Cardiac Arrhythmias & 12 Lead ECG Interpretation Module for 23 Continuing Education Credits ...

222 Pages·2015·24.4 MB·English

Cardiac Arrhythmias
&
12 Lead ECG Interpretation Module
for 23 Continuing Education Credits
Cardiac Arrhythmias
12 Lead Electrocardiography
Electrical Management of Arrhythmias
Carol Jacobson RN, MN
Karen Marzlin DNP, RN, CCNS, CCRN-CMC, CHFN
Cynthia Webner DNP, RN, CCNS, CCRN-CMC, CHFN
Complete this module and return the posttest to receive 23 continuing education credits.
Cardiac Arrhythmias & 12 Lead ECG
Interpretation Module
for 23 Continuing Education Credits

Cardiac Arrhythmias
12 Lead Electrocardiography
Electrical Management of Arrhythmias

Carol Jacobson RN, MN
Karen Marzlin DNP, RN, CCNS, CCRN-CMC, CHFN
Cynthia Webner DNP, RN, CCNS, CCRN-CMC, CHFN

Published by Cardiovascular Nursing Education Associates
July 2014
Instructions for Obtaining CE Certificate

One CE certificate comes free of additional charges for the purchaser of this module. Additional
users can obtain CE credit by completing the posttest and paying a fee of $1 per CE credit. The fee
for this Arrhythmias & 12 Lead ECG module is $23.

Instructions for original purchaser:

1. Complete the posttest answer sheet that came with your module.

2. Scan the answer sheet and email to: [email protected]

OR

3. Mail answer sheet to: CNEA
3324 SW 172nd St.
Burien, WA 98166

4. Please allow 2 weeks for delivery of CE certificate.

Instructions for additional users of this module:

1. Email [email protected] to obtain an answer sheet for each additional user. Each
additional answer sheet will have an individual ID number.

2. Complete the posttest answer sheet.

3. Return answer sheet with check for $23 to:
CNEA
3324 SW 172nd St.
Burien, WA 98166

OR

4. Scan the answer sheet and email to: [email protected] and use the Send Money feature
in Paypal to send the fee of $23 to [email protected].

5. Please allow 2 weeks for delivery of CE certificate.

This independent learning module is provided by
Cardiovascular Nursing Education Associates
www.cardionursing.com

Provider approved by the California Board of Registered Nursing,
Provider Number 15714 for 23 contact hours
Cardiac Arrhythmias and 12 Lead Electrocardiography Module Objectives

After completing this independent learning module the learner will be able to:

1. Name the parts of the cardiac conduction system and state their function.
2. Describe normal impulse initiation and conduction through the heart.
3. Name the waves of the cardiac cycle and state their origin.
4. Define the PR interval, QRS width, and QT interval and state their normal values.
5. List 5 steps of rhythm interpretation.
6. Identify the following rhythms from ECG strips:
a. Sinus: normal sinus rhythm, sinus bradycardia, sinus tachycardia, sinus arrhythmia, sinus
pause/arrest
b. Atrial: premature atrial complexes (PAC), wandering atrial pacemaker, multifocal atrial
tachycardia, atrial tachycardia, atrial flutter, atrial fibrillation
c. Supraventricular tachycardias: AV nodal reentry, AV reentry using an accessory pathway
d. Junctional: junctional rhythm, accelerated junctional rhythm
e. Ventricular: premature ventricular complex (PVC), ventricular escape beats,
idioventricular rhythm, accelerated ventricular rhythm, monomorphic ventricular
tachycardia, polymorphic ventricular tachycardia, torsades de pointes, ventricular
fibrillation
f. AV blocks: 1st degree, 2nd degree (type I and type II), high grade, 3rd degree
g. Asystole
h. Right and left bundle branch block
7. State the clinical significance of bradyarrhythmias and tachyarrhythmias and discuss
management.
8. State hemodynamic consequences of atrial fibrillation and discuss management for ventricular
rate control and for conversion to sinus rhythm.
9. Discuss QRS morphology criteria, AV dissociation, and fusion or capture beats in the differential
diagnosis of wide QRS tachycardias.
10. State common arrhythmias that occur in patients who have an accessory pathway.
11. Discuss electrode placement and lead selection for best practice in bedside arrhythmia
monitoring using a 5-wire and a 3-wire monitoring system.
12. Discuss the use of the Lewis lead and atrial electrograms as alternative monitoring leads for
arrhythmia recognition.
13. Describe normal and abnormal P waves, QRS complexes, ST segments, T waves, U waves, and
QT intervals on the 12 lead ECG.
14. State which leads of a 12 lead ECG face the anterior, inferior, and lateral walls of the heart.
15. Calculate the QRS axis using lead I and lead aVF on the 12 lead ECG.
16. Recognize left anterior and left posterior fascicular block on the 12 lead ECG.
17. Identify signs of atrial and ventricular chamber enlargement on the 12 lead ECG.
18. Identify signs of ventricular preexcitation on the 12 lead ECG.
19. State the indicative and the reciprocal changes of myocardial ischemia, injury, and necrosis.
20. Identify the following ST elevation myocardial infarctions on the 12 lead ECG: anterior, inferior,
lateral, right ventricular.
21. Identify signs of posterior wall MI on the 12 lead ECG.
22. Discuss diagnosis of myocardial infarction in the presence of right and left bundle branch blocks.
23. Identify myocardial ischemia and non-ST elevation MI on the 12 lead ECG.
24. Recognize signs of Wolff-Parkinson-White syndrome, Brugada syndrome, and long QT
syndromes on the 12 lead ECG.
25. Describe normal single chamber and dual chamber pacemaker function.
26. Identify loss of capture and loss of sensing on single and dual chamber pacemaker rhythm strips.
27. Describe cardiac resynchronization therapy and discuss its use in managing heart failure.
28. Discuss how right ventricular pacing contributes to the development of heart failure and atrial
fibrillation and describe pacing modes used to minimize unnecessary right ventricular pacing.
29. State the indications for implantable defibrillator (ICD) insertion.
30. Describe arrhythmia detection functions and treatment therapies in ICDs.
31. State the arrhythmias that can be treated with radiofrequency catheter ablation.
32. Discuss post-procedure care of patients receiving permanent pacemaker or ICD implants.
CARDIAC ARRHYTHMIAS

