topics

10/20/25

ALGrawany

18 Chapter 2

any other EKG, nor would we be able to compare several EKGs taken on one person at

different times. Similarly, if all EKG machines ran at different ,

we would not have a constant “norm” for comparing individual EKGs.

16. Since all graph paper has markings, we must learn what

these markings mean so that we will be able to interpret the EKG tracings that are

superimposed on the graph paper. Look at the sample graph paper shown in Figure 6.

You will notice that there are lines going up and down (vertical) and lines going across

(horizontal). Also notice that every fifth line is heavier than the other lighter lines. How

many light lines are there between two heavy ones?

17. The lines on the graph paper can help determine both the direction and the magnitude of deflections. When all electrical forces are equal, there is neither an upright nor a

downward deflection; an isoelectric line is created. If the electrical force is toward the positive electrode, the stylus will draw an wave. If the force travels primarily toward the negative electrode, the wave will be .

If no current is present, or if positive and negative forces are equal, the graph paper will

show a line, called an isoelectric line.

Voltage Measurements

18. It is the strength of the current, or its voltage, that will determine the magnitude of

the deflection. If it is a very strong positive wave, it will create a high spike above the

isoelectric line. If it is a very weak positive charge, the deflection will go only slightly

above the isoelectric line in response to the amplitude of the charge. Therefore, the

height of the deflection will indicate the of the electrical charge

that produced the deflection. The same principle holds for negative deflections: the

stronger the charge, the deeper the wave will go below the isoelectric line.

19. Since voltage produces either an upright or a downward deflection on the EKG,

the magnitude of the current can be measured by comparing the height of the spike

against the horizontal lines on the graph paper (Figure 7). Voltage can be measured

quantitatively (in millivolts), but you need not concern yourself with these figures for basic arrhythmia interpretation. On the graph paper, the horizontal lines

measure .

speeds

standardized

four

upright

downward (inverted)

straight

voltage (or amplitude)

voltage

Figure 6 Sample EKG Graph Paper

The three vertical lines in the upper margin are measures of time standard to all EKG graph paper. The distance between

two “tic” marks is 3 seconds; thus, this strip measures 6 seconds in duration.

Waves and Measurements 19

Time Measurements

20. The second, and more important, thing that the graph paper can provide is a determination of time. The vertical lines can tell you just how much time it took for the

electrical current within the heart to travel from one area to another. The vertical lines

are the most important markings for simple arrhythmia identification because they

can tell you about the it takes for the current to travel about

within the heart.

21. The standard rate at which the EKG machine runs paper past the stylus is 25 millimeters per second. At this standard rate, we know that it takes 0.20 second to get from

one heavy vertical line to the next heavy vertical line. Therefore, if a deflection began on

one heavy line and ended on the next heavy line, we would know that the electrical current within the heart that caused the deflection lasted second.

This is an essential figure to remember because it is the basis for many of the rates, rules,

and normal values you will learn in later sections. The distance (in time) between two

heavy vertical lines on the EKG graph paper is second.

22. If the time frame between two heavy vertical lines is 0.20 second and there are five

small squares within this same area, it would follow that each of these small squares is

equivalent to one-fifth of 0.20 second, or 0.04 second each. The distance (in time) between

two light vertical lines, or across one small square, is second.

23. You now can see that graph paper can be used to measure

and .

Cardiac Cycle

24. As you know, the heart has four chambers. The upper two are the atria and the

lower two are the ventricles. In most cases the atria function as a team and contract

together, and the ventricles also operate as a single unit. So for nearly all of our discussions we will consider the atria as a single unit and the ventricles as a single unit, even

though we realize that they are actually the separate chambers

that make up the heart.

time

0.20

0.04

voltage

time

four

Figure 7 Using Graph Paper Markings to Measure Voltage and Time

VOLTAGE is measured by comparing

the height of the spike to the horizontal

lines on the graph paper.

.20 sec .04 sec

TIME is measured by comparing

the markings to the vertical lines

on the graph paper.

ALGrawany

20 Chapter 2

25. The upper chambers of the heart are called the ,

and they will be considered a single . Likewise,

the are the lower chambers and will be considered

a unit.

26. In the normal heart, blood enters both atria simultaneously and then is forced into

both ventricles simultaneously as the atria contract. All of this is coordinated so that

the atria fill while the ventricles contract, and when the ventricles are filling, the atria

contract. In considering a cardiac cycle, we would expect the to

contract first.

27. Before the atria can contract, they must first receive an electrical stimulus to initiate

the muscle cells response. In fact, for any myocardial cell to contract, it must first receive

an stimulus. We know that the cells

have the ability to initiate an impulse. And we know that the same electrical impulses

that eventually produce contraction of the heart can also produce deflections on the

EKG graph paper. It is by careful scrutiny of these wave patterns that we are able

to determine the activity that is present in the heart, and

sometimes we can even speculate on the type of activity

that could be expected. But to make these determinations, we must first investigate

the patterns produced by the heart’s electrical activity.

28. During each phase of the cardiac electrical cycle, a distinct pattern is produced on

the EKG paper. By learning to recognize these wave patterns

and the cardiac activity each represents, we can study the relationships between the

different areas of the heart and begin to understand what is taking place within the

heart at any given time. For each pacemaker impulse, the electrical flow travels down

the pathways, depolarizing the atria and then the ventricles

as it goes. Following this, the pattern begins again with another impulse from the pacemaker. Each cardiac cycle includes all of the electrical activity that would normally be

expected to produce a single heart beat. The cardiac cycle begins with the initiating

impulse from the pacemaker and encompasses all phases until the ventricles are repolarized. On the EKG graph paper, the cardiac cycle includes all of the wave patterns

produced by electrical activity, beginning with the impulse

and including ventricular .

29. On the EKG, each of these phases is displayed by a specific wave pattern.

Figure 8 shows a series of cardiac electrical cycles that makes up a typical EKG

rhythm strip. In Figure 9, a single cardiac cycle has been enlarged so that we can see

each of the individual patterns more closely. A single cardiac cycle is expected to produce one beat. An EKG rhythm strip is composed of more than

one cycle.

atria

unit

ventricles

single

atria

electrical; electrical

electrical

mechanical

wave

graph

conduction

pacemaker

repolarization

heart

cardiac

Figure 8 A Typical EKG Rhythm Strip

In a healthy heart, each cardiac cycle would be expected to correlate with the patient’s

individual pulse beats.

PULSE PULSE

Q S

PULSE PULSE PULSE

Waves and Measurements 21

Waves, Intervals, Segments

30. In labeling the activity on the graph paper, the deflections above or below the

isoelectric line are called waves. In a single cardiac cycle there are five prominent

waves, and each is labeled with a letter. Look at Figure 9 and find the P, Q, R, S, and

T waves. An interval refers to the area between (and possibly including) waves, and

a segment identifies a straight line or area of electrical inactivity between waves.

Find the PR segment and the PR interval (PRI) on Figure 9. Does the PR segment

include any waves? Does the PR interval include any

waves?

P Wave and PRI

31. The first wave you see on the cardiac cycle is the P wave. Locate it in Figure 9.

The P wave starts with the first deflection from the isoelectric line. The

wave is indicative of atrial depolarization.

32. When you see a P wave on the EKG, does that mean that the atria contracted?

33. As the impulse leaves the atria and travels to the AV node, it encounters a slight

delay. The tissues of the node do not conduct impulses as fast as other cardiac electrical tissues. This means that the wave of depolarization will take a longer time to get

through the AV node than it would in other parts of the heart. On the EKG, this is

translated into a short period of electrical inactivity called the PR segment. This is the

straight line between the P wave and the next wave. Locate the PR segment on Figure 9.

The PR segment is indicative of the delay in the .

No.

Yes. The PRI includes the P wave

and the PR segment.

No, not necessarily. It means the

atria were depolarized, but it is

possible that the muscle cells did

not contract in response. It is

impossible to tell whether or not

the atria contracted simply by

looking at the EKG.

AV node

Figure 9 The EKG Complex

Segment

QRS

PRI

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22 Chapter 2

34. The AV node is the area of the heart with the slowest conduction speed. That

is, the conductive tissues of the sinus node, the atria, and the ventricles all conduct

impulses faster than the AV node does. This is necessary to allow time for atrial contraction and complete filling of the ventricles. On the EKG tracing, this delay at the

AV is seen as a short isoelectric segment between

the wave and the next wave. This segment is called

the segment.

35. If you wished to refer to all of the electrical activity in the heart before the impulse

reached the ventricles, you would look at the PR interval. This includes both the P wave

and the PR segment. The P wave displays depolarization, and

the PR segment is caused by the in the AV node. Therefore, the

PR includes all atrial and nodal activity.

QRS Complex

36. By definition, the PR interval begins at the first sign of the P wave and ends at the

first deflection of the next wave, called the QRS complex. The PR interval includes

all and all activity but does not

include ventricular activity.

37. Ventricular depolarization is shown on the EKG by a large complex of three waves:

the Q, the R, and the S. Collectively, these are called the QRS complex. This complex

is significantly larger than the P wave because ventricular depolarization involves

a greater muscle mass than atrial depolarization. The QRS complex starts with the

Q wave. The Q wave is defined as the first negative deflection following the P wave

but before the R wave. Locate the Q wave on Figure 9. The Q wave flows immediately into the R wave, which is the first positive deflection following the P wave. Next

comes the S wave, which is defined as the second negative deflection following the

P wave, or the first negative deflection after the R wave. Collectively, the QRS complex

signifies depolarization.

38. The QRS complex is larger and more complicated than the P wave, primarily

because it involves a larger part of the heart. Very often, the QRS complex looks different from the complex shown in Figure 9, but it is still called the QRS complex. Several

different configurations of the QRS complex are shown in Figure 10. Regardless of

appearance, these still indicate depolarization of the .

39. After the ventricles depolarize, they begin their repolarization phase, which results

in another wave on the EKG. The T wave is indicative of ventricular repolarization. The

atria also repolarize, but their repolarization is not significant enough to show up on the

EKG, so you do not see an atrial equivalent of the T wave. Ventricular repolarization

is much more prominent and is seen on the EKG as the wave.

