Pacing & Anesthetic Management For CIEDs Flashcards
What is the preferred pacing method in an emergency?
Transcutaneous
What energy does transcutaneous require to obtain capture?
40-80 mA
transcutaneous pacing shows (atrial, ventricular, both) pacing
ventricular
What are 2 options for transesophageal pacing?
- Awake patients: swallow a pill electrode that is connected to a pacing wire
- Sedated patients: flexible catheter connected to a pacing wire
transesophageal pacing paces the (atria, ventricle, both)
atria
What current does transesophageal pacing require to obtain capture?
20 mA
When is transvenous pacing used?
when a patient is stable or when transcutaneous pacing is not working
How is transvenous pacing placed?
through a central line
Transvenous pacing can pace (atria, ventricles, both)
both with atrial and ventricular leads
Which pacing method provides the most effective capture?
transvenous
What current does transvenous pacing require?
1.5-3 mA
When do you encounter epicardial pacing?
when the chest is open during cardiac surgery
-leads are sewn into the myocardium
Name 4 temporary pacing methods
- transcutaneous
- esophageal
- transvenous
- epicardial
A CIED is a (temporary/ permanent) pacemaker
permanent
A CIED has a ______ connected to pacing wires that are inserted into the heart via the ______
pulse generator
-SA node
subclavian vein
What are the 3 types of CIEDs?
- Pacemaker
- AICD (automated implantable cardioverter defibrillator)
- CRT (chronic resynchronization therapy) device
- biventricular pacemakers
What are the 2 primary reasons a patient would need a pacemaker?
- to pace patients with slow heart rates
2. to improve the timing of atrial and ventricular beats in patients with complete heart block
What is a single chamber pacemaker?
When pacemaker leads are inserted into the right atrium OR the right ventricle
what is a dual chamber pacemaker?
When pacemaker leads are inserted in BOTH the right atrium AND the right ventricle
Where is the lead located in an ICD and what does it have?
right ventricle
has a built in shocking coil that can sense and shock tachyarrhythmias
What 3 things can intravascular ICDs do?
- pacing
- synchronized cardioversion
- antitachycardia pacing (defibrillation)
What are subcutaneous ICDs used for?
defibrillation only
Where are the leads in a biventricular pacemaker?
one lead in the right ventricle and a second lead guided into the left ventricle through the coronary sinus
How is the pulse generator for the ICD programmed?
by the pacemaker rep
How does the pacemaker rep test an ICD in surgery?
the rep purposely places the patient in Vfib and then will shock them back into sinus rhythm
When testing the ICD in surgery, what should the anesthetist be sure to do?
give a small propofol bolus prior to shock delivery
____ refers to cardiac cells responding to pacemaker stimulation
capture
_____ refers to the minimum current level at which capture is observed
pacing threshold
_____ is the current at which the pacemaker maintains capture
maintenance threshold
What should the maintenance threshold be set at?
10% higher than the pacing threshold
_____ is how sensitive the pacemaker is to sensing electrical activity within the heart
sensitivity threshold
if the pacemaker sensitivity is too high, the pacemaker will?
- not pace as much as it should
- pace when its not supposed to
not pace as much as it should
if the pacemaker sensitivity is too low, the pacemaker will?
- not pace as much as it should
- pace when its not supposed to
pace when its not supposed to
How is the sensitivity threshold set?
by the pacemaker rep
a patient’s intrinsic heart rate is set by the _____ and is _____ bpm
SA node
60-100
a patient’s paced heart rate comes from the _____ and is usually set at _____ bpm
pacemaker
60
How do you know if the heart rate is coming from the pacemaker?
there will be a pacemaker spike on the ECG
if a patient has a pacemaker, can the patient’s heart still initiate heart beats?
yes
What phenomenon can occur when having 2 potential sources of heartbeats?
R on T phenomenon and can lead to Vfib/Vtach
What pacemaker mode prevents R on T phenomenon from happening?
