Transcript sinus rhythm with first degree AV block

11
Sinus Dysrhythmias
Fast & Easy ECGs, 2nd E – A SelfPaced Learning Program
Fast & Easy ECGs, 2E
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Sinus Rhythms
• Rhythms
originating
from the SA
node are
called sinus
rhythms
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Fast & Easy ECGs, 2E
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Normal Sinus Rhythm (NSR)
• During normal
heart activity,
SA node acts
as the primary
pacemaker
• NSR has a
heart rate of
60 to100 BPM
(in the average
adult)
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Sinus Bradycardia
• Has all the
characteristics of
NSR but the
heart rate is < 60
BPM
Q
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Causes of Sinus Bradycardia
• Often occurs
naturally as body’s
way to conserve
energy during
times of reduced
demand for blood
flow
• Other causes
include:
I
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Effects of Sinus Bradycardia
• Often insignificant and the patient is
asymptomatic
• Hypotension can result if the heart rate slows
to the point where cardiac output drops
sufficiently
– Patients are less tolerant of rates < 45 BPM
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Treatment of Sinus Bradycardia
• Asymptomatic patients require no treatment
but should be monitored in case there is a
progression of the bradycardia
• Symptomatic patients may improve with the
administration of atropine, transcutaneous
pacing, or administration of an IV infusion of
dopamine or epinephrine
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Sinus Tachycardia
• Has same
characteristics
as NSR but
has a rate
>100 BPM
Q
I
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Causes of Sinus Tachycardia
• Often occurs with
physical labor,
exercise, pain, fear,
excitement, anxiety,
and where
increased
sympathetic
stimulation occurs
in response to the
need for more
oxygen and
nutrients at the
cellular level
• Other causes
include those
shown to the right:
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Effects of Sinus Tachycardia
• Often of no clinical significance
• Can increase myocardial oxygen consumption
– which can aggravate ischemia (bringing on chest
pain), and infarction, particularly in those with
cardiovascular disease
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Treatment of Sinus Tachycardia
• Asymptomatic patients require no treatment
– However, patient should be encouraged to abstain
from triggers such as alcohol, caffeine, and nicotine
• Treatment for symptomatic sinus tachycardia is
directed at treating the cause
– Continued monitoring is indicated with an underlying
medical or traumatic condition
– For patients experiencing myocardial ischemia,
consideration may be given to additional treatments
that will slow the heart rate or vasodilate the coronary
arteries
Fast & Easy ECGs, 2E
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Sinus Dysrhythmia
• Same as NSR
except there is
a patterned
irregularity
• Described as a
cycle of
“slowing, then
speeding up,
then slowing
again”
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Sinus Dysrhythmia
• The beat-to-beat variation produced by
irregular firing of the SA node usually
corresponds with the respiratory cycle and
changes in intrathoracic pressure
• Heart rate increases during inspiration and
decreases during expiration
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Causes of Sinus Dysrhythmia
• Can occur
naturally in
athletes,
children,
and older
adults
• Other
causes
include:
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Effects of Sinus Dysrhythmia
• Usually of no clinical significance and
produces no symptoms
• In some patients and conditions it may be
associated with palpitations, dizziness, and
syncope
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Treatment of Sinus Dysrhythmia
• Provided the patient is asymptomatic, usually
no treatment is needed
• If unrelated to respirations, consideration may
be given to treating the underlying cause
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Sinus Arrest
• Occurs when
the SA node
transiently
stops firing
• Results in short
periods of
cardiac
standstill until a
lower-level
pacemaker
discharges or
the SA node
resumes its
normal function
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Sinus Arrest
• Most prominent characteristic is a pause in
ECG rhythm
• Produces an irregularity
• Rhythm typically resumes its normal
appearance after pause unless an escape
pacemaker resumes the rhythm
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Causes of Sinus Arrest
• Results from
marked
depression in
SA node
automaticity
• Causes
include:
I
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Effects of Sinus Arrest
• Becomes clinically significant with an extended pause
or when there are frequent occurrences of the pause
or arrest
– Can lead to a drop in cardiac output and decreased
blood pressure and tissue perfusion
• There is also a danger that SA node activity will
completely cease and an escape pacemaker may not
take over pacing
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Treatment of Sinus Arrest
• Asymptomatic patients require no treatment
