CARDIOLOGY - Junctional & Ventricular Dysrhythmias (Week 7) Flashcards
(95 cards)
1
Q
Types of Junctional Dysrhythmias
A
- Premature Junctional Complex (not a rhythm - occurs with a rhythm)
- Junctional Escape beat (see sinus arrest)
- Junctional Rhythm
- Junctional Bradycardia
-
Accelerated Junctional Rhythm
- Junctional Tachycardia
2
Q
Junctional dysrhythmias are rhythms originating in the
A
in and around the AV node (AV junction)
3
Q
An impulse originating from the AV junction travels in ______ direction(s). Which directions?
A
two directions:
1) up the conduction pathway towards the atria (backwards - retrograde motion) to depolarize the atria
2) down the conduction pathway towards the ventricles (forward - antegrade motion) to depolarize the ventricles
4
Q
AV node and surrounding tissue have an inherent rate of _______ bpm. It is NOT the normal pacemaker of the heart (not as efficienct as SA node) but may assuming pacing responsibility for heart if:
A
40-60bpm
- SA node fires an impulse, travels through the atria, but is not conducted to the ventricles (AV block)
- SA node fails to fire (sinus arrest)
- Rate of SA node is slower than AV junction (sinus bradycardia)
5
Q
How does the retrograde motion of an impulse impact the P wave on an ECG tracing?
A
- P wave changes into 3 different identifiable waves & their morphology is based on where the impulse originated from in the AV junction
- 1) HIGH - impulse generated near the beginning of the AV node
- 2) MIDWAY - impulse generated near the middle of the AV node
- 3) LOW - impulse generated near the end of the AV node
6
Q
P wave morphology: HIGH origin of impulse at AV node
A
- impulse generated high in the AV node (close to atria)
- impulse travels in a backwards direction towards atria FIRST before the ventricles SECOND
- P wave will be retrograde and inverted in the QRS complex
7
Q
P wave morphology: MIDWAY origin of impulse at AV node
A
- impulse originates midway in the AV node
- impulse travels in a backwards direction towards atria AND towards the ventricles SIMULTANEOUSLY
- because both are the same distance from the AV node, the P wave will be hidden by the QRS and therefore not visible
8
Q
P wave morphology: LOW origin of impulse at AV node
A
- impulse generated low in the AV node
- impulse travels forward toward ventricles FIRST and then backwards towards atria SECOND
- Impulse reaches atria second so P wave will be retrograde and inverted to the QRS complex (i.e. inverted P wave AFTER QRS)
9
Q
Premature Junctional Complex (PJC)
A
impulse originates from irritable tissue in the AV junction before next sinus beat is due (i.e. PJC occurs EARLY, before the next expected beat). AV node is usurping/taking over the SA node for that beat and therefore interrupting the sinus rhythm
10
Q
Conduction pathway of Premature Junctional Complex (PJC)
A
impulse originates in AV junction (higher pacemaker has failed)
heads upwards towards atria (retrograde) and downwards towards ventricles (antegrade) and ultimately depolarizes atria and ventricular muscle
11
Q
Premature Junctional Complex (PJC)
Rate
Rhythm
P wave
PR Interval
QRS Complex
A
Rate: can occur at ANY rate
Rhythm: occasionally irregular (remember can also be compensatory or non-compensatory pause but typically non-compensatory) - ALSO REMEMBER: it’s not a rhythm; it is a single beat occuring WITHIN an underlying rhythm (ex. Sinus bradycardia with a PJC (6th complex)
P wave: inverted before or after QRS, or buried in QRS complex (note that inverted P waves are normal in V1)
PR Interval: <0.12 seconds IF the P waves precedes QRS (it’s n/a if the P wave comes after QRS)
QRS Complex: <0.12 (can be >0.12 if BBB exist)
12
Q
Premature Junctional Complex (PJC)
Causes
Adverse Effects
Treatment
A
Causes: less common than PACs and PVCs
- Acute coronary syndromes
- Heart disease (i.e. rheumatic, valvular)
- CHF
- Drugs - cocaine, tobacco, caffeine
- Medications - Digitalis toxicity
- Electrolyte imbalance
- Fatigue
Adverse Effects: usually no ill effects
Treatment: None
13
Q
How to tell the difference between PAC and PJC?
