principles of the electrocardiogram ...1. an electrocardiogram (ecg) is best described as a. a heart...

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PRINCIPLES OF THE ELECTROCARDIOGRAM

PROCEDURE AND INTERPRETATION BASIC ELECTROCARDIOGRAPHY

JASSIN M. JOURIA, MD Dr. Jassin M. Jouria is a practicing Emergency Medicine physician, professor of academic medicine, and medical author. He graduated from Ross University School of Medicine and has completed his clinical clerkship training in various teaching hospitals throughout New York, including King’s County Hospital Center and Brookdale Medical Center, among others. Dr. Jouria has passed all USMLE medical board exams, and has served as a test prep tutor and instructor for Kaplan. He has developed several medical courses and curricula for a variety of educational institutions. Dr. Jouria has also served on multiple levels in the academic field including faculty member and Department Chair. Dr. Jouria continues to serve as a Subject Matter Expert for several continuing education organizations covering multiple basic medical sciences. He has also developed several continuing medical education courses covering various topics in clinical medicine. Recently, Dr. Jouria has been contracted by the University of Miami/Jackson Memorial Hospital’s Department of Surgery to develop an e-module training series for trauma patient management. Dr. Jouria is currently authoring an academic textbook on Human Anatomy & Physiology. ABSTRACT

Electrocardiograms are valuable tests for evaluating heart health and to

diagnose cardiac issues. But the test is only as good as the skill of the

clinician performing it. Medical clinicians must commit to learning and

updating their electrocardiogram procedure and interpretation skills to arrive

at a correct diagnosis, and these skills start with an understanding of the

basic function of the electrocardiogram. Being able to identify normal

readings on an electrocardiogram rhythm strip is the first step to recognizing

cardiac issues, and possibly saving lives.


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Policy Statement

This activity has been planned and implemented in accordance with the

policies of NurseCe4Less.com and the continuing nursing education

requirements of the American Nurses Credentialing Center's Commission on

Accreditation for registered nurses. It is the policy of NurseCe4Less.com to

ensure objectivity, transparency, and best practice in clinical education for

all continuing nursing education (CNE) activities.

Continuing Education Credit Designation

This educational activity is credited for 3 hours. Nurses may only claim credit

commensurate with the credit awarded for completion of this course activity.

Statement of Learning Need

Health clinicians in general practice and cardiology need to be able to

understand the function and information generated by an electrocardiogram.

The correct diagnosis and proper treatment of a cardiac condition is

dependent on competent and accurate interpretation of diagnostic tests,

which includes the electrocardiogram in both inpatient and outpatient

settings.

Course Purpose

To provide health clinicians with basic knowledge about the purpose,

function and diagnostic data of an electrocardiogram.


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Target Audience

Advanced Practice Registered Nurses and Registered Nurses

(Interdisciplinary Health Team Members, including Vocational Nurses and

Medical Assistants may obtain a Certificate of Completion)

Course Author & Planning Team Conflict of Interest Disclosures

Jassin M. Jouria, MD, William S. Cook, PhD, Douglas Lawrence, MA

Susan DePasquale, MSN, FPMHNP-BC – all have no disclosures

Acknowledgement of Commercial Support

There is no commercial support for this course.

Please take time to complete a self-assessment of knowledge, on page 4, sample questions before reading the article.

Opportunity to complete a self-assessment of knowledge learned will be provided at the end of the course.


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1. An electrocardiogram (ECG) is best described as

a. a heart blood pressure monitor. b. a pacemaker. c. a recording of the electrical activity of the heart. d. electrodes that mimic the bundle of His.

2. True or False: The rhythm strip output provides a clinician with a

“snapshot” of the heart’s activity at a moment in time.

a. True b. False

3. With the rhythm strip the placement of electrodes for the limb

and augmented voltage leads

a. are the same for all ECGs so the graphs may be compared. b. depends on the polarization of the cardiac cells. c. are different for a resting ECG compared to an exercising ECG. d. depends on the size of the electrical fields.

4. In a normal situation, depolarization of cardiac cells begins in

a. the atrioventricular node. b. the atria. c. the ventricles. d. the sinus node.

5. These electrical signals spread through the heart as wave fronts

of

a. depolarization. b. polarization. c. augmentation. d. electrical fields.


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Introduction

An electrocardiogram is a recording of the electrical activity of the heart. It

measures the electrical waves and impulses of the heart using 10 or 12

electrodes, which are placed on specific areas of the chest, arms, and legs

and are connected to wires. The electrodes pick up heart impulses and sends

them through the wires to produce a graph of the heart’s electrical

conductivity. This allows a clinician to diagnose a patient’s heart rate and

rhythm by analyzing an electrocardiogram rhythm strip using the triplet’s

method and the six second method. By identifying the classification system

of cardiac rhythms, the clinician is able to differentiate between the types of

rhythms, know how to identify a pacemaker rhythm, explain the relationship

between P wave and the QRS complex, and identify common causes of

dysrhythmia.

The 12-Lead Electrocardiogram

The 12-lead electrocardiogram is the standard diagnostic test a clinician will

use to view the electrical activity of a patient’s heart. The 12-lead

electrocardiogram records this activity from electrodes on the body surface.

The term “lead” is used in two ways: it refers to the wire that connects to

two or more electrodes, and it refers to the view of the electrical activity of

the heart from a certain angle of the body as seen on electrocardiogram

paper.4,94

Rhythm Strip Output

The rhythm strip output is different than a 12-lead electrocardiogram (ECG)

output in that a rhythm strip records the same leads (views of heart activity)

across the entire ECG paper. The placement of electrodes for the limb and


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augmented voltage leads are slightly different depending on whether the

ECG is a resting or exercising one.

A rhythm strip is a more precise method of detecting a problem on what is

an otherwise normal ECG. An ECG is like a snapshot of the heart’s activity at

a moment in time, while the rhythm strip is a continuous feed.

Rhythm Analysis

When analyzing a cardiac rhythm, it is critical that medical clinicians

recognize what the cardiac complex represents and what is considered

normal and abnormal. It is also important that clinicians practice cardiac

rhythm analysis. The more practice in rhythm analysis, the more

comfortable a clinician will be with the processes involved and all aspects of

interpretation.

The technique and interpretation of cardiac rhythms can be a combination of

science and art. When interpreting an ECG, a clinician is analyzing a graphic

record of the electrical activity of the heart.94 Each cardiac cell generates an

action potential. This is as it becomes depolarized and then repolarized

during a normal cycle. In a normal situation, depolarization of cardiac cells

proceeds in an orderly fashion. This begins in the sinus node. It then spreads

sequentially through the atria, atrioventricular node, and ventricles. These

electrical signals spread through the heart as wave fronts of depolarization.

The wave fronts result in minute electrical fields. These fields allow detection

at the body’s surface, which clinicians record as the activation and recovery

signals of working myocardial cells.2


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An electrocardiograph may have a default setting to trace each lead for 2.5

seconds. Longer settings of 6 or 10 seconds may be used to identify a

pattern in the heart’s rhythm.

Timing across an ECG report page is continuous. Needles trace each lead on

paper. Each row represents ECG lead activity as the paper is pulled under

the needle. A lead is the source of measurement of a vector. For the limb

leads, they are the comparison between two electrodes. For the precordial

leads, they are compared to a common lead.58 There are three sets of leads;

the limb, augmented limb, and precordial leads. The 12-lead ECG uses three

limb leads and three augmented limb leads that are arranged in a frontal

plane. Six chest (precordial) leads are used to view the heart from the

transverse or horizontal plane.

