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Major risk factor for PVD
atherosclerosis
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Atherosclerosis is an _______ process.
inflammatory, body recognizes LDL as a foreign substance, get pro-inflammatory cytokines
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Tell me about coronary artery plaques Ie- stable or unstable?, rupture or occlude?
- Unstable and prone to rupture
- Thin cap with thick lipid core
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Tell me about carotid artery plaques- ie stable or un?, rupture or occlude?
- Unstable, more likely to occlude
- Thin cap with thick lipid core (like coronary plaques)
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common sites for plaque lesions
- bifurcations! turbulent flow, high pressure, vessel wall shearing
- coronary arteries
- carotid bufurcation
- abdominal aorta
- illiac arteries
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PVD s/sx
- 50% have none or mild s/sx
- claudication
- numbness or weakness of LE
- Cold legs/ feet
- Non healing ulcers
- Hair loss on legs, shiny skin
- Impotence
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What are the 3 theories explaining PVD?
- Virchow's- endothelial injury is caused by physical and enviro factors, sub endothelium is exposed, smooth muscle proliferation and Plt adherence occurs
- Monoclonal- cell proliferates 2/2 a mutagen or virus
- Clonal senescence- smooth muscle proliferation inhibition decreases with aging
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What is an aneurysm?
localized dilation or out-pouching of a vessel wall
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Why is the aorta particularly susceptible to aneurysms?
- High constant stress to vessel wall
- Absence of penetrating vasa vasorum in the adventitial layer
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Major causes of aneurysms
- HTN and atherosclerosis
- Genetic component, most have a 1st degree relative who also has it
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What is systemic vasculitis?
blood vessel inflammation (caps, arteries, and veins)
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S/sx vasculitis
- fever
- wt loss
- fatigue
- muscle and joint pain
- loss of appetite
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Implications of vasculitis
Can rx blood flow to organs causing major damage
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Systemic vasculitis: Buerger's dz
- inflammation and clots in BV of arms and legs
- assoc with cigarette smoking
- typically occurs in middle aged jewish males
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Systemic vasculitis: Takayasu's arteritis
- includes largest arteries in the body, including the aorta
- typically occurs young asian females
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Systemic vasculitis: Kawasaki disease
- most often affects kids < 5 yo
- s/sx: fever, rash, eye inflammation
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Systemic vasculitis: Giant cell arteritis / temporal arteritis
- Usually occurs in ppl > 50 yo
- Inflammation of arteries in neck, upper body, arms, and head (esp. the temples)
- Most common vasculitis in US
- Assoc with PMR
- Tx= corticosteroids
- S/sx= H/A, scalp tenderness, jaw pain, blurred vision, blindness
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Systemic vasculitis: Raynaud's
- cold induced arterial spasm of the extremities
- Often found in adult females
- Assoc with SLE and scleroderma
- Avoid VC with regional anesthesia
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Systemic vasculitis: Wegener's granulomatosis
- inflammation of blood vessels in nose, sinuses, throat (URI), lungs, and kidneys
- s/sx= SOB, nosebleeds, nose ulcers
- Pts may be immunosuppressed due to tx with cyclophosphomide
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Systemic vasculitis: polyarthritis nodosa
- affects medium sized BV in many different parts of the body
- most common in F, ages 20-60
- s/sx= purpura, ulcers, muscle and joint pain, abd pain, HTN
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Systemic vasculitis: Moyamoya disease
- narrowing or occlusion of both IC arteries
- may cause TIAs in kids and IC hemorrhage and IC aneurysms in adults
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CAD risk in pts having vascular surgery
< 10% have normal coronaries
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Intermediate clinical predictors of increased peri-op CV risk (MI, HF, and death)
- mild angina
- previous MI
- CHF
- DM
- CRI (Cr > 2)
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Minor clinical predictors of increased peri-op CV risk (MI, HF, and death)
- adv age
- abn EKG
- Rhythm other than sinus
- Low func. capacity
- H/O CVA
- Uncontrolled HTN
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Major clinical predictors of increased peri-op CV risk (MI, HF, and death)
- Unstable coronary syndrome (acute or recent MI), unstable or severe angina
- Decomp HF
- Signif arrhythmias (high grade AVB, symptomatic vent arrhythmias, uncontrolled SVT)
- Severe valvular disease
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Most common cause of peri-op death with vascular surgery
- MI
- usually occurs post-op (but we play a role with our emergence and wake-up)
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When in the vascular surgery peri-op period to most MIs occur ?
24-48 hour period
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T or F, vascular surgery is considered intermediate risk
F, it's high risk
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Why is peripheral vascular surgery reserved for severe ischemia?
Limited durability of bypass graft
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What is the ankle/ arm index?
- Used to evaluate severity of arterial insufficiency
- Compare BP on arm and on calf
- Normal- ratio = 1 (they are equal)
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What type of vascular surgery involves aortic cross clamping?