A
PAC: typically, upright P wave before QRS (in leads II, III, aVF)
PJC: either no P wave present (buried) or inverted (retrograde) AND may or may not precede QRS (in leads II, III, aVF)
14
Q
When can PJCs often be misdiagnosed?
A
when the P wave of the PAC is buried in the preceding T wave (looks like a double hump)
15
Q
Junctional Escape Beat
A
- predominant pacemaker slows dramatically (or fails) and lower pacemaker takes over at its inherent rate
- initial pacemaker will resume functioning afer missing one/two beats OR
- the other pacemaker may continue as the new pacemaker, and possible creates a new rhythm
- junctional escape beat is an ectopic beat that occurs LATE (i.e. after preceding sinus beat, usually occurs following sinus arrest/block, after premature beats, or during pauses)
- same morphology as PJCs
16
Q
Conduction pathway of Junctional Escape Beat
A
impulse originates in the AV junction (the higher pacemaker has failed) → heads upwards (antegrade) and downward (retrograde) → ultimately depolarizes atria and ventricular muscle
17
Q
Junctional Escape Beat
Rate
Rhythm
P wave
PR interval
QRS Complex
A
Rate: can occur at any rate
Rhythm: occasionally irregular
P wave: inverted before or after QRS complex or buried in QRS (inverted P waves are notmal in V1)
PR interval: <0.12 seconds IF the P wave precedes the QRS
QRS Complex: <0.12 seconds (can be >0.12 if BBB exist)
18
Q
Junctional Escape Beat
Causes
Adverse Effects
Treatment
A
Causes: Typically occurs:
- during episodes of sinus arrest
- in healthy individuals during sinus bradycardia
- Myocardial Infarction
- Heart disease - rheumatic, valvular
- Hypoxia
- Sinus node disease
- Post cardiac surgery
- medications - Digitalis, quinidine, beta blockers, calcium channel blockers
Adverse Effects: usually no ill effects
Treatment: none
19
Q
True or False. Junctional Escape Beat is not a rhythm.
A
True. It is single beat occurring within an underlying rhythm (ex. sinus arrest with a junctional escape beat [2nd complex])
for testing purposes - can just write sinus arrest (or sinus arrest with junctional escape beat)
20
Q
If a junctional escape beat continues as the new pacemaker, it creates:
A
Junctional Rhythm
21
Q
Junctional Rhyhtm
A
several sequential slow and regular junction escape beats (junctional rhythm and junctional escape rhythm used interchangeably)
looks like NSR but is junctional rhythm because of buried P waves
basically it’s the normal rhythm of the AV node (junctional rhythm is at a rate of 40-60, which is the inherent rate of the AV node)
22
Q
Describe the conduction pathway in junctional rhythm
A
- Impulse originates in and around the AV node (AV junction) - the higher pacemaker has failed
- travels up the conduction pathway towards the atria and down towards ventricles
- depolarizes both atria and ventricles
23
Q
Junctional Rhythm
Rate
Rhythm
P wave
PR Interval
QRS complex
A
Rate: 40-60
Rhythm: Regular
P wave: inverted before or after QRS complex or buried in QRS
PR Interval: <0.12 secs IF the P wave precedes the QRS
QRS complex: <0.12 secs (can be >0.12 if BBB exist)
24
Q
Junctional Rhythm
Causes
Adverse Effects
Treatment
A
Causes: Typically occurs
- during episodes of sinus arrest
- in healthy individuals during sinus bradycardia
- Myocardial infarction
- Heart disease - rheumatic, valvular
- Hypoxia
- Sinus node disease
- Post cardiac surgery
- Medications - Digitalis, quinidine, beta blockers, calcium channel blockers
Adverse Effects: often no ill effects; may present with signs of decreased cardiac output it heart rate slow (i.e. ~ 40)
Treatment: None
25
Junctional Bradycardia
AV junction fires at a slower rate than normal
26
Describe the conduction pathway in junctional bradycardia.
