Aorta Flashcards
Cardiocasvular system
first system to begin to function in the embryo
Aorta developement
from mesodermal cells
angioblasts during 3rd week
vessel determination
location in relation to heart
arteries or veins
3rd week development
2 dorsal aortas
extensions of 2 endocardial heart tubes
quickly fuse into singel vessel
first single aorta
many branches to feed embryo
branches become lumbar arteries
common iliac artery developement
develope from intersegmental arteries
vitelline artery
branches anteriorly from aorta and extends into the yolksac
celiac artery
SMA
IMA
develope from this
umbilical artery
branches off the anterior aorta
gives rise to the internal iliac arteries
Aorta
carries blood from heart
enclosed in sheath containing nerve and vein
3 layers
tunica intima
tunica media
tunicat adventitia
tunica intima
inner vessel wall
tunica media
middle vessel wall
arteries have thicker to allow for great elasticity
tunica adventitia
outer vessel wall
Aorta sections
root
ascending
descending
abdominal and branches
bifurcation
Aortic root section
arises from left ventricle
Aorta ascending
arises short distance from root
forms aortic arch
supplies blood to head and upper extremities
3 branches arise from arch
Aorta descending
after aortic arch
posterior along back wall of heart
Aorta abdominal
supplies blood to all soft tissue organs in abdomen
starts after passing through diaphragm
Aortic bifurcation
into iliac arteries
Arteries arising from aortic arch
brachiocephalic
commom carotid
subclavian
Anatomy of Abdominal aorta
endters through aortic hiatus of diaphragm
descends anteriorly and slightly left of vertebral bodies
posterior and left of gastroesophogeal junction
flanked on either side by diaphragmatic crura
Aortic branches
Celiac Trunk
SMA
Left & Right Renal A
Left & Right Gonadal A
Root of IMA
Left & Right Common Iliac
Aortic bifurcation
common iliac arteries
at L4 into iliac arteries
5cm long
run anterior with corresponding veins
common iliac artery bifurcation
internal and external iliac arteries
Celiac trunk
common hepatic artery
left gastric artery
splenic artery
common hepatic artery
forms proper hepatic artery and GDA
left gastric artery
supplies stomach and esophagus
splenic artery
largest branch
forms gastroepiploic artery
supplies stomach and spleen
SMA
arises 1cm inferior to celiac trunk
5 main branches that feed small intestines, inferior pancreatic, duodenal, colic, ileocolic and intestinal arteries
each branch has 10-16 branches
IMA
arises at L3 or L$
proceeds left and supplies colon and rectum
3 main branches
3 branches of the IMA
left colic
sigmoid
superior rectal
indications for aortic ultrasound
pulsatile abd mass
hemodynamic compromise in lower limbs
abd pain
abd bruit
acoustic window for aorta
midline, left flank with patient supine
right lat decubitus and along lateral edge of rectus abd muscle to evaluate iliacs
aorta assessment
visualize entire aorta and branches
disections of atheromatous stenoses, aneurysmas, disections or other pathological process
measurements, including dilated segments
adjacent organs and structures
normal aorta measurements
tapers from cranial to caudal
- 5 to 1.8cm
- 5 at diaphragm
- 0 midline
- 8 distal
95% of people aorta less than 2.3 in men, 1.9 in women
increases with age
aorta in systole
acts as resevoir in response to pulsitile flow received from left ventricle
aorta in distole
decreases in size by discharging blood to rest of ciculation
considered high resistance flow in aorta
high resistance blood flow
shart increase in antegrade velocity during systole
sharp decrease in velocity and brief period of reversed flow in distole
low resistance blood flow
main aortic branches to
kidneys
liver
postprandial bowel
Goals of Doppler aorta
validate entire aorta and branches by determining patency
detect atheromatous stenoses, aneurysms, dissections or other pathology
characterize abnormalities with spectral doppler
determine high/low resistance in vessels to determine if possibility of pathological process
Stenosis
doppler shows increased pulsatility proximal
increased systolic/diastolic velocities
turbulence immediately after
Atheromatous disease
arteriosclerosis
vascular wall disorder with presence of lipid deposits in intima
atheromatous plaque is soft, porridge like material that may discharge into the vessel causing distal embolus or local thrombus or both
palques cause mural irregularity and narrowing of the vessel lumen with distal ischemia
Atheromatous disease factors
incidence increases with age
affects more men than women
involves aorta and iliac arteries and branches
most common on posterior wall in aorto-iliac area
atheromatous disease associations
smoking
diabetes mellitus
hypertension
increased levels of low density lioprotein of serum cholesterol
atheromatous disease signs
significant lower limb pain
ectasia occurs when aorta increases in length and diameter causing it to kink usually anteriorly and left
arterial thromus
very new=hypoechoic 1 hr or so
newer clot=hyperechoic due to fibrinogin
old clot=hypoechoic with debris
Aneurysm
swelling in bloos vessel eith focal or diffuse
2 types
true
false (pseudo)
True aneurysm
all 3 layers affected
pseudoaneurysm
does not affect all 3 layers
Predispostion to aneurysm
Marfan’s syndrome
ehlers-danlose syndrome
annuloaortic extasia
famlial aortic dissection
intimomeidal mucoid degeration
MOST true are idiopathic
Pseudoaneurysms description
blood escapes through a hole in intima but is contained in deeper layers of aorta by adjacent tissue
most are round or oval proituberances from the artery
blood circulates in and out with cardiac cycle