40. Now that you have learned the definitions of all of the waves on the EKG and what

each one means, turn to the Practice Strips at the end of this chapter and label each wave

on each practice strip in Part I (strips 2.1–2.12). Be sure to recall what each wave means

as you mark it on the EKG. When you finish marking the waves, go back and identify

the PR interval, the PR segment, and the QRS complex for each strip.

41. To interpret arrhythmias you must be able to measure the duration of both the

PR interval and the QRS complex. The grid markings on the graph paper are used

to determine just how many seconds it took for the impulse to create those intervals.

node

atrial

delay

interval

atrial; nodal

ventricular

ventricles

Practice Strips (Part I)

Waves and Measurements 23

To make these measurements, you will use EKG calipers. Let’s measure the PRI first.

You can use Figure 9 for practice. Place one point of the calipers on the very first deflection that marks the beginning of the P wave. Then place the other point of the calipers

on the final point of the PR interval, which you will recall is actually the very beginning

of the complex. Make sure you don’t have any part of the

QRS complex included in your measurement. Now, count the number of small boxes

within your caliper points, and multiply that number by second, which is the amount of time allotted to each small box. What is your measurement? second.

42. For the PR interval to be considered normal, it must be between 0.12 and 0.20

second. If it is less than 0.12 second, it is considered a short PRI, and if it is greater

than 0.20 second, it is said to be prolonged. The P wave itself does not contribute to

a long PRI; it is actually the delay in the AV node, or the PR ,

that varies according to how long the node held the impulse before transmitting it.

The normal PRI should be second; a long PRI would suggest

a in the .

43. Is the PRI measurement you determined for the complex shown in Figure 9

considered to be normal?

QRS

0.04

0.16

segment

0.12–0.20

delay; AV node

Yes. It is 0.16 second, which

is within the normal range of

0.12–0.20 second.

Figure 10 Various QRS Configurations

Q S Q S

R R

R R R

Q Q S S

24 Chapter 2

ST Segment and T Wave

44. You measure the QRS complex in the same way as the PR interval. Just make sure

your caliper points are exactly where the definitions tell you they should be. Starting

with the Q wave, measure where the deflection first begins to go below the isoelectric

line. This part usually isn’t so hard. The S wave is more difficult. Between the S wave

and the T wave is a section called the ST segment. Although segments are supposed

to be straight lines, the ST segment often gets caught up in the transition between

the QRS complex and the T wave and is very rarely a cut-and-dried configuration.

So you must look for some clue that indicates to you where the S wave stops and

the wave begins. If such an indication is present, it will usually

be a very small notch or other movement suggesting an alteration of electrical flow. Use

this point as the outside measurement of the QRS complex. Include in your measurement the entire S wave, but don’t let it overlap into the ST segment or the T wave. The

QRS measurement should include the beginning of the wave

and the end of the wave.

Measurements

45. For practice, measure the QRS complex shown in Figure 9. What is your measurement? second.

46. People very rarely agree on what a normal time range is for the QRS measurement. It is usually considered to be between 0.06 and 0.11 second. For simplicity, we’ll

define the normal QRS complex measurement as anything less than 0.12 second. This

means that the ventricles took a normal amount of time to depolarize if they did it in

less than second.

47. Is the QRS measurement shown in Figure 9 considered to be normal?

Practice

48. Now that you know how to measure PRIs and QRSs, the rest is up to you. All it takes

is practice, practice, and more practice. It is particularly helpful if you can get someone

to check your measurements in the beginning so you don’t develop bad habits. You can

start by measuring PRI and QRS intervals on each of the strips in Part II of the Practice

Strips at the end of the chapter (strips 2.13–2.30). The answer key shows you where the

calipers were placed to obtain the answers, so if your measurements differ from those

given, look to see where the complex was measured to arrive at the answer shown.

Artifact, Interference

49. The complexes on an EKG tracing are created by electrical activity within the heart.

But it is possible for things other than cardiac activity to interfere with the tracing you

are trying to analyze. Some common causes of interference, or artifact, are:

• Muscle tremors, shivering

• Patient movement

0.08

0.12

Yes. It measures 0.08 second,

which is less than 0.12 second.

Practice Strips (Part II)

Waves and Measurements 25

• Loose electrodes

• The effect of other electrical equipment in the room (called 60-cycle interference)

Each of these situations can cause on the EKG tracing, which

may interfere with your interpretation of the arrhythmia. When such external factors

cause deflections on an EKG strip, those deflections are considered to be artifact and are

important to recognize because they can with your interpretation of the arrhythmia.

50. Figure 11 shows you what each of these types of interference can look like on

an EKG tracing. As you can see, can often confuse you and

lead you to believe that the deflection was caused by cardiac activity when it was

not. As you practice identifying the P waves and QRS complexes, you will become

more and more familiar with the normal configurations of these wave forms

and will be more apt to distinguish them from artifact. When trying to determine whether or not a deflection was caused by artifact, you should try to identify

the waves and complexes of

the underlying rhythm and compare these configurations with the questionable

deflections.

artifact

interfere

artifact

P; QRS

Figure 11 Types of Interference

Muscle Tremors

Patient Movement

26 Chapter 2

Refractory Periods

51. Let’s go back to electrophysiology to make one final point. Since depolarization

takes place when the electrical charges begin their wave of movement by exchanging

places across the cell membrane, it would follow that this process cannot take place

unless the charges are in their original position. This means that the cell cannot depolarize until the process is complete. For depolarization to take

place, repolarization must be .

52. When the charges are depolarized and have not yet returned to their polarized

state, the cell is said to be electrically “refractory” because it cannot yet accept another

impulse. If a cell is , it cannot accept an impulse because it isn’t

yet .

53. On the EKG, the refractory period of the ventricles is when they are depolarizing or repolarizing. Thus, the QRS and the T wave on the EKG would be considered

the period of the cardiac cycle, since it signifies a period when

the heart would be unable to respond to an impulse.

54. Sometimes an electrical impulse will try to discharge the cell before repolarization is fully complete. In most cases nothing will happen because the cells aren’t back

to their original position and therefore can’t . But once in a

while, if the stimulus is strong enough, an impulse might find several of the charges

repolarization

complete

refractory

repolarized

refractory

depolarize

Figure 11 (Continued)

Loose Electrode

60-Cycle Interference

Waves and Measurements 27

in the right position and thus discharge them before the rest of the cell is ready. This

results in abnormal depolarization and hence is an undesirable occurrence. This

premature depolarization can occur only if most of the cell charges are back to

their positions. Thus, there is a small part of the refractory period that is not absolutely refractory. This small section is called the

relative refractory period because some of the charges are polarized and thus can

be if the impulse is strong enough.

55. So there are actually two refractory periods: an absolute refractory period, when

no impulse can cause depolarization, and a relative refractory period, when a strong

impulse can cause a premature, abnormal discharge. The refractory period would allow depolarization if the impulse were strong enough, while

the refractory period would not allow any response at all.

56. Figure 12 shows you where these refractory periods are located on the EKG. Notice

that while all of the T wave is considered a refractory period, the downslope of the

T wave is only relatively refractory. This means that if a strong impulse fell on the

downslope of the T wave, it could result in ventricular . This

fact will become more important to you when we begin to look at specific arrhythmias.

57. You now have all of the information you need to begin analyzing EKG rhythm

strips. You can identify all of the different waves that make up a cardiac cycle, and you

can measure the PRI and the QRS complex. You are now ready to turn to Chapter 3

and learn how to apply this knowledge as you develop a technique for analyzing EKG

rhythm strips.

original

depolarized

relative

absolute

depolarization

Figure 12 Refractory Periods

Absolute Refractory Period Relative Refractory Period

12 Chapter 1

Questions Referenced Frames Answers

4. How do you assess electrical activity in the heart? 5, 6, 7, 8, 10 Analyze the EKG.

5. Arrhythmias are manifestations of which type of

cardiac activity?

9, 10, 11, 12 electrical

6. What happens when the positive and negative electrical charges exchange places across the cell membrane

of a cardiac cell?

13, 14, 15, 16, 17 It initiates the flow of electrical

current.

7. Explain the polarized state. 14, 15, 16, 17, 19, 21 when electrical charges are balanced and in a state of readiness

for discharge

8. Explain depolarization. 16, 17, 20, 22 the discharge of electrical energy

that accompanies the transfer of

electrical charges across the cell

membrane

9. Is depolarization the same as contraction? 17 No, depolarization is an electrical phenomenon. Contraction is

mechanical and is expected to

follow depolarization.

10. What is repolarization? 18, 20, 21 the return of the electrical charges

to their original state of readiness

11. List the areas of the conduction system in the order in

which the impulses travel through the heart.

23, 24, 25, 26, 27, 29 1. SA Node

2. Intraatrial and Internodal

Pathways

3. AV Node

4. Bundle of His

5. Bundle Branches

6. Purkinje Fibers

12. Which site is normally the pacemaker of the heart,

and why?

24, 33, 34, 43, 44 The SA node, because it has the

fastest inherent rate.

13. Give the inherent rates for each of the following sites:

Sinus Node

AV Junction

Ventricles

30, 31, 32, 38, 39,

40, 41, 42

60–100 times per minute

40–60 times per minute

20–40 times per minute

14. What process is responsible for a site speeding up

and overriding a higher site, thus taking over as

pacemaker?

33, 34, 35, 45, 46 irritability

15. What mechanism is in play if a lower site takes over

responsibility for the pacemaking function following

failure of a higher site?

33, 36, 37, 47, 48 escape

16. Which nervous system has two branches that control

the activities of the heart?

49 autonomic

17. Name the two branches of the nervous system identified in the preceding question.

49, 52 sympathetic; parasympathetic

18. List three things that will happen to the heart if the

sympathetic branch is stimulated.

49, 50, 51, 53 increased rate, increased AV conduction, increased irritability

19. List three things that will happen to the heart if the

parasympathetic branch is stimulated.

49, 50, 51, 58 decreased rate, decreased AV

conduction, decreased irritability

Electrophysiology 13

Questions Referenced Frames Answers

20. What part of the heart does the sympathetic branch

innervate?

49, 54 the atria and ventricles

21. What part of the heart does the parasympathetic

branch innervate?

