Pacing & CIEDs Flashcards
1
Q
temporary cardiac pacing 4
A
transcutaneous
transesophageal
transvenous
epicardial
2
Q
transcutaneous is preferred when?
A
an emergency
3
Q
3 disadvantages to transcutaneous pacing
A
painful
least effective capture
ventricular only pacing
4
Q
two placement options for transesophageal pacing
A
pill electrode swallowed
flexible catheter can be inserted
5
Q
what does transesophageal pacing pace? atria? ventricle?
A
atria
6
Q
what current does transesophageal pacing require
A
high current
>20mA
7
Q
advantage to transesophageal
A
no need for xray or cath lab
8
Q
disadvantage to transesophageal
A
uncomfortable and requires sedation
9
Q
when is transvenous pacing indicated?
A
stable or transcutaneous isnt working (inability to capture)
10
Q
why does transvenous pacing take longer?
A
central line must be placed
pacing leads must be inserted through central line guided with balloon
11
Q
how is transvenous pacing function controlled?
A
external pacemaker box
12
Q
advantages to transvenous pacing 3
A
can place atrial and ventricular leads
more effective capture
doesnt require as much energy
13
Q
what is the energy requirement for capture for transvenous pacing
A
1.5-3mA
14
Q
disadvantages to transvenous pacing 2
A
more time consuming to establish (cant in emergency)
requires expert placement
15
Q
epicardial pacing
A
common with cardiac surgery
leads are sewn into myocardium
controlled with external box
16
Q
CIEDs
A
cardiovascular implantable electronic devices
17
Q
what is a CIED
A
permanent pacemaker
placed into pocket by surgeon
18
Q
what does a CIED consist of?
A
pulse generator (new SA node) pacing wires that have been inserted through subclavian vein into heart
19
Q
3 types of CIEDs
A
pacemaker
automated implantable cardioverter defibrillators (AICDs or ICDs)
chronic resynchronization therapy (CRT) devices (biventricular pacemaker)
20
Q
two reasons for patients to receive a pacemaker
A
pace pts with slow heart rates
improve timing of atrial and ventricular beats for pts with complete heart block
21
Q
what is an ICD?
A
CIED with specialized pacing lead placed in right ventricle that has a built in shocking coil
shock and sense tachyarrhythmias
22
Q
intravascular ICD
A
provide pacing, synchronized cardioversion and antitachycardia pacing (in addition to defib)
23
Q
subcutaneous ICDs
A
only indicated for defib (cannot pace or sync cardioversion)
24
Q
biventricular pacemakers or cardiac resynchronization therapy device
A
instead of the ventricles being paced by one lead they are paced by by two leads:
1 in RV
1 in coronary sinus to pace LV
25
5 intravascular CIED placement method
1- skin is localized
2- a pouch under skin is created
3- pacing wires placed through subclav vein via fluoroscopy
4- pulse generator is programmed by pacemaker rep, then leads are attached
5- device is sewn underneath skin
26
capture
cardiac cells responding to pacemaker stimulation
27
pacing threshold
minimum current that capture is observed
28
transvenous/epicardial approach capture current
1.5-3mA
29
transcutaneous approach capture current
40-80mA
30
why do we want to avoid high voltages?
cause discomfort
| myocardial damage
31
maintenance threshold
10% higher than pacing threshold to decrease chance of losing capture
32
sensitivity threshold
how sensitive the pacemaker is to sensing electrical activity in heart
33
if the sensitivity is too high?
not pace as much as it should
34
intrinsic heart rate
HR set by SA node 60-100bpm
35
paced HR
HR that comes from battery operated pacemaker ~60bpm
36
how can you tell on ecg if the beat is paced?
there is a pacer spike prior to a p wave or qrs complex
37
will pacemaker spikes automatically come up on the ecg?
no you must enable the pacemaker setting on the monitor
38
two potential sources of heart beat in pt with pacemaker
SA node
| pacemaker
39
why is it dangerous to have two potential sources of heart beats?
if they both go off it can be mistimed and lead to r-on-t phenonmenon and lead to vfib/vtach
40
what is demand mode
a pacing mode that makes it so that only one source (SA or pacemaker) is providing current to the heart
senses when intrinsic rate falls below a certain rate
41
what prevents mistimed beats and arrhythmias?
sensing by the pacemaker
42
if the intrinsic rate is faster than the paced rate, the pacemaker will?
be suppressed
43
if the paced rate is faster than the intrinsic rate then the intrinsic rate will
be suppressed
44
effect of cautery on pacemaker
pacemakers sense surgical cautery and interpret it as electrical activity of the heart
(wont pace during cautery)
45
pacemaker dependent
whenever a patient is reliant on their pacemaker to have a normal cardiac output
46
asynchronous mode
pacemaker cannot sense anything and they start pacing constantly
47
advantage of asynchronous mode
pacemaker will not stop during cautery
48
problem with asynchronous mode
it is possible for the two sources to be simultaneously pacing can lead to r-on-t phenonmenon and vfib
49
when is asynchonous mode safe?
