Lec 23 Peripheral Vascular Disease Flashcards Preview

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Flashcards in Lec 23 Peripheral Vascular Disease Deck (77)
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What is equation for blood flow [poiselle]?

Q = P*pi*r^4 / 8nL

Q = P/R


What factor has greatest impact on blood flow?

radius of the vessel


For two stenoses of same length and radius, what will higher flow rate due to pressure drop across the stenosis?

higher flow --> higher pressure drop


What happens to blood flow as area reduces?

- speed of flow increases
- becomes more turbulent


What happens to flow of blood in systole? diastole?

systole: early = rapid flow of blood out then slows down

diastole: have recoil [neg flow] as heart fills up


What are some examples of high resistance arteries?

- muscular arteries to arm, leg, external common carotid [to face muscles]
- mesenteric arteries before you eat


What is difference in flow high vs low resistance vessels?

high resistance --> get flow mostly just with systole; very low flow with diastole

low resistance --> still get good flow with diastole = more essential organs


What are some examples of low resistance arteries?

- internal carotids
- vertebral arteries
- renal arteries
- mesenteric arteries after you eat


Are peripheral veins high or low resistance?

low resistance --> communicate directly with heart


hat are some characteristics of normal venous waveform?

- respiratory phasicity
- augmented with calf muscle compression
- demonstrate valve competence [no retrograde flow w/ valsalva]


How do you detect valve competence?

ask patient to valvsalva
if you pick up blood flow = incompetent valve


What is peripheral artery disease?

atherosclerosis of aorta, iliac, and lower extremity arteries


What risks associated with peripheral artery disease?

regardless of symptoms it gives you a 3x increase risk in CV events


Who is at risk for getting peripheral artery disease?

- people who smoke and have diabetes
- people with chronic kidney disease


What are clinical manifestations of peripheral artery disease?

intermittent claudication or critical limb ischemia


What is intermittent claudication?

pain or fatigue in calf/thigh/buttock or low back that occurs with exertion and relieve by rest

location of symptoms correlates with one level below disease/obstruction


What are symptoms of critical limb ischemia? what exacerbates/improves?

- pain or parasthesia in lower extremity at rest
- ischemic uclerations
- gangrene

- exacerbated by leg elevation [or when supine] = elevation pallor

- relieved by hanging foot over the side of bed = dependent rubor [filled w/ blood]


What is leriche triad?

classic triad of symptoms related to aortic and iliac atherosclerosis

- bilateral butt and thigh claudication
- impotence
- global atrophy of extremity


What is most frequent location of peripheral artery disease?
A. aorto-iliac
B. femor-popliteal
C. tibial-peroneal?

femoro-popliteal is most common


What is prognosis of aorto-iliac peripheral artery disease? Where do you feel the pain?

collateral typically well developed --> good prognosis for revascularization with high patency

feel the pain in thigh


What is order of patency rates in revascularization procedures for peripheral artery disease of the following vessels:
A. aorto-iliac
B. femoro-popliteal
C. tibial-peroneal

patency decreases as you go down
Aorto-iliac > femoro-popliteal > tibial-peroneal


What is prognosis of femoro-popliteal peripheral artery disease? where do you feel the pain?

collateral determine course
intermediate patency rate with revascularization

thigh/calf pain


What is prognosis of tibial-peroneal peripheral artery disease? where do you feel the pain?

associated with DM
low graft patency rates

calf/foot pain


How do people with PAD initial present?

- asymptomatic
- atypical leg pain
- claudication
- very rare critical limb ischemia


What is 1 yr prognosis of critical limb ischemia?

50% alive w/ 2 limbs
25% amputation
25% CV mortality


What is 5 yr prognosis of pts with peripheral artery disease?

mostly fine at 5 yrs
20% have non-fatal CV event
15-30% dead


What physiologic testing to detect PAD?

