Cardiovascular pathophysiology 4 Flashcards
A patient with a bare-metal cardiac stent presents for a bunionectomy. What is the minimal amount of time that the patient should wait before she undergoes surgery?
30 days
A patient who receives a coronary stent requires
dual antiplatelet therapy to prevent stent thrombosis
Dual antiplatelet therapy consists of
aspirin
thienopyridine (usually clopidogrel or ticlopidine)
Withholding DAPT therapy after a coronary stent leads to
increased risk of thrombus formation and myocardial infarction
Continuing DAPT therapy after a coronary stent when doing another surgical procedure leads to
increased bleeding risk
The duration to wait for elective surgery after angioplasty without stent is
2-4 weeks
The duration to wait for elective surgery after bare metal stent placement is
1-3 months
The duration to wait for elective surgery after drug eluting stent is
6-12 months
How many days should clopidogrel be stopped before surgery?
7 days
How many days should ticlopidine be stopped before surgery?
14 days
For must surgeries, ______ can be continued throughout the perioperative period.
aspirin
________________- should NOT be used to “bridge” patients who’ve stopped all antiplatelet therapy.
Unfractionated heparin or LMWH
-heparin paradoxically increases platelet aggregation in the stent leading to an increased risk of thrombosis
The best treatment for stent thrombosis is
PCI- best outcome is achieved if blood flow is restored in <90 minutes
How long should elective surgery be delayed after a CABG?
6 weeks (3 months preferred)
Priming the cardiopulmonary bypass machine with a balanced salt solution reduces all of the following EXCEPT:
a. microvascular flow
b. plasma drug concentration
c. oxygen-carrying capacity
d. blood viscosity
a. microvascular flow
__________________ allows the surgeon to operate on an immobile heart.
Cardiopulmonary bypass
How does bypass work?
once the blood flows into the bypass circuit, O2 is added and CO2 is removed
Blood returning to the patient from the bypass machine resembles
arterial blood
Patients on CPB are rendered _____________- to reduce __
hypothermic to reduce metabolic rate
A ___________ pump is preferred over a ____________ pump
centrifugal; roller
A ____________ oxygenator is preferred over a ______________ oxygenator.
membrane; bubble
A ____________ oxygenator is preferred over a ______________ oxygenator.
membrane; bubble
If priming the pump with a balanced salt solution, you should expect
hemodilution
If priming the pump with a balanced salt solution, you should expect
hemodilution
_______________ can occur if air enters the
An airlock; venous line
The _______________ is the component of the CBP machine where gas exchange occurs (it replaces the lungs)
oxygenator
Why is a bubble oxygenator not preferred?
uses a blood-gas interface (no membrane)- carries a risk of cerebral air emoblism
The priming fluid for CBP can be
blood or a balanced salt solution (mannitol, albumin, heparin, HCO3-)
Hemodilution has the following effects:
decreased hematocrit
decreased oxygen-carrying capacity
decreased blood viscosity (good if hypothermia is used)
decreased plasma concentration of drugs and plasma proteins
increased microvascular flow (due to reduced viscosity
When is awareness MOST likely to occur during coronary artery bypass graft surgery with CBP?
a. induction of anesthesia
b. aortic cannulation
c. rewarming
d. sternotomy
d. sternotomy
What ACT is required to start CPB?
> 400
Systolic BP should be _______________ before aortic cannulation
<100
What should be used pre-bypass to conserve blood loss?
cell saver or antifibrinolytics
Cardioplegia is a
potassium-containing solution that arrest the heart in diastole
The best way to reduce myocardial oxygen consumption during CPB is
cardioplegia
CPB produces ________________________ that can result in critical organ injury and failure
systemic inflammation
_________ of protamine reverses 100 units of heparin given
1 mg
Radial artery pressure may be _____________________________ immediately after CPB
artificially low
What are common in the post-bypass period?
myocardial depression and heart block so vasoactive medications and cardiac pacing may be required
Heparin allergy or a history of heparin-induced thrombocytopenia requires
an alternative such as bivalirudin, hirudin, or another factor 10 inhibitor
Cardioplegia can be administered
antegrade, retrograde or both
Antegrade cardioplegia is introduced into the
aortic root, where the solution enters the coronary arteries
Retrograde cardioplegia is administered through a cannula placed in the
coronary sinus
________________ complicates our interpretation of blood gas results during CPB
Hypothermia
As temp decreases more ____________ dissolves in the blood and affects __________
CO2; pH
_____________ does not correct for the patient’s temperature and is associated with better outcomes in adults.
Alpha-stat
_________ corrects for the patient’s temperature and is associated with better outcomes in peds.
pH-stat
__________ is when all of the venous return is drained in the venous reservoir, while ______________ describes a situation where the heart receives and pumps a fraction of the venous return
Full bypass; partial bypass
How does protamine work?
neutralization reaction- it forms an acid/base complex with heparin
Administering protamine over 10-15 minutes reduces the likelihood of
systemic vasodilation as well as pulmonary vasoconstriction
it does not impact the probability of anaphylaxis
List 2 antifibrinolytics commonly used during cardiac surgery.
TXA
aminocaproic acid
What is a contraindication to antegrade cardioplegia?
incompetent aortic valve