1. Impulse originates in and around the AV node (AV junction) - higher pacemaker has failed
2. Travels up conduction pathway towards the atria and down conduction pathway towards ventricles
3. Depolarizes both atria and ventricles
27
**Junctional Bradycardia**
Rate
Rhythm
P wave
PR interval
QRS complex
**Rate:** \<40
**Rhythm:** regular
**P wave:** inverted before or after QRS complex or buried in QRS
**PR interval:** \<0.12 secs IF P wave precedes the QRS
**QRS complex:** \<0.12 (can be \>0.12 if BBB exist)
28
**Junctional Bradycardia**
Causes
Adverse Effects
Treatment
**Causes:** Typically occurs
* during episodes of sinus arrest
* in healthy individuals during sinus bradycardia
* **Myocardial infarction**
* **Heart disease** - rheumatic, valvular
* **Hypoxia**
* **Sinus node disease**
* **Post cardiac surgery**
* **Medications** - Digitalis, quinidine, beta blockers, calcium channel blockers
**Adverse Effects:** decreased cardiac output
**Treatment:** None
29
Accelerated Junctional Rhythm
AV junction fires at a faster rate than normal
30
Describe conduction pathway in accelerated junctional rhythm
1. impuulse originates in and around the AV node (AV junction) - higher pacemaker has failed
2. travels up conduction pathway towards atria and down conduction pathway towards ventricles
3. depolarizes both atria and ventricles
31
**Accelerated Junctional Rhythm**
Rate
Rhythm
P wave
PR interval
QRS complex
**Rate:** 61 - 100
**Rhythm:** regular
**P wave:** inverted before or after QRS complex or buried in QRS complex (inverted P wave are normal in V1)
**PR interval:** \<0.12 secs IF the P wave precedes the QRS
**QRS complex:** \<0.12 seconds (can be \>0.12 if BBB exist)
32
**Accelerated Junctional Rhythm**
Causes
Adverse Effects
Treatment
**Causes:**
* **Myocardial Infarction**
* **Cardiac surgery**
* **COPD**
* **Hypokalemia**
* **Fever**
* **Drugs** - Digitalis
**Adverse Effects:** usually asymptomatic because ventricular rate is 61-100 beats/min
**Treatment:** None
33
**Junctional Tachycardia**
3 or more sequential escape beats occuring at a rate of more than 100 beats/min
34
Describe the conduction pathway in junctional tachycardia
1. impulse originates in and around the AV node (AV junction) - the higher pacemaker has failed
2. Travels up conduction pathway towards the atria AND down conduction pathway towards to the ventricles
3. Depolarizes both the atria and ventricles
35
**Junctional Tachycardia**
Rate
Rhythm
P wave
PR Interval
QRS complex
**Rate:** 101 - 180
**Rhythm:** Regular
**P wave:** inverted before or after QRS complex or buried in QRS complex (inverted P wave are normal in V1)
**PR Interval:** \<0.12 seconds if the P wave precedes the QRS
**QRS complex:** \< 0.12 (can be \>0.12 if BBB exist)
36
**Junctional Tachycardia**
Causes
Adverse Effecs
Treatment
**Causes:**
* **Acute coronary syndromes**
* **CHF**
* **Drugs** - eg. Digitalis
**Adverse Effects:** decreased cardiac output (sweaty, confused, SOB)
**Treatment:** None
37
Types of Ventricular Dysrhythmias
1. **Premature ventricular complex** (NOT A RHYTHM)
1. **ventricular quadrigeminy**
2. **ventricular trigeminy**
3. **ventricular bigeminy**
4. **pairs** (with underlying rhythm included)
5. **Run of V-tach** (with underlying rhythm included)
6. **R on T** (with underlying rhythm included)
2. **Ventricular escape beat** (see sinus arrest)
3. **Idioventricular rhythm**
4. **Accelerated Idioventricular Rhythm**
5. **Agonal Rhythm**
6. **Ventricular Tachycardia**
7. **Torsades de Pointes**
8. **Ventricular Fibrillation**
9. **Asystole**
38
Ventricular dysrhythmias are rhythms originating in the
ventricles (most potentially lethal of all the rhythms)
39
Describe the conduction pathway in ventricular dysrhythmias
1. impulse originates in one or more foci in the ventricular tissue (if an area in the ventricles become ischemic or injured, it may be more irritable)
2. Travels very slowly from cell to cell in ventricles producing a **wide QRS complex** (equal or \>0.12 secs and **DOES not follow the normal conduction pathway**)
3. Impulse sometimes travels retrograde towards atria to depolarize them
4. The resultant P wave is **normally lost in the mammoth QRS complex** and has no consistent relationship with the QRS comple **(_AV dissociation_)**
40
The ventricles may assume pacing responsibility for the heart if:
1. SA node and AV node fail to fire
2. Irritable site in ventricles produces an early beat or rapid rhythm
3. Rate of the SA node is slower than that of the ventricles
**this may occur as a result of re-entry or enhanced automaticity**
41
Slow vs Fast Ventricular Rhythms
**Slow Ventricular Rhythms:** heart's last gasp as a pacemaker, kicking in when the higher pacemakers can't
**Fast Ventricular Rhythms:** emergency firing rate of 150-250 electrical impulses per minute; can result in decreased cardiac output and ultimately death
42
Premature Ventricular Complex (PVC)
A PVC can originate from an irritable site within the ventricular tissue before the next sinus beat is due
43
Describe conduction pathway in premature ventricular complex.