Demand mode
a pacemaker in ______ can “sense” electrical activity in the heart, and is programmed to only pace when the heart rate falls below a certain rate (usually ≈60 beats per minute)
demand mode
in demand mode, what happens when the intrinsic rate is faster than the paced rate?
the pacemaker will be suppressed
in demand mode, what happens when the intrinsic rate is slower than the paced rate?
the pacemaker will start to pace
When a pacemaker is in demand mode, and it senses cautery, the pacemaker (will, will not) pace
will not pace
-senses the cautery as being electrical activity of the heart
Whenever a patient is reliant on their pacemaker to have a normal cardiac output, they are ______
“pacemaker dependent”
In pacemaker dependent patients, what happens when cautery is used in demand mode?
cautery induced bradycardia
in patients who are NOT pacemaker dependent, will the pacemaker always pace?
no, sometime you will see pacing spikes and sometimes you will not
- sometimes the intrinsic rate is faster than the pacemaker and sometimes the intrinsic rate is slower than the pacemaker
- cautery induced bradycardia is not as severe
_______ mode means that the pacemaker cannot “sense” anything (intrinsic heart beats or cautery)
asynchronous
When a pacemaker is in asynchronous mode, and it senses cautery, the pacemaker (will, will not) pace
will
When do pacemakers in asynchronous mode pace?
always
Why is asynchronous mode advantageous in surgery?
the pacemaker will pace, even during cautery, so cautery induced bradycardia is no longer a concern
Why can asynchronous mode be a problem?
It will not sense the intrinsic rate either, and can pace when it is not supposed too.
Leads to 2 sources pacing the heart, R on T phenomenon, and Vfib
When is the only way asynchronous mode is safe?
When the paced rate is greater than the intrinsic rate
What are the 2 ways in which asynchronous mode is safe?
- when the paced rate is faster than the intrinsic rate
2. when the intrinsic rate is slower than the paced rate
Whan a pacemaker is programmed to asynchronous mode, what is the paced rate set at?
80-100 bpm
-ensures the paced rate stays greater than the intrinsic rate and the intrinsic rate stays suppressed
How does the anesthetist convert a pacemaker to asynchronous mode?
places a magnet over the pacemaker
-Alternatively, a pacemaker rep can also reprogram the pacemaker to go into asynchronous mode prior to surgery (without using a magnet)
How does a pacemaker with rate modulation work?
programmed to increase the paced heart when it senses increased movement and/or minute ventilation
allows pacemaker dependent patients to exercise by increasing cardiac output
how does antitachycardia pacing work?
terminates tachycardia by pacing faster than the intrinsic rate
- when the paced rate is faster than the intrinsic rate, the intrinsic tachycardia will be suppressed
- When the paced rate slows back down, the initial tachycardia will be gone
What 4 rhythms can antitachycardia pacing be helpful for?
- atrial fibrillation
- atrial flutter
- supra ventricular tachycardia
- monomorphic Vtach
if antitachycardia pacing fails several times, what will the pacemaker do?
shock the heart
List 5 indications for a pacemaker:
- sinus Brady
- sick sinus syndrome (SA node speeds up and slows down)
- 3rd degree AV block
- Mobitz Type II heart block
- atrial fibrillation with slow ventricular response
Suppose a patient has chronic bradycardia and/or sick sinus syndrome (as pictured above). What type of pacemaker should be used for this patient?
Atrial? Ventricular? Or dual chamber (atrial + ventricular)?
atrial
-single chamber in the right atrium
Suppose a patient has atrial fibrillation with slow ventricular response (as pictured above). What type of pacemaker should be used for this patient?
Atrial? Ventricular? Or dual chamber (atrial + ventricular)?
Ventricular
-an atrial pacemaker wouldn’t work because the constant atrial activity in afib would make it less likely to pace
-single chamber pacemaker in the right ventricle
when a single chamber pacemaker is placed in the right ventricle, what can it pace?
both right and left ventricles because the ventricular lead can pace the septum which causes both the right and left ventricles to contract
Suppose a patient has complete heart block (as pictured above). What type of pacemaker should be used for this patient?
Atrial? Ventricular? Or dual chamber (atrial + ventricular)?
Dual chamber
Dual chamber
- atria and ventricles are contracting but not in sync
2 ways that a dual chamber pacemaker can fix complete heart block
- if the atrial leas SENSES when the atria contract
2. the ventricular lead is set to PACE 120-200 msec after the atria contract
How does a single chamber lead for complete heart block work?
there is a “sensing portion” in the right atrium that senses atrial beats and a “pacing portion” in the right ventricle that is programmed to pace 120-200 msec after each atrial beat
In a single chamber lead for complete heart block, where will the pacing spike be located?
right before the QRS complex
- the atrial lead only “senses”
In what 2 heart conditions would a biventricular pacemaker be most useful?
- right or left bundle branch block
2. heart failure
What type of patients are ICDs placed in?
Patients with some type of chronic heart failure because they are more prone to ventricular arrhythmias
What happens when cautery is used with an ICD?
the ICD is inappropriately triggered to shock because it interprets cautery as vfib
At what energy is an ICD programmed to shock arrhythmias?