In the ECG, two leads are called contiguous if they reflect neighboring

anatomical areas. A lead is a connector to an electrode, which is a

conductive pad in contact with the body. It makes an electrical circuit with

the electrocardiograph. Leads can share the same electrode. A standard 12-

lead ECG needs only 10 electrodes. The 10 electrodes in a 12-lead ECG are

applied to the body as described below, and are identified as RA, LA, RL, LL,

V1, V2, V3, V4, V5, and V6. With each of the 12 ECG leads, there is a

recording of cardiac electrical activity from a different angle and anatomical

area of the heart. These differing orientations or views are described

below.95

Bipolar limb leads (frontal plane)

Lead I: RA (right arm) (-) to LA (left arm) (+) (Right Left, or lateral)

Lead II: RA (-) to LL (left foot) (+) (Superior Inferior)

Lead III: LA (-) to LL (+) (Superior Inferior)


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Augmented unipolar limb leads (frontal plane)

Lead aVR (augmented vector right): RA (+) to [LA & LL] (-) (Rightward)

Lead aVL (augmented vector left): LA (+) to [RA & LL] (-) (Leftward)

Lead aVF (augmented vector foot): LL (+) to [RA & LA] (-) (Inferior)

Unipolar (+) chest leads (transverse or horizontal plane)

Leads V1, V2, V3: (Posterior Anterior)

Leads V4, V5, V6:(Right Left, or lateral)

12-Lead ECG Placements

When placing the leads, the following locations and rules apply:

• RA (right arm): avoid thick muscle

• LA (left arm): avoid thick muscle

• RL (right leg): placed at the lower end of the medial aspect of the calf

muscle, avoiding the bony prominences

• LL (left leg): placed at the lower end of the medial aspect of the calf,

avoiding the bony prominences

• V1: placed at the fourth intercostal space between ribs 4 and 5, just to

the right of the sternum breastbone

• V2: placed at the fourth intercostal space between ribs 4 and 5, just to

the left of the sternum

• V3: placed between leads V2 and V4

• V4: placed at the fifth intercostal space between ribs 5 and 6 and in the

mid clavicular line

• V5: placed horizontally even with V4 in the left anterior axillary line

• V6: placed horizontally even with V4 and V5 in the mid axillary line


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ECG Rhythm Strip Report

A normal heart beats when electrical impulses spread through the cardiac

atria (upper chambers) to the cardiac ventricles (lower chambers), in an

organized and sequential manner. When analyzing an ECG tracing, the

clinician must first check R wave to R wave across the strip. If the intervals

vary by 1.5 small boxes or less, the heart rhythm can be considered regular.

When taking a person’s pulse, and repeating the pulse in 10 minutes, the

heart rate can be expected to be the same number. Several factors work

together to maintain the body’s homeostasis, and R wave to R wave analysis

refers to the normal rhythmicity of the cardiac ventricles; and, when

measuring P wave to P wave this refers to the rhythmicity of the atria.2

Several types of information can be determined from evaluating the cardiac

rhythm through an ECG, which indicates normal or abnormal conditions. An

abnormal heart rhythm, referred to as an arrhythmia or dysrhythmia, is an

abnormally slow or fast heart rate, or an irregular cardiac rhythm.

Arrhythmia and dysrhythmia are words used to describe the same condition

in a different way; the word arrhythmia describes a condition in which a

person does not have a regular heart rhythm, whereas dysrhythmia refers to

an abnormal rhythm, so these terms mean the same thing.

The ECG waveform has a number of indicators for each heartbeat. These

indicators are the P, Q, R, S, T, and U waveforms. The first movement of the

ECG tracing is usually an upward deflection and is the P wave. This indicates

electrical activity that triggers atrial contraction. The components of QRS

mark ventricular depolarization and contraction. They are usually of greater

amplitude than the P wave. The T wave is normally a waveform that has an

upward deflection and smaller than the QRS. This indicates ventricular

repolarization.


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A cardiac rhythm strip can provide information on essential dysrhythmia

categories. These include 1) atrial (premature atrial contractions, atrial

flutter, atrial fibrillation, multifocal atrial tachycardia, wandering atrial

pacemaker), 2) junctional (junctional tachycardia, premature junctional

contraction), 3) ventricular (supraventricular tachycardia, premature

ventricular contractions, accelerated idioventricular rhythm, ventricular

fibrillation, monomorphic ventricular tachycardia, polymorphic ventricular

tachycardia), 4) heart blocks (first degree heart block, second degree heart

block, third degree heart block), and 5) sudden arrhythmic death syndrome.

Second degree heart block can also include type 1 (mobitz I) and type 2

(mobitz II).2

Triplets Method Technique

The Triplets method heart rate technique is a quick estimate of the heart

rate. This technique gives the clinician an idea of the arrhythmia to be

interpreted; by example, for the heart rate, the beats per minute is found by

counting with the 0 and using the R wave deflection directly on top of a dark

line of a large box.

The math basis for the Triplets technique involves 1500 small boxes in one

minute. Taking the number of boxes, the clinician divides 1500 by the

number of boxes. If there are 5 small boxes, this is 1500/5 or 300 beats per

minute. The 1500 comes from 25 small boxes per second. The number of

small boxes per minute are determined with there being 60 seconds/minute

and by taking 25 x 60 = 1500 or 1500 small boxes per minute. The clinician

will estimate heart rate as 1500/6 small boxes or 250 beats per minute,

1500/7 small boxes or 214 beats per minute, or 1500/8 small boxes or 187

beats per minute.3


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Six Second Method of Rhythm Analysis

Using the 6-second method with an irregular rhythm to estimate a heart

rate, the number of R waves are counted in a 6-second strip and then

multiplied by 10. For example, if there are seven R waves in a 6-second

strip, the heart rate is 70, which is determined from 7x10=70. If there are

eight R waves in a 6-second strip, the heart rate is 8x10=80.4-8

Rhythm Classification Types

Considering the rhythm according to classification and types, classification

can be regular, regularly irregular, and irregularly irregular. Regular

classification refers to a normal heart rhythm or normal sinus rhythm (NSR)

for short. This normal sinus rhythm has a heart rate that is the same as the

pulse between 50 and 100 beats per minute. It also has a normal impulse

formation from the sinoatrial (SA) node (or P wave in the ECG).

Regularly irregular classification means the RR intervals or PP intervals

between beats are the same. With a sinus arrhythmia there is a cyclical

acceleration of the heart rate with inspiration and slowing with expiration.

The beat to beat interval is different. The rhythm is regularly irregular in that

there is a pattern to the irregularity.