49, 54 only the atria

22. What happens if one branch is blocked? 50, 51, 55, 56, 57, 58 The influence of the opposing

branch will control the heart.

ALGrawany

Overview

IN THIS CHAPTER, you will learn how cardiac electrical activity is transferred to graph paper

so that it can be seen and analyzed for arrhythmia interpretation. You will learn about the equipment used for monitoring, and you will learn all the specifics of the graph paper upon which EKG

images are typically drawn. You will learn the difference between a single cardiac cycle and an

EKG rhythm strip. You will find out about the different components that make up a single cardiac

cycle on the EKG, and you will learn to identify each component and know what it suggests is

happening within the heart.

Introduction

1. In Chapter 1, you learned that arrhythmias are manifestations of the heart’s

activity. And you learned that the study of arrhythmias is

called . To study arrhythmias, we have to transform the electrical activity into a format that can be seen.

electrical

electrocardiography

Waves and

Measurements

Waves and Measurements 15

Electrodes

2. The electrical patterns of the heart can be picked up from the surface of the skin by

attaching an electrode to the skin and connecting it to a machine that will display the

electrical activity on graph paper. An electrode is a small item attached to the patient’s

and then connected by wire to a machine capable of inscribing

the patterns on graph .

3. The electrical activity is displayed best if you can ensure good contact between the

electrode and the skin. This can be done in several ways:

• By abrading the skin slightly

• By removing any obstacles, such as dirt or hair

• By using a contact medium, such as saline or a commercial gel

All of these measures are intended to improve between the

electrode and the skin.

4. An placed on the skin can pick up electrical activity from

within the heart and display it on graph paper using an EKG machine. To ensure a

good tracing, you must provide good contact between the and

the .

5. Contact between the skin and the electrode can be improved by lightly

the skin, by wiping off excess , or

possibly by excess hair. An important way to ensure good

contact is to use some type of contact medium, such as or a

commercial .

6. When an EKG machine is turned on but isn’t yet connected to the patient’s electrodes, the writing point (stylus) of the machine will simply produce a straight line

on the paper. This line is called the isoelectric line because all of the electrical forces

are equal; no current is flowing. Once the machine is connected to the patient’s electrodes, the needle will move up or down on the paper (above or below the isoelectric

line) in response to the electrical forces it receives. If no current is flowing, or if the

forces balance each other out, the graph paper will show a .

If the machine receives a flow of electricity, the needle will move

or in response to the current.

Rule of Electrical Flow

7. A very basic rule of electrocardiography refers to the flow of electricity through

the heart and out to the electrodes. This rule states that if the electricity flows toward

the positive electrode, the patterns produced on the graph paper will be upright. The

converse of this rule is also true: if the electricity flows away from the positive electrode (or toward the negative electrode), the pattern will be a downward deflection.

If the flow of electricity is toward the positive electrode, the machine will produce

an deflection on the graph paper (Figure 4).

8. Look at Figure 4. If the electrical flow is toward the negative electrode, would you

expect the graph paper to show a positive or a negative deflection?

9. If the graph paper shows a positive deflection, you would assume that the electrical

activity is flowing primarily toward the electrode.

skin

paper

contact

electrode

skin; electrode

abrading; dirt

shaving

saline

gel

straight line

down

upright

negative

positive ALGrawany

16 Chapter 2

10. If the deflection on the graph paper is negative, you would assume that the

electrical flow is toward the electrode and away from

the electrode.

11. Thus, we can determine the direction of electrical flow by the type of deflection

made on the EKG paper. But to draw any conclusions based on this information,

we must be sure that the electrodes are always in the same place on the patient so

that the information is not misleading. The placement of the electrodes on patients is

always to avoid confusion or misinterpretation of information.

Monitoring Leads

12. The positioning of electrodes for monitoring the EKG allows you to see a single view

of the heart’s electrical pattern. By rearranging electrodes, many such views are possible.

(This concept can be compared to a camera that can photograph the heart from many

angles, each one giving additional depth to the overall visualization of the heart itself.)

Each view of the heart is called a lead. Leads can be changed by a knob on the machine

that diverts the flow of electricity through different electrodes. For sophisticated EKG

interpretation, many leads are inspected to visualize the entire heart. However, for basic

arrhythmia interpretation, it is necessary to monitor only a single lead. A monitoring

lead shows only one of the heart’s electrical activity.

negative

positive

the same (standardized)

view

Figure 4 Rule of Electrical Flow

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Waves and Measurements 17

13. When monitoring a patient for patterns of electrical activity such as arrhythmias,

a lead is selected to give a clear picture of the basic wave forms. Single leads that give

good pictures of the basic waves are called monitoring leads because they are used

to patterns such as arrhythmias. The first widely used monitoring lead was Lead II, but now it is common to use other leads as well, especially

variations of the chest leads (such as MCL1). The modified chest leads often give a

better view of the heart’s atrial activity, which is sometimes needed to differentiate

complex arrhythmias. The examples in this book all happen to be Lead II. This does

not mean that Lead II is better than MCL1, nor does it mean that you must always

use Lead II for monitoring arrhythmias. The same patterns apply whether you view

them in Lead II, MCL1, or any other monitoring lead. Regardless of which lead is used,

the remain the same, so it doesn’t matter which lead you use

to learn basic arrhythmias. Just because the examples in this book are Lead II doesn’t

mean that it is the only monitoring lead, or even the best. You will encounter other

monitoring leads as you learn more about EKGs, but for now you can assume that the

information in this book refers to unless otherwise specified.

14. Figure 5 shows the placement of electrodes to monitor Lead II. Note that the positive electrode is at the apex of the heart, and the negative electrode is below the right

clavicle. The third electrode is a ground electrode and does not measure electrical flow

in this lead. Since the pacemaker is normally in the and the

electrical current flows toward the ventricles, the primary thrust of electrical flow in

the heart will be toward the positive electrode in Lead II. Thus, the primary deflections

in Lead II will be .

Graph Paper

15. All EKG interpretation relies on the use of standardized, uniform graph paper.

The size of the graph on the paper and the speed at which the paper travels through

the EKG machine are both kept constant; all EKG paper is the same, and all EKG

machines operate at the same speed. By keeping the paper and the speed standardized, we can look at the patterns created by an individual’s heart activity and compare them to what has been established as “normal” activity. If the graph paper was

not , we would not be able to compare one person’s EKG to

monitor

patterns

Lead II

SA node

upright

standardized

Figure 5 Electrode Placement for Monitoring Lead II

–

Electrophysiology 7

This information would give you a clue that if an rate was between 20 and 40 beats per

minute (bpm), the electrical impulse that stimulated the rhythm probably originated

in the . If the rate was between 40 and 60 bpm, the impulse

probably came from the , and it most likely came from the

if the rate was between 60 and 100 bpm.

32. These rates are often helpful clues to be used in interpreting arrhythmias, but

they can be misleading unless they are understood to be mere guidelines and not

concrete .

33. Generally speaking, the fastest inherent rate will become the pacemaker of the

heart and override all other stimuli. The inherent rate of the SA node is the fastest and therefore keeps the heart at a rate between and

bpm. Thus, the normal is “sinus” in origin. The SA

node is the normal pacemaker for the heart because the rate of the SA node is

than the other conduction sites.

Irritability and Escape

34. If, however, a site becomes irritable and begins to discharge impulses at a fasterthan-normal rate, it can override the SA node and take over the pacemaking function

for the heart. If the SA node is discharging at a rate of 72 and the AV junction begins to

fire at a rate of 95, the will become the pacemaker.

35. This mechanism of an irritable site speeding up and taking over as pacemaker is

called irritability. It is usually an undesirable occurrence, since it overrides the normal pacemaker and causes the heart to beat faster than it otherwise would. Irritability

occurs when a site below the SA node and takes over the

pacemaking role.

36. Something very different happens if the normal pacemaker slows down for

some reason. If the SA node drops below its inherent rate, or if it fails entirely,

the site with the next highest inherent rate will usually take over the pacemaking

role. The next highest site is within the , so that site would

become the pacemaker if the SA node should fail. This mechanism is called escape

and is a safety feature that is built into the heart to protect it in case the normal

fails.

37. Escape mechanism, unlike irritability, is a safety feature to protect the heart.

Would you expect an irritable rhythm to be faster or slower than an escape rhythm?

38. The inherent rate of different areas of the conduction system refers to the rate at

which that site .

39. The SA node has an inherent rate of to

bpm. This means that the normal rate of the heart will usually

be within that range.

40. If the rate of an EKG is between 40 and 60, the impulse for that rhythm is probably

coming from the .

41. What is the inherent rate of the ventricular conductive tissues?

ventricle

AV junction

SA node

rules

100

faster

AV junction

speeds up

AV junction

pacemaker

faster

initiates impulses

100

AV junction

20–40 bpm

ALGrawany

8 Chapter 1

42. Because these rates cannot be relied upon as firm rules, they should be viewed

only as . If they are used as clues, the rates will be helpful in

interpreting arrhythmias, but if they are considered inflexible, they will simply confuse

the learner.

43. A rule regarding the pacemaker function of the heart states that the site that initiates impulses at the rate will usually become the pacemaker.

44. In the normal heart, the initiates impulses at the fastest

rate and therefore becomes the .

45. If the AV junction or the ventricle became irritable, either could become the pacemaker if it were able to accelerate until it

46. The process described in the preceding frame is called .

47. If the SA node failed as pacemaker, or if its rate dropped below its normal range,

the would probably take over as pacemaker.

48. The safety mechanism described in the preceding frame is called .

Nervous System Influence

49. In addition to the inherent rates, the heart can be influenced by the autonomic

nervous system. The two branches of this nervous system oppose each other and thus

keep the heart in a relative state of balance. The sympathetic branch influences both the

atria (i.e., the SA node, the intraatrial and internodal pathways, and the AV junction)

and the ventricles. If the sympathetic branch is stimulated, it will cause both the atria

and ventricles to react in these ways:

• Increased rate

• Increased conduction through the AV node

• Increased irritability

The parasympathetic branch has the opposite effects, but it influences only the atria; it has

little or no effect on the ventricles. While stimulation of the parasympathetic branch

causes the atria to slow down, as well as decreasing irritability and slowing conduction

through the AV node, stimulation of the sympathetic branch would cause what three

effects on the atria and ventricles?