• Symptomatic patients may be treated with
administration of atropine or temporary or permanent
ventricular pacing
– Reasons to pace include the development of an AV
junctional or ectopic ventricular pacemaker that is slow
enough to result in such problems as syncope, CHF, angina,
or frequent ventricular ectopic beats
• As needed, drugs affecting SA node discharge or
conduction, such as beta-adrenergic blockers, calcium
channel blockers, and digoxin, should be discontinued
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Sinoatrial Exit Block
• Occurs when the SA node fires but conduction
to the atria is delayed or blocked
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Causes of Sinoatrial Exit Block
• Include
the
following:
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Effects of Sinoatrial Exit Block
• Is usually insignificant
• Can be clinically significant when there is an
extended pause or when there are frequent
occurrences of the dropped P waves (and
subsequent QRS complexes)
– Can lead to decreased heart rate, a drop in cardiac
output, and decreased blood pressure and tissue
perfusion
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Treatment of Sinoatrial Exit Block
• No treatment is indicated provided the patient
is asymptomatic
• If the patient is symptomatic, treatment
includes administration of atropine or
temporary or permanent ventricular pacing
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Sick Sinus Syndrome
• Is a group of
abnormal rhythms
that occur with
malfunction of the
sinus node
– Bradycardiatachycardia
syndrome is one
variant in which
slow
dysrhythmias and
fast dysrhythmias
alternate
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Causes of Sick Sinus Syndrome
• Is a
moderately
uncommon
disorder
• Causes
include the
following:
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Effects of Sick Sinus Syndrome
• Although many types are symptom free,
patients may present with Stokes-Adams
attacks, fainting, dizziness or lightheadedness,
palpitations, chest pain, shortness of breath,
fatigue, headache, and nausea
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Treatment of Sick Sinus Syndrome
• Bradydysrhythmias are well controlled with
pacemakers whereas tachydysrhythmias
respond well to medications
– However, because both bradydysrhythmias and
tachydysrhythmias may be present, drugs to
control the rapid heart rates may worsen
bradydysrhythmia
– For this reason, a pacemaker is implanted before
drug therapy is begun for the tachydysrhythmia
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Sinus Rhythm as Underlying Rhythm
• Sinus rhythm may be what is referred to as an underlying
rhythm. What
• that means is the sinus rhythm is seen, but then there is
another dysrhythmia
• or cardiac condition seen as well. For example, if there is a
delay in
• conduction through the AV node (referred to as first degree
AV block, in
• chapter 15) then we call it sinus rhythm with first degree AV
block (Figure
• 11-9A). Similarly, if there are early beats, we call it sinus
rhythm with
• early beats
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Practice Makes Perfect
• Determine the type of dysrhythmia
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Practice Makes Perfect
• Determine the type of dysrhythmia
I
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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Practice Makes Perfect
• Determine the type of dysrhythmia
I
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
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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.
Summary
• Rhythms originating from the SA node are
called sinus rhythms.
• Normal sinus rhythm has a heart rate of 60 to
100 BPM (in the average adult).
Fast & Easy ECGs, 2E
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© 2013 The McGraw-Hill Companies, Inc. All rights reserved.
Summary
• Sinus bradycardia has all the characteristics of
normal sinus rhythm but the heart rate is less
than 60 BPM.
• Sinus tachycardia has the same characteristics
as normal sinus rhythm but has a rate of
greater than 100 BPM.
Fast & Easy ECGs, 2E
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Summary
• Sinus dysrhythmia is the same as sinus rhythm
except there is the presence of a patterned
irregularity. It can be described as a cycle of
“slowing, then speeding up, then slowing again.”
• With sinus arrest the ECG rhythm looks like
normal sinus rhythm except there is a pause in
the rhythm or an absence of the P, QRS, and T
waveforms until a pacemaker site reinitiates the
rhythm.
Fast & Easy ECGs, 2E
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Summary
• With sinoatrial exit block, there is a pause in the
rhythm with an absence of the P, QRS, and T
waveforms. Then the P wave (and associated QRS
complex) reoccurs at the next expected interval
• Sick sinus syndrome is a group of abnormal
rhythms that occur with malfunction of the sinus
node
• Sinus rhythms may be what are referred to as an
underlying rhythm. This is where the sinus
rhythm is seen but then another dysrhythmia or
cardiac condition is seen as well
Fast & Easy ECGs, 2E
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