Transcript Chapter 5 PPT

Electrocardiography for
Healthcare Professionals
Kathryn A. Booth
Thomas O’Brien
Chapter 5: Rhythm Strip
Interpretation and Sinus Rhythms
© 2016 McGraw-Hill Education. All Rights Reserved.
Learning Outcomes
5.1 Explain the process of evaluating ECG tracings and determining
the presence of dysrhythmias.
5.2 Describe the criteria used to classify dysrhythmias, including
rhythm, rate, P wave morphology, PR interval measurement, and
QRS duration measurement.
5.3 Identify normal sinus rhythm using the criteria for classification,
and explain how the rhythm may affect the patient, including basic
patient care and treatment.
5.4 Identify sinus bradycardia using the criteria for classification, and
explain how the rhythm may affect the patient, including basic
patient care and treatment.
5.5 Identify sinus tachycardia using the criteria for classification, and
explain how the rhythm may affect the patient, including basic
patient care and treatment.
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Learning Outcomes (Cont.)
5.6 Identify sinus dysrhythmia using the criteria for
classification, and explain how the rhythm may affect
the patient, including basic patient care and treatment.
5.7 Identify sinus arrest using the criteria for classification,
and explain how the rhythm may affect the patient,
including basic patient care and treatment.
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5.1 Rhythm Interpretation

ECG is an important tool for diagnosing and treating
various cardiac diseases.

Determining cardiac dysrhythmia can be challenging.

ECG analysis involves a systematic approach.
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5.1 Apply Your Knowledge
True or False: The best way to analyze an ECG
recording is to gather the data and match it to specific
rhythm criteria.
ANSWER: True
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5.2 Identifying the Components
of the Rhythm
Key Terms

Bradycardia-slow heart rate, less than 60 bpm

J point-a point on the QRS complex where the
depolarization is completed and repolarization starts

Morphology-overall form and structure (shape)

Tachycardia-fast heart rate, greater than 100 bpm
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5.2 Identifying Components
of the Rhythm

Five-step process
 Rhythm
(regularity)
 Rate
P
wave morphology
 PR
interval
 QRS

duration and morphology
Lead II used for rhythm evaluation
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5.2 Identifying the Components of
the Rhythm – Step One
Determining the ECG rhythm or regularity

Atrial: Measure P-P wave
interval
 Use
calipers.
 Measure
several
intervals.
 Compare
to determine
whether rhythm is
regular or irregular.
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5.2 Identifying the Components of
the Rhythm – Step One (Cont.)

Ventricular: Measure QRS complex intervals:
 R-R
interval is usually easiest.
 If
R wave is not present, use the Q and S wave
junction.
R-R Interval
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5.2 Identifying the Components of
the Rhythm - Step 2
Determining the atrial and ventricular rates

Regular rhythm


Atrial rate: divide number of small boxes between P
waves into 1,500

Ventricular rate – divide number of small boxes
between R waves into 1,500
Irregular rhythm

Use the 6-second method
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5.2 Identifying the Components of
the Rhythm - Step 3
Identifying the P wave morphology

Are shapes and waveforms all the same?

Does each P wave have a QRS complex following it?
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5.2 Identifying the Components of
the Rhythm - Step 4
Measuring the PR interval

Measure the distance from the start of the
P wave to the start of the QRS complex,

Normal range is 0.12 to 0.20 second,

Calculate in multiples of 0.02 because the human eye
cannot determine 0.01 second,
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5.2 Identifying the Components of
the Rhythm - Step 4 (cont.)
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5.2 Identifying the Components of
the Rhythm - Step 5
Measuring the QRS duration and
analyzing the morphology

Helps in discriminating between different dysrhythmias

Normal limits 0.06‒0.10 second

Measure from beginning of QRS complex to J point
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5.2 Identifying the Components of
the Rhythm - Step 5 (cont.)
J Point
QRS Duration
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5.2 Identifying the Components of
the Rhythm - Step 5