BASICS OF RHYTHM INTERPRETATION

The Cardiac Conduction System

Sinus Node (SA Node) – small group of cells in the high right atrium that functions as the normal

pacemaker of the heart because it has the fastest rate of automaticity (60-100 times per minute).

Atrioventricular (AV) Node – small group of cells low in the right atrium near tricuspid valve. The

AV node has three major functions:

 It slows conduction of the impulse from the atria to the ventricles to allow time for atrial
contribution to ventricular filling (atrial kick).

 Junctional cells surrounding the AV node have automaticity at a rate of 40-60 beats per minute, so
it can function as a backup pacemaker in case the sinus node fails.

 It screens out rapid atrial impulses to protect the ventricles from dangerously fast rates.

His Bundle– short bundle of fibers at the bottom of the AV node leading to the bundle branches.

Bundle Branches – bundles of fibers located along the septum that carry the impulse into the right

and left ventricles. The right bundle branch travels along the right side of the septum and carries the
impulse into the right ventricle. The left bundle branch has two main divisions, the anterior fascicle and
the posterior fascicle, which carry the impulse into the large left ventricle.

Purkinje Fibers – hair-like fibers that spread out from the bundle branches along the endocardial

surface of both ventricles and rapidly carry the impulse to ventricular muscle cells.

Figure 5.1 illustrates the cardiac conduction system.
Figure 5.1: Cardiac conduction system
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Origin and Spread of the Electrical Impulse in the Heart

The impulse originates in the SA node (because it has the fastest rate of automaticity) and spreads
through both atria simultaneously. It is delayed for a fraction of a second in the AV node so the atria
have time to contract and contribute to ventricular filling before the ventricles contract. As the impulse
leaves the AV node, it picks up speed and conducts rapidly down both bundle branches into the
ventricles and through the very rapid conducting Purkinje fibers to ventricular myocardium. The first
part of the ventricles to depolarize is the septum in a left to right direction, then both ventricles
depolarize simultaneously, from endocardium to epicardium. Since the left ventricle is the largest and is
posterior to the right ventricle, the main direction of depolarization through the ventricles is downward,
leftward, and posterior.

Origin of the ECG Waves and Intervals

P Wave – atrial depolarization as the impulse travels through the atria. Sinus node activity is not

recorded because the SA node is too small. P waves may be upright, biphasic, or inverted.

PR Interval – AV conduction time, or the time it takes the impulse to travel through the atria, through

the AV node, and down to where the ventricles begin to depolarize. Most of the length of the PR interval
is delay in the AV node.

 Measure from beginning of P wave to beginning of QRS.
 Normal = .12-.20 sec.