when the intrinsic rate is slower than the paced rate
50
pacemakers should only be placed in asynchonous mode if
pacing rate is high
| patients intrinsic HR is slow
51
pacing rate in asynchronous mode
programmed for pace rate to increase to 80-100 bpm
52
before putting in asynchronous mode what should the anesthetist check?
confirm intrinsic rate is slower than asynchronous rate
| consider beta blocker
53
when should asynchronous mode be necessary?
pacemaker dependent pt is experiencing profound cautery induced bradycardia
54
how to convert pacemaker to asynchronous mode
place magnet over it
55
rate modulation
during exercise the pt moves and breaths more and it senses this and can increase the paced HR
56
antitachycardia pacing (ATP)
senses tachycardia and paces faster than intrinsic rate to suppress it
57
what rhythms can ATP be effective for
afib
aflutter
svt
monomorphic vtach
58
if several attempts at ATP prove ineffective what will the pacemaker do?
shock the heart
59
indications for pacemaker 5
```
sinus brady
sick sinus syndrome (malfunctioning SA node)
3rd degree av block
mobitz type II heart block
afib with slow ventricular response
```
60
what pacemaker should be used for chronic sinus brady or SSS
atrial pacing
61
what type of pacemaker should be used for afib with slow ventricular response?
ventricular because atrial wouldnt work because it has constant electrical activity
62
where is the ventricular lead placed
close to septum and causes left and right ventricles to contract
63
what type of pacemaker should be used for 3rd degree av block?
dual chamber
| atrial lead senses when there is activity and signals for ventricular pace
64
how does dual chamber pacemaker fix complete heart block 2
atrial lead senses when atria contract
| ventricular lead pace 120-200 msec after atria contracts
65
newer pacemaker for complete heart block
single chamber pacemaker where it has sensing portion in RA and the pacing portion in the RV
66
will you see a atrial pacing spike with the single chamber pacemaker for complete heart block?
no
67
what are the 4 ecg that a dual chamber can have?
no pacing spikes (SAN is fast and AVN working)
atrial only pacing (SAN too slow and AVN working)
ventricle only pacing (SAN fast and complete heart block)
dual chamber pacing (SAN slow and complete heart block)
68
in biventricular pacing what does having a lead in both ventricles improve?
in HF the R and L ventricles may be out of sync lowering CO
| it improved the timing of ventricular beats
69
what does improved timing of ventricular beats do?
increases SV and CO
| decreases myocardial oxygen demand
70
what does an ICD have?
specialized ventricular pacing lead that has a built in shocking coil that senses and shocks tachyarrhythmias
71
who are ICDs usually placed in?
CHF pts bc they are more prone to tachyarrhythmias
72
what are ICDs capable of?
pacing and defibrillating
73
S-ICD
CANNOT pace
| only defibtrillate
74
advantage to S-ICD
no need to replace fibrosed leads
| just as effective as transvenous
75
disadvantages to S-ICD
not indicated in pts who require antibrady pacing, CRT, or antitachycardia pacing
higher energy requirements
not for ventricular arrhythmias at rates lower than 170bpm
76
why are ICDs dangerous
can be inappropriately triggererd to shock whenever cautery is used
77
what are ICDs programmed energy to shock
15-35 J
78
two ways to prevent accidental shock from an ICD during surgery
1 disable the shock function of the ICD (programmer or magnet over the ICD)
2 keep electrical current away from the ICD
79
how many cm should the grounding pad be placed away from ICD
15cm
80
what are alternatives to unipolar cautery
bipolar or harmonic scalpel
81
harmonic scalpel
cuts via vibration and seals tissue with protein denaturation
82
advantages to harmonic scalpel
cuts thicker tissue than bovie
less smoke
less thermal damage
83
disadvantages to harmonic scalpel
takes longer to cut and coagulate tissue
| can only coagulate as it cuts
84
magnet on ICD does what
diable the shock function only
85
does the magnet on ICD convert the pacing to asynchronous mode?
no
86
can cautery induced bradycardia occur with magnet on ICD?
yes
87
are magnets over a CIED predictable?
no some reports showed it didnt always work as it should
88
at a surgical site below _____ the shock function of a CIED doesnt have to be disabled
umbilius
89
pacemaker dependent patient has a magnet placed over their ICD what will happen during cautery
no shock, possible brady or asystole
90
pacemaker interrogation
15min procedure that checks the function and battery life of pacemaker
waves wand and connects to computer
91
pacemaker checks are
scheduled at regular intervals over the pts life
| recommended by doctor prior to elective procedure
92
how often should pacemaker be checked
every year
93
how often should ICDs be checked?
every 6mo
94
preop management of CIED
obtain/document results of last pacemaker interrogation and intraoperative recommendations by calling number on card in wallet or bracelet
95
9 things for anesthesia to know in preop CIED pts
```
1 type of device (pacemaker vs ICD)
2 programmability of device
3 underlying rhythm
4 pacemaker dependent?
