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