URR other cerebral abnormalities Flashcards
vertebral artery stenosis
-difficult to diagnose with US due to portions of the a are located within the trans proceses of the vertebrae
-normal flow is low resistive
-most common location of stenosis is at the vertebral origin
-can lead to steal phenomenon
diagnostic criteria for vertebral artery stenosis/occlusion
-abnormal PSV > 100 cm/sec in most stenosis
-ratio of pre and post stenotic velocities >2
-abnorm pulsatility (biphasic or triphasic)
-occlusion or stenosis or prox subclavian artery
-most common on left side
-dist subclavian artery fed by reversed flow through ipsilateral vert artery
-retrograde vert flow on affected side
-if suspected, bilat brachial pressures should be obtained, decreased or greater than 20 mmHg will be seen on affected side
-symptoms include limb paralysis, vertigo, ataxia, and syncope
subclavian steal
subclavian steal happens more often on what side?
left
proactive maneuvers can be done to make partial or complete steal
-if bidirectional or biphasic in vert , exercising the arm or applying a blood pressure cuff can be used to convert the flow to complete steal
-if suspected subclavian a should be evaled, mono flow detected on affected side
-ask patient to perform 40 flexion/ extensions of arm on affected side then re-eval the vert flow
-inflate above syustolic pressure on ipsilat arm and maintain for 1-2 mins, replace cuff and asess flow in abnormal vert a, if steal present, the flow should change from biphasic to complete reversal
early systolic deceleration in vert a
-stenosis of subclav a can cause changes in vert a flow
-systolic deceleration is a sign of a significant stenosis in ipsilat side
-systolic flow starts with sharp peak followed by a sharp decrease in flow to baseline
-then resumes, increase to decrease through diastole
-this is caused by stenosis in subclav a and less commonly the prox vert A
-waveform is considered a sign of “pre steal”
-provacative maneuvers can be done to make partial or complete steal
-inflammation of A wall
-causes difffuse or focal thickening of muscle layer
-may cause increased vasc in wall of inflamed segment
-increased velocities with decrease lumen size
arteritis
buerger, takayasu, polyarteritits, temporal (giant cell)
types of ateritits
the superficial temporal A courses anterior to the ear and can be palpated just above what?
the zygomatic arch
-inflammation of the superficial temp A leading to flow reduction to frontal and parietal branches
-stiffness in neck, jaw, claudication, headaches, and sudden uni blindness
-biopsy necessary for diagnosis
temporal arteritis (GIANT CELL)
what does temporal arteritis look like?
-images have thickened walls
-halo sign = ring of thickened vessel wall surrounding vessel
-normal flow patterns mimic ECA
-diffuse vessel wall thickening and distal ischemia cause increase velocity and decreased flow resistance
-areas of greater wall thickening can cause focal stenosis with increased resistance prox to stenosis and decrease resistance distal to stenosis
aneurysms area rarely seen where?
cervical carotid branches
if an aneurysm is found in intracranial vessels, it is what kind?
berry
-blood escapes into surrounding tissues and becomes encapsulated
-risk of hemorrhage/death, trauma, infection, or true aneurysm
pseudoaneurysm
what is an AVM?
congenital connection between arterioles and venules (lack of capillary bed); usually has multiple connections and surrounding venous collaterals and dilated veins
severe form of intracranial AVM in fetuses?
vein of galen aneurysm
what is an AV fistula?
direct connection between aterial and venous systems caused by tauma or vascular procedure, usually single connection and no surrounding collaterals
-causes increased volume of flow in venous system with pulsatility and turbulence
-reduces resistance in arterial inflow and increased diastolic flow
-large or chronic arteriovenous connections can lead to heart failure
-acute tear in vessel intima
-creates false lumen
-associated with marfan syndrome and ehler danlos syndrome
dissection
if ICA affected by dissection, usually affects which part?
first 2-4 cm
CCA dissection can by continuation into where?
aortic arch
dissection is more common in ICA or ECA?
ECA
-collagen growth in medial layer
-most common in renal A
-usually occurs mid-distal ICA (atherosclerosis more common in prox)
-causing flow limited lesions
fibromuscular dysplasia
what does fibromuscular dysplasia look like?
