EKG Interpretation

Just the beginning

King County

Introduction Cardiac monitoring has been

routinely used in the Fire Service for many years

Not without some liability Intent of this course is to provide

the basics in cardiac rhythm interpretation

Introduction cont. This course is not intended to teach

diagnosis of heart disease Lead II is not sufficient for EKG

diagnosis Recognition of the cardiac cycle will aid

in the understanding of EKG’s In order to remain proficient it is

necessary to commit time to ongoing training in EKG interpretation

Objectives

Understand basic cardiac terminology

Describe the anatomy of the heart Identify the electrical conduction

system Identify abnormal electrical cardiac

activity

Objectives

Identify common cardiac rhythms Identify and effect appropriate

therapy for the patient on a monitor

Course Completion

Participants are expected to pass a written exam and achieve a 70% score

Practical exam will include correct interpretation of static rhythms, 70% passing score

Primary Obligation It cannot be overemphasized that the

primary obligation for non-cardiac arrest patients is: ABC’s &

Attention to the patient’s symptoms Vital Signs, physical exam Any necessary treatment with

application of the monitor only when basic life support has been completed

Anatomy & Physiology

Heart is a muscle Divided into four chambers Receives blood from the body via

the inferior and superior vena cavae Chambers separated by valves Coronary arteries supply blood to

the myocardium

Electrical Conduction System

Specialized system of interconnected cells spread throughout the entire heart

Provides and conducts the signal to the heart muscle to contract in a coordinated fashion

Sinoatrial (SA) Node

Collection of electrical tissue that is the normal point of origin of electrical activity

Named because it is located in the sinus part of the atria

Generates “P” waves

Atrioventricular (AV) Node

A way station that receives the impulses from the atria

Named because it is located between the atria and the ventricles

Actually used to slow impulses from the atria to the ventricles

Bundle of His

Receives impulses from the AV node and passes them through the left and right bundle branches in the ventricular septum

Purkinje Fibers

Last receiving point of the electrical impulses

Fibers located in the ventricular musculature

Rapidly conducts impulses causing ventricular contraction

Automaticity

Any portion of the conduction system or heart muscle may initiate an electrical impulse

When the AV Node fails to generate an impulse, another cell/area of the heart will initiate electrical activity

Secondary Pacemakers

Any portion of the heart may initiate an electrical impulse and becomes a secondary pacemaker

Determining the location of a secondary pacemaker will become clearer as we proceed through this curriculum

Electrocardiographic paper

EKG paper

Grid of standard dimensions Simply used as a measurement of time Each small box represents 0.04

seconds Larger bolded boxes are .20 seconds Important to remember these values

as they aid in the identification of virtually all EKG strips

The Cardiac Cycle

P wave- indicates atrial “depolarization”

PR interval- the interval from the beginning of the P wave to the beginning of the QRS complex

PR interval represents the time from atrial depolarization to the beginning of ventricular repolarization

Cardiac Cycle Normal PR interval should not

exceed 0.2 seconds or one large bolded square on the EKG paper

QRS complex- represents electrical depolarization of the ventricle

Normal duration of the QRS complex is from 0.08-0.10 seconds (2 to 3 small boxes on the EKG paper

Cardiac Cycle T wave- represents repolarization of

the myocardium

Normal Sinus Rhythm

Characteristics- P wave for each QRS PR interval normal, <0.20 seconds QRS complex is normal, <0.10

seconds Uniform in shape Rate is regular and is between 60-

100

Normal Sinus Rhythm Most common rhythm seen in acute

MI Does not indicate that the patient is

stable or that there is an absence of heart disease

Indicates that the origin of the impulse is from the SA Node

Indicates normal function of the electrical system

Normal Sinus Rhythm

Normal Sinus Rhythm

Sinus Tachycardia

Characteristics- P wave for each QRS PR interval is normal, < 0.20 seconds QRS complex is narrow, < 0.10

seconds Uniform in shape Rate is regular, > 100/minute

Sinus Tachycardia

Accelerated discharge of electrical impulses from the sinus node

Treatment is “attention to symptoms”

