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Ventricular Dysrhythmias
Fast & Easy ECGs, 2nd E – A SelfPaced Learning Program
Fast & Easy ECGs, 2E
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Ventricular Dysrhythmias
• Premature
ventricular complex
(PVC)
• Ventricular escape
complexes or
rhythm
• Ventricular
tachycardia
• Ventricular
fibrillation
• Asystole
Fast & Easy ECGs, 2E
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Ventricular Dysrhythmias
• Key features:
– Wide (> 0.12 seconds in duration), bizarre QRS
complexes
– T waves in the opposite direction of the R wave
– Absence of P waves
Fast & Easy ECGs, 2E
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Ventricular Dysrhythmias
• Occur when:
– The atria, AV junction, or both, are unable to
initiate an electrical impulse
– There is enhanced automaticity of the ventricular
myocardium
Fast & Easy ECGs, 2E
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Ventricular Dysrhythmias
• Can be benign or they can be potentially lifethreatening (because the ventricles are
ultimately responsible for cardiac output)
I
Fast & Easy ECGs, 2E
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Premature Ventricular Complexes
(PVCs)
• Early ectopic beats
that interrupt the
normal rhythm
• Originate from an
irritable focus in
the ventricular
conduction system
or muscle tissue
Note: A PVC is not an entire
rhythm—it is a single beat
Fast & Easy ECGs, 2E
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Causes of PVCs
• Enhanced
automaticity or
reentry, brought
about by
disruption of the
normal
electrolyte shifts
during cell
depolarization
and
repolarization
• Causes include:
Fast & Easy ECGs, 2E
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Appearance of PVCs
• PVCs are
typically
followed by a
compensatory
pause
Q
Fast & Easy ECGs, 2E
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Appearance of PVCs
• PVCs that look the
same are called
uniform (unifocal)
• PVCs that look
different from each
other are called
multiform
(multifocal)
Note: “Uni” means single,
“multi” means many
Fast & Easy ECGs, 2E
Uniform
I
Multiform
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Groupings of PVC
• PVCs that appear
after every
– other normal beat
are called bigeminal
PVCs
– second normal beat
are called trigeminal
PVCs
– third normal beat
are called
qudrigeminal PVCs
Bigeminal
Trigeminal
Quadrigeminal
Fast & Easy ECGs, 2E
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Couplets of PVCs
• Two PVCs in a row are called a couplet and
indicate extremely irritable ventricles
Fast & Easy ECGs, 2E
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Interpolated PVCs
• PVCs that fall between two regular complexes
and do not disrupt the normal cardiac cycle
are called interpolated PVCs
Q
Fast & Easy ECGs, 2E
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Run of PVCs
• Three or more PVCs in a row are called a run
of ventricular tachycardia or a run of PVCs
Note: it may also be called a
salvo, run, or burst of VT
Fast & Easy ECGs, 2E
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R-on T PVCs
• PVCs occurring on or near the previous T wave
(R-on-T PVCs) may precipitate ventricular
tachycardia or fibrillation
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Fast & Easy ECGs, 2E
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Effects of PVCs
• PVCs can be significant for two reasons
– they can precipitate more serious dysrhythmias
such as VT or VF
– they can result in decreased cardiac output due to
reduced diastolic filling time and a loss of atrial
kick
Note: When no pulse is felt during a
PVC, it is called a nonperfusing PVC
I
Fast & Easy ECGs, 2E
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Treatment of PVCs
• Asymptomatic patients seldom require treatment
• Patients with myocardial ischemia, treatment of
frequent PVCs includes:
– administration of oxygen and placement of an IV line
– identifying and correcting the underlying factor causing
the PVCs
• in some settings, administering lidocaine or other
antidysrhythmics (e.g., amiodarone) by IV push and a continued
maintenance infusion
– administering potassium chloride intravenously to correct
hypokalemia or magnesium sulfate intravenously to
