junctional/ventricular/atrioventricular Flashcards
(82 cards)
1
Q
where is the first place to backup or kick in if impulse fails from the SA node?
A
- the AV junction
2
Q
are there impulse forming cells in the AV node?
A
no. but there is in the junctional tissue
3
Q
what is PJC
A
Premature Junctional Contraction:
- when impulse-forming cells fires ‘earlier’ than regular interval
4
Q
will there be a P wave in PJC? explain
A
Yes. But they will look different from each other (if visible) d/t PJC traveling through atria in different manner
depolarization starts at the AV junctin and proceeds from there
5
Q
3 key facts for PJC atrial depolarization and P waves
A
- P wave represents atrial depolarization NOT SA node depolarization
- Impulses arising in the AV junction will create atrial depolarization
- P waves associated with junctional rhythms (like PJC’s) can occur in different shapes or may be hidden in other parts of the ECG waveform
6
Q
The P wave of a PJC can appear in three ways:
A
- inverted - from junction, if wave goes to the atria first and then to vents, you will see inverted P wave preceding QRS (inverted d/t atrial depolarization occurring in retrograde manner)
- Buried in QRS complex - if depolarization goes into the vents and the atria at the same time, then the P wave is usually buried in the QRS complex.
- Occur after the QRS complex - if the vents are depolarized before the atria, then P wave usually occurs after QRS
7
Q
What happens to the PR interval in a PJC?
A
- the location of the P wave impacts the PR interval bc if the impulse originates at the AV junction the distance to travel to atria is less than normal (0.12 sec) and would precede the QRS
8
Q
PJC’s can occur as?:
A
single isolated beats or as clusters/groups
9
Q
what is JER?
A
Junctional Escape Rhythm
- when a secondary site in the junctional tissue takes over role of impulse formation: usually occurs when the primary pacemaker site in the SA node fails
10
Q
what is a normal rate for JER? what if it is greater than normal?
A
Normal 40-60 BPM
If greater than Accelerated Junctional Rhythm
11
Q
explain the P wave in a JER:
A
- similar to PJC, the impulse at the junctional tissue will depolarize in a retrograde manner
- the P wave will be inverted, buried or after a QRS
12
Q
what does the QRS look like in JER?
A
It appears normal
bc the wave of depolarization follows the normal pathway after it leaves the junction
13
Q
what does the interval and rhythm look like in JER?
A
the R-R is constant and rhythm is regular
14
Q
JER
conduction prob:
A
- prob with the SA node
- is the rate sufficient to meet the PTs needs.
- it is similar to sinus brady
- assess PT to determine their response
15
Q
JER
cause
A
whatever caused the SA node to fail
16
Q
JER
implication to O2 supply and demand
A
The impact the rhythm has on CO
- Slow HR
- Loss atrial kick
17
Q
JER
intervention
A
assess PT
IF CO compromised by rhythm then atropine
if no response then temporary transvenous pacemaker
18
Q
JER
Rate Rhythm P wave PR interval QRS complex
A
rate: 40-60
rhythm: reg
P wave: before, during or after QRS (if visible, may be inverted)
PR: if present 0.12 sec or less
QRS: 0.10 sec or less
19
Q
what is the difference between Junctional Tachycardia and Junctional Escape rhythm and Accelerated Junctional Rhythm?
A
The rate of firing of junctional focus
JT = > 100 / min
JER = 40-60
AJR = 60-100
20
Q
which rhythms depolarize in retrograde fashion?
A
JER, PJC and JT
then conduction through the vents are normal
21
Q
Junctional Tachy
conduction problem
A
junctional tissue around AV node
22
Q
Junctional Tachy
Cause
A
whatever caused SA node to fail allowing junctional tissue to take over
dig. tox, MI, HF…
23
Q
Junctional Tachy
Intervention
A
assess PT
If CO compromised by rhythm, treat cause
amiodarone, BB, CCB, ablation
24
Q
What is SVT and which dysrhythmias are in the category?
A
Dysrhythmias with fast rate whose site of impulse formation is above the vents.
- Atrial fibrillation
- Atrial flutter
- Atrial Tachycardia
- Junctional Tachycardia
sinus tachy, multifocal atrial tachy
25
SVT criteria
1. No defined P wave
2. vent rate > 150 (meaning impulse not originates from SA node
3. QRS complex is normal ( 0.10 sec or less) means that normal pathway from AV node, so not originating from vents. So atria or junctional
26
When are ventricular rhythms fast?
When irritable focus or multiple foci 'take over' from pacemaker site 'higher up' in the conduction system (ex. override pacemaker sites in SA node or junctional tissue)
27
When are ventricular rhythms slow?
