from the xiphoid process to the umbilicus (abdominal aorta)
- abdominal US - Gold STandard
- xray - calcified outline of aneurysm
- CT - can diagnose and size aneurysm
- contract aortography - invasive and require contract
- MR angiography - extremely accurate, used to plan for surgical repair
tx of abdominal aortic aneurysm
surgery - definitive
- indications - any size that is symptomatic
- any aneurysm that is rapidly expanding
- diameter >5.5cm
procedures: insertion of a prosthetic graft (open procedure) - endovascular stent graft
medical tx of abdominal aortic aneurysm
smoking cessation
- aggressive control of HTN
- control of hyperlipidemia
- beta blockers - reduce expansion and rupture
- serial imaging q6months to monitor size and rae of expansion for aneurysms >4 cm or greater
prognosis of AAA
if treated surgically - 5 year survival after tx 60%, MI is leading cause of death
-if n surgery 12% annual risk of rupture if>6cm 25% annual risk of rupture if >7cm
prevention/screening of AAA
- treat risk factors (HTN, hyperlipidemia)
- smoking cessation
- screening indications - all men age 665-75 yo who have ever smoked, siblings or offspring of people with thoracic aortic or peripheral arterial aneurysm
what is an aortic dissection
tear of the intima that results in the formatio of a false channel with in the media layer
how does the dissection usually progress
distally down the descending aorta and into ts branches
common sites of aortic dissection
- right lateral wall of the ascending aorta (shear stress is highest)
- descending thoracic aorta just below the ligamentum arteriosum
epidemiology of aoritc dissection
peak incidence in 7th and 8th decades of life
M>W 2:1
risk factors of aortic dissection
- HTN
- age
- bicuspid aortic valve
- marfans’ syndrome and Ehlers Danlos syndrome
- infalmmatory aortitis
- pregnancy (3rd tri)
- blunt trauma to aorta
two classification of aortic dissectin
- Debakey classification
2. standored classification
debakey classification of aortic dissection
- type I - originates in ascending aorta, continues to the aortic arch and many times beyond the arch distally
- type III - originates and is confined to the ascending aorta
- type III - originates in the descending aorta with extension distally
stanford classification of aortic dissection
type A - all dissection involving the ascending aorta
type B - all dissections not involving he ascending aorta
symptoms of aortic dissection
- severe, persistent, sudden onset CP most common initial symptom
- pain described as tearing, ripping and sharp
- may localized to the front or back of chest, lower back
- pain may migrate as it progresses
- ascending dissection: neck throat, jaw pain
- descending dissection - chest pain +/- radiation to back, inter scapular or anterior chest
- less common symptoms: dyspnea, syncope, weakness, CHF, CVA, paraplegia, cardiac arrest
signs of aortic dissection
HTN, hypotension
aortic regurg
-periph pulses decreased or unequal
-pulm edema
-intestinal ischemia or renal insufficiency
-neuro findings dt carotid artery obstruction (hemiplegia, hemianestheisa)
-paraplegia (spinal cord ischemia)
imaging/dx of aortic dissection
- CXR - may show widened mediastinum and pul edma
- EKG - may be normal, may show LVH, acute changes may develop if it involves the coronary artery
- CT IS DIAGNOSTIC test of coice - should include chest and abdomine
- ECHO and MRI - also diagnositc but not sued first line in an acute setting
tx of aortic dissection
goal is to stop the progression of dissection
- medical - BP control is essential
- beta blocker unless contraindicated to get HR down to 60bpm
- sodium nitroprusside to lower SBP
surgery for aortic dissection
superior to medical tx in acute proximal dissections
- indications
- acute distal dissections w/ vital organ compromise, rupture or impending rupture
- dissections in Marfans’ syndrome or
- continued pain
- involves incising the intimal flap, obliterating the false lumen and placing a graft in the lumen of the vessel
what is the largest blood vessel in the body
aorta