correct hypomagnesemia; adjusting drug therapy; or
correcting acidosis, hypothermia, and/or hypoxia
Fast & Easy ECGs, 2E
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Ventricular Escape Beats
• Occur when
there is
temporary
cessation of
the heartbeat
such as with
sinus arrest or
when the rate
of the
underlying
rhythm falls to
less than that
the inherent
rate of the
ventricles
Fast & Easy ECGs, 2E
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Causes of Ventricular Escape Beats
• Are compensatory in nature, occur when a
higher pacemaker fails to initiate a heartbeat
– Meant to preserve cardiac output
• Can occur in sinoatrial pause/arrest, by a
failure of the conductivity from the SA node to
the AV node, or by AV (especially 3rd degree
AV block)
Fast & Easy ECGs, 2E
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Effects of Ventricular Escape Beats
• Low heart rate associated with the event
leading up to the appearance of ventricular
escape beats can result in a drop in blood
pressure and syncope
• Ventricular escape beats should be temporary
as the heart should resume its normal
electrical activity
Fast & Easy ECGs, 2E
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Treatment of Ventricular Escape Beats
• Centers on treating the underlying condition
• Support circulation, airway, and breathing; deliver oxygen;
monitor the ECG, blood pressure and pulse oximetry; and
establish an IV infusion
• Continually reassess the clinical status and correct any
reversible conditions
• A primary goal of treatment is to maintain a ventricular rate
sufficient to produce adequate cardiac output
– Atropine or transcutaneous pacing can be used to treat the
symptomatic patient
– Drugs used to suppress ventricular activity such as lidocaine and
amiodarone are contraindicated and may be lethal
Fast & Easy ECGs, 2E
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Idioventricular Rhythm
• Slow
dysrhythmia
(rate of 20
to 40 BPM)
with wide
QRS
complexes
that arise
from the
ventricles
Q
I
Fast & Easy ECGs, 2E
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Causes of Idioventricular Rhythm
• Massive
myocardial
ischemia or
MI, digoxin
toxicity,
pacemaker
failure, and
metabolic
imbalances
• Other causes
include:
Fast & Easy ECGs, 2E
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Effects of Idioventricular Rhythm
• Slow ventricular rate and loss of atrial kick can
significantly decrease cardiac output
– resultant decreased cardiac output will likely cause
patient to be symptomatic
• Signs of decreased cardiac output such as
disorientation, unconsciousness, hypotension,
and/or syncope, and the patient may complain of
dizziness, chest pain, and/or shortness of breath
• In extreme cases, patient is pulseless
I
Fast & Easy ECGs, 2E
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Treatment of Idioventricular Rhythm
• For symptomatic patients:
– Support the airway and breathing
– Deliver oxygen, perform an ECG, monitor the blood pressure
and pulse oximetry, and place an IV infusion
– Continually reassess the clinical status, and correct any
reversible conditions
– Maintain a ventricular rate sufficient to produce adequate
cardiac output
• Administer atropine or deliver transcutaneous pacing
• In unresolved idioventricular rhythm, the atropine dose may be
repeated
– Lidocaine and amiodarone are contraindicated
• If there is no pulse, treat the dysrhythmia as if it is pulseless
electrical activity (PEA)
Fast & Easy ECGs, 2E
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Accelerated Idioventricular Rhythm
• Idioventricular
rhythm that
exceeds the
inherent rate
of the
ventricles (60
to 100 BPM)
Fast & Easy ECGs, 2E
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Causes of Accelerated Idioventricular
Rhythm
• Same conditions that lead to
idioventricular rhythm
• Also, it is very common following acute MI
• Further, it is often seen after administering
thrombolytic medications
– For that reason, it is considered a reperfusion
dysrhythmia
Fast & Easy ECGs, 2E
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Effects of Accelerated Idioventricular
Rhythm
• While accelerated idioventricular rhythm is
usually short lived and because the heart rate
is close to normal, no ill effect may be seen
• However, with accelerated idioventricular
