Download SECTION 2

41: Assisting With Cardiac Monitoring
Objectives
(1 of 2)
1. To gain an understanding of basic terminology and
techniques of cardiac monitoring.
2. To give you the knowledge and tools you need to
assist the advanced provider with the use and
implementation of an ECG.
3. To better understand the basic anatomy and
physiology of the heart.
Objectives (2 of 2)
4. Identify the components of basic cardiac
arrhythmias.
5. Evaluate the rate and rhythm of a patient’s
cardiovascular system, and become familiar with
the normal ECG.
6. Familiarize yourself with and apply 4-lead
electrodes and identify placements for the 12-lead
systems.
*All of the objectives in this chapter are noncurriculum
objectives.
Cardiac Monitoring
• Use of 12-lead ECGs in the prehospital setting is
becoming the norm.
• Early identification of AMIs allows hospitals to be
prepared.
• The EMT-B should know how to place electrodes
and leads.
Electrical Conduction System (1 of 2)
• A network of specialized tissue in the heart
• Conducts electrical current throughout the heart
• The flow of electrical current causes contractions
that produce pumping of blood.
Electrical Conduction System (2 of 2)
The Process of
Electrical Conduction
• Electrical conduction occurs through a pathway of
special cells.
• SA node: the heart’s main pacemaker
– Paces at a rate of 60–100 beats/min
– Average of 70 beats/min
Electrodes and Waves
Electrodes pick up electrical activity of the heart.
The ECG Complex
• One complex represents one beat in the heart.
• Complex consists of P, QRS, and T waves.
ECG Paper
• Each small box on the
paper represents 0.04
seconds.
• Five small boxes in
larger box represents
0.20 seconds.
• Five large boxes equal
1 second.
Normal Sinus Rhythm
• Consistent P waves
• Consistent P-R interval
• 60–100 beats/min
Formation of the ECG (1 of 4)
Formation of the ECG (2 of 4)
Formation of the ECG (3 of 4)
Formation of the ECG (4 of 4)
Sinus Bradycardia
• Consistent P waves
• Consistent P-R interval
• Less than 60 beats/min
Sinus Tachycardia
• Consistent P waves
• Consistent P-R interval
• More than 100 beats/min
Ventricular Tachycardia
• Three or more ventricular complexes
in a row
• More than 100 beats/min
Ventricular Fibrillation
• Rapid, completely disorganized rhythm
• Deadly arrhythmia that requires immediate
treatment
Asystole
• Complete absence of electrical cardiac activity
• Patient is clinically dead.
• Decision to terminate resuscitation efforts depends
on local protocol.
Cardiac Monitors
• May be 3-, 4-, or 12-lead system
• Compact, light, portable
• Many monitors now combine functions beyond
ECG.
12-Lead ECG
• Used to identify possible myocardial ischemia
• Studies show 12-lead acquisition takes little extra
time.
• Early identification of acute ischemia and accurate
identification of arrhythmias
Lead Placement
• EMT-Bs can help in efficient cardiac monitoring by
placing electrodes.
• Electrodes can be placed while ALS provider
prepares other parts of call.
4-Lead Placement
• Four leads are called
limb leads.
• Leads must be placed
at least 10 cm from
heart.
12-Lead Placement
• Limbs leads placed at
least 10 cm from heart.
• Chest leads must be
placed exactly.
Lead
Location
View
V1
4th intercostal space, right sternal border
Ventricular septum
V2
4th intercostal space, left sternal border
Ventricular septum
V3
Between V2 and V4
Anterior wall of left ventricle
V4
5th intercostal space, midclavicular line
Anterior wall of left ventricle
V5
Lateral to V4 at anterior axillary line
Lateral wall of left ventricle
V6
Lateral to V5 at midaxillary line
Lateral wall of left ventricle
Troubleshooting
• Clean skin.
• Use benzoin.
• Shave hair.
Review
1. Which of the following represents the normal path of
electrical conduction through the heart?
A. SA node, AV node, internodal pathways, Purkinje
system, bundle branches, bundle of His
B. Internodal pathways, SA node, AV node, bundle
branches, bundle of His, Purkinje system
C. AV node, internodal pathways, bundle of His, SA
node, Purkinje system, bundle branches
D. SA node, internodal pathways, AV node, bundle of
His, bundle branches, Purkinje system
Review
Answer: D
Rationale: The cardiac electrical conduction system
creates an electrical impulse and transmits it
through the heart, through a specific pathway, in an
organized manner. The normal path of electrical
conduction is the SA node, the internodal
pathways, the AV node, the bundle of His, the left
and right bundle branches, and the Purkinje
system.
Review
1. Which of the following represents the normal path of electrical
conduction through the heart?
A. SA node, AV node, internodal pathways, Purkinje system,
bundle branches, bundle of His
Rationale: The intranodal pathways come before the AV node.