15-35 J
How can the anesthetist disable the shock function of an ICD?
place a magnet over it
-pacemaker rep can also reprogram the ICD prior to surgery
What are 2 ways to prevent accidental shock from an ICD during cautery without placing a magnet
- place the grounding plate as far away from the ICD as possible (at least 15cm)
- surgeon to use an alternative to unipolar cautery (like bipolar cautery or a harmonic scalpel)
How does a harmonic scalpel cut and seal tissue?
cuts by vibration and seals by denaturing proteins
3 advantages of a harmonic scalpel
- cuts thicker tissue than a bovie
- less smoke
- less thermal damage
2 disadvantages of a harmonic scalpel
- takes longer to cut and coagulate tissue
2. can only coagulate as it cuts
What is the effect of the pacemaker function of an ICD with magnet placement?
(is the pacemaker in demand mode or asynchronous mode?)
the pacemaker will be in demand mode
-can still have cautery induced bradycardia
if the surgeon will be using cautery, what should be done with the ICD?
the shock function of the ICD should be disabled by either the pacemaker rep preoperatively or by the anesthetist with magnet placement
What is the only circumstance when the shock function of the ICD does NOT have to be disabled?
When the surgery site is below the umbilicus
-cautery below the umbilicus is far enough away from the ICD that the ICD will not be able to sense the cautery as Vfib
A pacemaker dependent patient has a magnet placed over their ICD. What will happen during cautery?
cautery induced bradycardia
A pacemaker dependent patient has a magnet placed over their ICD,
How can anesthesia prevent cautery induced bradycardia in this patient?
Get a pacemaker rep to reprogram the ICD to become asynchronous with magnet placement
a traditional ICD consists of a right ventricular lead (inserted through a central line) that is capable of (pacing, shocking, both)
both pacing AND shocking
a subcutaneous ICD is capable of (shocking, pacing, both)
shocking ONLY
What is 1 advantage to the subcutaneous ICD
intravascular leads become fibrosed in place over time, lead revision and extraction procedures are challenging and not without risk
3 disadvantages to the ICD
- S-ICDs are not indicated in patients who require anti-bradycardia pacing, cardiac resynchronization therapy, or antitachycardia pacing
- energy requirements approximately threefold for successful defibrillation.”
- S-ICDs are not designed to treat ventricular arrhythmias at rates lower than 170 bpm
What is a pacemaker interrogation?
a 15 minute procedure that checks the function and battery life of a pacemaker
how often should pacemakers be checked?
every year
how often should ICDs be checked?
every 6 months
9 things the Anesthetist should know Preop about the CIED
- what type of device?
- pacemaker or ICD - the programmability of the device (VOO)
- the underlying rhythm (why was the pacemaker placed in the first place)
- is the patient pacemaker dependent?
- if yes, need to get a second method for pacing if pacemaker fails - does the pacemaker have rate modulation?
- does the pacemaker capture effectively
- what is the magnet response
- is there adequate battery life (> 3-6 months)
- what are the manufacturers perioperative recommendations
How should a rate modulation pacemaker be handled in surgery?
rate modulation should be disabled so the heart rate doesn’t change with ventilation or movement
if a patient has a pacemaker or an ICD, what 3 things should be readily available
- external pacemaker with pacing pads
- magnet
- anti-bradycardia drugs (atropine, epi)
A female patient has an intravascular ICD, and her ECG is shown above. (pacing spike before every p-wave) The surgeon will be using cautery for the procedure.
- is she pacemaker dependent?
- After magnet placement, what is the cautery effect on heart rate?
- How should she be managed?
- yes
- cautery induced bradycardia
- ask the surgeon to use bipolar cautery or harmonic scalpel
- prior to surgery have rep reprogram pacemaker to become asynchronous with magnet placement
A male patient has a regular demand pacemaker, and his ECG is shown above. ( no pacing spikes with normal rhythm)
- Is he pacemaker dependent at the moment?
- What is the cautery effect on his heart rate?
- What is magnet placement most likely to do?
- Should a magnet be placed on this patient?
- no
- no effect
- put the magnet into asynchronous mode and increase the paced rate to 80-100 bpm
- will cause arrhythmias - no
A male patient has an intravascular ICD, and his ECG is shown above. (pacing spikes before the p-wave and QRS complex with slow rhythm) No cautery is planned for the procedure. Should a magnet be placed on this patient?