rhythm there may be decreased cardiac
output, particularly when the rate is slower
Q
I
Fast & Easy ECGs, 2E
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Treatment of Accelerated
Idioventricular Rhythm
• Depends on whether the rhythm is sustained and
whether or not cardiac output is diminished
• For the symptomatic patient, transcutaneous pacing or
atropine can be used
– In unresolved idioventricular rhythm, the atropine dose
may be repeated
• A permanent pacemaker may be required in sustained
symptomatic accelerated idioventricular rhythm
• Lidocaine and amiodarone are contraindicated and
may be lethal
• If there is no pulse, treat the dysrhythmia as if it were
pulseless electrical activity (PEA)
Fast & Easy ECGs, 2E
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Ventricular Tachycardia (VT)
• Fast
dysrhythmia
(100 to 250
BPM) that
arises from
the ventricles
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Fast & Easy ECGs, 2E
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Ventricular Tachycardia
• Present when there are 3 or more PVCs in a
row
• May come in bursts of 6 to 10 complexes or
may persist (sustained VT)
Fast & Easy ECGs, 2E
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Causes of Ventricular Tachycardia
•
•
Increased myocardial
irritability that may
be triggered by:
– enhanced
automaticity,
– PVCs that occur
during the
downstroke of
the preceding T
wave,
– reentry in the
Purkinje system
Other causes include:
Fast & Easy ECGs, 2E
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Effects of Ventricular Tachycardia
• Always significant
• May be perfusing or nonperfusing
• Even if the rhythm produces a pulse, it should be
considered as potentially unstable because patients are
likely to develop more life-threatening rhythms which
progress into cardiac arrest
• The rapid rate and concurrent loss of atrial kick associated
with VT results in compromised cardiac output and
decreased coronary artery and cerebral perfusion
• Severity of symptoms varies with the rate of the VT and the
presence and degree of underlying myocardial dysfunction
I
Fast & Easy ECGs, 2E
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Treatment of Ventricular Tachycardia
• Maintain a patent airway, administer oxygen, and place an IV
line
• Stable patient can be treated with antidysrhythmics (such as
procainamide, amiodarone, or sotalol)
• Unstable patients are managed with immediate synchronized
cardioversion (100 J)
– Energy level may be increased if the tachycardia does not
convert with initial treatments (100, 200, 300, 360 J or the
biphasic equivalent)
• Contributing causes should be considered and treated
• Patients with pulseless VT should be treated as though they
are in VF
I
Fast & Easy ECGs, 2E
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Ventricular Tachycardia
• Monomorphic - appearance of each QRS
complex is similar
• Polymorphic - appearance varies considerably
from complex to complex
Fast & Easy ECGs, 2E
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Causes of Torsades de Pointes
• Associated
with long QT
syndrome, a
condition
whereby
prolonged QT
intervals are
visible on the
ECG
• Causes
include:
Fast & Easy ECGs, 2E
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Effects of Torsades de Pointes
• Depends on the rate and duration of
tachycardia and the degree of cerebral
hypoperfusion
• Findings include rapid pulse, low or normal
blood pressure, or syncope or prolonged loss
of consciousness
• Pallor and diaphoresis may be noted,
especially with a sustained episode
• Can degenerate into VF
Fast & Easy ECGs, 2E
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Treatment of Torsades de Pointes
• Cannot be reliably synchronized and should be managed like
ventricular fibrillation (VF), with an initial unsynchronized shock
• Standard antidysrhythmic drugs (such as procainamide) can
worsen the condition, leading to cardiac arrest
• Amiodarone may be effective in stable patients with normal QT
interval
• Magnesium sulfate should be administered in stable patients
with prolonged QT interval
• Offending drug(s) should be discontinued and electrolyte
imbalance corrected
• Patients with pulseless VT should be treated as though they are
