Exam 3 Cardiac Flashcards
What needs to be evaluated pre-operatively in patients having cardiac surgery?
cardiac history
past surgical history
angina presentation
dysrhythmias
past medical history
co-morbid diseases
medications
When asking a patient about their cardiac history, what is prevalent?
severity of disease/ hemodynamic status
catheterization, ECHO, ECG reports
what is the baseline disease? (low EF, LVEDP, pulmonary HTN, valvular & congenital lesions, CHF)
What preoperative testing needs to be completed prior to cardiac surgery?
cardiac catheterization (locate blockages)
ECG: recent MI
ECHO report (EF, valve function, wall abnormalities, calcified aorta, atrial thrombus (no CVA)
Hematologic studies (Pt, ptt, baseline ACT)– clotting studies, platelet # and functionality (TEG)
CXR: calcifed aorta, cardiomegaly
renal function: decreased function increases post op mortality
liver function test: CPB my hypo-perfuse liver
T/C
What medications need to be continued?
antiarrhythmics
calcium channel blockers
beta blockers
nitrates
What are the goals of cardiac anesthesia? (4)
decrease cardiac oxygen utilization
maintain oxygen supply
anticoagulation
maintain BP in target range
How do you decrease cardiac oxygen utilization?
anesthesia, hypothermia, electrical silence, cardioplegia use, empty cardiac chambers, specifically in the LV (avoid distention)
How do you maintain oxygen supply?
maximize oxygen carrying capacity and flow
Hemodilution is acceptable perfusion pressure and flow
Describe myocardial protection strategies
cardioplegia induced systole
hypothermia
hemodilution
What is cardioplegic induced systole
electrical and mechanical activity ceases
potassium given continuously during cross clamping
must be able to cross clamp aorta (calcifications/clots present?)
blood vs. clear prime
hyperkalemia is issue with renal patients
How does hypothermia protect the myocardium?
alters platelet function and reduces fibrin enzyme function
inhibits initation of thrombin formation
reduces metabolic demands and increases tolerance to ischemia
Describe hemodilution’s role in myocardial protection?
increases flow due to decreased blood viscosity
List the order of events for a CAGB (15)
pre-operative preparation
monitors
lines
induction
wait
incision
drop lungs
sternotomy
surgical dissection
cannulation
on-bypass
off bypass
dry- up: give protamine
close chest
ICU
What monitors are needed for cardiac surgery? (7)
pulse ox
TEE
ECG (leads 2 and 5)
temperature
ABP (usually radial, sometimes femoral)
CVP (mandatory for infusion of drugs)
PA catheter
When do patients require a PA catheter?
severe LV dysfunction
profound pulmonary HTN
What does a transesophageal echo assess? (8)
evaluation of ventricular filling, estimation of cardiac output, assessment of ventricular systolic and diastolic function, valvular pathology, cardiac tamponade, calcified aorta, atrial thrombus
What interventions can a TEE help guide?
volume administration
start vasoactive drips
re-examine graft
assessment of surgical repair
What are contraindications for a TEE?
esophageal pathology (Alcoholic varices)
empty stomach prior to placing tube
When do you know the swan catheter has entered the pulmonary artery?
the waveform shows an increase diastolic pressure in the PA vs the RV
What are complications of the PAC/Swan? (11)
ventricular arrhythmias
heart block
pneumothorax
unintended arterial punction
valve damage
hematoma/ thromboembolism
vascular injury
perforation of thorax leading to hemothorax
PA rupture
cardiac tamponade
BSI
What patients have an increased risk of heart block with a Swan catheter?
LBBB
What is the most common acute injury of a PA catheter?
unintended arterial puncture
When is a pneumothorax from a PA catheter placement most common?
subclavian approach
What are the goal pre-bypass hemodynamics?
BP between 20% of patient’s baseline
HR between 40-80 are generally fine depending on situation prior to bypass
What are hemodynamic goals pre-bypass for aortic stenosis?
maintain preload
maintain SVR
HR 50-80
NSR
What are the hemodynamic goals of pre-bypass for aortic regurgitation?
Forward, fast and full
maintain preload
Low SVR
HR 50-80
NSR
What are the hemodynamic goals of pre-bypass for mitral stenosis?
Maintain preload
maintain SVR
HR 50-80
NSR
What are the hemodynamic goals of pre-bypass for mitral regurgiation?
maintain preload
HR 50-80
NSR
low SVR
What is needed for OR set up in cardiac cases? (6)
airway/ equipment
pacemaker
drips (NTG/NTP, E/NE, Phenylephrine/epedrine, dopamine/dobutamine, antiarrhythmics- esmolol, labelotol, magnesium, amiodarone)
heparin and coagulation monitoring
emergency drugs
PRBCs
magnesium
insulin drip
antifibrinolytics
Pre-induction patient preparation (7)
Nasal Cannula
mild sedation
PIVs x2, arterial line
baseline ABG and baseline ACT
cross matched blood
placed external defibrillation pads prior to induction
make sure team is aware rolling back
When can propofol be safely used for induction?
patients with ischemic and valvular heart disease
Describe the use of ketamine during induction
CV effects are advantangous
Biggest challenge is CV stimulation
What needs to be avoided during induction and CPB?