These nervous influences are outlined in Figure 3.

50. If the vagus nerve (which is part of the parasympathetic branch) is stimulated,

you would expect the heart rate to . On the other hand, if both

the sympathetic and the parasympathetic branches are balanced, the heart rate would

remain normal. What would you expect if you blocked the normal influence of the

vagus nerve?

guidelines

fastest

SA node

pacemaker

became faster than the SA node

irritability

AV junction

escape

increased heart rate;

increased AV conduction;

increased irritability

heart rate would decrease

You would get a response similar

to stimulation of the sympathetic

branch: heart rate would increase

as well as irritability and AV

conduction.

Electrophysiology 9

51. If a patient had a heart rate that was too slow, you might try to speed it up by giving

a drug that would either stimulate the sympathetic branch or

52. The two branches of the autonomic nervous system that influence heart rate are the

branch and the branch.

53. Which of these branches, when stimulated, will produce an increase in heart rate,

AV conduction, and irritability?

54. One of the branches has control over the atria and the ventricles, while the

other influences only the atria. Which one affects both the atria and the ventricles?

55. If both branches are exerting equal influence over the heart, what will happen to

the rates?

56. What will happen if one of the branches of the autonomic nervous system is

blocked?

block the parasympathetic branch

sympathetic

parasympathetic

sympathetic

They will stay within the ranges of

the normal inherent rates.

The heart will respond to the influence of the opposing branch.

Figure 3 Innervation of the Heart by the Autonomic Nervous System

SYMPATHETIC

• Affects the atria

and the ventricles

• Increases:

—heart rate

—conduction

—irritability

PARASYMPATHETIC

• Affects only the atria

• Decreases:

—heart rate

—conduction

—irritability

ALGrawany

10 Chapter 1

57. Using the reasoning described in the preceding frame, explain what would happen

to the heart rate if the parasympathetic branch were blocked.

58. The vagus nerve is part of the branch of the autonomic

nervous system. Therefore, stimulation of the vagus nerve would cause the heart rate

to , and blocking of the vagus nerve would cause the heart

rate to .

59. All of this discussion is about activity and does not yet connect with mechanical activity. In order to discuss the heart contracting and producing

a pulse, we must connect the electrical activity with activity.

60. If the muscle cells receive an electrical stimulus, they will respond to it by contracting. Sometimes, however, the muscle itself contract because it is injured or

chemically imbalanced. In these cases, the electrical component is all right, but the

component needs attention. In such a patient you would

expect to find the essentially normal, but the would be absent

or diminished.

61. The opposite situation is more common and is the reason you are reading this book.

This is when the heart muscle is able to respond but the electrical activity is erratic.

Sometimes the electrical stimuli will make the ventricles contract before the atria do,

or maybe there will just be too many electrical stimuli, so that the heart is not able to

respond effectively to any of them. And sometimes the electrical impulse will discharge

before the ventricles have time to fill with blood, thereby causing the ventricles to contract early, and eject insufficient blood for an adequate pulse. In all of these conditions,

the erratic electrical activity will be seen on the as an .

It would increase.

parasympathetic

decrease

increase

electrical

mechanical

pulse

arrhythmia

KEY POINTS

■ The heart has two types of cells:

• Electrical cells, which initiate and conduct impulses

• Mechanical cells, which contract in response to

stimulation

■ Arrhythmias are graphic representations of electrical

activity.

■ Electrical activity precedes mechanical activity.

■ Electrical activity can occur without mechanical response

(pulse).

■ If the electrical impulse stimulates the mechanical cells

to contract, the heart is expected to contract and pump

blood, thus producing a pulse.

■ Polarization is when the electrical charges are balanced

and ready for discharge.

■ Depolarization is the discharge of energy that accompanies the transfer of electrical charges across the cell

membrane.

■ Repolarization is the return of electrical charges to their

original state of readiness.

■ Depolarization differs from contraction in that depolarization is an electrical phenomenon, whereas contraction

is mechanical and is expected to follow depolarization.

■ As shown in Figure 2, electrical flow in the normal heart

originates in the SA node, then travels via the intraatrial

and internodal pathways to the AV node, then through

the Bundle of His to the left and right bundle branches,

and finally to the Purkinje fibers, where the mechanical

cells are stimulated.

■ The inherent rates of the conduction system are as

follows:

SA Node 60–100 bpm

AV Junction 40–60 bpm

Ventricles 20–40 bpm

■ The site with the fastest rate will be the pacemaker.

■ The SA node is the normal pacemaker of the heart.

■ Irritability is when a site speeds up and takes over as

pacemaker.

■ Escape is when the normal pacemaker slows down or

fails and a lower site assumes pacemaking responsibility.

■ The influence of the autonomic nervous system can also

affect the heart:

• Sympathetic stimulation causes:

Increased heart rate

Increased AV conduction

Increased irritability

• Parasympathetic stimulation causes:

Decreased heart rate

Decreased AV conduction

Decreased irritability

■ The sympathetic branch influences both the atria (i.e., the

SA node, the intraatrial and internodal pathways, and

the AV junction) and the ventricles; the parasympathetic

branch influences only the atria.

■ If one branch of the autonomic nervous system is

blocked, the effects of the opposing branch will prevail.

SELF-TEST

Directions: Complete this self-evaluation of the information you have learned from this chapter. If your answers are

all correct and you feel comfortable with your understanding of the material, proceed to the next chapter. However,

if you miss any of the questions, you should review the

referenced frames before proceeding. If you feel unsure of

any of the underlying principles, invest the time now to go

back over the entire chapter. Do not proceed with the next

chapter until you are very comfortable with the material

in this chapter.

Questions Referenced Frames Answers

1. Name the two types of cardiac cells and tell what type

of activity each is responsible for.

1, 2, 3, 4 electrical: conduction;

mechanical: contraction

2. How do these two types of cells work together to produce cardiac activity?

1, 2, 3, 4 Electrical cells stimulate

muscle cells to contract.

3. What physical signs are used to reflect the mechanical

function of the heart?

5, 6, 7, 8 pulses, blood pressure, and other

perfusion parameters

ALGrawany

7. You might occasionally encounter a situation in which the heart muscle is not able

to contract in response to the electrical stimulus. In this case, you could have electrical

activity but no response. If you had a functioning electrical

system but a failing heart muscle, you could very likely see a viable tracing, but the

patient might not have palpable or blood pressure.

8. To evaluate a patient’s cardiac function, you must assess the mechanical function

by examining and and evaluate the

electrical function by analyzing the tracing.

9. An EKG tracing is designed to give a graphic display of the electrical activity in the

heart. The pattern displayed on the EKG is called the heart rhythm. Technically, the word

arrhythmia refers to an abnormal heart rhythm, although the term is also used more

generally to refer to all cardiac electrical patterns. The term dysrhythmia is synonymous

with arrhythmia; both are used to refer to patterns of activity

within the heart. All three terms are used loosely (and often interchangeably) to refer

to the heart’s activity.

10. An EKG can’t tell you about the heart’s mechanical activity—you have to assess the

patient’s pulse and blood pressure to determine that. But an EKG can tell you about the

activity, which can be a vital part of your patient assessment.

This data is provided in the form of recognizable patterns, called arrhythmias. Arrhythmias are graphic representations of the heart’s activity.

11. To understand and interpret arrhythmias, it is necessary to understand the

electrical activity that is occurring within the heart. This is because all arrhythmias

are actually graphic displays of electrical activity. The term electrocardiography is

given to the study of arrhythmias because arrhythmias are manifestations of

activity within the heart.

12. To help you understand and eventually be able to interpret individual arrhythmia

patterns, you might want to know a little bit about the electrical processes that take

place in the heart to produce the arrhythmia. To do this, we’ll consider the electrical

mechanical

electrical

contracting

electrical

electrical; mechanical

electrical

pulses

blood pressure

mechanical

pulses

pulses; blood pressure

EKG

electrical

Electrophysiology 3

component independent of the mechanical component. For now, we are discussing only

the activity in the heart.

Impulse Formation

13. The electrical (pacemaking) cells in the heart are distinctive in that they can create their own electrical impulses without an outside stimulus. On the cellular level,

they create a change in electrical balance in the cell, causing an electrical current to

form. This ability of cardiac cells to initiate electrical impulses on their own is called

automaticity. Automaticity is the ability of cardiac cells to create their own impulses

an outside stimulus. It is not the whole heart that creates

the charge, it’s the individual pacemaking within the heart’s

electrical system.

14. The creation of an electrical impulse is a function of electrolytes within cardiac

cells, or more accurately, the way those electrolytes move across cell walls. The primary

electrolytes involved in creating the heart’s electrical stimulus are sodium (Na+) and

potassium (K+). Sodium and are the primary electrolytes that

allow the heart to initiate impulses. Both carry a positive electrical charge, but they

are not present in equal quantities. The sodium “outweighs” the potassium, making

the potassium relatively negative to the sodium. It is the difference in that potential that

allows electrolytes to move through cell membranes. Movement of electrolytes through

the cell is what creates the electrical impulse.

electrical

without

cells

potassium

membrane

Figure 1 The Sodium Pump: Chemical Basis for Impulse Formation

+ +

+ – – +

– –

Na+

K+

POLARIZATION

(the ready state)

DEPOLARIZATION

(the discharge state)

REPOLARIZATION

(the recovery state)

ALGrawany

4 Chapter 1

15. In a resting cell, the potassium is on the inside and the sodium is on the outside.

The outside of the cell is positive, and the inside is relatively negative. The charges are

balanced so no electricity flows (Figure 1A). As the sodium enters the cell, and the

potassium leaves, an electrical charge is created (Figure 1B). The sodium then returns

to the outside of the cell and the potassium goes back in (Figure 1C). This phenomenon is commonly referred to as the sodium pump. The cycle is repeated for every

heartbeat. The term refers to the movement of electrolytes

in and out of the cell to create an electrical stimulus. When the positive and negative

charges are , no electricity flows. When the positive and negative charges exchange places, an impulse is formed.