Important QRS questions
 Are
all QRS complexes of equal length?
 What
is the actual measurement, and is it within
normal limits?
 Do
all QRS complexes look alike?
 Are
unusual QRS complexes associated with ectopic
beat?
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5.2 Apply Your Knowledge
What are the five steps in rhythm data gathering?
ANSWER:
Rhythm
Rate
P wave configuration
PR interval
QRS duration and morphology
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5.2 Apply Your Knowledge
What is the normal range for the PR interval?
ANSWER:
0.12‒0.20 second
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5.3 Rhythms Originating from
the Sinus Node
Key Terms

Cardiac output-the volume of blood the heart pumps
each minute

Stroke volume-the volume of blood ejected by one or
both ventricles with each contraction
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5.3 Rhythms originating from
the Sinus Node

Normal sinus rhythm

Sinus bradycardia

Sinus tachycardia

Sinus dysrhythmia

Sinus arrest
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5.3 Normal Sinus Rhythm Criteria

Originates at the SA node

Rhythm: Intervals between two P and two R waves occur
in a consistent pattern.
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5.3 Normal Sinus Rhythm Criteria

Rate: 60‒100 bpm (atrial and ventricular)

P wave morphology
 Uniform
 Upright
P
shape
deflection
wave appears prior to every QRS complex.
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5.3 Normal Sinus Rhythm Criteria (cont.)

PR interval
 0.12‒0.20
 Same

second
appearance, without variations
QRS duration and morphology
 0.06‒0.10
second
 Morphology
consistent, without variations
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5.3 Normal Sinus Rhythm:
What You Should Know

This is the normal, desired rhythm.

Rhythm is typical of patient with normal cardiac output.

If patient has returned to sinus rhythm from another
dysrhythmia:


Check for low cardiac output

If patient is pale or breathing rapidly, cardiac output may be low
If symptoms of low cardiac output are present, inform a
licensed practitioner.
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5.3 Apply Your Knowledge
What does normal cardiac output mean?
ANSWER: The heart is beating adequately,
pumping blood to the body’s vital organs to
maintain normal function.
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5.4 Sinus Bradycardia

Originates from the SA node

Atrial and ventricular rates are the same and are less
than 60 beats per minute.
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5.4 Sinus Bradycardia Criteria

Criteria for rhythm, P wave morphology, PR interval, and
QRS duration and morphology are the same as for
normal sinus rhythm.
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5.4 Sinus Bradycardia:
What You Should Know

Patient may or may not exhibit signs of low cardiac
output.

If symptoms of low cardiac output are present, inform a
licensed practitioner.

Rhythm may require medication or pacemaker.
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5.4 Apply Your Knowledge
What characteristic differentiates sinus bradycardia
from normal sinus rhythm?
ANSWER: The heart rate is less than 60 bpm.
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5.4 Apply Your Knowledge
What treatment may be required in a patient who has
sinus bradycardia?
ANSWER: Medication or pacemaker
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5.5 Sinus Tachycardia
Key Term

Palpitations-fast heartbeat sensation felt by the patient,
which may or may not be associated with complaints of
chest pain
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5.5 Sinus Tachycardia

Originates from the SA node.

Atrial and ventricular rates are the same and are
between 100 and 150 beats per minute.
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5.5 Sinus Tachycardia Criteria

Criteria for rhythm, P wave morphology, PR interval, and
QRS duration and morphology are the same as in sinus
rhythm and sinus bradycardia.
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5.5 Sinus Tachycardia:
How Patient Is Affected

Increased heart rate could be normal response to
recent exercise.

Sinus tachycardia can cause low cardiac output.
 Patient
may complain of heart fluttering or
palpitations.
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5.5 Sinus Tachycardia:
What You Should Know

Sinus tachycardia may be life-threatening in patients with
recent myocardial infarctions.