B. Internodal pathways, SA node, AV node, bundle branches,
bundle of His, Purkinje system
Rationale: The SA node is before the intranodal pathways.
C. AV node, internodal pathways, bundle of His, SA node, Purkinje
system, bundle branches
Rationale: The SA node is always first.
D. SA node, internodal pathways, AV node, bundle of His, bundle
branches, Purkinje system
Rationale: Correct answer
Review
2. In the adult, the sinoatrial (SA) node normally
paces the heart at a rate of:
A. 40 to 60 per minute.
B. 60 to 100 per minute.
C. 80 to 110 per minute.
D. 100 to 120 per minute.
Review
Answer: B
Rationale: For the heart to pump, one of the parts of
the electrical conduction system must act as the
pacemaker—the area that generates an electrical
impulse. In a normally functioning heart, the
sinoatrial (SA) node performs this function. In the
adult, the SA node paces at a rate of 60 to 100 per
minute, hence the normal adult heart rate of 60 to
100 beats/min.
Review
2. In the adult, the sinoatrial (SA) node normally paces the heart
at a rate of:
A. 40 to 60 per minute.
Rationale: This would be bradycardia.
B. 60 to 100 per minute.
Rationale: Correct answer
C. 80 to 110 per minute.
Rationale: The normal rate is 60 to 100 beats/min.
D. 100 to 120 per minute.
Rationale: This would be tachycardia.
Review
3. The positive (red) lead should be placed on the
patient’s:
A. left leg.
B. left arm.
C. right leg.
D. right arm.
Review
Answer: A
Rationale: Correct lead placement is important in
order to obtain an accurate ECG tracing. When
using a 4-lead configuration, the negative (white)
lead is placed on the right arm, the ground (black)
lead is placed on the left arm, the positive (red)
lead is placed on the left leg, and the green lead is
placed on the right leg.
Review
3. The positive (red) lead should be placed on the patient’s:
A. left leg.
Rationale: Correct answer
B. left arm.
Rationale: The left arm needs the black lead. Remember smoke
is over fire.
C. right leg.
Rationale: The green lead is in a 4-lead configuration.
D. right arm.
Rationale: The right arm needs the white lead. Remember, white
on the right.
Review
4. After applying the ECG leads to a patient with
chest pain, you look at the cardiac monitor and
note that all of the complexes are inverted. What
has MOST likely happened?
A. The patient is experiencing a dysrhythmia
B. The ground lead is not properly connected
C. The patient is moving around excessively
D. The positive and negative leads are switched
Review
Answer: D
Rationale: An electrical impulse that is moving away
from a negative pole and toward a positive pole will
produce a positive deflection on the ECG tracing. If
all of the complexes and waveforms are inverted
on the ECG, the positive and negative leads are
most likely switched. The electrical impulse is still
moving toward a positive pole; you are simply
viewing the opposite.
Review
4. After applying the ECG leads to a patient with chest pain, you
look at the cardiac monitor and note that all of the
complexes are inverted. What has MOST likely happened?
A. The patient is experiencing a dysrhythmia
Rationale: Dysrhythmias appear as unusual looking wave forms
— not inverted.
B. The ground lead is not properly connected
Rationale: The ground will not give a reading.
C. The patient is moving around excessively
Rationale: Movement appears as artifact.
D. The positive and negative leads are switched
Rationale: Correct answer
Review
5. The QRS complex represents:
A. atrial depolarization.
B. ventricular contraction.
C. atrial repolarization.
D. ventricular depolarization.
Review
Answer: D
Rationale: The QRS complex represents ventricular
depolarization, or discharge of electricity.
Remember that the electrical impulse stimulates
contraction of the heart. Contraction of the
ventricles is evidenced by the presence of a pulse.
The P wave represents atrial depolarization.
Review
5. The QRS complex represents:
A. atrial depolarization.
Rationale: This is represented by the p wave.
B. ventricular contraction.
Rationale: This is represented by the presence of a pulse.
C. atrial repolarization.
Rationale: Atrial repolarization occurs during the ventricular
depolarization and does not show up as a wave form.
D. ventricular depolarization.
Rationale: Correct answer
Review
6. You are looking at an ECG tracing in which every
waveform is upright and looks the same and the
rate is 70/min. What is the name of the rhythm in
which the SA node is acting as the pacemaker?
A. Junctional escape
B. Sinus tachycardia
C. Normal sinus rhythm
D. Atrial tachycardia
Review
Answer: C
Rationale: Normal sinus rhythm is characterized by
waveforms and complexes that are all upright and
look the same, and a rate between 60 and 100 per
minute. Sinus tachycardia has all the components
of a normal sinus rhythm; however, the rate is
greater than 100 per minute.