16. For an electrical current to form, there must be a difference between the electrical

charges. In the resting cell, the charges are balanced; hence no electricity flows. This is called

the polarized state; the cell charges are and ready for action.

Polarization refers to a ready state where the electrical charges are

and no current flows. When the cell is in its ready state, it is said

to be . When the charges exchange places in the cell, the result

is formation of an current. Once the pacemaker cells provide

the stimulation, the flow is passed from cell to cell along the conduction pathways until

the cardiac cells are stimulated to contract.

Polarization and Depolarization

17. The polarized state is considered a “ready for action” phase. When the two chemical charges (sodium and potassium) trade places, the electricity flows in a wave-like

motion throughout the heart. This wave of electrical flow is called depolarization and

is how the electrical stimulus travels through the heart (Figure 1B). Polarization refers

to the “ready” state, while refers to the process of electrical

discharge and flow of electrical activity. Depolarization does not mean that the heart

muscle contracted. Depolarization is an function. Contraction

is , and is expected to follow depolarization.

18. After the cell depolarizes, the positive and negative electrical charges will again

return to their original positions around the cell, and the cell will prepare itself for

another discharge (Figure 1C). The process that follows depolarization, when the cell

charges are returning to their original state, is called repolarization. Repolarization

refers to the return of the electrical charges to their position.

Repolarization occurs depolarization.

19. If each of the positive charges on the outside of the cell is balanced by a negative

charge on the inside of the cell, the electrical charges will be balanced, and there will

be no movement of electricity. This state is called and can be

considered a “ready” state.

20. The wave of electrical activity that takes place when the electrical charges surrounding the cell trade places is called , and the return of the electrical

charges to their original state is called .

21. If polarization is considered the ready state, and is considered the discharge state, then would be considered the

recovery state.

22. Now let’s relate this cellular activity to what is actually happening in the heart. All

of the sequences described in the preceding frames are happening to single cells within

the heart, but they do it in a -like movement, resulting in the

entire heart responding electrically to the same stimuli.

sodium pump

balanced

electrical

balanced

electrical

polarized

electrical

muscle

depolarization

electrical

mechanical

original

after

polarization

depolarization

repolarization

depolarization

repolarization

wave

Electrophysiology 5

Conduction System

23. The electrical cells in the heart are all arranged in a system of pathways called

the conduction system. The physical layout of the conduction system is shown in

Figure 2. This information is an essential part of arrhythmia interpretation and should

therefore be memorized now. Normally, the electrical impulse originates in the SA

node and travels to the ventricles by way of the AV node. Look at Figure 2 and trace

a normal electrical impulse. Where would the impulse go after it left the AV node and

the Bundle of His?

24. In the normal heart, the first impulse that starts the flow of electrical current

through the heart comes from the SA node. The impulse travels through the atria by

way of the intraatrial pathways and to the AV node by way of the internodal pathways.

If you look microscopically at the cells along these pathways, you would not see any

physical difference between them and the cells in other areas of the atria, so researchers have questioned whether they actually exist. However, current electrophysiologic

studies support the concept that these pathways do exist, if only as a preferred route

by which impulses travel to the AV node. As it leaves the SA node, where does the

current go?

down the left and right bundle

branches and then to the Purkinje

fibers

down the internodal and intraatrial

pathways

Figure 2 Conduction System

ELECTRICAL CONDUCTION THROUGH THE HEART

Sinoatrial (SA) node

Internodal pathways

Right bundle branch

Purkinje fibers

Intraatrial pathway

Atrioventricular

(AV) junction

Bundle of His

Left bundle branch

ALGrawany

6 Chapter 1

25. The next area of conductive tissue along the conduction pathway is at the site

of the AV node. The AV node is unique in that it does have conductive tissue, but

it does not have any pacemaker cells like other areas of the conduction system.

The pacemaking cells are actually located at the junction between the AV node

and the atria, in an area called the AV junction. Thus, the term AV node can be

used when talking about conduction, but the term AV junction is more accurate

if you are referring to formation of impulses. Let this confuse you. It is simply an

explanation of what might otherwise appear to be indiscriminate use of the two

phrases. We will use the term AV node if talking only about ,

but if we’re specifically discussing pacemaking capabilities, we will call it the AV

26. After leaving the area of the AV node, the impulses go through the

to reach the right and left bundle branches. These branches

are located within the right and left ventricles, respectively.

27. At the terminal ends of the bundle branches, smaller fibers distribute the electrical

impulses to the muscle cells to stimulate contraction. These terminal fibers are called

fibers.

28. Are the muscle cells themselves part of the electrical conduction system?

29. Rearrange the following parts of the conduction system to place them in the actual

order of conduction:

(1) (a) Bundle of His

(2) (b) SA node

(3) (c) Purkinje fibers

(4) (d) left and right bundle branches

(5) (e) AV node

(6) (f) intraatrial pathways

Inherent Rates

30. Each of the three major areas of the conduction system has its own preferred rate,

called an inherent rate, at which it initiates impulses. An inherent rate means simply that each site has a rate range at which it usually produces impulses. A site can

exceed or fall below its inherent rate, indicating that these rates are not concrete rules.

But generally speaking, the sites will produce impulses at a rate within their own

rate ranges.

31. The inherent rate ranges of the major sites are as follows:

SA node 60–100 beats per minute

AV junction 40–60 beats per minute

Ventricles 20–40 beats per minute

conduction

junction

Bundle of His

Purkinje

No, they are made up of mechanical cells, not electrical cells.

1. b

2. f

3. e

4. a

5. d

6. c

inherent

8.1.1 Outline the physiologic mechanisms common

to ventricular pacemakers.

8.1.2 Describe the expected path of conduction for

an impulse originating in the ventricles.

8.1.3 Identify EKG features common to all

arrhythmias in the ventricular category.

8.2 Outline the identifying features specific to each of

the arrhythmias originating in the ventricles.

8.2.1 Describe Premature Ventricular Complexes,

including etiology, conduction, and resulting

EKG features (regularity, rate, P waves, PR

intervals, and QRS complexes).

8.2.2 Describe Ventricular Tachycardia, including

etiology, conduction, and resulting EKG

features (regularity, rate, P waves, PR

intervals, and QRS complexes).

8.2.3 Describe Ventricular Fibrillation, including

etiology, conduction, and resulting EKG

features (regularity, rate, P waves, PR

intervals, and QRS complexes).

8.2.4 Describe Idioventricular Rhythm, including

etiology, conduction, and resulting EKG

features (regularity, rate, P waves, PR

intervals, and QRS complexes).

8.2.5 Describe Asystole, including etiology,

conduction, and resulting EKG features

(regularity, rate, P waves, PR intervals, and

QRS complexes).

Section II: Practice Strips

Chapter 9 PRACTICE MAKES PERFECT

9 Identify basic cardiac arrhythmias as presented on

6-second rhythm strips.

9.1 Apply techniques learned in Chapters 1–8 to

analyze each of the rhythm strips in Chapter 9.

9.1.1 Use a methodical process to approach data

collection (regularity, rate, P waves, PR

intervals, and QRS complexes).

9.1.2 Analyze collected data and apply it to rules

of each arrhythmia to identify the presenting

arrhythmia.

Chapter 10 FINAL CHALLENGE

10 Test yourself on your ability to identify basic cardiac

arrhythmias as presented on 6-second rhythm strips.

10.1 Apply techniques learned in Chapters 1–8 to

analyze each of the rhythm strips in Chapter 10.

10.1.1 Use a methodical process to approach data

collection (regularity, rate, P waves, PR

intervals, and QRS complexes).

10.1.2 Analyze collected data and apply it to

rules of each arrhythmia to identify the

presenting arrhythmia.

10.2 Demonstrate your competency by approaching

all 100 strips in a self-test format, without

referring to outside resources.

ALGrawany

xvi Learning Objectives

Section III: Appendices

Appendix A CARDIAC ANATOMY AND

PHYSIOLOGY

A.1 Describe the heart’s location and structure.

A.2 Identify the four internal chambers of the heart.

A.3 Describe the heart walls and the pericardial sac.

A.3.1 Name the walls between the heart’s chambers.

A.3.2 Describe the three layers of the heart wall.

A.3.3 Differentiate between left and right heart

pumping functions.

A.3.4 Describe the pumping activity in a single

cardiac cycle.

A.4 Explain the heart’s valves.

A.4.1 Name the four valves.

A.4.2 Explain the valves’ role in the heart’s pumping

cycle.

A.5 Identify the four heart sounds.

A.5.1 Explain the first and second heart sounds.

A.5.2 Explain the third and fourth heart sounds.

A.5.3 Explain gallop rhythms.

A.5.4 Explain heart murmurs.

A.6 Explain systole and diastole.

A.6.1 Describe atrial diastole and systole.

A.6.2 Describe ventricular diastole and systole.

A.7 Explain coronary circulation.

A.7.1 State the purpose of coronary circulation.

A.7.2 Describe the functions of the coronary arteries,

cardiac veins, and coronary sinus.

A.8 Identify the heart’s surfaces.

Appendix B PATHOPHYSIOLOGY

AND CLINICAL IMPLICATIONS OF

ARRHYTHMIAS

B.1 Describe the clinical effects of arrhythmias.

B.1.1 Define cardiac output.

B.1.2 Give the formula for a calculated cardiac

output.

B.1.3 Name three categories of arrhythmia that can

interfere with cardiac output.

B.1.4 List eight symptoms of reduced cardiac output.

B.2 Explain the general principles of treating

arrhythmias.

B.2.1 Name additional measures that may be

needed to support perfusion.

B.2.2 Explain the role of the American Heart

Association in developing and maintaining

Advanced Cardiac Life Support

recommendations for treating arrhythmias.

B.3 Explain the significance of each of the 22 basic

arrhythmias in this book, and describe the clinical

picture of each.

Appendix C 12-LEAD

ELECTROCARDIOGRAPHY

C.1 Explain the advantage of a 12-lead EKG tracing.

C.2 State the fundamental rules of electrocardiography.

C.3 Explain leads and electrode placement.

C.3.1 Differentiate between bipolar and unipolar

leads.

C.3.2 Define monitoring lead.