1. impulse originates in an automaticity focus (usually in the ventricular wall) **- ectopic focus in ventricles**
2. a small area begins to depolarize, propagating from cell-to-cell through one ventricle and eventually to the next ventricle (normally both ventricles depolarize simultaneously)
3. PVCs begin to depolarize the ventricles
4. If the higher pacemaker has not failed, the SA node discharges on time (which you can see as the regular P wave within the PVC) BUT the SA node cannot depolarize the entirety of the heart until the ventricles have finished repolarizing
5. Once the ventricles have finished repolarizing, a "compensatory pause" occurs making them receptive to the next sinus generated cycle
44
Describe morphology of PVC on an ECG tracing.
* PVCs occur early (before the next expected beat)
* PVC is an enormous ventricular complex, wider, taller, and deeper than a normal QRS complex
* Equal or \>0.12 secs due to the ventricles firing prematurely in an abnormal manner
* As well, T wave is usually opposite direction of the QRS
45
**Premature Ventricular Complex (PVC)**
Rate
Rhythm
P wave
PR Interval
QRS Complex
**Rate:** can occur at any rate (count PVCs as well)
**Rhythm:** occasionally irregular (depending on origin and frequency)
**P wave:** difficult to visualize and therefore NOT USUALLY IDENTIFIABLE
* P waves not usually seen with ventricular dysrhythmias and if they are, have no consistent relationship with the QRS complex (**AV dissociation**)
**PR Interval:** n/a because no p wave
**QRS Complex:** equal or \> 0.12 secs
* _Left ventricular PVC:_ upwards deflection in V1
* _Right ventricular PVC:_ downwards deflection in V1
* slopes opposite of the T wave
46
**Premature Ventricular Complex (PVC)**
Causes
Adverse Effects
Treatment
**Causes:**
* 3 big causes
* **Hypoxia** - poor oxygenation can make automaticity focus become irritable
* **Heart Disease:** acute coronary syndrome, CHF, etc.
* **Hypokalemia:** electrolyte imbalance
* Other causes:
* Normal variant
* **Increased sympathetic tone** - stress/anxiety, exercise, etc.
* **Medications** - Digitalis, sympathomimetics, antidepressants
* **Drugs** - caffeine, tobacco
* **Acid-base imbalance**
**Adverse Effects**: Occasional PVCs are no cause for concern BUT
* Frequent PVCs (6 or more per min) or
* Multifocal PVCs (multiple irritable foci) and
* PVCs that are close to T wave
* **can progress to lethal dysrhythmias**
**Treatment:** usually none is needed and can occur in healthy individuals; If PVCs are more frequent, treat the cause
47
PVCs can be classified by:
1) site of origin
2) frequency
48
PVC Classification: Site of Origin
**1) Unifocal (monomorphic):** when PVCs originate from the same single anatomic foci/location in the ventricle and therefore look alike
**2) Multifocal (polymorphic):** when PVCS originate from different anatomic foci/location in the ventricle and therefore DO NOT look alike
49
PVC Classification: Frequency
* frequency of PVC is an indication of exactly how irritable the cardiac cells are (if cells are more irritable such as during hypoxia, less stimulation is needed to cause depolarization) - can lead to serious dysrhythmias
* when PVCs occur, ventricles have less time to fill with an adequate amount of blood, which can cause poor cardiac output
* 6 types:
* **Quadrigeminal PVCs - ventricular quadrigeminy**
* **Trigeminal PVCs - ventricular trigeminy**
* **Bigeminal PVCs - ventricular bigeminy**
* **Pairs - couplet**
* **Runs of V-tach**
* **R-on-T phenomenon**
50
Quadrigeminal PVCs - Ventricular quadrigeminy
Every 4th complex is a PVC
51
Trigeminal PVCs - Ventricular Trigeminy
Every 3rd complex is a PVC
52
Bigeminal PVCs - Ventricular Bigeminy
Every 2nd complex is a PVC
53
Pairs - Couplet
Two sequential PVCs (could also be unifocal or multifocal)
54
Runs/Run of V-tach/Bursts
Three or more PVCs in a row at a rate of more than 100 beats/min
55
R-on-T phenomenon PVC
* occurs when R wave falls on the T wave of the preceding beat (remember that the last half of the T wave is vulnerable to electrical stimulation i.e. relative refractory)
* Dangerous dysrhythmias may result (eg. VT or VF)
56
Ventricular Escape Beat
Predominant pacemaker slows dramatically (or fails) and lower pacemaker takes over at its inherent rate
either
**a) initial pacemaker will resume funcitoning after missing one two beats**
or
**b) the other pacemaker may continue as the new pacemaker, and possibly create a new rhythm**
57
Describe conduction pathway in ventricular escape beats.