- ankle/brachial or toe/brachial index
- pulse volume recordings
- segmental limb pressures
- continuous wave doppler


What is purpose of ankle-brachial index? how do you calculate?

to detect pressure differences between arms and legs that tell you if there is an obstruction between the two

calculate left ABI
take highest systolic BP of L posterior tibial or L dorsalis pedis = L ankle BP

take highest brachial systolic BP between R and L [ex. if R = 160 and L = 120 use 160 for all calculations]

L ABI = L ankle BP / highest brachial BP


What is a normal ABI? obstructed?

normal = 0.9-1.4
< 0.9 = mild obstruction
0.4-0.7 = moderate obstruction
< 0.4 = severe obstruction

> 1.4 = calcified vessel


What happens if ankle-brachial index > 1.4

means the vessel is calcified so its not really a valid reading
need to do the toe brachial instead


How do you calculate toe-brachial index? normal value?

great toe pressure / brachial pressure
normal > 0.7


When do you use toe-brachial index instead of ankle-brachial index?

in setting of vessel non-compressibility [BP > 250 mmHg] or ABI > 1.4

b/c smaller vessels are not affected by calcification


What is association ankle-brachila index and mortality?

pts with low ABI = much higher mortality than normal

pts with > 1.4 have slightly higher mortality than normal


How do you measure arterial pulse volume recordings?

leave BP cuff inflated
measure volume displacement of blood in each wave form


What is use of segmental BP?

identify location of disease [>20 mmHg drop]


What is duplex US?

non invasive imaging for elavaluating hemodynamics and detect stenosis > 50%


What is use of MR angiography in peripheral artery disease?

may over estimate degree of stenosis
limited in setting of metal, intravascular stents/coils


When can you not use MR and CT angiography?

limited in renal failure


Does MR angiography under or over estimate degree of stenosis?

over estimate


What is limitation of CT angiography in peripheral artery disease?

limited in evaluation of calcified vessels


What are goals of peripheral artery disease treatment?

decrease cardiac events/death
improve symptoms/function


What are measures to decrease cardiac events and death in PAD?

- stop smoking
- control BP: ACE inhibitor
- control lipids: statins
- antiplatelets: aspirin/clopidogrel
- regular exercise
- control diabetes


What medications do you give in peripheral vascular disease?

- ACE inhibitor to control BP
- statins to control lipids
- aspirin/clopidogrel = decrease risk clots
- cilostazol = improve symtpoms


What are measures do increase function/symptoms in PAD?

walking program = walk to point of pain repeatedly --> develop collateral circulation and build up tolerance

drugs: cilostazol = decreases symptoms; mech unknown

revascularization if doesn't respond to med therapy


What are 2 major causes of acute arterial occlusion?

- in situ thrombosis --> atherosclerotic plaque rupture
- embolism from heart or aorta


What care the 6 causes of acute arterial occlusion?

- in situ thrombosis
- embolism
- arterial trauma
- vasculitis
- hypercoagulable state
- severe venous thrombosis [phlegmasia cerulea dolans]


What are the 6 P symptoms of acute limb ischemia?

- pulseless
- pain
- paralysis
- parasthesia = tingling
- pallor
- poikilothermia = can't maintain body temp


What time frame for acute limb ischemia?

symptoms for less than 2 weeks


What is class I limb ischemia? treatment?

class I = no rest pain
palpable/audible pulses

not immediately treated


What is class II limb ischemia? treatment?

class II = ischemic rest pain, ankle pressure < 50 mmHg
mild-moderate sensory and motor deficits

treat: salvagable limb --> promptly revascularize


What is class III limb ischemia? treatment?

class III = absent doppler signals, paralysis, muscle rigor

treat: not viable limb --> amputation needed


What is buerger's diease? who gets it?

segmental inflammation of medium sized arteries and veins; involves distal vessels of upper and lower extremities. eading to thrombosis and vaospasm

men > women
age < 40 yrs
TOBACCO = cause/necessary for progression of disease


What are signs of buerger's disease? how do you differentiate from other causes?