in VF, with the treatment of choice being prompt defibrillation
Fast & Easy ECGs, 2E
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Ventricular Fibrillation (VF)
• Results from
chaotic firing of
multiple sites in
the ventricles
• Causes heart
muscle to
quiver rather
than contract
efficiently,
producing no
effective
muscular
contraction and
no cardiac
output
I
Fast & Easy ECGs, 2E
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Ventricular Fibrillation
• Most commonly
associated with
significant
cardiovascular
system disease
• Causes include:
Fast & Easy ECGs, 2E
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Ventricular Fibrillation
• Death occurs if patient not promptly treated
(defibrillation)
• Most common cause of prehospital cardiac
arrest in adults
Fast & Easy ECGs, 2E
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Treatment of Ventricular Fibrillation
• Prompt delivery of CPR and defibrillation
• Organize ACLS actions around uninterrupted periods of CPR
• Initiate securing the airway and placing an IV line in the course of
treatment
• After one shock and a 2-minute period of CPR, administer
epinephrine or vasopressin
• Amiodarone may be considered when VF/VT is unresponsive to
CPR, defibrillation, and vasopressor therapy
– If amiodarone is unavailable, lidocaine may be considered if allowed
by local protocol
• Continue CPR, stopping only to defibrillate and reassess rhythm.
– Minimize interruptions in chest compressions before and after shock;
resume CPR beginning with compressions immediately after each
shock
I
Fast & Easy ECGs, 2E
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Treatment of Ventricular Fibrillation
• If the rhythm is successfully converted to an
effective electromechanical rhythm (with a
pulse and good perfusion):
– assess vital signs, support airway and breathing,
– provide medications to support blood pressure,
heart rate, and rhythm and to prevent
reoccurrence
Fast & Easy ECGs, 2E
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Asystole
• Absence of any
cardiac activity
• Appears as a
flat (or nearly
flat) line
• Complete
cessation of
cardiac output
I
Fast & Easy ECGs, 2E
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Ventricular Standstill
• Called
ventricular
standstill
when the
atria
continue to
beat but the
ventricles
have stopped
• Seen as the
presence of
only P waves
Fast & Easy ECGs, 2E
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Asystole
• Terminal rhythm
• Chances of recovery extremely low
I
Fast & Easy ECGs, 2E
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Treatment of Asystole
• Promptly initiate CPR, deliver high-concentration oxygen, place an
IV line, and secure the airway
• Administer epinephrine, repeating its administration every 3 to 5
minutes
– One dose of vasopressin may replace either the first or second dose of
epinephrine
• Continue CPR throughout the resuscitation effort, stopping
periodically to reassess for a change in rhythm and to check for
presence of a pulse
• Follow local protocols for terminating resuscitation efforts
• Always verify the presence of asystole in two leads prior to initiating
treatment
– Misplacement of an ECG lead or a loose wire can mimic asystole (or
VF) on the monitor
Fast & Easy ECGs, 2E
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Pulseless Electrical Activity (PEA)
• Condition that
has an
organized
electrical
rhythm on the
ECG monitor
(which should
produce a
pulse) but
patient is
pulseless and
apneic
I
Fast & Easy ECGs, 2E
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Treatment of PEA
• Includes prompt initiation of CPR, highconcentration oxygen, placing an IV line, securing
the airway and confirming placement
• Administer epinephrine, repeating its
administration every 3 to 5 minutes
– One dose of vasopressin may replace either the first
or second dose of epinephrine
• Continue CPR throughout the resuscitation effort,
stopping periodically to reassess for a change in
rhythm and to check for a pulse
Fast & Easy ECGs, 2E
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Practice Makes Perfect
• Determine the type of dysrhythmia
I
Fast & Easy ECGs, 2E
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© 2013 The McGraw-Hill Companies, Inc. All rights reserved.