Underlying cause is the concern Causes include; shock, stimulants,

acute MI where decrease in cardiac output causes heart rate increase

Sinus Tachycardia

Sinus Tachycardia

Supraventricular Tachycardia

P waves may not be seen due to accelerated rate

QRS complex is narrow, < 0.10 seconds

Uniform in shape Rate is regular, > 150/ minute Patient’s heart rate is too fast

Supraventricular Tachycardia

Supraventricular Tachycardia

Sinus Bradycardia

Characteristics- P wave for each QRS PR interval is normal, < 0.20 seconds QRS complex is normal, < 0.10

seconds Uniform in shape Rate is regular, < 60/ minute

Sinus Bradycardia Transmission of impulses from the

SA node is slowed to < 60/ minute Heart rates less than 50/ minute

should never be considered to be normal

Beta blockers, digoxin, hypoxia, being athletic or with history of a slow heart rate can be the cause

Patient’s heart rate is too slow

Sinus Bradycardia

Sinus Bradycardia

Premature Ventricular Contractions Characteristics- Early occurring beats that have a

characteristic “compensatory pause”

Premature QRS complex that is wide and bizarre, conduction time > 0.10 seconds

Same shape except when from different focus in the heart

Premature Ventricular Contractions Can occur in a healthy individual Viewed with caution in the patient

who presents with cardiac symptoms

Significant if: occur in 2’s (couplets), 3’s (triplets),run of 4 is Ventricular Tachycardia

Frequent occurring with syncope be cautious

Premature Ventricular Contractions

Ventricular Tachycardia

Characteristics- P waves are usually present but are

obscured by wide, rapidly occurring QRS complex

QRS complex is wide > 0.10 and bizarre

Uniform in shape typically Rate is regular and > 150/ minute

Ventricular Tachycardia

Life threatening arrythmia Rapid rate decreases cardiac output Place patient supine, anticipating

shock Cause can be electrical and not

always acute MI If patient unconscious and pulseless

is a a shockable rhythm

Ventricular Tachycardia

Ventricular Tachycardia

Idioventricular Rhythm

Characteristics- P waves typically obscured or follow

the QRS complex QRS complex is wide, > 0.10

seconds Sometimes uniform in shape Rate is irregular, most often seen

with rate < 40/minute

Idioventricular Rhythm Observed after defibrillation & can be

endpoint in arrest resuscitation attempt Conduction system above the ventricles

fails to generate an electricle impulse Inherent rate of 30-40/minute Will likely be in cardiac arrest If unconscious and B/P <60, initiate CPR

Idioventricular Rhythm

Ventricular Fibrillation

Characteristics- P waves are absent QRS complex absent Baseline wavy, chaotic and

inconsistent Rhythm irregular Rate is not countable

Ventricular Fibrillation

Sudden death & cardiac arrest immediately follow the onset

Immediately defibrillate with 200 joules and proceed with standing orders

Remember that we now do CPR for 2 minutes between shocks

Asystole

Characteristics- P waves are not present QRS complex is not present Absence of any complexes indicate

complete cessation of electrical activity

The heart is motionless

Asystole

Pacemakers

Characteristics- P waves sometimes are visible but

are not associated QRS complex of times is wide, >

0.10 seconds Preceded by a small spike with

either a negative or positive deflection

Pacemakers

Presence of a pacemaker indicates that there is an underlying rhythm disturbance, usually heart block

Technology makes it harder to see when they are present

Failure can occur, look for pacer spikes without complex initiated

Pacemakers

Look for the presence of Ventricular Fibrillation in the patient who is in cardiac arrest

Spikes will appear even in the presence of fibrillatory waves

Paced Rhythm

Paced Rhythm (AV Sequential)

Atrial Pacemaker

Pacemaker Failure

Sinus Arrhythmia

Characteristics- P waves for each QRS PR interval is < 0.20 seconds QRS complex is narrow, < 0.10

seconds Rate varies, will speed up during

inhalation and slow down on expiration

Sinus Arrythmia

This rhythm is commonly found in healthy children or athletic adults

Treat specific complaint or injury

Sinus Arrythmia

Atrial Flutter Characteristics- P waves are referred to as flutter waves

and are uniform in shape, resembling a sawtooth pattern, mirror effect

QRS complex is narrow, < 0.10 seconds Rate is both regular and irregular Can be rapid, often seen at 150/minute

Atrial Flutter

This rhythm is rarely seen in patients with healthy hearts

Can be seen in patients with heart disease, acute MI, lung disease and pulmonary embolism