- superficial thrombophlebitis
- raynaud's [vasospasm]
- distal arterial occlusion --> claudication

corkscrew collaterals; alternating areas of stenosis/occlusion with normal arterial segments; lack of atherosclerosis in proximal vessels; 2 or more extremities involved

rule out others by: negative test for autoimmune markers; exclude atherosclerotic embolus as cause


What is treatment for buerger's diease?

stop smoking + amputation


What should you think if you see corkscrew collaterals?

probably buergers


What is raynaud's phenomenon?

vasospasm of digital arteries
triphasic color response
- fingers/toes blanch to white = ischemia
- cyanosis = blue
- blood flow resumes = rubor/red

colors may be accompanies by numbness, parasthesias, or pain of affected digits

brought on by cold exposure, emotional stress


How do you diagnose primary raynauds? who gets it?

- bilateral, present at least 2 yrs without secondary cause

- onset 15-40 yrs [younger than secondary]
- women > men
- some spontaneously improve, others progress


What are symptoms of venous thrombosis?

leg pain/swelling
palpable cord


What are varicose veins?

dilated tortuous superficial veins often in lower extremities; most common in saphenous veins

family history, women > men

due to intrinsic weakness of vessel wall from increased intraluminal pressure


What is difference primary vs secondary varicose veins?

primary = originate in superficial system; associated with pregnancy, standing, obestity

seoncdary = abnormality in deep venous system is the cause; associated with deep venous insufficiency/occlsion


Where does DVT usually occur?

calves in popliteal or higher


Where does superficial thrombophlebitis usually occur?

in saphenous


What is virchows triad?

puts you at risk of increased blood clot:
1 stasis of blood
2 endothelial injury
3 hypercoagulable state


What is phlegmasia cerulea dolans?

most severe form of deep vein thrombosis --> limb gets blood in but can't come out

get compartment syndrome with increasing fluid
blue painful leg --> venous gangrene
massive red/purple swelling, diminished pulses
limb and life threatening emergency!


What are some signs of DVT on ultrasound?

- dilated non-compressible veins with incomplete filling
- lack of respiratory phasicity and flow augmentation


What are the 2 major consequences of DVT?

- pulmonary emobolism
- postphlebetic syndrome


Is DVT more common in proximal vs distal veins? which are more likely to cause PE?

- distal veins more likely to develop DVT
- proximal veins at more risk of PE

proximal = iliac, femoral, popliteal
distal = deep muscular veins


What is postphlebitic syndrome?

postphlebitic syndrome = chronic venous insufficiency

- damaged venous valves / persistent occlusion by DVT --> leads to chronic leg swelling, stasis pigementation, skin ulceration

blood and fluid backflows into periphery with valsalva [increased intra-thoracic P] or even at rest = get reversal of flow; less venous return to heart


What are symptoms of pulmonary embolism?

SOB, chest pain, hemoptysis, tachycardia, hypoxia


What happens in massive PE?

have RV strain with hemodynamic compromise

--> syncope, cardiac arrest, resp failure, cor pulmonale


What happens in submassive PE?

have RV strain with hemodynamic stability and normal BP


What is chronic thromboembolic pulm HTN?

if get repeated pulm emboli over time get HTN


What are symtpoms of chronic venous insufficency?

swelling, pain, skin flaking, ulceration, varicose veins

inverted champagne bottle inflammation and fibrosis of lower 2/3 of leg


What is stasis cellulitis?

often mistaken for infectious cellultiis
does not respond to antibiotics

= warm, red tender swollen leg; inflammatory process related to venous stasis and excess interstitial fluid

treat with compression


What are 3 causes of swollen limb?

- chronic venous insufficiency
- lipedema
- lymphedema


What is lipedema?

- dispropotionate fat deposition in lower half of body but torso relateively normal

- spares foot = ankle cut off sign
- bilateral and symmetric; non pitting; tender; soft
- "fat pad sign" anterior to lateral malleoli


What is lymphedema?

begins distally; involves toes and feet

buffalo hump = dorsum of foot
stemmers sign = pathognomonic = inability to pinch the skin at the base of 2nd toe

early have pitting; late = firm and non-pitting

at risk for recurrent cellulitis