can be cause by infection, trauma, surgery or interventional procedures
abdomial aorta aneurysm
AAA
95% are infrarenal
30-60% are assymptomatic
may have ab, leg or back pain
higher ince=idence in Men over 60
incidence of AAAis 70-90% in men over 65
complications of AAA
rupture
thromsosis
dissection
distal embolism
infection
obstruction and invasion of adjacent structures
Most common complications of AAA
branch artery occlusions or stenosis
most common in IMA and renal arteries
Dissecting aneurysm
type of pseudoaneurysm
blood leaves lumen through intimal defect and course as variable distance in the wall and reenters aorta farther distal in the arterial system
aortic rupture
most catastrophic of AA complications
mortality rate at least 50%
some contained in the retroperitoneum and are chronic
retroperitoneal fluid collections are the most common findings
mural thrombus AAA
prevalent in most large AAA
thrombus poorly attached and friable meaning it can be distant source of emboli
thrombus has no bearing on whether the AAA will rupture or not
inflammatory AA
variant of atherosclerotic AAA
wall of aneurysm is thickened and surrounded by fibrosis
surgical repair has high mortality rate
pain present in 84%
Sonographic appearance of AAA
focal dilation of aorta larger than 3cm
elongate as the grow
most deflect to left or kink anteriorly or both
aventitia is generallly echogenic from adjacent fibrofatty tissue
mural thrombus is usually low to med echogenicity and makes up most of wall
intimal lining may be smooth or irregula with calcifications
AAA measurement
measure outer to outer
maximum true lenght and width and transvers dimensions
document locatoin include suprarenal extension or iliac involvement
document wall type: calcified plaque, flowing blood, soft plaque or well established plaque
AAA analysis
patent channel should be documented
look for dissection
look at both kidneys checking flow of renal arteries, especially if kidney is shrunken of if patient has hypertension
Descriptive terms for AAA
Bulbous
fusiform
saccular
dumbell
Bulbous AAA
sharp junction between normal and abnormal
Fusiform AAA
gradual transition between normal and abnormal
Saccular AAA
sharp sudden transition between normal and abnormal
Dumbell AAA
figure 8 appearance
Repair of AAA
surgery with aortic grafts
many factors to weight in repair decision
arterial grafts very echogenic and textured
native aorta usually wrapped around graft, may see fluid between aorta and graft
Iliac and suprarenal Aneurysms
patients with iliac have higher incidence of aneurysms elsewhere in body
trauma, syphili and mycotic disease shoujld all be considered if aneurysms are found suprarenally
Dissections
defect in intima and internal weakness in wall must exist
most are idiopathic
begins in thorax and extends into the abdomen
less than 5% begin in abdomen
Dissection relations
marfan’s disease
pregnancy
bicuspid aortic valve
trauma
focal stenoses
hypertension
Types of dissections
Type 1
Type 2
Type 3
Type 1 dissection
begins at root of aorta and may extend entire length of arch, descending aorta and even inot the abdominal aorta
most dangerour kind
Type 2 dissection
starts at left subclavian artery and extends down towards the descending aorta
it may or may not extend in to the abdominal aorta
associated with Marfan’s disease
Type 3 dissection
begins at the descending aorta and extends into the abdominal aorta
may block renal arteries
aneurysm infection
may invade a precediong aneurysm and produce a focal abcess
septic emboli often associated with valvular heart disease often cause the disease
pseudoaneuryms
arteriorvenous fistula
most result at site of angiographic puncture or at site or surgical anastomosis
hs a neck to aneurysm
during systole can see blood enter and diastole can see turbulent blood flow with color doppler
can be treated with ultrasound guided thrombin injection
Celiac/mesenteric arteries
artery has high resistive pattern at its origin with a small amount of reversed early diastolic flow
as go more distally it loses the reversed flow component
splenic and hepatic areteries are usually low resistance
splenic artery is tortuous
SMA
blood flow pattern depends on whether patient is fasting or has eaten
fasting pattern is high resistance
eaten pattern is low resistance
low resistance pattern in most prominent 45 min after eating
Intestinal Ischemia
deficiency in blood delivery to bowel
usually has a significant narrowing or obstruction of both the celiac axis and SMA
Splanchic aneurysm
aneuryms in the hepatic artery, plenic artery, SMA, GDA, IMA
may be saccular or fusiform
can be congenital, artherosclerotic, post trauma, mycotic or inflammatory
Renal arteries
22% have 2 to one kidney
should show low resistance waveform
velocities should decrease as once goes farther into kidney
Renal artery stenosis
produces rare but treatable cause of hypertension
may be due to atherosclerotic disease or fibromuscular hyperplasia (rare disease affecting young women)
RA stenosis is treatable with angioplasty
Reanl aneurysms
AV fistulas
mostly acquired
may be post trauma or post large bore needle biopsy
usually pseudoaneurysms
1/4 are congenital
produce a mosaic color in kidney (doppler image)
Aneurysm measurements
Abdominal > 3 cm
Common iliac >2cm
Popliteal >1cm
25% of popliteal also have AAA
rupture risk in AAA in 5 yrs
5 cm=5%
6cm=16%
7cm=75%
clinical findings of aortic rupture
decreased hemocrit
hypotension
pulsitile abd mass
abd bruit
back pain
abd pain
lower extremity pain
aortic grafts
tube graft
aortoiliac graft
aoto-bifemoral graft
wrapped-native aorta is opened longitudinally and the graft is placed inside