C.3.3 Describe the placement of leads on the frontal

and horizontal planes.

C.4 Explain the vectors and axis of electrical flow

through the heart.

C.4.1 Define mean QRS axis.

C.4.2 Explain lead axes.

C.4.3 Explain the EKG features of R waves,

Q waves, S waves, QS waves, Intrinsicoid

Deflections, J Points, and QT Intervals.

C.4.4 Explain vector relationships.

C.4.5 Describe axis deviation and give the

significance of left and right axis deviation.

C.4.6 Describe a method for quickly estimating

QRS axis.

C.5 Describe the standardized format for a printed

12-lead EKG report.

C.5.1 Explain the importance of learning to

recognize normal in 12-lead EKGs.

C.6 State the limitations of 12-lead EKGs.

Appendix D BASIC 12-LEAD

INTERPRETATION

D.1 Explain interpreting myocardial damage on the

EKG.

D.1.1 Define ischemia.

D.1.2 Define myocardial infarction.

D.1.3 Describe EKG changes associated with

myocardial damage.

D.1.4 Describe the evolution of ischemic changes

(age of infarction).

D.1.5 State which leads identify damage on specific

surfaces of the heart.

D.2 Explain interpreting chamber enlargement on the

EKG.

D.2.1 State causes of chamber enlargement.

D.2.2 Describe the appearance of chamber

enlargement on the EKG.

Learning Objectives xvii

D.3 Explain interpreting bundle branch block on the

EKG.

D.3.1 Define bundle branch block.

D.3.2 Describe the appearance of bundle branch

block on the EKG.

D.3.3 Differentiate between right and left bundle

branch block on the EKG.

D.4 Explain interpreting other abnormalities on the EKG.

D.4.1 Describe the appearance of pericarditis on the

EKG.

D.4.2 Describe the appearance of digitalis toxicity on

the EKG.

D.4.3 Describe the appearance of hyperkalemia and

hypokalemia on the EKG.

D.4.4 Describe the appearance of hypercalcemia and

hypocalcemia on the EKG.

D.5 Explain the format for analyzing a 12-lead EKG.

D.5.1 Explain the importance of a methodical

approach to analysis.

D.5.2 Name the subjects that the summary analysis

of an EKG should address.

Appendix E PACEMAKERS

E.1 Describe pacemakers.

E.1.1 Explain the purpose of artificial pacemakers.

E.1.2 Define capture.

E.1.3 Name the three components of pacemakers.

E.2 Name the chambers of the heart that a pacemaker

may pace.

E.3 Describe a “smart” pacemaker.

E.4 Explain the two basic ways in which pacemakers can

initiate impulses.

E.4.1 Define triggered pacemaker.

E.4.2 Define inhibited pacemaker.

E.5 Explain the three-letter code system used to classify

pacemakers.

E.6 Explain assessment of pacemaker function.

E.6.1 Describe the appearance of pacemakers on the

EKG.

E.6.2 Describe the basic sequence of assessing

pacemaker function.

E.6.3 Name the information that can be revealed by

the relationship between pacemaker spikes

and the patient’s complexes.

E.7 Name and describe four common types of

pacemaker malfunctions.

E.8 Explain how pacemaker malfunction is treated.

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Overview

IN THIS CHAPTER, you’ll learn how cardiac arrhythmias reflect what is actually happening

electrically in the heart. You will explore the uses and limitations of cardiac arrhythmia monitoring.

You will learn how cardiac impulses are formed and how the heart’s electrical system conducts

electrical impulses throughout the heart. You will also learn how the nervous system can influence

the rate at which the heart forms electrical impulses.

Electrical vs. Mechanical Function

1. The human heart is intended to pump blood to the rest of the body. This process has

two distinct components:

• The electrical impulse that tells the heart to beat

• The mechanical beating of the heart in response to the electrical stimulation, resulting in pumping of blood

To perform these two functions, the heart has two distinct types of cells. There are

electrical (conductive) cells, which initiate electrical activity and conduct it through

the heart, and there are mechanical (contracting) cells, which respond to the electrical

stimulus and contract to pump blood. After the cells initiate

Electrophysiology

electrical

ALGrawany

2 Chapter 1

the impulse and conduct it through the heart, the cells respond

by contracting and pumping blood.

2. The heart will respond with contraction only if it is stimulated by electrical activity. Thus,

you cannot have a mechanical response if there is no stimulus.

3. After the electrical cells have discharged their stimuli, the mechanical cells are

expected to respond by .

4. Without stimulus, the mechanical cells can’t be expected

to contract.

5. Since it is not practical to see inside a living patient’s heart, we must rely on

external evidence to evaluate the status of both electrical and mechanical cardiac function. For a complete assessment of cardiac status, we must evaluate both

and functions.

6. As part of our assessment of mechanical function, we use blood pressure, pulses,

and other perfusion parameters to determine whether the heart is pumping adequately. We must also look for external evidence to evaluate the heart’s electrical activity. The best way to do this is to monitor the electrocardiogram (EKG). An

EKG tracing is used to evaluate the activity of the heart,

while the mechanical activity is evaluated by assessing and

1.3.3 Describe the usual pattern of electrical flow

through the conduction system.

1.3.4 Give the inherent rates for the SA node, the

AV junction, and the ventricles.

1.4 Explain the influence of the nervous system on rate

of cardiac impulse formation.

1.4.1 Differentiate between irritability and escape.

1.4.2 Name the nervous system that exerts an

influence over rate of cardiac impulse formation.

1.4.3 Identify the two opposing branches of the

above-named nervous system, and tell how

each would influence the heart if stimulated.

1.4.4 Describe the effect on the heart if one of the

branches is blocked.

Chapter 2 WAVES AND MEASUREMENTS

2 Convey cardiac electrical stimuli to a visible graphic

medium suitable for arrhythmia interpretation.

2.1 Demonstrate the monitoring equipment used to

detect cardiac electrical activity.

2.1.1 Prepare equipment/materials for monitoring.

2.1.2 Demonstrate electrode placement for basic

arrhythmia monitoring.

2.1.3 Optimize contact between electrode and skin.

2.1.4 Select a lead that gives good wave visibility

for arrhythmia interpretation.

2.2 Cite specifications of the graph paper used to

display cardiac electrical activity.

2.2.1 Given the standardized speed at which EKG

graph paper is run through the EKG machine,

identify the time intervals associated with

each of the following:

a. time notches in the margins

b. one small box

c. one large box

2.3 Relate the components of a single cardiac cycle to

the electrophysiological events that created them.

2.3.1 Differentiate between the following graphic

deflections:

a. wave

b. segment

c. interval

d. complex

2.3.2 Given a single cardiac cycle, locate each of

the following components and describe the

electrical events that created it:

a. P wave

b. PR segment

c. PR interval

d. Q wave

e. R wave

f. S wave

g. QRS complex

h. ST segment

i. T wave

2.3.3 Give the normal time duration for each of the

following:

a. PR interval

b. QRS complex

2.3.4 Identify the two phases of the refractory

period.

2.3.5 Identify the vulnerable phase of the cardiac

cycle.

2.3.6 Recognize deflections on an EKG tracing that

were created by something other than cardiac

electrical activity.

2.4 Differentiate between a single cardiac cycle and an

EKG rhythm strip.

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xiv Learning Objectives

Chapter 3 ANALYZING EKG RHYTHM

STRIPS

3 Utilize an organized analysis format to gather necessary

data from a rhythm strip to interpret the presenting

arrhythmia.

3.1 Relate the use of a systematic analysis format to the

eventual interpretation of an arrhythmia.

3.2 Outline the five components of an organized

approach to rhythm strip analysis.

3.2.1 Describe the pertinent aspects of a systematic

analysis of regularity, including R–R intervals,

P–P intervals, patterns, and ectopics.

3.2.2 Describe the pertinent aspects of a systematic

analysis of rate.

3.2.3 Describe the pertinent aspects of a systematic

analysis of P waves, including location,

morphology, and patterns.

3.2.4 Describe the pertinent aspects of a systematic

analysis of PR intervals, including duration,

changes, and patterns.

3.2.5 Describe the pertinent aspects of a systematic

analysis of ORS complexes, including duration,

morphology, and patterns.

Chapter 4 SINUS RHYTHMS

4 Recognize arrhythmias that originate in the sinus node.

4.1 Describe the characteristics of a sinus pacemaker.

4.1.1 Outline the physiologic mechanisms common

to the sinus node.

4.1.2 Describe the expected path of conduction

for an impulse originating from a sinus

pacemaker.

4.1.3 Identify EKG features common to all

arrhythmias in the sinus category.

4.2 Outline the identifying features specific to each of

the arrhythmias originating in the sinus node.

4.2.1 Describe Normal Sinus Rhythm, including

etiology, conduction, and resulting EKG

features (regularity, rate, P waves, PR intervals,

and QRS complexes).

4.2.2 Describe Sinus Bradycardia, including etiology,

conduction, and resulting EKG features

(regularity, rate, P waves, PR intervals, and

QRS complexes).

4.2.3 Describe Sinus Tachycardia, including etiology,

conduction, and resulting EKG features

(regularity, rate, P waves, PR intervals, and

QRS complexes).

4.2.4 Describe Sinus Arrhythmia, including etiology,

conduction, and resulting EKG features

(regularity, rate, P waves, PR intervals, and

QRS complexes).

Chapter 5 ATRIAL RHYTHMS

5 Recognize arrhythmias that originate within the atria.

5.1 Describe the characteristics of an atrial pacemaker.

5.1.1 Outline the physiologic mechanisms common

to atrial pacemakers.

5.1.2 Describe the expected path of conduction for

an impulse originating from within the atria.

5.1.3 Identify EKG features common to all

arrhythmias in the atrial category.

5.2 Outline the identifying features specific to each of

the arrhythmias originating within the atria.

5.2.1 Describe Wandering Pacemaker, including

etiology, conduction, and resulting EKG

features (regularity, rate, P waves,

PR intervals, and QRS complexes).

5.2.2 Describe Premature Atrial Complexes, including

etiology, conduction, and resulting EKG

features (regularity, rate, P waves, PR

intervals, and QRS complexes).