Irregularly irregular classification means there is no pattern at all. All of the

intervals are haphazard. All of the intervals also do not repeat with an

accidental exception that is occasional. Irregularly irregular rhythms include

atrial fibrillation, wandering atrial pacemaker, and multifocal atrial

tachycardia.9


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Identifying ECG Rhythm Types

As mentioned, the classification system of rhythm refers to regular, regularly

irregular, or irregularly irregular. Rhythm is best analyzed when looking at a

rhythm strip. For a 12-lead ECG, this can be a 10-second recording from

lead II. The clinician should confirm or corroborate findings in lead II by

checking other leads. It can be helpful to look at a longer rhythm strip

recorded at a slower speed.9

Considering examples of broad complex tachycardia (BCT), a regular broad

complex tachycardia includes ventricular tachycardia, antidromic

atrioventricular re-entry tachycardia (AVRT) and any regular

supraventricular tachycardia with aberrant conduction; for example,

aberrant conduction may be due to bundle branch block and rate-related

aberrancy. Irregular broad complex tachycardia includes ventricular

fibrillation and polymorphic ventricular tachycardia, including torsades de

pointes. Also included are atrial fibrillation with Wolff-Parkinson-White

(WPW) syndrome (a condition in which there is an extra electrical pathway

in the heart) and any irregular supraventricular tachycardia with aberrant

condition. Again, an aberrant condition may be due to bundle branch block

and related aberrancy.63

Types of Cardiac Rhythms

To differentiate between the types of rhythms a medical clinician should first

consider the difference between rate and rhythm. In a normal heart, the

heart rate is the rate in which the sinoatrial node depolarizes as it is the

source of depolarization of the heart. As with other vital signs such as blood

pressure and respiratory rate, heart rate changes with age. In an adult, a

normal heart rate is between 60 and 100 beats per minute (normocardiac).

For a child, the heart rate will be higher.


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Bradycardia is less than 60 beats per minute in adults and involves a heart

rate less than normal. Tachycardia is higher than 100 in adults and is higher

than normal. If the atria and ventricles are not in synchrony, this is a

complication and the heart rate must be specified as atrial or ventricular. For

example, the atrial rate in atrial fibrillation is 300 to 600 bpm. A ventricular

rate can be normal at 60 to 100 bpm or faster at 100 to 150 bpm.

For a normal resting heart, the physiologic rhythm of the heart is normal

sinus rhythm (NSR). This normal sinus rhythm produces the prototypical

pattern of P wave, QRS complex, and T wave. The first step in interpreting a

rhythm strip or ECG is whether there is a sinus rhythm. A criterion for

evaluating sinus rhythm is that the P wave and QRS complex are 1 to 1,

implying that the P wave generates the QRS complex.

After establishing a sinus rhythm, the heart rate is next determined by

counting the (1 to 1) P waves and QRS complexes. If the rate is too fast, it

is a sinus tachycardia. If the rate is too slow, it is a sinus bradycardia. If it is

not a sinus rhythm, the clinician must determine the rhythm before

proceeding with additional interpretation.

Generally, a deviation from normal sinus rhythm is considered to be a

cardiac arrhythmia. Here are some arrhythmias with characteristic findings.

• Absent P waves and irregularly irregular QRS complexes are signs of

atrial fibrillation.

• A saw tooth pattern with QRS complexes is the sign of atrial flutter.

• A sine wave pattern is the indicator of ventricular flutter.

• Absent P waves with wide QRS complexes with fast rate are signs of

ventricular tachycardia.


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The clinician must make a determination of rate and rhythm to make further

interpretation possible. Remember that a sinus rhythm means a normal

heart beat with respect to the heart rate and rhythm. The heart rate will fall

between 60 and 100 beats per minute. The shape of the tracing on the

rhythm strip or ECG will show the key attributes needed to be considered

normal.

A sinus rhythm occurs with any cardiac rhythm that has depolarization of the

cardiac muscle beginning at the sinus node. It shows a correctly oriented P

wave on the rhythm strip or ECG. Sinus rhythm is needed but is not

sufficient for normal electrical activity in the heart.

Normal sinus rhythm is where all other measurements of the ECG fall in

designated normal limits and show the characteristic appearance of the ECG

when the electrical conduction system of the heart functions normally. Other

sinus rhythms can be normal in certain patient groups and clinical situations,

and include sinus tachycardia, sinus bradycardia, and sinus arrhythmia. A

sinus rhythm could be seen together with other cardiac arrhythmias on the

same ECG.10,11

The term sinus relates to or denotes the sinoatrial node of the heart or its

function as a pacemaker. The sinoatrial node is a small body of specialized

muscle tissue in the wall of the right atrium of the heart that acts as a

pacemaker by producing a contractile signal at regular intervals. This group

of cells located in the wall of the right atrium of the heart is the sinoatrial

node, also called SA node or sinus node.10


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Cardiac Rhythms

Types of cardiac rhythms are identified as sinus, atrial, supraventricular,

ventricular, premature ventricular contractions (PVC), Torsades de Pointes,

asystole, pulseless electrical activity (PEA), and artificial pacemaker. A sinus

rhythm is required for normal electrical activity of the heart however is not

entirely sufficient for normal cardiac electrical activity.

As mentioned above, arrhythmia is a term that means a heartbeat is

irregular. This does not mean the heart is beating too slowly or too fast. It

just means the heart is not functioning in a normal rhythm. A person can

feel that their heart has skipped a beat, added a beat, is fluttering, or is

beating too fast (tachycardia) or too slow (bradycardia). Some arrhythmias

are silent so the person is not aware of the condition.23

An arrhythmia can lead to a medical emergency. It can also be harmless. A

person can have an arrhythmia if the person’s heart is healthy or when heart

disease is present. Changes in the heart muscle, injury from a heart attack,

healing after heart surgery, or the wrong balance of electrolytes in the blood

including sodium or potassium can cause an arrhythmia.

Among the many types of arrhythmias, premature atrial contractions involve

early extra beats that start in the heart's upper chambers (atria), and are

considered harmless and typically need no treatment. Premature ventricular

contractions are among the most common arrhythmias and cause a skipped

heart beat type of feeling. They can be related to too much nicotine or

caffeine. Sometimes they can be caused by an electrolyte imbalance or heart

disease. If a patient has frequent premature ventricular contractions, a

cardiologist should be consulted.


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Atrial fibrillation is a common irregular heart rhythm that causes the upper

chambers of the heart to contract abnormally. Atrial flutter is an arrhythmia

that is usually more organized and regular than atrial fibrillation. This

happens often in a person with heart disease and shortly after heart surgery.

It can change into atrial fibrillation.

Paroxysmal supraventricular tachycardia is a rapid heart rate, usually with a

regular rhythm. It starts from above the heart's ventricles, and begins and

ends suddenly. With accessory pathway tachycardias, a patient can get a

rapid heart rate because there is an extra pathway between the heart's

upper and lower chambers. When this happens the impulses that control

heart rhythm travel quickly and cause the heart to beat unusually fast.

Sinus Rhythm

A sinus rhythm refers to any cardiac rhythm where depolarization of the

cardiac muscle begins at the sinus node. A correctly oriented P wave on the

electrocardiogram or rhythm strip is how a sinus rhythm is characterized.

This sinus rhythm is needed, but not entirely sufficient, for normal electrical

activity in the heart.

Normal sinus rhythm is where all measurements on an electrocardiogram fall

within designated normal limits. This gives rise to a characteristic

appearance on the electrocardiogram when the electrical conduction system

of the heart functions normally. As mentioned earlier, a sinus rhythm can

include a sinus tachycardia, sinus bradycardia, and sinus arrhythmia. A sinus

rhythm can present with other cardiac arrhythmias on the same

electrocardiogram or rhythm strip.64


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P Waves and QRS Complex

To briefly summarize, in a normal

rhythm strip there are three distinct

waves. The first is the P wave. This

represents depolarization of the atria

and happens before the atria contract

and push blood into the ventricles. The

next wave is called the QRS wave. The

third wave is the T wave. The P wave

can show right or left atrial

hypertrophy or atrial arrhythmias. It is

best determined in leads II and V1

during sinus rhythm. A normal P wave

is positive in II and AVF and biphasic

in V1.