Not required but depends on the provider
This patient has an intravascular ICD, and her ECG is shown above. (normal sinus rhythm with no pacing spikes) Cautery is planned for the procedure.
- What is magnet placement most likely to do?
- Should a magnet be placed on this patient?
- disable the shock function
2. yes
A male patient has a regular demand pacemaker, and he goes asystolic whenever cautery is used. How should he be managed during surgery?
place a magnet to put the pacemaker into asynchronous mode
A female patient has a intravascular ICD and is pacemaker dependent. The shock function of her device was disabled by the pacer rep prior to surgery. During surgery, she becomes asystolic whenever cautery is used. How should she be managed at this point?
- Ask surgeon to use bipolar cautery
2. call a pacer rep to reprogram the ICD to become asynchronous with magnet placement
A male patient has a regular demand pacemaker, and his ECG is showing that all P waves are preceded by pacing spikes. How do we explain his ECG?
(heart rate is speeding up/slowing down)
Perhaps rate modulation was not disabled and movement may cause pacemaker to change its rate
Most healthcare workers refer to a _____ letter classification code for pacemakers
3
pacemakers actually have a ____ letter classification code
5
What does the first letter in pacemaker classification refer too?
which chambers have pacing leads (atria, ventricle, or both)
What does the second letter in the pacemaker classification refer too?
which chambers can “sense” electrical activity
What does the third letter in the pacemaker classification refer too?
how a pacemaker responds after it senses electrical activity
What does the 4th letter in the pacemaker classification refer too?
its programmability
What does the 5th letter in the pacemaker classification refer too?
antitachyarrhythmia function
1st letter of pacemaker classification:
Which letters are possible?
A=atria
V=ventricle
D=dual
2nd letter in the pacemaker classification
which letters are possible?
A=atria
V=ventricle
D= dual
O= none
When the second pacemaker letter is “O”, what does this mean?
the pacemaker cannot sense anything= the pacemaker is in asynchronous mode
-will pace constantly
3rd letter in the pacemaker classification
Which letters are possible?
I= inhibits
T=triggered
D= dual (triggered and inhibits)
O=none
When the 3rd letter in pacemaker classification is “I”, what does this mean?
the pacemaker will “inhibit” itself (prevent itself) from pacing whenever it senses intrinsic/electrical activity in the heart
-The pacemaker is in DEMAND mode
When the 3rd letter in pacemaker classification is “T”, what does this mean?
the VENTRICULAR lead will be TRIGGERED TO PACE WHEN IT SENSES intrinsic/electrical activity
-usually when the ventricular lead is programmed to pace a few seconds after each atrial beat (heart block)
What is the main scenario that we would see the 3rd pacemaker classification letter be a “T” (triggering)
dual chamber pacemaker that was placed for complete heart block
What is another scenario where we may see the 3rd pacemaker classification letter be a “T”
biventricular pacemaker
-allows the right ventricle and left ventricle to contract at the same time, and this function is only possible because the left ventricle is TRIGGERED to pace when the pacemaker senses a right ventricular beat
When the 3rd pacemaker letter is “D”, what does this mean?
the pacemaker is both “triggered (T) and inhibited (I)”
-usually when the SA node is working properly (pacemaker is inhibiting itself) but AV node is delayed ( ventricular pacing is triggered)
When the 2nd pacemaker letter is “O”, the 3rd letter will ALWAYS be _____
O
5th letters in pacemaker classification
Which letters are possible
P=pacing
S=shock
D= dual (pacing and shock)
O= none
Name The 3 Letter Pacemaker Codes For These Patients
sinus bradycardia
AAI
Name The 3 Letter Pacemaker Codes For These Patients
Slow Afib/Atrial flutter
VVI
Name The 3 Letter Pacemaker Codes For These Patients
Complete AV block, normal sinus node
DDD or VDD
Name The 3 Letter Pacemaker Codes For These Patients
Complete AV block & sinus bradycardia
DDD
Name The 3 Letter Pacemaker Codes For These Patients
Sinus bradycardia with a magnet placed on the pacemaker
AOO
AAI pacing has a single lead in the ______ and is indicated in patients with _____ or ______
right atrium
sinus bradycardia or sick sinus syndrome
_____ pacing is asynchronous pacing from the right atrium, and can be activated with magnet placement over a regular (non-ICD) atrial pacemaker
AOO
VVI pacing utilizes a single lead in the _____ and is indicated in patients with ______
right ventricle
atrial fibrillation
____ pacing is asynchronous pacing from the right ventricle, and can be activated with magnet placement over a regular (non-ICD) ventricular pacemaker
VOO
DDD pacing utilizes leads in the _______, and is indicated in patients with _____ (with or without sinus bradycardia)
right atrium and right ventricle
complete heart block
____ pacing is asynchronous pacing from the right atrium and right ventricle, and can be activated with magnet placement over a regular (non-ICD), dual chamber pacemaker
DOO
VDD pacing utilizes a specialized lead in the _______ that has the ability to sense ____
and is indicated in patients with ______
right ventricle
atrial beats
complete heart block and a normally functioning SA node
MRI is _____ for all patients with CIEDs
contraindicated
CT can cause _____ with some ICDs
interference
What should you do with an ICD for radiation therapy
shield it as much as possible if it lies directly in the radiation field
(ICDs/ Pacemakers) have been show to be more sensitive to radiation therapy
ICDs
______ uses waves to ablate areas of the heart/terminate arrhythmias
Radiofrequency (RF) ablation
______ is a medical device used to relieve acute or chronic pain. The electrodes are placed on the skin and connected to a pulse generator
A transcutaneous nerve stimulator
What is the transcutaneous nerve stimulator effect on an ICD
can result in inappropriate shock
What is the transcutaneous nerve stimulator effect on a pacemaker?
