Basic Arrhythmias With 12-Lead EKGs
Ninth Edition
Chapter 8
Ventricular Rhythms
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Figure 61 Mechanism of Premature
Ventricular Complex
A single irritable focus within the ventricles that fires
prematurely to initiate an ectopic complex. This is a single
beat, not an entire rhythm; the underlying rhythm also
must be identified.
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Figure 62 T Wave Configuration in PVCs
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Figure 63 Examples of Typical
Examples of PVC Configuration (1 of 2)
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Figure 63 Examples of Typical
Examples of PVC Configuration (2 of 2)
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Figure 64 Compensatory Pause
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Figure 65 Interpolated PVC
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Figure 66 Unifocal PVCs
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Figure 67 Multifocal PVCs
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Figure 68 R on T Phenomenon
• Ectopic A exhibits R on T phenomenon; Ectopic B does
not.
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Figure 69 PVCs Occurring as a Couplet
(Pair)
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Figure 70 PVCs Occurring in a Run
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Figure 71 Patterns of Grouped Beating (1 of 3)
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Figure 71 Patterns of Grouped Beating (2 of 3)
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Figure 71 Patterns of Grouped Beating (3 of 3)
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Rules for Premature Ventricular
Complex
• Regularity: Ectopics will disrupt regularity of underlying
rhythm
• Rate: Depends on underlying rhythm and number of
ectopics
• P Waves: Will not be preceded by a P wave; dissociated
P wave may be seen near PVC
• PRI: Since the ectopic comes from a lower focus, there
will be no PRI
• QRS: Wide and bizarre; 0.12 seconds or greater; T wave
is usually in opposite direction from R wave
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Figure 72 Rules for Premature
Ventricular Complex
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Figure 73 Mechanism of Ventricular
Tachycardia
An irritable focus within the ventricles fires regularly at a
rapid rate to override higher sites for control of the heart.
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Rules for Ventricular Tachycardia
• Regularity: Usually regular; can be slightly irregular
• Rate: 150–250 bpm; can exceed 250 bpm if the rhythm
progresses to Ventricular Flutter; may occasionally be
slower than 150 bpm, in which case it is called slow VT
• P Waves: Will not be preceded by P waves; dissociated
P waves may be seen
• PRI: Since the focus is in the ventricles, there will be no
PRI
• QRS: Wide and bizarre; 0.12 second or greater; T wave
is usually in opposite direction from R wave
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Figure 74 Rules for Ventricular
Tachycardia
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Figure 75 Mechanism of Ventricular
Fibrillation
Multiple foci within the ventricles become irritable and
generate uncoordinated, chaotic impulses that cause the
heart to fibrillate rather than contract.
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Rules for Ventricular Fibrillation
• Regularity:
• Rate:
• P Waves:
• PRI:
Totally chaotic with no
discernible waves or
complexes
• QRS:
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Figure 76 Rules for Ventricular
Fibrillation
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Figure 77 Mechanism of Idioventricular
Rhythm
In the absence of a higher pacemaker, the ventricles initiate
a regular impulse at their inherent rate to take control of the
heart.
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Rules for Idioventricular Rhythm
• Regularity: usually regular
• Rate: 20–40 bpm; can drop below 20 bpm
• P Waves: none
• PRI: none
• QRS: wide and bizarre; 0.12 second or more
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Figure 78 Rules for Idioventricular
Rhythm
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Figure 79 Mechanism of Asystole
The heart has lost its electrical activity. There is no
electrical pacemaker to initiate electrical flow.
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Rules for Asystole
• Regularity:
• Rate:
• P Waves:
Straight line indicates
no electrical activity
• PRI:
• QRS:
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Figure 80 Rules for Asystole
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Agonal Rhythm
Agonal is the term used to describe a terminal, lethal
arrhythmia, especially when the heart has stopped beating
in a reliable pattern; also called a dying heart.
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