EKG
CARDIOVASCULAR
ANATOMY &
PHYSIOLOGY
Basic Heart Anatomy
▪ The heart is a muscle made of 3 layers
▪ Pericardium aka= pericardial sac is a connective tissue
layer around the heart
1. Epicardium is the smooth outer surface of the heart
2. Myocardium is the muscular middle layer of heart tissue
▪ It is made of cardiac muscle cells that give the heart the
ability to contracts to push out blood
3. Endocardium is the innermost layer of the heart
 made up of smooth thin connective tissue
 This smooth layer allows blood to flow easily throughout the heart
Basic Heart Anatomy
▪ The heart is a muscle
▪ Referred to as a 2 sided PUMP
▪ Right side
▪ Left side
▪ Each side has 2 hollow chambers ( total of 4
chambers
▪ 2 upper chambers are called=Atrium ( singular)
Atria ( plural)
▪ 2 lower chambers are called = Ventricle(s)
Heart Anatomy- CONTINUED
▪ Both upper chambers receive blood back to the heart
▪ RA- receives blood from the superior & inferior vena
cava
▪ LA- receives blood from the lungs
▪ Both lower chambers pump blood away from the heart
▪ RV – pumps blood to the lungs for re-oxygenation
▪ LV- pumps blood into the systemic circulation
Basic Heart Anatomy
▪ Valves of the Heart
♥The 4 valves of the heart allow blood to flow only in one direction
♥There are 2 sets of valves
♥Atrioventricular valves
♥Are located between the atria and the ventricles
♥Right sided valve is the tricuspid valve
♥Left sided valve is the bicuspid valve or the mitral valve
♥Semilunar valves
♥ Serve to prevent blood from flowing back into the ventricles
♥Right sided semilunar valve = Pulmonary valve is located between the
right ventricle and the pulmonary artery
♥Left sided semilunar valve = Aortic valve is located between the left
ventricle and the trunk of the aorta
Heart AnatomyCONTINUED
Atria
Are the 2 upper chambers
(LEFT & RIGHT)
Upper chambers are located
in what is called the BASE of
the heart
Ventricles
Are the 2 lower chambers
(LEFT & RIGHT )
Lower chamber are located
in what is called the APEX of
the heart
Heart
AnatomyCONTINUED
• Blood flow through the
heart
•Refer to handout on
cardiac/pulmonary
circulation
•Heart Blood Flow
Animation
Basic
Physiology
of the Heart
CARDIAC CYCLE
STROKE VOLUME
CARDIAC OUTPUT
AUTONOMIC NERVOUS SYSTEM
Cardiac Cycle
♥ The heart functions as a unit:
♥ Both atria contract simultaneously then both ventricles contract
♥ Blood is ejected into both the pulmonary and systemic circulation when the
ventricles contract
♥ Both the tricuspid and mitral valves will also close during ventricular contraction
♥ The cardiac cycle=Represents the time sequence between ventricular
contraction and ventricular relaxation
♥ Systole is ventricular contraction
♥ Diastole is ventricular relaxation
♥ SO--- One cardiac cycle is equal to one systole and one diastole of the ventricle
or one heart beat
♥ In a normal heart the cardiac cycle lasts for 0.8 seconds
Stroke Volume
♥ Stroke volume (SV)= is the amount or volume of
blood pumped out of the one ventricle in a single
beat or contraction
♥ Normal SV is 70 cubic centimeters (cc) per beat
♥ The number of contractions or beats per minute
is known as the heart rate
♥ The normal heat rate in an adult is 60-100 beats
per minute
Cardiac Output
♥ Cardiac output is the amount of blood PUMPED by the
LEFT VENTRICLE in ONE MINUTE
♥ The formula for Cardiac Output is:
♥CARDIAC OUTPUT(CO) = STROKE VOLUME (SV) X HEART
RATE (HR)
HR= 80
SV= 70 cc
What is the Cardiac Output of this patient in cc’s_______
and in _______liters????
Cardiac Output
▪ Inadequate, CO will result in patients having any of
the following symptoms:
▪Shortness of breath
▪Dizziness
▪Drop in blood pressure
▪Chest pain
▪Cool and clammy skin
PRELOAD and AFTERLOAD
♥ PRELOAD
▪ Pre-load is the filling pressure of the heart, the pressure the
heart has when it is relaxing. (Volume- In)
♥ Afterload
▪ is the RESISTANCE against which the heart must pump
▪ After-load is the pressure of the contracting heart. (Resistancepush- Out)
▪ This pressure will greatly affect the stroke volume and the
cardiac output
Autonomic Nervous System
▪ ANS regulates functions of the body that are INVOLUNTARY
▪ Both HR and BP are regulated by this component of the nervous
system
▪ There are 2 major divisions of the nervous system:
▪sympathetic and parasympathetic
▪ The major organs of the body are innervated by both systems with
the exception of blood vessels which are only innervated by the
sympathetic system
Sympathetic Nervous System
▪ Sympathetic nervous system (or Adrenergic)
▪ 1. Accelerates the heart
▪ 2. Two chemicals are influenced by the sympathetic system –
▪ epinephrine & norepinephrine
▪ 3. These chemicals increase heart rate, contractibility,
automaticity, and AV conduction
Parasympathetic Nervous System
▪ Parasympathetic nervous system ( or Cholinergic)
▪ 1. Slows the heart
▪ 2. The vagus nerve is one of this systems nerves,
when stimulated slows heart rate and AV
conduction.