use with caution especially if the patient is pacemaker dependent
______ a medical procedure in which transcutaneous electrodes are placed on the head and used to induce a tonic clonic seizure. It is a safe and effective treatment for depression
electroconvulsive therapy (ECT)
how often is ECT performed?
twice weekly until no further improvement of symptoms (usually 3-4 weeks)
is the length of seizure or amount of current more important for ECT?
length of current
In ECT, what is the INITIAL cardiovascular response?
Should it be treated?
there is an initial parasympathetic discharge (which lasts 10-15 seconds) leading to possible bradycardia and hypotension,
No, this is followed by a sympathetic response (which lasts longer than the parasympathetic response; peaks at 3-5 minutes) where heart rate, blood pressure, and myocardial oxygen consumption all increase)
in ECT, cerebral oxygen consumption, blood flow, and ICP all (increase, decrease)
increase
What 2 popular drugs are used for induction for ECT?
Brevital (Methohexital) or Etomidate
-they do not raise the seizure threshold
Which drug results in the longest seizure duration for ECT, brevital or etomidate?
etomidate
Etomidate (does/ does not) blunt the sympathetic response for ECT
does not
Propofol (increases, decreases) the seizure duration and (does, does not) blunt the sympathetic response in ECT
decreases
does
Ketamine ensures (longer/ shorter) seizure duration, however ______ could be of concern in ECT
longer
increased intracranial pressure
(Hyperventilation/ hypoventilation) (through cerebral vasoconstriction) lowers the seizure threshold and can (shorten/ prolong) the seizure duration in ECT
Hyperventilation
prolong
Which neuromuscular blocking agent is most commonly used in ECT
succinylcholine
-Muscle relaxants reduce muscular convulsions and decrease the risk of serious injury
how should demand pacemakers an ICDs be handled in ECT therapy?
demand pacemakers should be converted to asynchronous mode, especially if the the patient is pacemaker dependent
the shock functions of ICDs should be deactivated
______ uses transcutaneous ultrasonic shock waves to disintegrate kidney or ureteric stones (no cysto is required)
Extracorporeal Wave (ESW) Lithotripsy
Synchronized litho shocks are triggered by the___ wave on the ECG, and are delivered in the _____ period of the cardiac cycle
R
refractory
What is the advantage of synchronized litho shocks?
carries a lower risk of causing PVCs/arrhythmias than non-synchronized shocks
What is the disadvantage of synchronized litho shocks?
the procedure goes slower because it can only shock as fast as the heart rate
Non-synchronized litho shocks are delivered at ____ per minute
96
what is the advantage of non-synchronized litho shocks?
the procedure goes faster
what is the disadvantage of non-synchronized litho shocks?
they are more likely to cause PVCs/arrhythmias (due to mechanical stresses on the conduction system exerted by the shock waves)
How do CIEDs interpret lithotripsy shocks?
the same way they interpret cautery
- A pacemaker to stop pacing
- An ICD to inappropriately shock the patient
If a patient has a CIED in ESW lithotripsy, how should it be managed?
a magnet should be placed
CIED Atrially paced patients in ESWL should ONLY use (synchronized/ unsynchronized) shocks
unsynchronized