Aortofem bypass
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Factors to be avoided post-op for prevention of MI with vascular surgery
- tachycardia
- hypothermia
- hypervolemia
- pain
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Adv / disadv of use of regional anesthesia in vascular surgery
- IV anticoag must be stopped prior to regional
- Stable HD with incremental dosing
- Improved graft patency
- limited duration (case may be long)
- thoracic epidurals are difficult to place
- risk sympathectomy
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Adv / disadv of use of general anesthesia in vascular surgery
- pt can stay on IV anticoag
- able to graft UE
- hypercoagulable state
- increased post-op catecholamines
- possible ventilatory challenges post-op (abd surgery)
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Neuraxial level needed for vascular surgery
- T10-T12
- T8 if exposing the pelvis
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Major risks associated with CEA
MI and CVA
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For what degree of ICA narrowing is CEA beneficial
- 60-90%
- No benefit in pts with < 60% narrowing
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T or F, its with LM CAD are more likely to have carotid disease
T
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S/sx carotid stenosis
TIA, CVA, UE or LE numbness or weakness, unilateral monocular blindness
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What type of CVA is likely to occur with a CEA
embolic
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Increased risk of poor neuro outcome is seen in its undergoing CEA with what issues?
- Poor collaterals
- Contralateral carotid occlusion
- Renal insufficiency, (Cre > 2)
- Poorly controlled HTN
- CAD requiring bypass
- Decreased LOC pre-op
- Active neuro process pre-op
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The glossopharyngeal nerve (CN 9) runs alongside what structures? What are the implications?
- Of concern with a CEA
- Runs along side ICA, where the carotid body and sinus are located
- Damage to carotid body- insensitivity to hypoxia
- Damage to carotid sinus- vagal response (baroreceptor)
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2 major vessels supplying the brain
IC and vertebral artery
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What structure provides collateral circulation to the brain? How does it work?
circle of willis, so if either the IC or vertebral artery is occluded, brain still receives adequate flow
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Goal ETCO2 for CEA, why?
- normocarbia
- avoid steal as thick stenotic vessels aren't affected by CO2 level so blood is directed away from areas that need it
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Anesthetic agent selection for CEA
- short acting to allow a smooth and fast wakeup
- assess neuro status
- avoid coughing and bucking with emergence
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Goal fluid management for CEA
euvolemia
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What factors can increase myocardial O2 demand?
Increase in: HR, diastolic volume, contractility, BP
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What factors can decrease myocardial O2 supply?
- Decrease in coronary blood flow (incr HR, diastolic volume, coronary VC or thrombosis)
- Decrease in O2 content (decr Hct or O2 sat)
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Goal BP for CEA
20% ABOVE baseline
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Normal cerebral blood flow
50 ml / 100g brain
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Factors that will affect EEG with CEA
propofol, volatiles, bovie
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How is an awake CEA performed- what's the benefit
- With a carotid plexus block (C2-4)
- Adv= Constant neuro assessment
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T or F, use of carotid plexus block is associated with a decrease in post-op CVA incidence
F, no difference with regional vs. GA
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contraind to regional anesthesia for CEA
- high carotid lesion
- language barrier
- claustrophobia
- pt preference
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Adv of using GA for CEA
- ability to manip HD
- decrease O2 demand and catecholamine level
- airway security
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Can N20 be used for a CEA
Yes, however there's a risk of air exposure with shunt placement and during release of cross clamp- so if using shut it off prior
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Risks associated with CEA
- Damage to recurrent laryngeal nerve
- CVA
- Carotid body denervation
- Hyperperfusion syndrome (HA, sz, vision changes)
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T or F, barbs and etomidate are known to be cerebral protectant and are rec for use with CEA
F
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Risk of AAA rupture increases with diameter of ____.
> 4.5- 5 cm
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Elective repair of AAA is indicated with a diameter of ____ or _____.
- 6 cm or greater
- > 0.5 cm increase in 6 mo or symptomatic
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Risk factors for AAA
- adv age
- smoking > 40 yrs
- HTN
- incr LDL
- low Plt count
- atherosclerosis
- more prevalent in males
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CV changes assoc with aortic cross clamping for AAA repair
- Increased MAP and SVR
- Slight decrease in CO
- Decreased O2 consumption
- Preload may increase with myocardial dysfunction
- MI
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Interventions to counteract CV changes assoc with aortic cross clamping
vasodilators (nitroprusside, fenoldapam, volatiles, NTG, BB)
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Metabolic changes assoc with aortic cross clamping for AAA repair
- decreased total body O2 consumption (above and below clamp)
- decreased CO2 prod
- incr epi and NE
- resp alk
- met acidosis
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T or F, renal blood flow is preserved with infra-renal aortic cross clamping?
F, RBF is decreased
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Strategies to maintain renal perfusion with AAA repair
- euvolemia (optimize pre-op)
- mannitol
- lasix
- dopa
- mucomyst
- fenoldopam
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Coagulation changes assoc with aortic cross clamping
- Clotting factor consumption, can get DIC
- Hypocalcemia
- Thromboxane causes increased vasc permeability leading to pulm edema
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artery of adamkiewicz
- risk of damage with AAA repair
- can lead to SC ischemia
- joins anterior spinal artery btw T8-12
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Goal BP with aortic dissection / decr thoracic aneurysm
SBP 90-120 mmHg
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What type of endoleaks are the most concerning and why?
- Type 1 and 3
- assoc with incr risk of rupture, require aggressive tx
- both involve leaking with forward flow of blood into aneurysm sac
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Which procedure is safer open or endovascular AAA repair
endovascular
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Possible post-op complication of desc thoracic aneurysm
post-op paraplegia due to interruption of blood flow from artery of adamkiewwicz
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What is the mainstay of tx for AAA repair
volume and fluid replacement
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Why is it difficult to estimate EBL with AAA repair surgery
due to the venous capacitance of the splanchhic circulation
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therapeutic interventions with aortic cross clamp release
- volume
- neo
- calcium
- ephedrine
- epi
- Na bicarb
- incr MV
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