5 does it have rate modulation
6 pacemaker capture effectively
7 what is magnet response?
8 adequate battery life
9 manufacturers perioperative recommendations?
```
96
normal battery life
7-10 years
97
adequate battery life for surgery
>3-6mo
98
intraoperative management supplies and drugs CEID
external pacemaker
magnet
atropine
epi
99
postop management CEID
all devices should be interrogated or reprogrammed to original function after surgery
not discharged until interrogated
100
first letter chamber classification
what chambers have pacing leads
101
second letter chamber classification
what chambers can sense electrical activity
102
third letter chamber classification
how pacemaker responds after it senses electrical activity
103
fourth letter chamber classification
programmability
104
fifth letter chamber classification
antitachyarrhythmia function
105
options for first letter
```
a= atria
v= ventricle
d= dual
```
106
options for second letter
```
a= atria
v= ventricle
d= dual
o= none
```
107
what does it mean when the second pacemaker letter is O?
it is in asynchronous mode
108
options for third letter
```
I= inhibits
T= triggered
D= Dual (t+i)
O= none
```
109
pacemaker code for pt with sinus brady
AAI
110
pacemaker code for pt with slow afib/aflutter
VVI
111
pacemaker code for pt with av block, normal sinus node
DDD
112
pacemaker code for pt with av block and sinus brady
DDD
113
pacemaker code for pt with sinus brady and magnet on pacemaker
AOO
114
AAI
single lead in RA for pts with sinus brady or SSS
115
AOO
asynchronous pacing from RA activated by magnet
116
VVI
single lead in RV for pts with afib
117
VOO
asynchronous pacing with the lead in the RV activated by magnet
118
DDD
leads in RA and RV for pts with complete heart block
119
DOO
asynchonous pacing with leads in RA and RV activated by magnet
120
VDD
specialized lead in RV that has a sensing portion in the RA indicated for pts with complete heart block and normal sinus node function
121
can pt with pacemaker have MRI
NO
122
CT scan and pacemaker
some ICDs receive interference
123
are ICDs or pacemakers more sensitive to radiation therapy?
ICDs
124
what to do if pt with ICD and radiation therapy
shielded as much as possible and moved if it lies directly in radiation field
125
radiofrequency ablation
waves to ablate areas of the heart/terminate arrhythmias
| acceptable with certain precautions
126
emergency defibrillation for pt with pacemaker
place the defib pads away from pacemaker
127
TENS
transcutaneous electrical nerve stimulation
| used to relieve acute or chronic pain
128
TENS and CIEDs
reported to interfere with ICDs to cause inappropriate shock
| cautioned about use
129
ECT
electroconculsive therapy
transcutaneous electrodes placed on head to induce a tonic clonic seizure
treat depressio
130
how often is ECT performed
twice weekly for usually 3-4 weeks
131
what is too short or too long of seizure?
<10 sec
| >120 sec
132
which is more important the length or seizure or current delivered?
current delivered
133
cardiovascular effects of ECT
initial parasympathetic discharge (brady and hypotension) then sympathetic response
134
cerebral effects of ECT
cerebral oxygen consumption, blood flow, and iCP all increase
135
what are the more popular induction agents for ECT
brevital or etomidate
136
methohexital
pro convulsant
does not change duration
blunt sympathetic response
137
etomidate
longest seizure duration but does not blunt the sympathetic response
138
propofol
decreases seizure duration but does blunt the sympathetic response
139
ketamine
longer seizure duration
| ICP elevates
140
airway management for ECT
usually not ETT unless indicated
| hyperventilate to lower the threshold for seizure and prolong the duration
141
neuromuscular blocking agents and ECT
reduce muscular convulsions and decrease risk of serious injury (sux most common)
142
CIED implications for ECT 4
1 skeletal muscle potentials during seizure may trigger pacemaker
2 regular demand should be asynchronous
3 shock function deactivated
4 risks are low bc small amounts of electricity reach device
143
ESWL
extracorporeal wave lithotripsy
| transcutaneous ultrasonic shock waves breaks up kidney or ureteric stones
144
synchronized litho shocks
triggered by the R wave and delivered in refractory period
145
advantage to synchronized shock
carries lower risk of PVCs and arrhythmias
146
disadvantage to synchronized shock
procedure is slower
147
non synchronized litho shocks
shocks delivered at specific rate
148
advantage of non synchronized litho shock
procedure is faster
149
disadvantage to non synchronized litho shock
more likely to cause PVCs or arrhythmias
150
ESWL and CIEDs
may interpret shocks same as cautery
| magnets should be placed on ICD pt or pacemaker dependent pt
151
what can happen in atrially paced pts with ESWL?
the synchronized shock can read the atrial pace as the R wave and deliver a shock prior to the R wave causing arrhythmia