Review
6. You are looking at an ECG tracing in which every waveform is
upright and looks the same and the rate is 70/min. What is
the name of the rhythm in which the SA node is acting as
the pacemaker?
A. Junctional escape
Rationale: This occurs when the SA node fails and the AV node
takes over, but the rate is 40 to 60 beats/min.
B. Sinus tachycardia
Rationale: It would look the same, but the rate is greater than
100 beats/min.
C. Normal sinus rhythm
Rationale: Correct answer
D. Atrial tachycardia
Rationale: Multifocal atrial tachycardia presents with a rate
greater than 100 beats/min.
Review
7. When looking at the ECG paper, how much time is
represented by 5 big boxes?
A. 1 second
B. 0.20 seconds
C. 0.04 seconds
D. 0.40 seconds
Review
Answer: A
Rationale: The smallest box represents 0.04 seconds
(four-hundredths of a second). It takes five of the
smallest boxes to represent 0.20 seconds (twotenths of a second), which is equal to one big box.
Five big boxes represents 1 second (0.20 × 5 = 1).
Review
7. When looking at the ECG paper, how much time is
represented by 5 big boxes?
A. 1 second
Rationale: Correct answer
B. 0.20 seconds
Rationale: This would be five little boxes.
C. 0.04 seconds
Rationale: This would be one small box.
D. 0.40 seconds
Rationale: This would be ten little boxes or two big boxes.
Review
8. Ventricular tachycardia is characterized by:
A. Narrow QRS complexes and a rate between 140
and 200 per minute.
B. QRS complexes greater than 0.11 seconds and a
rate greater than 100 per minute.
C. Inverted P waves, wide QRS complexes, and rate
between 100 and 120 per minute.
D. QRS complexes greater than 0.06 seconds and a
rate greater than 200 per minute.
Review
Answer: B
Rationale: The normal width of the QRS complex is
0.06 to 0.11 seconds. If the QRS width is greater
than 0.11 seconds, it is considered wide.
Ventricular tachycardia (V-tach) is characterized by
wide (> 0.11 seconds) QRS complexes and a rate
greater than 100 per minute. A rate between 140
and 200 per minute is common.
Review (1 of 2)
8. Ventricular tachycardia is characterized by:
A. Narrow QRS complexes and a rate between 140 and 200
per minute.
Rationale: The rate is greater than 100 beats/min but the QRS
is greater than 0.11 seconds.
B. QRS complexes greater than 0.11 seconds and a rate
greater than 100 per minute.
Rationale: Correct answer
Review (2 of 2)
8. Ventricular tachycardia is characterized by:
C. Inverted P waves, wide QRS complexes, and rate between
100 and 120 per minute.
Rationale: There are no P waves with ventricular tachycardia.
D. QRS complexes greater than 0.06 seconds and a rate
greater than 200 per minute.
Rationale: The complexes must be greater than 0.11 seconds.
Review
9. Which of the following terms MOST accurately
describes ventricular fibrillation?
A. Chaotic
B. Irregular
C. Slow
D. Wide
Review
Answer: A
Rationale: Ventricular fibrillation (V-fib) is a rapid,
completely disorganized ventricular dysrhythmia
with chaotic characteristics. V-fib is characterized
by undulations of varying shapes and sizes with no
specific pattern and no identifiable P waves, QRS
complexes, or T waves.
Review
9. Which of the following terms MOST accurately describes
ventricular fibrillation?
A. Chaotic
Rationale: Correct answer
B. Irregular
Rationale: There are no organized activity or identifiable waves.
C. Slow
Rationale: Ventricular fibrillation is not slow.
D. Wide
Rationale: Wave forms are chaotic and can be narrow, wide, or
both.
Review
10. The 12-lead electrocardiogram (ECG) is used to:
A. identify and stop a myocardial infarction.
B. reperfuse areas of ischemic myocardium.
C. artificially increase the heart’s pacemaker rate.
D. identify areas of myocardial ischemia or injury.
Review
Answer: D
Rationale: The purpose of the 12-lead ECG—whether
used in the hospital or prehospital setting—is to
identify areas of myocardial ischemia, injury, or
infarction. By doing this, the most appropriate
treatment can be given. The ECG cannot stop a
heart attack, nor can it reperfuse areas of ischemic
myocardium; fibrinolytic medications (clot-busters)
and invasive procedures (eg, cardiac
catheterization) are used for this.
Review
10. The 12-lead electrocardiogram (ECG) is used to:
A. identify and stop a myocardial infarction.
Rationale: An ECG can identify if an acute MI is taking place,
but it can not stop an MI from occuring.
B. reperfuse areas of ischemic myocardium.
Rationale: This can only be accomplished with medications.
C. artificially increase the heart’s pacemaker rate.
Rationale: A 12-lead does not produce energy that can act as a
pacemaker.
D. identify areas of myocardial ischemia or injury.
Rationale: Correct answer