* ventricular escape beat occurs LATE (after the next expected sinus beat)
* impulse originates in the ventricles (higher pacemakers have failed)
* heads upwards (antegrade) and ultimately atria and ventricular muscle depolarize
58
**Ventricular Escape Beat**
Rate
Rhythm
P wave
PR Interval
QRS complex
**Rate:** can occur at any rate
**Rhythm:** occasionally irregular
**P wave:** usually absent OR may appear after QRS (with retrograde conduction to atra)
**PR Interval:** N/A - remember that the beat originate in the ventricle
**QRS complex:** equal or \>0.12 secs
59
Idioventricular Rhythm (IVR)
three or more slow and regular ventricular escape beats occur in a row ("wide and slow = idio")
60
Describe the conduction pathway of the electrical impulse in an idioventricular rhythm.
1) impulse originates in an automaticity focus (higher pacemakers have failed)
2) a small area begins to depolarize propogating cell to cell through one ventricle and eventually to the next ventricle (which is not normal; normally, both ventricles depolarize simultaneously)
3) heads upwards (antegrade) towards atria
4) ultimately atria and ventricular muscle depolarize
61
**Idioventricular Rhythm**
Rate
Rhythm
P wave
PR interval
QRS complex
**Rate:** 20 - 40
**Rhythm:** regular
**P wave:** usually absent OR with retrograde conduction to atria may appear AFTER QRS
**PR interval:** n/a - remember the beat originated in the ventricle
**QRS complex:** equal or \>0.12 seconds (frequently slopes opposite of T wave)
62
**Idioventricular Rhythm**
Causes
Adverse Effects
Treatment
**Causes:** usually from cardiac damage or hypoxia
**Adverse Effects:** decreased cardiac output, cardiovascular collapse (may or may not provide a pulse)
**Treatment:** if the patient DOES NOT have a pulse despite the organize electrical activity, **pulseless electrical activity (PEA)** may exist, _CPR_
63
What is Pulseless Electricity Activity (PEA)? Describe the prognosis and priority in these patients.
* absence of a detectable pulse AND presence of a rhythm OTHER than V-tach or V-fib
* prognosis is poor unless underlying cause is identified and corrected
* **priority:** maintain circulation
64
Common causes of PEA
**5T's and 5H's**
* Toxicity
* Tension pneumothorax
* Tamponade (cardiac)
* Thromboembolism - MI or PE
* Trauma
* Hypovolemia
* Hypoxia
* Hypo/hyperkalemia
* Hypo/hyperthermia
* Hydrogen ions (acidosis)
65
Accelerated Idioventricular Rhythm (AIVR)
three or more ventricular escape beats occurs in a row at a rate of more than 40 beats/min
66
Descibe the conduction patthway of the electrical impulse in an Accelerated Idioventricular Rhythm (AIVR)
1) impulse originates in an automaticity focus (the higher pacemakers have failed)
2) a small area begins to depolarize, propoagating cell to cell through one ventricle and eventually to the next ventricle (normally both ventricles depolarize simultaneously)
3) heads upwards (antegrade) - ultimately atria and ventricular muscle depolarize
67
**Accelerated Idioventricular Rhythm (AIVR)**
Rate
Rhythm
P wave
PR Interval
QRS complex
**Rate:** 41 - 100
**Rhythm:** regular
**P wave:** usually absent, OR with retrograde conduction to atria may appear after QRS
**PR Interval:** N/A - remember the beat originated in the ventricle
**QRS complex:** equal or \>0.12 seconds (frequently slopes opposite of the T wave)
68
**Accelerated Idioventricular Rhythm (AIVR)**
Causes
Adverse Effects
Treatment
**Causes:** common after an MI (see PVCs)
* common after thrombolytic (clot dissolving) medication administration and therefore considered a "reperfusion dysrhythmia"
* ventricular tissue becomes irritable after ischemic cells receive an abrupt amount of oxygenated blood
**Adverse Effects:** usually no ill effects as rate of close to normal
**Treatment:** usually no tx is necessary as AIVR tends to be a self-limiting rhythm (the rhythm is often transient and spontaneously resolves on its own)
69
Agonal Rhythm ("Dying Heart")
A very irregular and severely impaired heart is only able to produce an occasional beat
70
Describe the conduction pathway of an electrical impulse in an agonal rhythm.