Likes to go fast, needs ALS eval and is never normal for patients

Atrial Flutter

Atrial Fibrillation

Characteristics- P waves are not clearly visible or

uniform for each QRS complex QRS complex is typically narrow,

but can be wide Is irregular-irregular, depending on

ventricular response can be rapid

Atrial Fibrillation Cells within the atria fire chaotically Will be observed to have a rapid

ventricular response with new onset Digoxin, beta blockers, calcium channel

blockers can be used to control rate Also coumadin prescribed to reduce the

incidence of clots in the heart chambers

Atrial Fibrillation

Atrial Fibrillation

Atrial Fibrillation

Atrial Fibrillation

Nodal Rhythm

Characteristics- P waves are absent QRS complex is narrow, < 0.10

seconds Uniform in shape Rate is regular, typically >

40/minute but may be in excess of 100/minute

Nodal Rhythm Nodal rhythm occurs when the SA

node fails to function Expect to see narrow QRS complex,

<0.10 seconds Can be caused by Digitalis Toxicity,

acute MI, hypoxia, diseased sinus node

In some patients this may be their normal rhythm

Nodal Rhythm

Nodal Rhythm

Accelerated Nodal Rhythm

First Degree Heart Block

Characteristics- P wave for each QRS PR interval is >0.20 seconds Rate is regular QRS complex is narrow, < 0.10

seconds Uniform in shape

First Degree Heart Block

Occurs when there is delayed conduction of an impulse through the AV node

Patients presentation dictates need for intervention

Some patients may have first degree heart block as their primary rhythm

First Degree Block

First Degree Heart Block

First Degree Heart Block

First Degree Heart Block

Second Degree Heart BlockWenckebach, Mobitz Type 1

Characteristics- P waves are present P wave occurs at a regular rate QRS complex is uniform in shape

and narrow, <0.10 seconds PR interval progressively lengthens

until QRS complex is dropped

Wenckebach, Mobitz Type 1 Sinus impulse is progressively

delayed through the AV node until no conduction occurs

Causes include ischemic heart disease, acute MI, digitalis toxicity

Patient’s presentation determines intervention, if ventricular rate is slow the patient may not have symptoms

Wenckebach, Mobitz Type 1

Wenckebach, Mobitz Type 1

Wenckbach, Mobitz Type 1

Second Degree Heart Block Mobitz Type II

Characteristics- P waves are present P waves occur at a regular rate PR interval is fixed , may be

prolonged On occasion there will be more than

one P wave for each QRS complex

Mobitz Type II QRS complex may be narrow, <

0.10 or may be wide, > 0.10 Series of non conducted P waves

may be seen (atrial depolarization only)

Ratio at which the QRS complex is conducted varies and is noted as a ratio, 2:1, 3:1, etc. (#P’s for each QRS complex)

Mobitz Type II Most often seen in the setting of

acute MI Frequently have syncope

associated due to the slow rate Commonly progresses to complete

heart block ALS evaluation paramount, since

patient will often times be in shock

Mobitz Type II

Mobitz Type II

Mobitz Type II

Third or Complete Heart Block Characteristics- P waves occur at a regular interval,

typically at a rate of 60-100 beats/min.

P waves do not have a fixed, or constant relationship to the QRS complex

PR interval abnormally prolonged, > 0.20 and changing

Complete Heart Block QRS complex may be narrow, <

0.10 or wide, > 0.10 depending on where in the heart the impulse originates

QRS rate is usually constant, typically between 20-40 beats/min.

Indicates that there is no transmission of impulses between the atria and the ventricles

Complete Heart Block Often occurs in the setting of acute MI Can occur with Digitalis toxicity,

elderly with conduction system problems

May present with syncope This type of heart block may be

transient ALS evaluation paramount, since

patient will often times be in shock

Complete Heart Block

Complete Heart Block

Complete Heart Block

P.E.A.Pulseless Electrical Activity

Characteristics- P waves may be present PR interval may be normal, < 0.20

sec. QRS complex may be narrow, < 0.10

or wide, > 0.10 Rate can be regular or irregular Can be normal rhythm

P.E.A

Pulseless Electrical Activity is indicated by the absence of a detectable pulse and the presence of some type of electrical activity

Seen during cardiac arrest secondary to acute MI, pulmonary embolus, cardiac tamponade, tension pneumothorax or a hypovolemic state

P.E.A. (sinus tachycardia)

Treatment Protocols Do not attempt to treat any patient

from what is seen on the monitor alone, unless V. Tach with unconsciousness or V. Fib.

Patient presentation will direct intervention

Request ALS evaluation when possible lethal arrythmias are identified

Ongoing Education It is recommended that EMT’s receive

regular ongoing education to remain proficient at EKG recognition

Quarterly review/refresher by a paramedic or equivalent

Attach EKG strips to your MIRF forms for department reviewer for feedback and identification confirmation

EKG Interpretation

Questions?

The end or just the beginning?