The QRS complex is a name for the combination of three of the graphical

deflections as seen on a rhythm strip. It is usually the central and most

visually obvious part of the tracing on the rhythm strip. It corresponds to the

depolarization of the right and left ventricles of the heart. In an adult it

normally lasts 0.06–0.10 s, and in a child and during physical activity it

could be shorter.

The Q, R, and S waves occur in rapid succession. They do not appear in all

leads. They reflect a single event and are usually considered together. The Q

wave is any downward deflection after the P wave. An R wave follows as an

upward deflection. The S wave is any downward deflection after the R wave.

The T wave follows the S wave. In some cases, an additional U wave follows

the T wave.


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The P wave, representing atrial depolarization and preceding the QRS

complex, looks like a small bump up from the baseline. The amplitude for

the P wave is normally 0.05 to 0.25 mV. This is 0.5 to 2.5 small boxes.

Typical abnormalities for a P wave include a P mitrale (bifid P waves), seen

with left atrial enlargement. Another is P pulmonal (peaked P waves), seen

with right atrial enlargement. Another is P wave inversion, seen with ectopic

atrial and junctional rhythms.20

Atrial Rhythms

Atrial rhythms can include atrial fibrillation, atrial tachycardia, atrial flutter,

premature atrial contraction, and multifocal atrial tachycardia. Atrial

fibrillation, also known AF or A-fib, is an abnormal heart rhythm

characterized by rapid and irregular beating of the atria. Atrial tachycardia is

a type of heart rhythm problem in which the heart's electrical impulse comes

from an ectopic pacemaker. Atrial flutter (AFL), is a common abnormal heart

rhythm. It starts in the atrial chambers of the heart.

Premature atrial contractions (PACs), atrial premature complexes (APCs), or

atrial premature beats (APB) are a common cardiac dysrhythmia. Multifocal

atrial tachycardia is also known as a multiform atrial tachycardia (MAT),

which is an abnormal heart rhythm and a type of supraventricular

tachycardia.

Supraventricular Tachycardia

Supraventricular tachycardia (SVT) and a paroxysmal supraventricular

tachycardia (PSVT) is an abnormally fast heart rhythm arising from improper

electrical activity in the upper part of the heart. Paroxysmal supraventricular


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tachycardia is a type of supraventricular tachycardia. Someone with this

condition could have no symptoms.

Supraventricular tachycardia is also broadly defined as an abnormally fast

heartbeat. The problem originates supraventricular or in the atria or atrial

ventricular node.24 Tachycardia involves a heart rate that is greater than 100

beats per minute, and occurs when the electrical impulses coordinating heart

beats do not work properly. It can feel like a racing heart or fluttering. Many

who have a rare episode of supraventricular tachycardia can live a healthy

life with no restrictions or interventions. For some, treatment and lifestyle

changes can help to eliminate or control the rapid heartbeats of tachycardia.

Types of supraventricular tachycardia include atrial tachycardia and

atrioventricular nodal reentry tachycardia (AVNRT). Symptoms include a

supraventricular tachycardia that can come and go suddenly. There can be

stretches of normal heart rate in between. Symptoms can last for a few

minutes and can also last a few days. Some people with the condition have

no symptoms. If supraventricular tachycardia occurs frequently it can

become a problem. If it is ongoing it can be a problem if a patient has heart

damage or another coexisting medical condition or problem.

Signs and symptoms of supraventricular tachycardia can include palpitations

that are a rapid heartbeat, fluttering in the chest, shortness of breath,

lightheadedness, dizziness, sweating, a pounding sensation in the neck,

fainting known as syncope or near fainting. For a young child or an infant,

signs and symptoms can be difficult to identify. A child with a pulse rate of

over 200 beats a minute, poor feeding, and pale skin can indicate

supraventricular tachycardia.


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Ventricular Tachycardia

Ventricular tachycardia can also be called V-tach or VT and include a

catecholaminergic polymorphic ventricular tachycardia (CPVT) and familial

polymorphic ventricular tachycardia (FPVT). Ventricular tachycardia is a type

of regular and fast heart rate that arises from improper electrical activity in

the ventricles. Catecholaminergic polymorphic ventricular tachycardia can

also be called catecholamine-induced polymorphic ventricular tachycardia.25

Ventricular tachycardia is a heart rhythm disorder and arrhythmia that is

caused by abnormal electrical signals in the lower chambers of the heart

(ventricles). Electrical signals regulate the heart rate as the signals are sent

across heart tissues. The rate of a healthy heart normally is about 60 to 100

times a minute at rest. This is defined by signals that originate in the upper

atria.

In ventricular tachycardia, abnormal electrical signals in the ventricles cause

the heart to beat faster than normal. This is usually 100 or more beats a

minute and out of sync with the upper chambers. When this happens the

heart might not pump enough blood to the body and lungs. This is because

the chambers are beating fast and out of sync with each other. They do not

have time to properly fill.

Ventricular tachycardia can be brief. It can last for a few seconds and

possibly not cause symptoms. In some cases, it can last much longer. It can

cause symptoms such as dizziness, lightheadedness, and palpitations. It can

even cause a loss of consciousness. Ventricular tachycardia can also cause a

heart to stop with sudden cardiac arrest, a life-threatening, medical

emergency. The condition can occur when a person has another heart


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condition. For example, it could be a previous heart attack or other

structural heart disease, such as cardiomyopathy.

Ventricular fibrillation is a dangerous condition related to ventricular

tachycardia. With ventricular fibrillation the lower heart chambers contract in

a very rapid and uncoordinated way. At times this rhythm could result from

ventricular tachycardia that degenerates into ventricular fibrillation. Or it

could originate from single ventricular beats. Most often this abnormal

rhythm happens with established heart disease or a prior heart attack. It

could also occur due to an electrolyte abnormality or, rarely, even in what is

an otherwise normal heart. An electrolyte abnormality could be a high or low

potassium level. Ventricular fibrillation can also cause sudden cardiac arrest

and can lead to death if not treated immediately.65

Premature Ventricular Contractions

As previously mentioned, the heart is made up of four chambers - two upper

chambers (atria) and two lower chambers (ventricles) and the rhythm of the

heart is normally controlled by the sinus node. The sinus node is an area of

specialized cells located in the right atrium known as a natural pacemaker. It

produces electrical impulses and triggers the normal heartbeat. From the

sinoatrial node, electrical impulses travel across the atria to the ventricles.

This causes them to contract and pump blood to the lungs and body.11

Premature ventricular contractions are abnormal contractions that begin in

the ventricles. They are extra contractions that usually beat sooner than the

next expected regular heartbeat and often interrupt the normal order of

pumping from atria to the ventricles. What results is extra and out of sync

beats that is usually less effective at pumping blood throughout the

body.12,13


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Torsades de Pointes

Torsades de Pointes is also known as torsade de pointes, TdP, or torsade(s).

In translation from the French it means twisting of the points. It is a specific

type of abnormal heart rhythm and can lead to sudden cardiac death.

Torsades de Pointes is a polymorphic ventricular tachycardia and exhibits

distinct characteristics on an ECG or rhythm strip. Prolongation of the QT

interval can increase the risk a person has of developing this abnormal heart

rhythm.14-16

Asystole

Asystole is the absence of ventricular contractions that last longer than the

maximum time sustainable for life, which is about two seconds. Asystole is

the most serious form of cardiac arrest. It is usually irreversible.