1) impulse orignates in an automaticity focus (the higher pacemakers have failed)
2) a small area begins to depolarize, propagating cell to cell through one ventricle and eventually to the next ventricle (normally both ventricles depolarize simultaneously)
3) heads upward (antegrade) - ultimately atria and ventricular muscle depolarize
71
**Agonal Rhythm**
Rate
Rhythm
P wave
PR interval
QRS complex
**Rate:** \<20
**Rhythm:** irregularly irregular
**P wave:** usually absent OR with retrograde conduction to atria may appear after QRS
**PR interval:** n/a - remember beat originated in ventricle
**QRS complex:** equal or \>0.12 seconds (frequently slopes opposite of the T wave)
72
**Agonal Rhythm**
Causes
Adverse Effects
Treatment
**Causes:** patient is DYING - usually from cardiac damage and/or hypoxia
**Adverse Effects:** usually DOES NOT provide a pulse; profound shock, unconsciousness and/or death if not treated
**Treatment:** CPR
73
Ventricular Tachycardia
A wide and rapid "saw tooth-like" rhythm originate in the ventricles
74
Ventricular Tachycardia (V-tach)
What are the two types?
Three or more PVCs in a row at a rate of more than 100 beats/min (aka monomorphic ventricular tachycardia)
**Non-sustained V-tach:** V-tach lasting \<30 seconds
**Sustained V-tach:** \>30 seconds
75
Describe conduction pathway of an electrical impulse in (monomorphic) ventricular tachycardia
1) impulse originates from a SINGLE automaticity focus in the ventricles
2) a small area begins to depolarize, propagating cell to cell through one ventricle and eventually to the next ventricle (normally both ventricles depolarize sumltaneously)
3) heads upwards (antegrade) and ultimately ventricular muscle depolarizes
76
**Ventricular Tachycardia**
Rate
Rhythm
P wave
PR interval
QRS complex
**Rate:** \>100 - 250 (typically)
**Rhythm:** Regular
**P wave:** usually absent OR with retrograde conduction to atria may appear after QRS
**PR interval:** n/a - remember beat originated in ventricle
**QRS complex:** equal or \>0.12 seconds (QRS have the same shape and amplitude) - frequently slopes opposite of the T wave
77
**Ventricular Tachycardia**
Causes
Adverse Effects
Treatment
**Causes:** see PVCs
**Adverse Effects:**
* May only be tolerated in short bursts
* almost always DOES NOT provide a pulse
* profound shock, unconsciousness and/or death if not treated
**Treatment:** CPR, if pulseless; DEFIBRILLATION (if unconscious and no pulse)
78
Torsades de Pointes (aka TdP)
French for "twisting of the points" which describes the morphology of the QRS
aka polymorphic ventricular tachycardia
79
Describe conduction pathway of an electrical impulse in Torsades de Pointes (TdP)
1) Impulse originates from MULTIPLE automaticity foci in the ventricles
2) propagating cell to cell through one ventricle and eventually to the next ventricle (normally both ventricles depolarize simultaneously)
3) heads upwards (antegrade) - ultimately depolarizes atria and ventricular muscle
80
**Torsades de Pointes (TdP)**
Rate
Rhythm
P wave
PR interval
QRS complex
**Rate:** \>150 - 300
**Rhythm:** Irregularly irregular
**P wave:** usually absent OR with retrograde conduction to atria may appear after QRS
**PR interval:** n/a (remember beat originated in ventricle)
**QRS complex:** equal or \>0.12 seconds (QRS will **vary in shape**) and amplitude; appears to "twist" around the isoelectric line, resembling a spindle
81
**Torsades de Pointes**
Causes
Adverse Effects
Treatment
**Causes:** see PVCs
**Adverse Effects:**
* may only be tolerated in short bursts
* almost always DOES NOT (should never) provide a pulse
* profound shock, unconsciousness and/or death if not treated
**Treatment:** CPR (if pulseless); DEFIBRILLATION (if unconscious and no pulse)
82
Ventricular Fibrillation
A chaotic rhythm that begins in the ventricles with no organized depolarization; the muscle quivers, like a bag of worms, with no effective contraction (no pulse)
Two types:
**a) Coarse ventricular fibrillation**
**b) Fine ventricular fibrillation**
83
Coarse Ventricular Fibrillation (V-Fib)
Waveforms equal or greater than 3mm in amplitude
84
Fine Ventricular Fibrillation (V-Fib)
Waveforms less than 3mm in amplitude
85
Describe conduction pathway of an eletrical impulse in ventricular fibrillation.