When SA node or AV junction pacemaker sites fail (or completely blocked), and pacemaker site in the conduction system below the AV junction assumes the pacemaker role
28
unifocal and multifocal PVC?
same and more than one abnormal focus.
29
ventricular bigeminy
every second beat is a PVC
30
vent trigeminy
every third beat is a PVC
31
Couplet
2 PVC's together
32
Triplet
3 PVC's together
33
Run
more than 3 PVC's together
34
post cardiac arrest management: induced therapeutic hypothermia is for?
PTs who have been resuscitated from cardiac arrest associated with vent fib and pulseless vent tachy but DO NOT gain some level of consciousness post-defib
35
what is induced therapeutic hypothermia?
deliberately cooled to goal core temp of 32-34C
target being reached in 4 hours of return of spontaneous circulation (ROSC) ex. a perfusing rhythm
36
why induced therapeutic hypothermia?
> out of hosp cardiac arrest survivors have high incidence of significant, permanent neurological deficit from cerebral edema and other neurological damage resulting from hypoxia and brain anoxia
> ischemia result in loss of cell membrane integrity and increased permeability, electrolyte shifts and metabolic acidosis = temp or permanent change in neurological function
37
what is the goal of induced therapeutic hypothermia?
focus on blocking or minimizing the destructive processes that arise from cellular anoxia (complete absence of O2; severe hypoxia)
38
process of induced therapeutic hypothermia
hypothermia blankets or ice packs. NS cold lavage may be used
- PT kept cool for 12-24 hours before controlled warming
- rewarming goals = increasing temp by 0.2C to 0.5C/hour is important to avoid negating the therapeutic effects gained by hypothermia period
39
specific criteria for induced therapeutic hypothermia:
1. primary dysrhythmia: Vent fib or V. tach
2. time from collapse to ACLS (advance cardiac life support) < 15 min
3. Time from collapse to ROSC (return of spontaneous circulation) < 60 min (pulse and BP present)
4. adult > 18
5. persistent GCS < 10
40
these things will exclude PTs from induced therapeutic hypothermia:
1. pregnant
2. Hx of terminal illness
3. improving neurological status (making purposeful movements)
4. coma/arrest secondary to non-cardiac factors
5. persistent hypoxia (SaO2 < 85% for > 15 min)
6. significant coagulopathy
7. hemodynamic instability despite vasopressors: MAP < 60mmHg for > 30min
41
clinical significance of AV block depends on: 3
1. degree (severity ) of block
2. rate of secondary pacemaker
3. PTs response to the ventricular rate
42
If there is a pacemaker spike on the ECG strip not followed by a contraction complex what are you seeing? Failure to
Capture
43
The 3 letters in the pacemaker code stand for what in the appropriate order?
a. Chamber paced, sensed, how to respond to a sensed event
44
what is failure to pace?
failure to fire- complete lack of pacemaker activity. no spike.
**spike/response - spike/response - no spike/no response - spike response**
could be battery, circulatory, leads, disconnect...
45
what is failure to capture?
when electrical impulse is emitted from the generator but fails to depolarize the myocardium.
Spike but no response**
you see a pacemaker spike on ECG that is NOT followed by appropriate ECG waveform (atrial or vent response)
caused: anything that makes it more diff for the electrical impulse from the pulse generator to cause depolarization of cells (transvenous/electrode wires out of position**, voltage too low, metabolic acidosis, electrolyte imbalance, myocardial ischemia).
check connections and strength of electrical discharge: reposition PT**, increase output setting, review for PT related issues, contact MD
46
what is failure to sense?
** pacemaker spikes that fall where they shouldn't. Anywhere in the cycle**
1. oversensing--> when pacemaker senses extraneous (non-cardia) electrical signals. (muscle tremors) that lead to pacemaker being inappropriate inhibited or triggered
2. undersensing--> if the sensitivity setting is such that a larger electrical activity needs to be generated in order for the pacemaker to recognize it, then good possibility that PTs intrinsic activity will not be recognized or sensed. **can be life threatening**
- If Pacemaker doesnt know that there is intrinsic activity, it will continue to fire, emitting electrical activity to PTs heart. can cause life-threatening dysrhythmia
- recognize- spike may occur in the middle of QRS
47
For arrhythmias would you need a pacemaker? 5
1. sinus brady
2. sinus arrest/block
3. JER
4. VER
5. AV blocks
48
what is the diff btwn atrial and junctional tachy?
Atrial might not have any P waves because they might be hidden in the QRS.