-string of pearl appearance
-abnorm growth of medial layer
-doesnt shadow
-causes stenosis/occlusion
carotid body (sinus):
-located at CCA bif, near angle of jaw
-above this numerous baroreceptors are located to monitor BP
what is the therapeutic and diagnostic carotid sinus massages?
therapeutic:
-used to interrupt paroxysmal atrial tachycardia
-performed to reduce heart rate
-causes transient block in conduction of the electrical signal in heart
diagnostic
-used to eval patients hypersensitivity of the sinus
-may be performed if no stenosis in extracranial As
-abnormal response will lead to hypotension, bradycardia, and dizziness
cant be performed on patients with hx of TIA, bruit, or stenosis
carotid body tumor/glomus tumor, chemodectoma/paraganglionoma?
-rare neoplasm composed of paraganglion tissue
-more common in females
-seen in people living in high altitudes
-high vasc structure fed by ECA
-overgrowth of normal structure that is responsible for detecting blood gasses/pH
-can compress ICA
-pulsatile lat cervical mass
-dysphasia, syncope, hoarseness, dyspnea, cough
-horner syndrome
-pharyngeal bulge
thromboembolic disease?
-thrombus accumulation within arterial system that produces embolisms that travel distally
-symptoms vary with occlusion site of embolism
-can cause multiple TIAs
neointimal hyperplasia (myointimal hyperplasia)
-intimal thickening post endarterectomy or stent placement (smooth muscle rapid thickening)
-flow limitations lesions
-causes higher velocities in ICA
-leads to restenosis or occlusion within 2 years of surgery
PHACE syndrome
-Posterior fossa malformations (such as dandy walker) , Hemangioma, Arterial anomalies, Coarctation of the Ao and other cardiac anomalies, Eyes
-arterial stenosis or occlusion of cerebral As
-abarent origin or coarse
-saccular aneurysms of any cerebral As
-elongation of the styloid process or a calcified sytlohyoid ligament causes carotid compression
-most common bilat
-visual disturbances, syncope, carotid dissection
eagle syndrome
increased heart output can cause ?
increased flow in As
decreased heart output can cause ?
reduced resistance and flow velocity in A system and pulsatile flow in venous system
right heart valvular disease can cause abnormal?
pulsatile decreased flow
80-90% of atrial emboli are from what?
cardiac source
atrial fibrilation (irregular HR) can lead to clot formation in the left atrium which could lead to what?
-if it breaks off, can float anywhere
-if foramen ovale is patent, could go into right heart
aortic stenosis?
-usually degenerative disase causes but can also be from congenital malformation of bicuspid valve
-flow increases in velocity
-flow into ascending aorta will be turbulent
-brachial pressures decrease
-characteristics can be passed to carotids
aortic regurgitaiton
-blood flows back through aortic valve to left ventricle during diastole
-caused by disease valve, congenital defects, and chamber of aortic dilatation
-significant can lead to volume overload occurs in left vent
-pulsns bisferiens can occur in carotis
-waveforms have double diastolic peaks
-severe regurg is associated with diastolic flow reversal in carotids (water hammer pulse)
mitral stenosis
-bilat tardus parvus in CA can indicate severe
-blood flow reduced in left atrium to left vent
-significant stenosis can cause left atrial pressure overload with reduced cardiac output
-CA will have low resistance, low velocity
mitral regurg
-blood moves back through mitral valve into left atrium during systole
-caused by diseased valve, congenital defects and changer dilatation
-significant regurg results in volume overload in chamber recieving the retrograde flow
-with mitral regurg, volume overload occurs in left atrium
-usually has no effect on atrial or venous doppler
cardiac temponade?
-critical
-severe pericardial effusion within fibrous pericardium causes intrinsic compression of right heart chambers
-respiratory variation in arterial flow
-flow decreases with inspiration and normalizes with expiration
-another indication: pulsus alternans(peak systolic velocity alternates btwn 2 levels with each beat), also associated with dilated cardiomyopathy and constrictive pericarditis
intra-aortic balloon pump (IABP)
-for severly and left vent function
-implanted in descending ao and expands and contracts to cause blood to flow
-have 2 systolic peaks for each pulse
-2nd : balloon inflation
-EDV cant be determined because of flow reversal
left vent assist device (LVAD)
-used for end stage heart failure
-can prolong life for transplant patients and those who cant transplant
-pulls blood from LV into a pump transports blood to AO
-brachial measurements must be recorded
-diminished PSV, increased diastolic
-can cause fake negative for CA stenosis