A cardiac flat line, asystole, is the state of complete cessation of electrical

activity from the heart. This means no tissue contraction from the heart

muscle. It also means no blood flow to the rest of the body. As a state of

cardiac standstill, asystole involves no cardiac output. There is also no

ventricular depolarization. This occurs eventually in all dying patients. An

ECG rhythm strip confirms asystole.26

Bradyasystolic rhythms are slow rhythms. They can have a narrow or wide

complex with or without a pulse. They are often interspersed with periods of

asystole. Additionally, pulseless electrical activity (PEA) is a term that

applies to a group of dysrhythmias unaccompanied by a pulse that is

detectable. Concerning PEA, ventricular fibrillation and ventricular

tachycardia are excluded.26


23

Asystole can be diagnosed as primary or secondary. With primary asystole

the heart’s electrical system intrinsically fails to generate a ventricular

depolarization. This can result from ischemia or degeneration as with

sclerosis of the sinoatrial node or atrioventricular conducting system.

Usually, primary asystole is preceded by a bradydysrhythmia due to sinus

node block-arrest, complete heart block, or both.

When there is ocular surgery, retrobulbar block, eye trauma, direct pressure

on the globe, maxillofacial surgery, hypersensitive carotid sinus syndrome,

or glossopharyngeal neuralgia, the result can be reflex bradyasystole or

asystole. There are reports of episodes of asystole and bradycardia as

manifestations of left temporal lobe complex partial seizures. Patients

experienced either fainting or dizziness. There were no reports of sudden

death, but it was possible for asystole to persist with the longest interval

being 26 seconds.27

With secondary asystole, factors outside of the heart's electrical conduction

system result in a failure to generate any electrical depolarization. The final

common pathway is usually severe tissue hypoxia with metabolic acidosis.

Ventricular fibrillation asystole or bradyasystole follows and typically occurs

after unsuccessful attempts at defibrillation.26

Cardiac Arrest

A result of idiopathic degeneration of the sinoatrial or atrioventricular node

can be sinus arrest-block and/or AV heart block, respectively. While this

process is progressive and slow, the symptoms can be acute and result in

asystole or cardiac arrest. What is required for these conditions is usually an

implantable pacemaker. Asystolic sudden death can occur from congenital

heart block, cardiac trauma, or local tumor.


24

Primary and Secondary Asystole

When cellular metabolic functions are no longer intact and no electrical

impulse can be generated this is when primary asystole develops.

Implantable pacemaker failure can also be the cause of primary asystole.

Severe ischemia can create a situation where pacemaker cells cannot

transport the ions needed to affect the transmembrane action potential. With

proximal occlusion of the right coronary artery can come ischemia or

infarction of both the sinoatrial (SA) and the atrioventricular (AV) nodes.

With extensive infarction can come bilateral bundle-branch block, which is

infranodal complete heart block.

Secondary asystole can result from common conditions such as suffocation,

near drowning, massive pulmonary embolus, stroke, hyperkalemia,

hypothermia, myocardial infarction (MI) complicated by VF or VT that

deteriorates to asystole, post defibrillation, and sedative-hypnotic or narcotic

overdoses leading to respiratory failure. A special circumstance is

hypothermia. This is because asystole can be tolerated for a longer period

under such conditions and can be reversed with rapid rewarming while CPR

is being performed.26

Epidemiology of Asystole

It is difficult to measure accurately the number of adults in the U.S.,

identified with cardiopulmonary arrest who had bradyasystole as the initial

arrest rhythm. Reports vary plus could be skewed by the patient population

studied and/or by the method of reporting the initial rhythm. As an example,

a 1991 study reported on 185 patients in cardiopulmonary arrest at the time

of arrival to the emergency department. Of these patients, 9% had survived

to hospital admission but none were discharged alive. This study did not

report on patients with asystole only. In another Swedish study, asystole


25

was the presenting rhythm in the field in 35% of patients with cardiac

arrest.

Race is not a factor in asystole except when related to underlying conditions

that can lead to cardiac arrest. This includes chronic hypertension, coronary

artery disease, renal failure, congestive heart failure, or cardiac

dysrhythmias. When a certain race of people has a relatively low incidence of

coronary artery disease, asystole is relatively more common as a

manifestation of cardiopulmonary arrests. In this case, cardiac ischemia

more frequently results in ventricular fibrillation.

Concerning the factor of age, the prevalence of asystole as the presenting

cardiac rhythm is lower in adults (25-56%) than in children (90-95%).

Asystole is most likely found in cardiopulmonary arrests occurring in

children. This is typically secondary to another non-cardiac event meaning

respiratory arrest due to sudden infant death syndrome, chocking,

infections, drowning, or poisoning. An infant is more statistically likely to

suffer a cardiac arrest compared to an older child or adolescent.

In the Resuscitation Outcomes Consortium Epistry-Cardiac Arrest trial, non-

traumatic cardiac arrest occurred at a rate of 72.1 per 100,000 infants. This

is versus 3.73 per 100,000 in children and 7.37 per 100,000 in adolescents.

Investigators found the adult rate of cardiac arrest was 126.52 per 100,000.

This is when they evaluated 25,405 adults and 624 patients younger than 20

years. Pediatric patients with ventricular fibrillation or ventricular tachycardia

were 4 times more likely to survive an out-of-hospital cardiac arrest (20%)

than those with asystole (5%). Patients younger than 20 years had an

overall better survival rate than adults when all rhythms are included and

traumatic arrests are excluded.


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Concerning gender, the frequency of asystole, as a percentage of all

cardiopulmonary arrests, is higher in women than in men. The frequency of

cardiac arrest in general is proportional to the underlying incidence of heart

disease, which is more common in males until around age 75 years.26

Prognosis

The prognosis for asystole depends on the cause of the asystolic rhythm,

timing of interventions, and failure or success of advanced cardiac life

support. Resuscitation will likely be successful if it is secondary to an event

that can be corrected immediately. This is in a case such as cardiac arrest

due to choking on food and only if an airway can be established and the

patient may be rapidly re-oxygenated. There are occasions where reversal of

primary asystole is possible if it is due to pacemaker failure, which could be

either intrinsic or extrinsic, and if this is corrected immediately by external

pacing.

In general, the prognosis for asystole is not good regardless of its cause.

Individuals with post-counter shock asystole have an especially poor survival

rate. In the Termination of Resuscitation study, when no shock was advised

in patients with unwitnessed cardiac arrest, there were no survivors. In the

Goteborg, Sweden study, 10% of 1,635 asystolic patients survived to

hospital admission; and, only 2% survived to hospital discharge.

