vascular Flashcards
most common cause of PVD
atherosclerosis
Primary risk factors for MI, stroke, chronic mesenteric ischemia, renovascular HTN, and extremist aneurysm:
PVD
end organ involvement PVD
diminished pulses, s4 gallop, residual defect from previous stroke
CV decompensation of PVD
murmur
JVD
third heart sound
rales
SOB
peripheral edema
Baseline lab studies for vascular surgeries
CBC
coags
BMP
biomarkers
12 lead
echo
preop pharm management of patients high risk for MI
Beta Blocker 50-60
Statins
Aspirin
Carotid Endarterectomy indication
TIA w/ >70% stenosis
severe ipsilateral stenosis in pt w stroke
30-70% occlusion w/ ipsilateral symptoms
Asymptomatic are stented
periop MI rate for CEA
2-5%
where is the most common site of CEA?
Bifurcation of the carotid artery & PROXIML internal carotid involvement
Anatomix structures near CEA?
RLN & VAGUS
GLOSSOPHARYNGEAL
HYPOGLOSSAL
MANDIBULAR / FACIAL
Chronic HTN shift cerebral autoregulatory curve to thew
Right
The right shift in autoregulatory curve –> Higher than normal MAP required & causes CBF to become
BP dependent (about 20%)
Cerebral steal occurs (cerebral vascular dilation) with
Hypercarbia –> decreased CBF and increased regional ischemia
Cerebral vasoconstriction occurs with
Hypocarbia –> decreased CBF
inhalation effect on CBF
increased
anesthetic agents on CMRO2
decrease (except ketamine)
Normal Cerebral Blood Flow
50ml/100g/min
20ml of oxygen per 100 ml blood
CMRO2
3-5ml/100g/min
CPP =
MAP - ICP
most common perioperative complication of CEA?
MI
How to protect the brain during CEA?
normocarbia (PaCO2 35-44) (EtCO2 gradient (lower) >5mm)
left shift in the oxyhemoglobin curve
extreme hypocarbia
what is abolished in the area surrounding an acute cerebral infarction due to loss of BV reactivity d/t acid products?
autoregulation
Refers to a condition in which there is an increased blood flow to a particular region of tissue, often after an initial period of reduced blood supply (ischemia).
luxury perfusion
Occurs when blood flow is diverted away from a particular region of the body due to changes in the circulatory system. This often happens when there is a blockage in a major artery, and as a result, blood is “stolen” from one area to supply another region with higher demands. This can occur in the brain, heart, or other organs and may result in ischemia (reduced blood flow) in the area that is deprived of blood
Steal phenomenon (or vascular steal)
(hypercapnia)
Refers to a situation in which blood flow is redistributed from areas of the brain that are less ischemic (suffering from reduced blood flow) to more ischemic areas, potentially improving blood supply to the more critically affected regions
The Robin Hood phenomenon (also known as the reverse steal phenomenon)
(hypocapnia)
Protect the brain
Hypothermia (controversial)
Glucose control (avoid glucose fluid)
Anesthetics drop CMRO2 in the brain
hemodilution
normocarbia
tight BP control
anestherics have cerebral protective properties
use a shunt or decrease CMRO2
Blood supply to the brain depends on
Circle of Willis or leptomeningeal pathways (secondary collateral channels that bridge vessels to the sides)
cross clamp
common carotid
internal “
external “
maintain map 20% higher than baseline
30min
gold standard for identifying neuro deficits in cross clamping
EEG
limitation of EEG
effect of BP, temp, and anesthetic effect on EEG
only detects superficial laters
what vessels perfuse the brain during aortic cross clamp
basilar artery
other carotids
to circle of Willis
stump pressure
gross measurement of the circle of willis pressure
< 40 mmHg = hypoperfusion = shunt placement
how much heparin before carotid cross clamp and protamine after?
50-100u/kg
50-150 mg
CEA local (cervical plexus C2 and C4) or general?
no standard
meds not to use during CEA
ketamine
nitrous
etomidate?
Have Cardene on standby
most shared post op complication of CEA
hypertension (fluid overload common culprit)
often to go pacu on nitro or prusside gtt
Sudden bradycardia/hypotension due to surgical stimulation of ____ _____.
carotid sinus
treatment of carotid sinus brady/hypotension
1% lidocaine into bifurcation
alternative to CEA
angioplasty and stenting
FYI about angioplasty
local / min sedation
needs to be arousable
heparin & ACT >250s
brady/hypot reflex
Who is angioplasty (CAS) better in?
COPD
CHD
Valvular heart disease
CHF
Contralateral heart failure EF
Contralateral RLN dysfunction
Severe obesity
Who is angioplasty (CAS) worse in?
cant take antiplatelet drugs
old age >80
severe kidney injury
Risk factors for AAA?
50-80 years
Male
Fam Hx
Smoking
COPD
Caucasion
CAD, HTN, PVD, HLD
Contraindications to elective repair of AAA
bad angina
recent MI
bad lungs
bad kidneys
Aneurysms are defined as those that approach the renal artery origin
Juxtarenal
Aneurysms that involve the renal artery origin
Pararenal
Law of Laplace
Tension = Pressure x Radius
most common reason for poor intraop outcomes in AAA
MI
beta blockers for
AAA
PVD
What is the most important technique for enhancing cardiac function in AAA?
preoperative fluid loading
What should urine output be in AAA repair?
1ml/kg/hr
How much heparin before the aortic cross-clamp?
100-300 u/kg 5 min before aortic cross-clamping
Bloody tap prior to AAA epidural?
cancel surgery
4 main AAA goals
keep warm
keep HR slow
Avoid anemia
Prevent HTN
Triad of AAA symptoms
- severe back/abdominal pain
- AMS d/t hypotension
- pulsatile abdominal mass
What is the most common placement of cross-clamp?
infrarenal
central hypervolemia
cross-clamp application
central hypovolemia
removal of cross-clamp
How does BP change above and below the cross clamp
HTN above
HoTN below
CO & HR w/ CC
decreases or stays the same
Hr unchanged
increased venous return
decreased with CC
BP below clamp
EF
CO
Renal blood flow
total O2 consumption
increases w CC
BP above clamp
segmental wall motion abnormalities
Preload
Afterload
Contractility
LV wall tension
Wedge pressure
CVP
Coronary flow
MvO2
Myocardial O2 demand