If symptoms of low cardiac output are present, inform a
licensed practitioner immediately.
 Medication
may be necessary.
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5.5 Apply Your Knowledge
What characteristic differentiates sinus tachycardia
from other sinus rhythms?
ANSWER: The heart rate is between 100 and
150 bpm.
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5.6 Sinus Dysrhythmia
Key Term

Vagal tone-a condition in which tension on the vagus
nerve causes variation in the heart rate
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5.6 Sinus Dysrhythmia

Originates from the SA node

Irregular rhythm is caused by pressure on the heart from
respiratory cycle and variations of vagal tone.

Overall rate is 60-100 beats per minute.
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5.6 Sinus Dysrhythmia: Criteria

Criteria for P wave morphology, PR interval, and
QRS duration and morphology are the same as in
sinus rhythm.
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5.6 Sinus Dysrhythmia:
What You Should Know

Patient usually shows no visible signs.

Severe rhythm irregularity may cause dizziness or
palpitations due to slow rate.

Place copy of rhythm strip in patient’s record for
documentation.
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5.6 Apply Your Knowledge
What characteristic distinguishes sinus dysrhythmia
from other sinus rhythms?
ANSWER: The rate is irregular; the P-P and R-R
intervals widen progressively, then narrow,
following vagal tone and the patient’s breathing
pattern.
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5.7 Sinus Arrest
Key Terms

Hypotension-a lower than normal blood pressure that
can cause reduction of blood flow to vital organs

Ischemia-occurs when there is a sudden loss or
reduction in blood supply (oxygen) to a region of the
heart tissue; this occurs due to the presence of
atherosclerotic plaque, blood clot, emboli, or even
vascular spasm (Prinzmetal’s angina)

Syncope- loss of consciousness (fainting)

Asystole-when no rhythm or electrical current is
traveling through the cardiac conduction system
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5.7 Sinus Arrest

SA node stops firing, causing a pause in electrical
activity.

During the pause, atrial and ventricular contractions
do not occur.
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5.7 Sinus Arrest: Criteria

Rhythm: Regular before and after sinus arrest period,
but considered irregular because of the pause.

Rate: Atrial and ventricular rates are the same, but rate
varies depending on electrical activity from SA node.

Criteria for P wave morphology, PR interval, and QRS
duration and morphology are the same as in sinus
rhythm.
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5.7 Sinus Arrest: Criteria (Cont.)

Length of pause
 Measure
 Multiply
 Note
number of small boxes by 0.04.
frequency of pauses.
 Pause

the R-R interval around the pause.
of 6 seconds or more is medical emergency.
Frequency of pauses
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5.7 Apply Your Knowledge
A condition in which the SA node stops firing, causing
a pause in electrical activity, is known as:
ANSWER: Sinus arrest
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Chapter 5 Summary

Evaluating an ECG requires basic knowledge of the
components of the rhythm.

The process of evaluating an ECG tracing includes
determining the rhythm, rate, P wave morphology, PR
interval, and QRS duration and morphology.

Rhythms that originate from the SA node include normal
sinus rhythm, sinus bradycardia, sinus tachycardia, sinus
dysrhythmia, and sinus arrest.
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Chapter 5 Summary (Cont’d)

In normal sinus rhythm, all characteristics are within
normal parameters.

In sinus bradycardia, all characteristics are within normal
parameters except heart rate, which is slower than 60
beats per minute.

In sinus tachycardia, all characteristics are within normal
parameters except heart rate, which is between 100 and
150 beats per minute.
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Chapter 5 Summary (Cont’d)

In sinus dysrhythmia, the rate is irregular due to the
influence of vagal tone.

In sinus arrest, activity in the SA node stops for short
periods, causing contractions to stop; except during the
pauses, the patient may be in normal sinus rhythm or
may have another dysrhythmia.

Sinus arrest is considered a medical emergency if the
pause lasts for 6 seconds or more.
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