According to the American Heart Association (AHA) guidelines to improve

cardiocerebral resuscitation, improved outcomes in all adults with out of

hospital cardiac arrest was evident for ventricular tachycardia and

ventricular fibrillation only. Complications from asystole include permanent

neurologic impairment. Complications can also be due to cardiopulmonary

resuscitation (CPR) or conditions such as liver laceration, fractured ribs,


27

pneumothorax, hemothorax, aspiration, air embolus, and gastric/esophageal

rupture. It has been reported that death often occurs.26

Pulseless Electrical Activity

Pulseless electrical activity (PEA) or electromechanical dissociation involves

cardiac arrest where the electrocardiogram shows a heart rhythm that

should produce a pulse but does not. PEA is found at first in about 55

percent of people with cardiac arrest. In a normal circumstance electrical

activation of muscle cells precedes mechanical contraction of the heart. This

is known as electromechanical coupling. With PEA there is electrical activity,

however, the heart either does not contract or there is another reason this

results in an insufficient cardiac output to generate a pulse and supply blood

to the organs. This is classified as a form of cardiac arrest but significant

cardiac output can still be present. This may be determined and best seen

with a bedside ultrasound.28

Pulseless electrical activity is characterized by unresponsiveness and lack of

palpable pulse in the presence of organized cardiac electrical activity. A lack

of ventricular activity always implies a lack of ventricular mechanical activity

or asystole. The reverse is not always true as asystole does not always imply

a lack of ventricular activity. Electrical activity is a necessary but not

sufficient condition for mechanical activity. With cardiac arrest, organized

ventricular electrical activity is not necessarily accompanied by ventricular

mechanical activity that is meaningful. By meaningful ventricular activity,

this means a degree of mechanical activity that is sufficient to generate a

palpable pulse.

Pulseless electrical activity does not mean mechanical quiescence or cell

cycle arrest. A patient could have weak ventricular contractions plus a


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recordable aortic pressure or pseudo pulseless electrical activity. True

pulseless electrical activity refers to a condition where cardiac contractions

are absent and coordinated electrical activity is present. Pulseless electrical

activity can encompass a number of organized cardiac rhythms. These

include supraventricular rhythms as sinus versus non-sinus. They also

include ventricular rhythms as accelerated idioventricular or escape. An

absence of peripheral pulses is not necessarily indicative of pulseless

electrical activity. It could be due to severe peripheral vascular disease.28

Detecting a Heart Rhythm During PEA

Pulseless electrical activity (PEA) is evident on an ECG rhythm strip.

Pulseless electrical activity can also be known as electromechanical

dissociation. It refers to cardiac arrest in which the electrocardiogram shows

a heart rhythm that should produce a pulse, but does not. About half of

people in cardiac arrest are found initially with pulseless electrical activity.16

Normally, electrical activation of muscle cells precedes a mechanical

contraction of the heart. This is known as electromechanical coupling. With

PEA there is electrical activity. However, the heart either does not contract

or there is a reason this results in an insufficient cardiac output to generate

a pulse and supply blood to organs. Pulseless electrical activity is classified

as a type of cardiac arrest and significant cardiac output can still be present.

This can be determined and visualized best by a bedside ultrasound.16

The first treatment for PEA is cardiopulmonary resuscitation (CPR), which

commences while potential underlying causes are identified and treated.

Administration of medication, such as epinephrine, is possible. The rate of

survival is about twenty percent.16


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The condition of pulseless electrical activity leads to the loss of cardiac

output. In addition, the blood supply to the brain is interrupted. PEA is

usually observed when a person loses consciousness and stops

spontaneously breathing. Confirmation comes upon examining the airway for

obstruction plus observing the chest for respiratory movement plus feeling

the pulse usually at the carotid artery for a period of ten seconds.

Some in the medical community use a mnemonic to remember possible

causes. The mnemonic is six Hs and six Ts.

• Six Hs

1) Hypovolemia, 2) Hypoxia, 3) Hydrogen ions (Acidosis), 4) Hyper-

or Hypokalemia, 5) Hypoglycemia, and 6) Hypothermia.

• Six Ts

1) Tablets or Toxins (drug overdose), 2) Cardiac Tamponade,

3) Tension pneumothorax, 4) Thrombosis (for example, myocardial

infarction, pulmonary embolism), 5) Tachycardia, and 6) Trauma (for

example, hypovolemia from blood loss).

The above list is not comprehensive; for example, it does not include

anaphylaxis, but this list is a starting point. A clinical diagnosis of PEA can

also be connected to pressure effects associated with artificial ventilation

that can also contribute to significant reduction in cardiac output.

The possible mechanisms where conditions can cause pulseless in PEA are

those recognized as producing a circulatory shock state. These include

impairment of cardiac filling, impaired pumping effectiveness of the heart,

circulatory obstructions, and pathological vasodilation causing loss of

vascular resistance and excess capacitance. It is possible to have more than

one mechanism involved in a case.


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A clinical diagnosis of cardiac arrest is confirmed by the absence of a pulse.

However, distinguishing PEA from other causes of cardiac arrest can come

only with a device capable of electrocardiography. With PEA there is semi-

organized electrical activity in the heart in contrast to asystole (flatline) or to

disorganized electrical activity of ventricular fibrillation or ventricular

tachycardia.

Cardiopulmonary resuscitation should be initiated promptly to maintain

cardiac output until there is correction of the PEA. This is what ACLS/BCLS

cardiac resuscitation guidelines advise. In treating PEA, the approach is to

treat the underlying cause as known. For example, this could include

relieving a tension pneumothorax. When there is not a determination of the

underlying cause for the PEA or it cannot be reversed, treatment of pulseless

electrical activity can be similar to the treatment for asystole.

External cardiac compression may not increase cardiac output for any

situations involving PEA. This includes hemorrhage where impairment of

cardiac filling is the underlying mechanism that produces the loss of a pulse

that is detectable.

Medications should be provided through an intravenous or intraosseous line.

Drug therapy for PEA can include epinephrine 1 mg every 3-5 minutes. The

AHA in 2010 withdrew the recommendation of what was previously used

with atropine in the treatment of PEA/asystole. This was due to lack of

evidence for therapeutic benefit. Not recommended also is the routine use of

sodium bicarbonate except with special situations such as a preexisting

metabolic acidosis, hyperkalemia, or tricyclic antidepressant overdose. Any

administered drugs should go along with cardiopulmonary resuscitation


31

techniques. A cardiac defibrillator cannot correct this rhythm because the

problem lies in the response of technocardial tissue to electrical impulses.

Summary

An electrocardiogram is a recording of the electrical activity of the heart.

This allows a clinician to diagnose a patient’s heart rates and palpitations,

arrhythmia or dysrhythmia.

Several types of information can be determined from evaluating the cardiac

rhythm through an ECG, which indicates normal or abnormal cardiac

conditions. The classification system of cardiac rhythm refers to regular,

regularly irregular, or irregularly irregular. Cardiac rhythm is best analyzed

when looking at an ECG rhythm strip. An ECG is like a snapshot of the

heart’s activity at a moment in time, while the rhythm strip is a continuous

feed. Clinicians caring for cardiac patients should be able to analyze an

electrocardiogram rhythm strip using validated methods and they should

also be able to identify the classification system of cardiac rhythms, be able

to differentiate between the types of rhythms and know how to identify a

pacemaker rhythm as well as serious ventricular rhythms.

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1. An electrocardiogram (ECG) is best described as

a. a heart blood pressure monitor. b. a pacemaker. c. a recording of the electrical activity of the heart. d. electrodes that mimic the bundle of His.



a. True b. False



a. are the same for all ECGs so the graphs may be compared. b. depends on the polarization of the cardiac cells. c. are different for a resting ECG compared to an exercising ECG. d. depends on the size of the electrical fields.


a. the atrioventricular node. b. the atria. c. the ventricles. d. the sinus node.

5. These electrical signals spread through the heart as wave fronts

of

a. depolarization. b. polarization. c. augmentation. d. electrical fields.

6. An electrocardiograph may have a default setting to trace each

lead for

a. 2.5 seconds. b. 10 seconds. c. a minute of tracing. d. 12 heartbeats.