Junctional will have inverted or weird P waves
49
Chamber paced:
Where it creates impulse
```
0= none
A = atrium
V = vents
D = Dual
```
50
Chanmber sensed:
senses intrinsic electrical activity
```
0= none
A = atrium
V = vents
D = Dual
```
51
Response to sensing:
denotes what the pacemaker will do
```
0 = none
T = triggered
I = inhibited
D = dual (applies to permeant)
```
52
Most common mode of vent pacing?
VVI = ICU
53
asynchronous contraction of the atria and ventricles =?
loss of atrial kick with ventricular filling. = decreased CO
54
If the lead is placed in the atria...
you will have a spike and then P wave followed by QRS
55
If the lead is placed in the vent you will see
no p wave, spike and wide bizarre QRS
56
if you see a pacemaker spike not followed by a P wave or QRS that means?
failure to capture
difficult for the electrical impulse from the pulse generator to cause the cells to depolarize. These can be patient-related issues such as acidosis, electrolyte imbalance, and myocardial ischemia,
reposition pt so lead closer to the surface of the heart
57
The 4th beat is the patient’s intrinsic beat. Close after that, we can see a pacer spike
Failure to sense. doesnt sense the PTs intrinsic beat and fires after
decrease mV setting
58
If there is a pacemaker spike on an ECG strip not followed by a contraction complex what are you seeing?
failure to capture
59
What pacemaker setting most mimics the normal heart activity thereby maintaining the closest CO as a healthy heart would?
DDD - 4 morphologies
60
In a synchronous pacemaker, failure to sense is represented on an ECG rhythm strip by
a pacemaker spike not followed by a contraction/complex
61
sensed activity...
inhibits pacing
62
if 100% vent paced you cannot...
have the ability to assess sensed
63
In a synchronous pacemaker, failure to sense is represented on an ECG rhythm strip by
A spike in the presents of intrinsic activity
64
which rhythms need cardioversion as interventions?
1. uncontrolled A.fib
2. A. flutter
3. vent tachy
65
which rhythms need pacemaker?
1. JER
2. Blocks
3. Bradycardia
66
with what rhythms do you defibrillate?
anything with no pulse
1. Vent fib
2. pulseless vent tachy
3. SVT (A. fib, A flutter, A. tach, J tach)
67
why does the Dr. perform and carotid massage?
to stimulate the vagus nerve to decrease the HR
decrease AV conduction rate
68
cardioversion timed with?
R wave. Avoid T wave timing to avoid refractory period of the cycle. The machine searches for QRS and flags it
R on T can cause? V. tach
69
what do you need to remember for vent tachy?
ACLS Too fast:
wide QRS
is there a pulse or no pulse?
pulseless- ABC, code, IV, intubate, defib/CPR**, EPI* (also applies for pulseless Vent Fib)
pulse- stable? = drugs (Adenosine, Amiodarone, BB, CCB)
Pulse unstable = cardioversion
70
what is the difference between defibrillation and cardioversion?
Defib is done with pulseless and is non-synchronized
Cardiovert- with pulse, synchronized with R waves
71
ACLS too slow:
: SB, Junctional escape or Brady, VER, 2AVB, 3AVB
Stable: monitor
Unstable: drugs = atropine, dopamine, Epi
: pacemaker
72
When you see a PVC, what is the meaning of the ST?
because they are from the vents they are abnormal so the ST is not significant
73
paroxysmal SVT
starts and stops abruptly. It will go away and the PT is fine
74
1st degree considerations:
1P:1QRS
| Sinus Rhythm with PR prolonged, but constant
75
2nd degree type 1 considerations:
PR lengthens and then drops
When drops there is an extra P and no QRS
76
2nd degree type 2 considerations:
More P than QRS's
| PR prolonged but will be the same length for all complexes
77
3rd degree considerations:
QRS is wider > 0.12 if from vents, or narrow if from below junction. influenced by site of AV block
P-P is regular and R-R is regular
** there is no relationship between P's and QRS's
78
Does ST matter in heart blocks?
Depends where QRS is coming from.
If narrow = from junction then it matters
If wide = from ventricles/purkinji then does not matter
79
Any rhythm can be a PEA except...
VT, VF and asystole
80
which meds slow the HR?
stable PTs:
unstable PTs:
for stable PTs:
For narrow and wide QRS (A.tach, A. fib, JT.... VT)
- Amiodarone (Na, K, BB, CCB)
- Adenosine
unstable:
cardiovertion
81
which meds are used to speed up HR?
unstable PTs:
stable:
for unstable PTs:
(SB, junctional, VER, 2AVB, 3 AVB)
- Atropine
- Dopamine
- Epi
Stable: monitor
82
what can you give to no pulse, asystole, and PEA?
Epinephrine