5.2.3 Describe Atrial Tachycardia, including etiology,

conduction, and resulting EKG features

(regularity, rate, P waves, PR intervals,

and QRS complexes).

5.2.4 Describe Atrial Flutter, including etiology,

conduction, and resulting EKG features

(regularity, rate, P waves, PR intervals, and

QRS complexes).

5.2.5 Describe Atrial Fibrillation, including etiology,

conduction, and resulting EKG features

(regularity, rate, P waves, PR intervals, and

QRS complexes).

Chapter 6 JUNCTIONAL RHYTHMS

6 Recognize arrhythmias that originate in the AV junction.

6.1 Describe the characteristics of a junctional

pacemaker.

6.1.1 Outline the physiologic mechanisms common

to junctional pacemakers.

6.1.2 Describe the expected path of conduction for

an impulse originating in the AV junction.

6.1.3 Identify EKG features common to all

arrhythmias in the junctional category.

6.2 Outline the identifying features specific to each of

the arrhythmias originating in the AV junction.

6.2.1 Describe Premature Junctional Complexes,

including etiology, conduction, and resulting

EKG features (regularity, rate, P waves,

PR intervals, and QRS complexes).

6.2.2 Describe Junctional Escape Rhythm, including

etiology, conduction, and resulting EKG

features (regularity, rate, P waves, PR intervals,

and QRS complexes).

Learning Objectives xv

6.2.3 Describe Junctional Tachycardia, including

etiology, conduction, and resulting EKG

features (regularity, rate, P waves,

PR intervals, and QRS complexes).

6.2.4 Describe Accelerated Junctional Rhythm,

including etiology, conduction, and resulting

EKG features (regularity, rate, P waves,

PR intervals, and QRS complexes).

6.2.5 Describe the term Supraventricular Tachycardia,

and define circumstances in which it can be

used appropriately.

Chapter 7 HEART BLOCKS

7 Recognize arrhythmias that are manifestations of

conduction defects at the AV node.

7.1 Describe the characteristics of the category of

arrhythmias known as AV heart blocks.

7.1.1 Outline the physiologic mechanisms involved

in AV heart block.

7.1.2 Describe the conduction defects encountered

in AV heart blocks.

7.1.3 Identify EKG features common to all

arrhythmias in the heart block category.

7.2 Outline the identifying features specific to each

of the arrhythmias included in the heart block

category.

7.2.1 Describe First-Degree Heart Block, including

etiology, conduction, and resulting EKG

features (regularity, rate, P waves,

PR intervals, and QRS complexes).

7.2.2 Describe Type I Second-Degree Heart Block

(Wenckebach), including etiology,

conduction, and resulting EKG features

(regularity, rate, P waves, PR intervals, and

QRS complexes).

7.2.3 Describe Type II Second-Degree Heart Block,

including etiology, conduction, and resulting

EKG features (regularity, rate, P waves,

PR intervals, and QRS complexes).

7.2.4 Describe Third-Degree Heart Block, including

etiology, conduction, and resulting EKG

features (regularity, rate, P waves,

PR intervals, and QRS complexes).

Chapter 8 VENTRICULAR RHYTHMS

8 Recognize arrhythmias that originate in the ventricles.

8.1 Describe the characteristics of a ventricular

pacemaker.

Flash Cards 605

Preface

There are many ways to learn electrocardiography and

many levels of expertise within this complex field. For ease

of reference, the various levels of knowledge/ability can

be outlined as follows:

Type Level Knowledge/Ability

Single Lead

(Arrhythmias)

I Ability to recognize a

limited number of familiar

patterns, usually the major

life-threatening rhythms. No

understanding of rules or

mechanisms.

II Basic understanding of

the rules and mechanisms

of common arrhythmias

according to pacemaker

sites. No familiarity with

more sophisticated features

that complicate basic

arrhythmias.

III Ability to interpret

arrhythmias that include

more sophisticated features

such as sinus arrest,

pacemakers, aberrancy, and

blocked beats.

12-Leads

(Complexities)

IV Familiarity with 12-lead

EKGs (e.g., bundle branch

block, infarction location,

axis deviation).

V Ability to distinguish

subtle EKG findings

(e.g., concealed conduction,

reciprocal conduction,

trifascicular block, His

bundle recordings).

It is best for a student to move through these levels in a

relatively logical progression from simple to complex.

Unfortunately, new students often lack a solid foundation

upon which to build more sophisticated understanding.

Basic Arrhythmias is designed to provide that sound

conceptual base. Its primary area of concentration is

Level II: basic understanding of common, uncomplicated

rhythms. It is hoped that Basic Arrhythmias will provide an

enjoyable and interesting way for people to develop the

framework that will later support continued learning in

the area of electrocardiography.

Basic Arrhythmias is designed to provide a solid

foundation for ongoing EKG learning. For this reason,

great care has been taken to instill simple, basic concepts

while avoiding misconceptions or erroneous impressions. The driving goal has always been to build a very

strong, but basic, understanding of arrhythmia interpretation. A fair amount of legitimate information was necessarily omitted from the text because it is considered

beyond the scope of a basic foundation. However, over

the years, readers lobbied strongly for some areas to be

added. In those cases, the content was included as appendices, rather than as part of the basic, programmed section of the book. Examples include: Cardiac Anatomy and

Physiology, Pathophysiology and Clinical Implications of

Arrhythmias, 12-Lead Electrocardiography, Basic 12-Lead

Interpretation, and Pacemakers. The Appendices are the

only sections in the book not considered “basic” arrhythmia interpretation.

About the Ninth Edition

Basic Arrhythmias has been well received for many years

and has been used successfully by hundreds of thousands

of students as they begin to study electrocardiography.

It is always a challenge to update and refresh it without

detracting from what makes it such a success. With this

edition, we’ve fixed a few bugs, switched out some troublesome EKG strips, added some new illustrations and

upgraded some old ones, expanded some sections, and

clarified a few ambiguous areas. Please note that a compiled list of learning objectives is presented later in this

section. These objectives outline in depth what you can be

expected to learn and do after completing each chapter.

In addition, we have expanded and improved the

digital learning resources for the Basic Arrhythmias

program. The new Pearson eTextbook integrates an

updated version of our Rhythm Randomizer an innovative

self-study exercise where you can use virtual calipers and

test your strip-reading knowledge against a database of

over 600 strips.

I am very excited about this ninth edition of Basic

Arrhythmias and hope you find it as enjoyable as I do.

With all its upgrades and its fresh new look, it promises to

continue the long tradition of helping students embark on

their studies of electrocardiography.

ALGrawany

x Preface

Acknowledgments

It is impossible to fully acknowledge all the people who

have contributed over the years to making Basic Arrhythmias

what it is today. There have been literally hundreds of

people over the years from all across the country who have

offered ideas and suggestions, contributed strips, provided

clinical reviews, and debated interpretation with me.

Without that clinical help, this book would not have

achieved the reputation for excellence that it enjoys today.

Coupled with the clinical excellence, the team at

Brady Publishing has set the standard for excellence in

the publication of such works. Going all the way back to

the original family members at Brady Publishing, countless publishing professionals have added their mark to this

book. In recent years, Pearson has continually moved us to

new heights with its print and media expertise. It is always

a joy to work with such professionals. Thank you.

GAIL WALRAVEN

La Jolla, California

Instructor Reviewers

The reviewers of Basic Arrhythmias provided excellent suggestions for improving the text. Their reviews were an important aid in the revision and updating of material, and

their assistance is greatly appreciated.

Reviewers of the Ninth Edition

Linda M. Abrahamson, RN, EMT-P, EMS Education

Coordinator, Advocate Christ Medical Center,

Downers Grove, IL

Gary W. Bonewald, EMS Program Director, Wharton

County Junior College, Wharton, TX

Jim Cueno, Paramedic Program Director, Lead

Instructor, Butte Community College, Oroville, CA

Reviewers of Previous Editions

Lauri Beechler, RN, MSN, CEN, Director, Paramedic

Program, Loyola University Medical Center,

Maywood, IL

Ashley Cheryl, BSN, RN, Education Instructor, Saint

Francis Hospital, Department of Education and

Professional Development, Tulsa, OK

Jackilyn E. Cypher, RN, MSN, NREMT-P, Paramedic

Program Course Director, Lead Instructor, Portland

Community College, Cascade Campus, Portland, OR

Deborah Ellis, RN, MSN, NP-C Assistant Professor,

Missouri Western State University, Saint Joseph, MO

Mary Fuglaar, PHRN, NREMT-B Training Lieutenant,

Fort Bend County EMS Rosenberg, TX

Brian Hess, Star Technical Institute Philadelphia, PA

Scott Jones, MBA, EMT-P, EMS Professor, Victor Valley

College Regional Public Safety Training Center,

Yucaipa, CA

Bradley K. Jordan, EMT-P EMT-P/Level 1 EMS

Instructor, Rockingham Community College,

Wentworth, NC

Lawrence Linder, PhD, NREMTP, Program Manager,

Hillsborough Community College, Tampa, FL

Christine Markut, PhD, RN, BC, CNE, Associate

Professor, Stevenson University, Stevenson, MD

Lynette McCullough, NREMT-P, MCH Program

Coordinator, Paramedic Technology, Griffin Technical

College, Griffin, GA

Jeff McDonald, BS, LP Program Coordinator Tarrant

County College, Hurst, TX

Mike McEvoy, EMS Coordinator, Saratoga County, NY

Matthew F. Powers, RN MS CEN MICP EMS Chief,

North County Fire Authority Fire/Emergency

Nursing, Daly City, CA

Trent Ragsdell, MBA, Life Support Program Manager/

EMS Coordinator, 55th Medical Group Education and

Training Department, Offutt AFB, NE

Ken Schoch, Program Director, Yavapai College

Prescott, AZ

Douglas P. Skinner, BS, NREMTP, NCEE, Training

Officer, Loudoun County Fire Rescue, Leesburg, VA

Michael Smertka, EMT-P, EMS, Assistant Instructor,

Cleveland Clinic EMS Academy Cleveland, OH

Kimberly Tew, BSN, RN, University of Iowa College of

Nursing, Iowa City, IA

Paul S. Visich, PhD, MPH, Director of the Human

Performance Laboratory, Central Michigan University

Mt. Pleasant, MI

Carl Voskamp, MBA, LicP, EMS Program Coordinator,

The Victoria College Victoria, TX

Michael L. Wallace, MPA, E T-P, CCEMTP, EMS

Captain/Educator, Central Jackson County Fire

Protection District, Blue Springs, MO

Charlotte A. Wisnewski, PhD, RN, BC, CDE, CNE,

Associate Professor, University of Texas Medical

Branch School of Nursing, Galveston, TX

Navigating Through the Text

The text is broken up into three sections: Section 1:

Self-Instructional Unit, Section II: Practice Strips, and

Section III: Appendices. The first eight chapters of this text,

found in Section 1 are structured as a self-instructional

unit in a “programmed learning” format. As such, it is an

entirely self-contained learning package; the only

SECTION I: Self-Instructional Unit

Chapters 1–8 each include the following sections:

• Programmed Content The narrative will teach you any rules and explanatory materials you’ll need to know to

interpret arrhythmias. Each content section (called a frame) is numbered. As you are asked to respond, write your

answer in the blank space provided. The answers are given in the right-hand margin directly across from the question. If you have trouble with an answer, go back over the referenced frames to find the explanation.

