Cardiovascular pathophysiology 6 Flashcards
_____________ is the most common cause of postoperative death for AAA.
Myocardial infarction
The classic triad of AAA rupture consists of
hypotension
back pain
pulsatile abdominal mass
only present in 50% of patients
Independent risk factors for AAA include
cigarette smoking
male gender
advanced age
___________ correlates with the risk of rupture
Diameter of the AAA
What law is applied to aneurysms?
law of Laplace
Most aneurysms rupture in the
left retroperitoneum
Which factors increase following cross-clamp removal during abdominal aortic aneurysm repair? (select 2)
a. pulmonary vascular resistance
b. venous return
c. total body oxygen consumption
d. coronary blood flow
a. pulmonary vascular resistance
c. total body oxygen consumption
Application of aortic cross-clamp creates _______________ by increasing _____________ & shifting a greater proportion of the blood volume _______ to the clamp
central hypervolemia; venous return; proximal
How does aortic cross-clamp affect MAP, SVR, and SvO2?
increases all of them
Clamping starves distal tissues of
oxygen so these cells convert to anaerobic metabolism
____________ are washed into the systemic circulation when the clamp is released
Metabolic byproducts
__________ is a minimally invasive approach of correcting an abdominal aortic aneurysm.
EVAR
Removal of aortic cross-clamp creates ____________ by restoring venous capacity ad shifting blood to ___________
central hypovolemia; the lower body
Compared to open aortic procedures, EVAR has several benefits including
shorter operative times
lower rate of transfusion
shorter length-of- stay
reduced morbidity
______________ occurs when the original graft fails to prevent blood from entering the aortic sac
An endoleak
The patient’s physiologic response to the aortic cross-clamp is related to 3 factors:
location of AoX placement (infrarenal most common)
intravascular volume status
cardiac reserve
With an EVAR, the patient will receive
IV contrast dye so complications related to the dye must be considered
Complications of EVAR include
activation of the baroreceptor reflex
massive hemorrhage
aortic rupture
cerebral embolism
Occlusion of the artery of Adamkiewicz during thoracic aneurysm repair may result in all of the following EXCEPT:
a. flaccid paralysis of the lower extremities
b. bowel and bladder dysfunction
c. loss of proprioception
d. loss of temperature and pain sensation
c. loss of proprioception
The most important radicular artery perfusing the anterior spinal cord in the thoracolumbar region is the
artery of Adamkiewicz
Interruption of blood flow to the artery of Adamkiewicz can cause
ischemia or infarction to the corresponding spinal cord segments
An aortic cross-clamp placed above the artery of Adamkiewicz can cause
ischemia to the lower portion of the anterior spinal cord
Anterior spinal artery syndrome is also known as
Beck’s syndrome
Symptoms of anterior spinal artery syndrome include
flaccid paralysis of the lower extremities
bowel and bladder dysfunction
loss of temperature and pain sensation
Anesthetic considerations for aortic surgery include
thoracic cross-clamp times <30 minutes
moderate hypothermia (30-32 degrees C)
CSF drainage
MAP ~100 mmHg
avoidance of hyperglycemia
SSEP & MEP monitoring
partial CPB
drugs- corticosteroids, CCBs, and/or mannitol
Where does the artery of adamkiewicz originate?
typically between T8-12
Injury to which spinal tract explains flaccid paralysis of the lower extremities?
corticospinal tract
Injury to which spinal tract explains loss of pain and temperature sensation?
spinothalamic tract
What is the BEST monitor of neurologic integrity during carotid endarterectomy?
a. cerebral oximetry
b. awake patient
c. electroencephalography
d. transcranial doppler
b. awake patient
Patients with carotid stenosis are at higher risk of
transient ischemic attacks or stroke
In symptomatic patients, CEA significantly reduces stroke risk when the degree of carotid stenosis exceeds
70%
____________ is a sign of impending stroke.
Amaurosis fugax (temporary blindness in one eye)
CEA can be performed under
regional or general anesthesia
_________ is the best method to assess neurologic integrity
The awake patient
______________ on the day of surgery has been associated with an increased risk of stroke and death.
Hyperglycemia (>200 mg/dL)
During cross-clamping, how should BP be managed?
normal or slightly elevated BP
After the cross-clamp is removed, how should BP be managed?
keep the SBP under 145 mmHg to reduce the risk of bleeding at the graft site
Postoperative considerations of BP include
hematoma, RLN injury, labile BP, and stroke (most common embolic)
What ACT is desired for carotid artery angioplasty stenting?
ACT >250 seconds
Balloon inflation with carotid artery angioplasty stenting can activate the
baroreceptor reflex leading to bradycardia and hypotension- pretreat with atropine or glyco to attenuate this response
Embolic stroke is treated with
recombinant tissue plasminogen activator
In the patient with right subclavian steal syndrome, arterial flow is diverted from the:
a. right vertebral artery to the right subclavian artery
b. right subclavian artery to the left subclavian artery
c. left vertebral artery to the right subclavian artery
d. left subclavian artery to the right subclavian artery
a. right vertebral artery to the right subclavian artery
Subclavian steal occurs when
there is an occlusion of the subclavian or innominate artery proximal to the origin of the ipsilateral vertebral artery
The ___________ is much lower in the ipsilateral arm with subclavian steal syndrome
BP- pulse may be diminished
The treatment of choice for subclavian steal syndrome is
subclavian endarterectomy
Signs and symptoms of subclavian steal syndrome include
syncope
vertigo
ataxia
hemiplegia
ischemia to the ipsilateral arm
upper extremity weak pulse
Is subclavian steal syndrome more common on the left or right side?
left side
Subclavian steal syndrome “steals” blood from which vessel?
vertebral artery