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7. True or False. Pulseless electrical activity is characterized by unresponsiveness and lack of palpable pulse in the presence of disorganized cardiac electrical activity.

a. True b. False

8. In the ECG, two leads are called _______________ leads if they

reflect neighboring anatomical areas.

a. split b. contiguous c. simultaneous d. remote

9. The 12-lead ECG uses ______ chest (precordial) leads.

a. two b. ten c. six d. four

10. True or False: When placing leads for a 12-Lead ECG, the RA

(right arm) lead should be placed on the right arm over an area with thick muscle.

a. True b. False

11. Which of the following transverse leads is placed at the fourth

intercostal space between ribs 4 and 5, just to the right of the sternum breastbone?

a. V1 b. V2 c. V4 d. V5


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12. Using the 6-second method with an irregular rhythm to estimate a heart rate, if there are seven R waves in a 6-second strip, the heart rate is

a. 60 (6-seconds x 10) b. 52 ((6 x 7) + 10) c. 130 ((6+7) 10) d. 70 (7 x 10)

13. When analyzing an ECG tracing, the clinician must first check

_______________________ across the strip.

a. P wave to P wave b. the QRS components c. R wave to R wave d. the T wave

14. The sinus node is an area of specialized cells located in the right

atrium known as

a. a natural pacemaker. b. the QRS components. c. the repolarization center. d. a natural electrocardiogram.

15. Which of the indictors of the ECG waveform indicates ventricular

repolarization?

a. The R wave b. The QRS components c. The P wave d. The T wave

16. Regularly irregular classification means the RR interval or PP

interval between beats

a. have no pattern. b. are the same. c. are haphazard. d. are different.


35

17. Regular classification refers to a normal heart rhythm or normal sinus rhythm that is the same as the ________ between 50 and 100 beats per minute.

a. P wave b. impulse c. pulse d. rhythm

18. True or False: An arrhythmia refers to a rapid, abnormal heart

rhythm, whereas a dysrhythmia is a condition of an irregularly slow heart rhythm.

a. True b. False

19. With a 12-lead ECG, rhythm is best analyzed when looking at a

10-second rhythm strip recording from lead II and the clinician should confirm or corroborate findings in lead II

a. by rechecking lead II. b. by looking at an ECG snapshot. c. by checking the patient’s pulse. d. by checking other leads.

20. Wolff-Parkinson-White (WPW) syndrome is a condition in which

there is

a. a bundle branch block. b. an irregularly irregular rhythm. c. a wandering atrial pacemaker. d. an extra electrical pathway in the heart.

21. After establishing a sinus rhythm, the heart rate is determined

and if the heart rate is too fast, the patient has

a. a sinus tachycardia. b. Wolff-Parkinson-White (WPW) syndrome. c. a sinus bradycardia. d. an irregularly irregular rhythm.


36

22. True or False: As with other vital signs such as blood pressure and respiratory rate, heart rate changes with age.

a. True b. False

23. A person can have an arrhythmia

a. only if the person has heart disease. b. only if the person has a heart injury or disease. c. if the person’s heart is healthy. d. None of the above

24. Paroxysmal supraventricular tachycardia is a rapid heart rate,

usually with

a. a regularly irregular rhythm. b. Wolff-Parkinson-White (WPW) syndrome. c. a regular rhythm. d. an irregularly irregular rhythm.

25. Electromechanical dissociation involves cardiac arrest where the

electrocardiogram shows a heart rhythm

a. a is regularly irregular. b. that is regular. c. that should produce a pulse but does not. d. that should not produce a pulse but does.


37

CORRECT ANSWERS: 1. An electrocardiogram (ECG) is best described as

c. a recording of the electrical activity of the heart. “An electrocardiogram (ECG or EKG) is a recording of the electrical activity of the heart.”



b. False “The rhythm strip output is different than a 12-lead ECG output in that a rhythm strip records the same leads (views of heart activity) across the entire ECG paper..... An ECG is like a snapshot of the heart’s activity at a moment in time, while the rhythm strip is a continuous feed.”



c. are different for a resting ECG compared to an exercising ECG. “The rhythm strip output is different than a 12-lead ECG output in that a rhythm strip records the same leads (views of heart activity) across the entire ECG paper. The placement of electrodes for the limb and augmented voltage leads are slightly different depending on whether the ECG is a resting or exercising one.”


d. the sinus node. “In a normal situation, depolarization of cardiac cells proceeds in an orderly fashion. This begins in the sinus node. It then spreads sequentially through the atria, atrioventricular node, and ventricles.”


38

5. These electrical signals spread through the heart as wave fronts of

a. depolarization. “These electrical signals spread through the heart as wave fronts of depolarization. The wave fronts result in minute electrical fields.”

6. An electrocardiograph may have a default setting to trace each

lead for

a. 2.5 seconds. “An electrocardiograph may have a default setting to trace each lead for 2.5 seconds. Longer settings of 6 or 10 seconds may be used to identify a pattern in the heart’s rhythm.”

7. True or False. Pulseless electrical activity is characterized by

unresponsiveness and lack of palpable pulse in the presence of disorganized cardiac electrical activity.

b. False. “Pulseless electrical activity is characterized by unresponsiveness and lack of palpable pulse in the presence of organized cardiac electrical activity.”

8. In the ECG, two leads are called _______________ leads if they

reflect neighboring anatomical areas.

b. contiguous “In the ECG, two leads are called contiguous if they reflect neighboring anatomical areas.”

9. The 12-lead ECG uses ______ chest (precordial) leads.

c. six “The 12-lead ECG uses three limb leads and three augmented limb leads that are arranged in a frontal plane. Six chest (precordial) leads are used to view the heart from the transverse or horizontal plane.”


39

10. True or False: When placing leads for a 12-Lead ECG, the RA (right arm) lead should be placed on the right arm over an area with thick muscle.

b. False “When placing the leads, the following locations and rules apply: RA (right arm): avoid thick muscle; LA (left arm): avoid thick muscle; RL (right leg): placed at the lower end of the medial aspect of the calf muscle, avoiding the bony prominences.”

11. Which of the following transverse leads is placed at the fourth

intercostal space between ribs 4 and 5, just to the right of the sternum breastbone?

a. V1 “When placing the leads, the following locations and rules apply: ... V1: placed at the fourth intercostal space between ribs 4 and 5, just to the right of the sternum breastbone.”

12. Using the 6-second method with an irregular rhythm to estimate

a heart rate, if there are seven R waves in a 6-second strip, the heart rate is

d. 70 (7 x 10) “Using the 6-second method with an irregular rhythm to estimate a heart rate, the number of R waves are counted in a 6-second strip and then multiplied by 10. For example, if there are seven R waves in a 6-second strip, the heart rate is 70, which is determined from 7x10=70. If there are eight R waves in a 6-second strip, the heart rate is 8x10=80.”

13. When analyzing an ECG tracing, the clinician must first check

_______________________ across the strip.

c. R wave to R wave “When analyzing an ECG tracing, the clinician must first check R wave to R wave across the strip.”


40

14. The sinus node is an area of specialized cells located in the right atrium known as

a. a natural pacemaker. “The sinus node is an area of specialized cells located in the right atrium known as a natural pacemaker.”

15. Which of the indictors of the ECG waveform indicates ventricular

repolarization?

d. The T wave “The T wave is normally a waveform that has an upward deflection and smaller than the QRS. This indicates ventricular repolarization.”