1) Impulses originate from multiple automaticity foci in the ventricles
2) the impulses DO NOT follow any specific conduction pathway and DO NOT provide organized depolarization of both atria and ventricles
86
**Ventricular Fibrillation**
Rate
Rhythm
P wave
PR interval
QRS Complex
**Rate:** unable to determine rate (no discernable waves or complexes)
**Rhythm:** irregularly irregular
**P wave:** not discernable
**PR Interval:** n/a
**QRS Complex:** not discernable
87
**Ventricular Fibrillation**
Causes
Adverse Effects
Treatment
**Causes:** (same as V-Tach and PVC)
* 3 big causes:
* **hypoxia** - poor oxygenation can make automaticity focus become irritable
* **heart disease** - ACS, CHF, etc.
* **hypokalemia** - electrolyte imbalance
* Other causes:
* normal variant
* increased sympathetic tone - stress/anxiety, exercise, etc.
* Medications - Digitalis, sympathomimetics, antidepressants
* Drugs - caffeine, tobacco
* Acid-base imbalance
**Adverse Effects:**
* no cardiac output
* profound shock, unconsciousness and/or death if not treated
* Coarse v-fib changes progressively to fine v-fib the longer it lasts
**Treatment:** CPR (if pulseless); defibrillation
*_**\*artifact can mimic v-fib and therefore always check the patient's pulse before beginning treatment\***_*
88
Asystole (Flat line)
No impulse has originated as all pacemakers have failed
A total absence of cardiac electrical activity
89
Describe the conduction pathway of an electrical impulse in asystole.
No impulse is generated in any cardiac tissue, no impulse follows any conduction pathway
90
**Asystole**
Rate
Rhythm
P wave
PR Interval
QRS Complex
**Rate:** 0
**Rhythm:** n/a
**P wave:** none (if only th eP waves are present, rhythm is **ventricular standstill**)
**PR Interval:** n/a
**QRS Complex:** n/a
91
**Asystole**
Causes
Adverse Effects
Treatment
**Causes:** same as V-Tach and V-fib
* 3 big causes:
* **hypoxia** - poor oxygenation can make automaticity focus become irritable
* **heart disease** - ACS, CHF, etc.
* **hypokalemia** - electrolyte imbalance
* Other causes:
* normal variant
* increased sympathetic tone - stress/anxiety, exercise, etc.
* Medications - Digitalis, sympathomimetics, antidepressants
* Drugs - caffeine, tobacco
* Acid-base imbalance
**Adverse Effects:** Death if untreated
**Treatment:** CPR
92
Ventricular Standstill
Occurs as the SA node is still functional, even though there are no impulses passing through to the ventricles
Only atrial depolarization is present and there is no ventricular depolarization (if there is no ventricular depolarization, there is no ventricular contraction and therefore no pulse)
93
Defibrillation
* A delivery of an unsynchronized electrical current through the myocardium over a very brief period to terminate a cardiac dysrhythmia
* electrical current (shock) attempts to simultaneously depolarize ventricular cells causing momentary **asystole**, which provides an opportunity for the heart's natural pacemakers to resume function
* this pacemaker with the highest degree of automaticity should assume repsonsibility for pacing the heart
94
Adult defib pad placement
pads are placed in specific locations in order to allow the path of current to pass through the heart
electrical current is measured in joules
95
What are the shockable rhythms?
**pulseless** ventricular tachycardia
and
ventricular fibrillation