• Flash Cards Some of the chapters will ask you to take time out from the program to memorize material such as

specific rules for each arrhythmia. For your convenience, material that must be committed to memory has been

printed on the flash cards that are provided with this book. This is an effective method of memorizing material in

a short period of time.

• Key Points All major points contained in a chapter are presented in a bulleted list at the end of that chapter. This

is provided for your review as you complete the chapter, and as a reference should you need to look up a point in

the future.

• Self-Test Each chapter closes with a self-test of the important information contained in that chapter. The format

of the self-tests is very similar to the format of the text, except that each question is keyed back to the frames in the

chapter that provide the answer to that specific question. Since the self-test is intended to tell you whether or not

you learned the material in the chapter, you will want to let a little time pass between completing the chapter and

beginning the self-test. If you take the test immediately after finishing the chapter, you might simply be recognizing

familiar terms, rather than truly understanding the information. So, once you finish the chapter, take a break from

the subject for an hour or two. Then come back to take the test. If you do well on the test, go on to the next chapter.

If your results indicate that you did not really learn the material, go back and remedy that before you move on. Otherwise, you won’t have a solid foundation for learning future subjects well.

• Practice Strips Starting in Chapter 2, practice rhythm strips are provided at the end to illustrate key points in the

chapter, and to allow the student to practice what was learned in that chapter.

SECTION II: Practice Strips

Chapters 9 and 10 both have collections of EKG strips to practice analyzing; however, each has its own purpose.

• Ch 9: Practice Strips This collection of strips is designed for practice only.

• Ch 10: Self-Test This collection is a fully weighted self-test in case you’d like to see how you’re doing.

additional materials you will need are a pencil and a set

of EKG calipers, which are available at most medical supply houses and medical bookstores. Everything else is provided here in a format designed to make this learning an

enjoyable and worthwhile process. The internal structure

of the individual chapters is as follows:

ALGrawany

xii Navigating Through the Text

SECTION III: Appendices

Over the years, a number of topics have been requested by readers, some of which were beyond the scope of the original

introductory course. Those topics have been added as appendices to differentiate them from the original scope of the book. The

format in the appendices is not self-instructional; it is covered in a more traditional text style.

A Cardiac Anatomy and Physiology

B Pathophysiology and Clinical Implications of Arrhythmias

C 12-Lead Electrocardiography

D Basic 12-Lead Interpretation

E Pacemakers

xiii

Learning Objectives

The objectives below outline in depth what you can be

expected to learn and do after completing each chapter.

Section I: Self-Instructional Unit

Chapter 1 ELECTROPHYSIOLOGY

1 Describe the electrophysiologic basis of cardiac

arrhythmias.

1.1 Give the uses and limitations of cardiac arrhythmia

monitoring.

1.1.1 Distinguish between the electrical and the

mechanical functions of the heart.

1.1.2 Relate cardiac arrhythmia monitoring to

pulse/perfusion assessment.

1.2 Explain how cardiac impulses are formed.

1.2.1 Briefly describe the sodium pump.

1.2.2 Define polarization and describe the

polarized state.

1.2.3 Define depolarization and explain how it occurs.

1.2.4 Define repolarization and explain how it occurs.

1.3 Describe the heart’s electrical conduction system.

1.3.1 Identify the five major areas of electrical

conduction.

1.3.2 Outline the physical layout of the conduction

system.

Basic Arrhythmias

With 12-Lead EKGs

ALGrawany

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Basic Arrhythmias

With 12-Lead EKGs

Ninth Edition

Gail Walraven

Brady is an imprint of PEARSON

ALGrawany

ISBN-10: 0-13-816495-9

ISBN-13: 978-0-13-816495-9

$PrintCode

Library of Congress Cataloging-in-Publication Data

Names: Walraven, Gail, 1949- author.

Title: Basic arrhythmias: With 12-Lead EKGs / Gail Walraven.

Description: Ninth edition. | [Hoboken, NJ] : Pearson, [2024] | Revised

edition of: Basic arrhythmias / Gail Walraven. Eighth edition. 2016.

Identifiers: LCCN 2023053103 | ISBN 9780138164959 (paperback) | ISBN

0138164959 (print) | ISBN 9780138164911 (ebook) | ISBN 9780138165079

(other ebook)

Subjects: LCSH: Arrhythmia--Diagnosis--Programmed instruction. |

Electrocardiography--Programmed instruction.

Classification: LCC RC685.A65 W33 2024 | DDC 616.1/28--dc23/eng/20231214

LC record available at https://lccn.loc.gov/2023053103

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PEARSON and ALWAYS LEARNING are exclusive trademarks in the U.S. and/or other countries

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authors, licensees or distributors.

Dedication

To the men in my life:

Bruce, Kellen, Dustin, and Case

ALGrawany

This page intentionally left blank

vii

Contents

Preface ix

Navigating Through the Text xi

Learning Objectives xiii

1 Electrophysiology 1

Self-Instructional Unit

Electrical vs. Mechanical Function 1

Impulse Formation 3

Polarization and Depolarization 4

Conduction System 5

Inherent Rates 6

Irritability and Escape 7

Nervous System Influence 8

KEY POINTS 11

SELF-TEST 11

2 Waves and Measurements 14

Self-Instructional Unit

Introduction 14

Electrodes 15

Rule of Electrical Flow 15

Monitoring Leads 16

Graph Paper 17

Voltage Measurements 18

Time Measurements 19

Cardiac Cycle 19

Waves, Intervals, Segments 21

P Wave and PRI 21

QRS Complex 22

ST Segment and T Wave 24

Measurements 24

Practice 24

Artifact, Interference 24

Refractory Periods 26

KEY POINTS 28

SELF-TEST 28

PRACTICE STRIPS (PART I) 31

PRACTICE STRIPS (PART II) 33

3 Analyzing EKG Rhythm Strips 48

Self-Instructional Unit

Analysis Format 48

Regularity 50

Rate 51

P Waves 53

PR Intervals and QRS Complexes 54

Role of the AV Node 55

Ventricular vs. Supraventricular 55

KEY POINTS 57

SELF-TEST 57

PRACTICE STRIPS (PART I) 60

PRACTICE STRIPS (PART II) 64

4 Sinus Rhythms 68

Self-Instructional Unit

Introduction 68

Normal Sinus Rhythm 69

Sinus Bradycardia 71

Sinus Tachycardia 71

Sinus Arrhythmia 73

Review 74

KEY POINTS 76

SELF-TEST 76

PRACTICE STRIPS 78

INTERPRETATION OF CHAPTER 3 RHYTHM STRIPS 93

5 Atrial Rhythms 94

Self-Instructional Unit

Atrial Rhythms 94

Wandering Pacemaker 95

Ectopics 97

Premature Atrial Complex 97

Atrial Tachycardia 99

Atrial Flutter 100

Atrial Fibrillation 102

KEY POINTS 105

SELF-TEST 105

PRACTICE STRIPS 108

6 Junctional Rhythms 137

Self-Instructional Unit

Junctional Pacemaker 137

Junctional P Wave 139

Premature Junctional Complex 141

Junctional Escape Rhythm 143

Junctional Tachycardia 144

Accelerated Junctional Rhythm 145

ALGrawany

viii Contents

Supraventricular Tachycardia 148

KEY POINTS 150

SELF-TEST 150

PRACTICE STRIPS 153

7 Heart Blocks 174

Self-Instructional Unit

Conduction Through the AV Node 174

Heart Blocks 175

First-Degree Heart Block 176

Second-Degree Heart Blocks 178

Type II Second-Degree Heart Block 180

Wenckebach (Type I Second-Degree Heart Block) 182

Third-Degree Heart Block (Complete Heart Block) 185

KEY POINTS 190

SELF-TEST 190

PRACTICE STRIPS 193

8 Ventricular Rhythms 214

Self-Instructional Unit

Ventricular Rhythms 214

Premature Ventricular Complex (PVC) 215

Unifocal vs. Multifocal 219

R on T Phenomenon 220

Runs and Couplets 221

Grouped Beating 222

Ventricular Tachycardia (VT) 224

Ventricular Fibrillation 226

Idioventricular Rhythm 227

Asystole 228

Pulseless Electrical Activity (PEA) 230

KEY POINTS 232

SELF-TEST 233

PRACTICE STRIPS 237

9 Practice Makes Perfect 276

Introduction 276

PRACTICE STRIPS 278

10 Final Challenge 403

Introduction 403

SELF-TEST 404

Appendix A: Cardiac Anatomy and Physiology 454

Appendix B: Pathophysiology and Clinical

Implications of Arrhythmias 462

Appendix C: 12-Lead Electrocardiography 467

Appendix D: Basic 12-Lead Interpretation 480

Appendix E: Pacemakers 534

Glossary 544

Answers Key 551

Index of Practice Strips by Rhythm Names 586

Subject Index 593

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خلفيات وصور / wallpapers and pictures images / fond d'écran photos galerie / fondos de pantalla en i

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10/20/25

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