QRS Complex – ventricular depolarization as the impulse travels through both ventricles. The QRS

width represents intraventricular conduction time.

 Q wave = first negative deflection from baseline

 R wave = positive deflection from baseline

 S wave = negative deflection following an R wave

 Measure from beginning of Q or R wave to end of complex

 Normal = .04-.10 sec.
T Wave – ventricular repolarization as ventricles return to resting electrical state. May be upright,

biphasic, or inverted.

ST Segment – early repolarization phase that extends from end
of QRS to beginning of T wave. The ST segment should be at
the isoelectric line (baseline). ST segment elevation or
depression can represent myocardial injury or ischemia.

QT Interval – represents the sum of ventricular depolarization
and repolarization and is measured from the beginning of the
QRS to the end of the T wave. The QT interval varies with heart
rate: at fast rates the QT shortens; at slow rates it lengthens. The
QT interval should not exceed half the preceding R-R interval at
normal heart rates. Bazett’s formula for correcting QT interval
is: measured QT (in seconds) divided by the square root of the R
-R interval (measured in seconds).

Figure 5.2 shows the waves and intervals of the cardiac cycle.

Figure 5.2: Waves and intervals
of cardiac cycle.
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Steps in Rhythm Interpretation

Regularity

 Regular = equal distance between R waves

 Irregular = varying distances between R waves

Rate (Atrial and Ventricular)

 Count number of R-R intervals (or P-P intervals for atrial rate) in a 6-second strip and multiply by 10
(best method for irregular rhythms).

5 R-R intervals x 10 = rate of 50 beats per minute

 Count number of large boxes between R waves and divide into 300:
# boxes Rate # boxes Rate
1 300 6 50
2 150 7 43
3 100 8 37
4 75 9 33
5 60 10 30
R-R interval = 4 big boxes = rate of 75 beats per minute

P Waves

 Presence, shape, similarity to each other, relationship to QRS complexes

PR Interval

 Measure from beginning of P to beginning of QRS.
 Normal = .12 -.20 sec.

QRS Width

 Measure from beginning to end of QRS.
 Normal = .04 -.10 sec.
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Measurement of the ECG

ECG Paper

The horizontal axis measures time. ECG paper usually moves at
a speed of 25 mm/sec. At that speed, these are standard
intervals on ECG paper (see Figure 5.3):

 One tiny box = .04 sec. (40 msec)

 One large box (5 tiny boxes) = .20 sec. (200 msec)

 Vertical lines at top edge of paper are 3 seconds apart.
 There are 300 large boxes in a one-minute strip of paper. Time

 There are 1,500 tiny boxes in a one-minute strip of paper.
Figure 5.3: Standard intervals on

ECG paper
Practice Strips:

On the following strips, label P waves, QRS complexes, T waves. Measure the heart rate, PR interval,
QRS width, and QT interval.
Rate ______ PRI ______ QRS ______ QT ______

Rate ______ PRI ______ QRS ______ QT ______

Rate ______ PRI ______ QRS ______ QT ______

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Answers :

1. HR = 75, PR = .12, QRS = .08, QT = .40

2. HR = 50, PR = .12, QRS = .06, QT = .64

3. HR = 120, PR = .16, QRS = .08, QT = .32

If your answers varied a little that is OK. Were you “in the ballpark?”

RHYTHMS ORIGINATING IN THE SINUS NODE
T he sinus node is the normal pacemaker of the heart because it has the fastest rate of automaticity of all
potential pacemaker sites. The sinus node usually fires regularly at a rate between 60 and 100 beats/
minute.
Normal Sinus Rhythm
Regularity: regular

Rate: 60-100 beats/minute

P waves: precede every QRS and are consistent in shape

PR interval: .12-.20 sec

QRS complex: .04-.10 sec

Conduction: The impulse originates in the sinus node and conducts through both atria. Conduction is
slowed through the AV node, then accelerates through the His bundle, right and left bundle branches,
and both ventricles simultaneously.

Two examples of normal sinus rhythm follow:

Sinus Tachycardia

Regularity: regular.

Rate: faster than 100 beats/minute; not usually > 150 beats/minute, unless associated with exercise.
When rate is > 150 beats/minute, consider other rhythms (i.e. atrial tachycardia). Rate increases and
decreases gradually, not suddenly. The maximum rate for the sinus node is 220 minus years of age
(Olgin & Zipes, 2011; Surawicz & Knilans, 2008).

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