N2O
Describe the effect of VAs during cardiac anesthesia (6)
produce dose dependent global cardiac depression
negative effects of volatile anesthetics are due to alterations in intracellular Ca++
sensitized myocardium to the effects of EPI in varying degrees
may prevent or faciliate atrial or ventricular arrhythmias during myocardial ischemia or infarction
produce weak coronary artery dilation and depresses baroreceptor reflex control of arterial pressure
How can you treat hypertension from incision?
deepen anesthetic, vasoactive agents (NTG, NTP)
Discuss events from incision to bypass (7)
intense surgical stimulation
hypertension
handling of heart by surgeon
bleeding can be significant
identifying and localizing ischemia
drop lungs for sternotomy
arterial and saphenous veins are harvested
What is the MOA of heparin?
binds to antithrombin 3 and potentiaes its natural anticoagulant properties
What is the dose of heparin prior to initating bypass?
300-400u/kg
wait 3-5 minutes for ACT
What is a normal ACT
<130seconds (80-120)
What is the goal ACT during CPB
400-450
How is the heparin administered for bypass?
CVP or RA
What can happen to the patient’s hemodynamics after the administration of heparin?
decrease in SVR and BP by 10-20%
What are two special circumstances with the administration of heparin?
AT3 deficiency (FFP or thrombate 3)
HIT (antiplatelet antibodies lead to platelet aggregation and potentially life threatening thromboemoblic events
Describe interventions need post heparinzation, but pre-bypass
drop BPs prior to aortic cannulation
fluid administration via perfusionist in arterial line
cannulation of coronary sinus for retrograde cardioplegia
Make sure patient is adequately paralyzed
Where are the cannulas for bypass placed?
aorta (arterial), RA (venous)
What can happen while placing the venous cannula?
BP drop, arrhythmias
What are frequently encountered problems pre-bypass?
arrhythmias (d/t cardiac manipulation and cannulation) (first sign of myocardial ischemia)
HTN
Hypotension
heart failure
sternotomy lacerates RV or aorta causing bleeding
What occurs when transitioning to CPB?
perfusionist opens the venous clamp > blood drains passively into venous reservoir, immediately begins to cool patient
What does the CRNA needs to do after transitioning to CPB? (5)
arterial trace goes flat, ECG present
pull back PAC 2-3 cm
look at head for swelling
check pupils andBIS
stop ventilator once heart is empty
What occurs when the patient is placed on pump?
significant hemodilution and decrease in O2 carrying capacity
Hct 20% acceptable
What is hemodilution associated with on pump?
decreased viscosity, decreased SVR and promotes blood flow to tissues
What is important to measure prior to coming off CPB?
urine
What are issues related to CPB
HTN related to SVR
renal ischemia from hypoperfusion and/or hemodilution
CVA from thrombus in CPB system (clot or foreign object)
Air emboli introduced into CPB system
thrombocytopenia
increased inflammatory response
altered post-op mental state (pump head)
What are two processes an inflammatory process is trigger in cardiac surgery?
surgical
perfusion
technology
pharmacology
How does surgery trigger the inflammatory process?
aortic manipulations
minimally invasive approach
bank blood utilization
duration of CPB
How does perfusion trigger the inflammatory process?
ultrafiltration
shed-blood management
circuit prime volume
beating-heart technique
How does technology trigger the inflammatory process?
roller/centrifugal
open/closed circuits
surface coating
selective filtration
How does pharmacology trigger the inflammatory process?
steroids
statins
others
What are signs of inflammation? (initators) (2)
systemic cytokine signaling and complement system activation
expression of cell adhesion molecules
What are signs of inflammation? (effectors) (2)
margination of neutrophils, monocytes, and platelets
release of granule proteases
What are the biggest culprits of emobli?
hypothermia
blood gas management
adequate BP
cerebral oximetry
When will re-warming begin?
prior to aortic cross clamp removal OR
last distal anastomosis in angioplasty procedure OR
all the valve sutures are in and knots are being tied down
Describe what needs to be prepared for coming off bypass? (13)
core temperature above 35
correct labs, ABG (fix K first)
inflate lungs
removal of cross clamp
defibrillation
pace around 90 (av or v paced)
venous return line clamped slowly, turn down flows and allow RA to fill
measure CO, monitor PA and arterial line pressures
monitor SvO2 (supply and demand balance)
shivering (paralyze)
airway (turn vent on)
Off bypass means
when pump comes off and venous cannula clamped
When coming off cross clamp, what can occur?
myocardial damage and limit extent of recovery
What are complications of an aortic cross clamp?
hemorrhage (at cannulation site), dislodgement of clots, aortic dissection
What is voltage is used to defibrillate a patient during cardiac surgery
10-30J
What is important to assess when coming off bypass?