Practice Makes Perfect
• Determine the type of dysrhythmia
I
Fast & Easy ECGs, 2E
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© 2013 The McGraw-Hill Companies, Inc. All rights reserved.
Practice Makes Perfect
• Determine the type of dysrhythmia
I
Fast & Easy ECGs, 2E
51
© 2013 The McGraw-Hill Companies, Inc. All rights reserved.
Practice Makes Perfect
• Determine the type of dysrhythmia
I
Fast & Easy ECGs, 2E
52
© 2013 The McGraw-Hill Companies, Inc. All rights reserved.
Practice Makes Perfect
• Determine the type of dysrhythmia
I
Fast & Easy ECGs, 2E
53
© 2013 The McGraw-Hill Companies, Inc. All rights reserved.
Practice Makes Perfect
• Determine the type of dysrhythmia
I
Fast & Easy ECGs, 2E
54
© 2013 The McGraw-Hill Companies, Inc. All rights reserved.
Practice Makes Perfect
• Determine the type of dysrhythmia
I
Fast & Easy ECGs, 2E
55
© 2013 The McGraw-Hill Companies, Inc. All rights reserved.
Practice Makes Perfect
• Determine the type of dysrhythmia
I
Fast & Easy ECGs, 2E
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© 2013 The McGraw-Hill Companies, Inc. All rights reserved.
Practice Makes Perfect
• Determine the type of dysrhythmia
I
Fast & Easy ECGs, 2E
57
© 2013 The McGraw-Hill Companies, Inc. All rights reserved.
Summary
• Ventricular dysrhythmias occur when the atria, AV
junction, or both, are unable to initiate an electrical
impulse or when there is enhanced excitability of the
ventricular myocardium
• A key feature of ventricular dysrhythmias are wide
(greater than 0.12 seconds in duration), bizarre QRS
complexes that have T waves in the opposite direction
of the R wave and an absence of P waves
• Ventricular dysrhythmias include: premature
ventricular contraction (PVC), ventricular escape
complexes or rhythm, ventricular tachycardia,
ventricular fibrillation, and asystole
Fast & Easy ECGs, 2E
58
© 2013 The McGraw-Hill Companies, Inc. All rights reserved.
Summary
• Premature ventricular complexes are early
ectopic beats that interrupt the normal
rhythm and originate from an irritable focus in
the ventricular conduction system or muscle
tissue
• Idioventricular rhythm is a slow dysrhythmia
with wide QRS complexes that arise from the
ventricles at a rate of 20 to 40 beats per
minute
Fast & Easy ECGs, 2E
59
© 2013 The McGraw-Hill Companies, Inc. All rights reserved.
Summary
• Ventricular tachycardia is a fast dysrhythmia,
between 100 to 250 beats per minute that
arises from the ventricles.
– It is said to be present when there are three or
more PVCs in a row.
– It can occur with or without pulses, and the
patient may be stable or unstable with this
rhythm.
Fast & Easy ECGs, 2E
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© 2013 The McGraw-Hill Companies, Inc. All rights reserved.
Summary
• VT may be monomorphic, where the appearance of
each QRS complex is similar, or polymorphic, where the
appearance varies considerably from complex to
complex
• Ventricular fibrillation (VF) results from chaotic firing of
multiple sites in the ventricles causing the heart muscle
to quiver rather than contracting efficiently, producing
an absence of effective muscular contraction and
cardiac output
• Asystole is the absence of any cardiac activity
– Appears as a flat (or nearly flat) line on the monitor screen
and produces a complete cessation of cardiac output
Fast & Easy ECGs, 2E
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Summary
• Pulseless electrical activity (PEA) is a condition
in which there is an organized electrical
rhythm on the ECG monitor (which should
produce a pulse) but the patient is pulseless
and apneic
– Sinus rhythm, sinus tachycardia, idioventricular
rhythm, or other rhythms may be the electrical
activity seen with PEA
Fast & Easy ECGs, 2E
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