16. Regularly irregular classification means the RR interval or PP

interval between beats

b. are the same. “Regularly irregular classification means the RR intervals or PP intervals between beats are the same. With a sinus arrhythmia there is a cyclical acceleration of the heart rate with inspiration and slowing with expiration. The beat to beat interval is different. The rhythm is regularly irregular in that there is a pattern to the irregularity.”

17. Regular classification refers to a normal heart rhythm or normal

sinus rhythm that is the same as the ________ between 50 and 100 beats per minute.

c. pulse “Regular classification refers to a normal heart rhythm or normal sinus rhythm (NSR) for short. This normal sinus rhythm has a heart rate that is the same as the pulse between 50 and 100 beats per minute. It also has a normal impulse formation from the sinoatrial (SA) node (or P wave in the ECG).”


41

18. True or False: An arrhythmia refers to a rapid, abnormal heart rhythm, whereas a dysrhythmia is a condition of an irregularly slow heart rhythm.

b. False “An abnormal heart rhythm, referred to as an arrhythmia or dysrhythmia, is an abnormally slow or fast heart rate, or an irregular cardiac rhythm. Arrhythmia and dysrhythmia are words used to describe this same condition but in a different way: the word arrhythmia describes a condition in which a person does not have a regular heart rhythm, whereas dysrhythmia refers to an abnormal rhythm, so these terms mean the same thing.”

19. With a 12-lead ECG, rhythm is best analyzed when looking at a

10-second rhythm strip recording from lead II and the clinician should confirm or corroborate findings in lead II

d. by checking other leads. “Rhythm is best analyzed when looking at a rhythm strip. For a 12-lead ECG, this can be a 10 second recording from lead II. The clinician should confirm or corroborate findings in lead II by checking other leads. It can be helpful to look at a longer rhythm strip recorded at a slower speed.”

20. Wolff-Parkinson-White (WPW) syndrome is a condition in which

there is

d. an extra electrical pathway in the heart. “Irregular broad complex tachycardia includes ventricular fibrillation and polymorphic ventricular tachycardia, including torsades de pointes. Also included are atrial fibrillation with Wolff-Parkinson-White (WPW) syndrome (a condition in which there is an extra electrical pathway in the heart) and any irregular supraventricular tachycardia with aberrant condition.”


42

21. After establishing a sinus rhythm, the heart rate is determined and if the heart rate is too fast, the patient has

a. a sinus tachycardia. “After establishing a sinus rhythm, the heart rate is next determined by counting the (1 to 1) P waves and QRS complexes. If the rate is too fast, it is a sinus tachycardia. If the rate is too slow, it is a sinus bradycardia.”

22. True or False: As with other vital signs such as blood pressure

and respiratory rate, heart rate changes with age.

a. True “As with other vital signs such as blood pressure and respiratory rate, heart rate changes with age.”

23. A person can have an arrhythmia

c. if the person’s heart is healthy. “An arrhythmia can lead to a medical emergency. It can also be harmless. A person can have an arrhythmia if the person’s heart is healthy or when heart disease is present. Changes in the heart muscle, injury from a heart attack, healing after heart surgery, or the wrong balance of electrolytes in the blood including sodium or potassium can cause an arrhythmia.”

24. Paroxysmal supraventricular tachycardia is a rapid heart rate,

usually with

c. a regular rhythm. “Paroxysmal supraventricular tachycardia is a rapid heart rate, usually with a regular rhythm.”


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25. Electromechanical dissociation involves cardiac arrest where the electrocardiogram shows a heart rhythm

c. that should produce a pulse but does not. “Pulseless electrical activity (PEA) or electromechanical dissociation involves cardiac arrest where the electrocardiogram shows a heart rhythm that should produce a pulse but does not.”

Reference Section The References below include published works and in-text citations of published works that are intended as helpful material for your further reading. [These References are for a multi-part series on Basic Electrocardiography]. 1. Prutkin, J.M. (2017). ECG tutorial: Basic principles of ECG analysis.

UpToDate. Retrieved online at https://www.uptodate.com/contents/ecg-tutorial-basic-principles-of-ecg-analysis?source=search_result&search=electrocardiogram&selectedTitle=1~150.

2. O’Brien, T. (2016). Introduction to cardiac rhythm strip analysis. EKG.Academy. Retrieved online at https://ekg.academy/learn-ekg?courseid=318&seq=1

3. Tso, Colin, et al (2015). Electrocardiography: A Technologist’s Guide to Interpretation. Journal of Nuclear Medicine Technology. Vol. 43 no. 4 247-252.

4. Prutkin, J. (2017). ECG tutorial: Electrical components of the ECG. UpToDate. Retrieved online at https://www.uptodate.com/contents/ecg-tutorial-electrical-components-of-the-ecg?soure=search_result&search=6+second+method+ECG+rhythm+strip&selectedTitle=4~150

5. Goldberger, A. (2016). Basic principles of electrocardiographic interpretation. UpToDate. Retrieved online at https://www.uptodate.com/contents/basic-principles-of-electrocardiographic-interpretation?source=see_link


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6. Goldberger, A., et al (2017). Goldberger's Clinical Electrocardiography: A Simplified Approach, 9th ed; Retrieved from Elsevier, Philadelphia.

7. Mirvis, D.M. and Goldberger, A. (2014). Electrocardiography. In: Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 10th ed, Bonow, RO, Mann, DL, Zipes, DP, Libby, P (Eds), W.B. Saunders Company, Philadelphia

8. Sauer, W.H. (2017). Left bundle branch block. UpToDate. Retrieved online at https://www.uptodate.com/contents/left-bundle-branch-block?source=see_link

9. Jones & Barlett Learning. (n.d.). Rhythms. Retrieved online at http://samples.jbpub.com/9780763712846/12841_CH08_Garcia.pdf

10. Hampton, John R (2013). The ECG Made Easy (8th ed.). Retrieved from Edinburgh: Churchill Livingstone. p. 4. ISBN 9780702046421.

11. Mayo Clinic (2014). Premature ventricular contractions. Retrieved online at http://www.mayoclinic.org/diseases-conditions/premature-ventricular-contractions/basics/causes/con-20030205

12. Manolis, A. (2017). Supraventricular premature beats. Retrieved online at https://www.uptodate.com/contents/supraventricular-premature-beats?source=search_result&search=premature+ventral+contraction&selectedTitle=2~150

13. Conen, D., et al. (2012). Premature atrial contractions in the general population: frequency and risk factors. Circulation 126:2302.

14. Prutkin, J. (2015). ECG tutorial: Ventricular arrhythmias. UpToDate. Retrieved online at https://www.uptodate.com/contents/ecg-tutorial-ventricular-arrhythmias?source=search_result&search=torsades+de+pointes&selectedTitle=5~150

15. Seslar, S.P., et. al. (2014). Clinical features of congenital long QT syndrome. UpToDate. Retrieved online at https://www.uptodate.com/contents/clinical-features-of-congenital-long-qt-syndrome?source=search_result&search=torsades+de+pointes&selectedTitle=3~145

16. Baldzizhar, A., et al. (2016). Ventricular Tachycardias: Characteristics and Management. Critical care nursing clinics of North America; 28 (3): 317-29.

17. EKG.Academy. (2017). Introduction to pacemaker rhythms. Clinical Skills Education. Retrieved online at www.ekg.academy/pacemaker-rhythms.

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