CONTRACTILITY
watch with eyes,
look at TEE (volume, wall motion, valve function)
What interventions are made coming off bypass?
inspection for bleeding
protamine adminstered slowly
What can type of scenerio can occur when the chest is closed?
cardiac tamponade
What is the dose of protamine needs to come off bypass?
1mg/100U of heparin
What are challenges to coming off CPB? (7)
recall and neurocognitive changes
bleeding
organ hypoperfusion
non-pulsatile flow, emobli, thrombi
systemic inflammatory response
residual hypothermia
What makes it harder to come off CPB?
extend CPB and aortic cross clamp times
may require IABP
Why does bleeding occur after CPB?
loss of clotting factors
fibrinolysis
thrombocytopenia
surgical blood loss
transfusion reaction
vessel trauma
metabolic byproducts
What are reperfusion interventions?
spend time paying back by re-perfusing the empty heart at adequate perfusion pressure (20-30 minutes)
allows heart to recover by washing out metabolic by products
correct metabolic abnormalities
What can protamine cause?
R heart failure
pulmonary HTN
administer slowly
What is the MOA of protamine
neutralize and reverse effects of heparin so heparin is unable to form a complex with ATIII
What type of allergic reactions cause histamine release?
1-3
WHat is the heparin rebound?
Half life of protamine is shorter then heparin therefore after 30-60 minutes may need to trend ACTs or correct
What do you need to transport a post CABG to the ICU?
ambu bag, o2 tank
ECG, arterial line, emergency drugs
What is the typical recipient for a heart transplant?
NYHA functional class IV, life expectancy <12 months, EF<20%
What is the most common implication for heart transplant?
idiopathic cardiomyopathy
What are contraindications for a heart transplant?
> 70Y, chronic renal disease, obesity
What is the anesthetic goal of heart transplantation?
go on CPB as fast as possible
What are anesthesia considerations for heart transplant?
timed so CPB is inititated when heart is available
preop- VAD, IABP, ICD, inotropic drug infusion
considered full stomach
lines prior to induction
smooth rapid control of airway
slow adminstration of medications
maintain HR and intravascular volume, avoid decrease in SVR
adhere to immunosuppression
What medications should be available for heart transplnat?
E/isoproterenol, milrinone, nitric oxide, inhaled prostagladins
vasopressin preserves SVR without effect on PVR
What are anesthestic considerations post-transplant?
loss of parasympathetic tone-> fast HR
Direct acting myocardial adrenergic agents
inotropes and vasoconstrictors available for HR BP And CO support
volume dependent, frank starling mechanism still intact
accelerated CAD w/o angina
2 p waves
What are the anesthetic considerations for off pump CABG?
immobilzation of the heart by compression and/or suction
prevent hypotension and reduced coronary artery perfusion
How do you prevent hypotension and reduced CPP in off pump CABG?
volume load, head down, pressors
What is a MIDCAB? (minimally invasive direct coronary artery byass)
grafting of a single vessel
LIMA to LAD
What is required in MIDCAB?
lung isolation with double lumen endbronchial tubes
off pump case
left anterior thoractomy incision
Anesthetic implications for minimally invasive aortic and mitral valve replacements
good preload, decrease HR
arrhythmias
CPB needs to be available
decrease heparin dose
needs to have defibrillation pads
DLT for lung isolation
femoral cannulation
transvenous pacing (placed and tested)
pads on
central venous access
Anesthetic implications for total aortic valve repair/ total aortic valve implanation
approached through femoral artery or transapical (apex of left ventricle)
IV sedation or GETA
large bore IV, arterial line, central access
TEE/TTE
external defibrillator pads (R2 pads)
vasopressors
What are blood conservation strategies in cardiac surgery?
anti-fibrinolytic drugs, minimizing hemodilution, cell saver, retrograde priming of pumo, normovolemic hemodilution, POC testing to support transfusion
What pathways are activated in cardiac surgery?
intrinsic and extrinsic
How is platelet function loss?
hemodilution, hypothermia, contact with CPB circuit
WHy does right ventricular dysfunction or failure occur after CPB?
inadequate myocardial protection or inadequate revascularization wiht resultant right ventricular ischemia
How do CNS insults occur?
micro-emboli, cerebral hypoperfusion and SIRS
What can increase the risk of post operative renal dysfunction?
renal insufficiency, Type 1Dm, vascular pathology and nephrotoxic agents
What does a midline sternotomy (or thoractomy) cause?
reduction in total lung capacity, vital capacity, and force expiratory volume