Basic Electrophysiology
Basic Cell Groups
▪ The heart is made up of thousands of myocardial cells
▪ There are 2 basic myocardial cell groups:
▪ myocardial working cells
▪ pacemaker cells of the electrical conduction system
▪ MYOCARDIAL CELLS responsible for generating the physical contraction an
d relaxation of the heart muscle
▪ PACEMAKER CELLS
▪ do not contain contractile fragment and can not contract
▪ Responsible for controlling the rate & rhythm of the heart by regulating
depolarization
Characteristics of Cardiac Cells
Cardiac cells possess primary cell characteristics:
 Extensibility
 Ability to be stretched
▪ Excitability
▪ Ability of cardiac cells to respond to electrical stimulation
▪ Conductivity
▪ Ability of cardiac cells to receive electrical stimulation and transmit the stimulus to
other cells
▪ Contractility
▪ Ability of cells to shorten and cause a muscle contraction
▪ Automaticity
▪ Ability of cardiac pacemaker cells to make their own electrical impulses
ELECTRICAL CELLS OF THE HEART
▪ Electrical cells
▪ a) Make up the conduction system of the heart
▪ b) Are distributed in an orderly fashion through the heart
▪ c) Possess specific properties
▪ (1) automaticity – the ability to spontaneously generate and
discharge an electrical impulse
▪ (2) excitability – the ability of the cell to respond to an electrical
impulse
▪ (3) conductivity – the ability to transmit an electrical impulse from
one cell to the next
MYOCARDIAL CELLS
▪ Myocardial cells
▪ a) Make up the muscular walls of the atrium and
ventricles of the heart
▪ b) Possess specific properties
▪ (1) contractility – the ability of the cell to shorten
and lengthen its fibers
▪ (2) extensibility – the ability of the cell to stretch
Major Electrolytes that Affect Cardiac Function
An electrolyte is a substance with charged components
producing positive and negative charged ions
▪ a positive ion is called a cation
▪ a negative ion is called a anion
 3 major cations that affect heart muscle are:
Potassium
Sodium
Calcium
Magnesium
K+
Na+
Ca+
Mg
DEPOLARIZATION & REPOLARIZATION
▪ Depolarization and Repolarization
▪ 1. Cardiac cells at rest are considered polarized, meaning no
electrical activity takes place
▪ 2. The cell membrane of the cardiac muscle cell separates different
concentrations of ions, such as sodium, potassium, and
calcium. This is called the resting potential
▪ 3. Electrical impulses are generated by automaticity of specialized
cardiac cells
▪ 4. Once an electrical cell generates an electrical impulse, this
electrical impulse causes the ions (Na+ rush into the cell making
inside more +) cross the cell membrane and causes the action
potential, also called depolarization
Depolarization & Repolarization
Continued
▪ 5. The movement of ions across the cell membrane through
sodium, potassium and calcium channels, is the drive that causes
contraction of the cardiac cells/muscle
▪ 6. Depolarization with corresponding contraction of myocardial
muscle moves as a wave through the heart
▪ 7. Repolarization is the return of the ions to their previous resting
state, which corresponds with relaxation of the myocardial muscle
▪ 8. Depolarization and repolarization are electrical activities which
cause muscular activity
▪ 9. This electrical activity is what is detected on ECG, not the
muscular activity
Conduction System
THE PATH OF AN ELECTRICAL SIGNAL
▪ Step One: The S-A node creates an electrical signal
▪ The S-A node controls your heart rate, it is called your heart's "natural pacemaker." Electrical signals created by
the S-A node travel down pathways to the A-V node creating the P WAVE
▪ It has as inherent rate of 60-100 bpm
▪ Step Two: The signal follows natural pathways through both atria. This causes the blood to contract, pushing blood
into the ventricles
▪ Step Three: The signal reaches the A-V node. There, the signal pauses very briefly to give the ventricles time to fill
with blood.
▪ This delay is seen as the PR interval
▪ Step Four: The signal spreads through the His-Purkinje system. This makes the ventricles contract, pushing blood
out to your lungs and body.
▪ This generates the QRS complex
▪ Bundle of His have pacemaker cells that can self-initiate a rate of 40-60 bpm
▪ Purkinje pacemaker fibers are normally within 20-40 bpm
Electrical Conduction VIDEO
▪ Electrical Flow in the Heart
EKG Conduction Animation
▪ Conduction and EKG Waveform Animation
The Electrocardiogram
EKG or ECG
▪ Graphic representation of the electrical activity of
the heart
▪ It is a tracing of the electrical activity of the heart
NOT the mechanical activity
▪ The machine used to record the activity is called
an: electrocardiograph
▪ It is a diagnostic tool
Information Obtainable from
EKG RHYTHM ANALYSIS
▪ Heart Rate
▪ Rhythm & regularity
▪ Impulse conduction time intervals
▪ Abnormal conduction pathways
▪ WE CANNOT HOWEVER determine:
▪ Pumping action
▪ Cardiac output
▪ Blood pressure
▪ Cardiac muscle hypertrophy
EKG Machine
▪ An EKG machine is a voltmeter– it reads electrical energy from the
body
▪ The heart uses electrical energy to contract muscles
EKG LEADS and ELECTRODES
▪ ELECTRODE is the adhesive pad that contain conductive gel and is placed on the
patients skin
▪ LEADS are the wires that are then connected to the electrode – they are color coded
to be user-friendly
▪ In order for the machine to give a clear picture– there must be a positive, negative
and ground lead
▪ EKG will look at the heart from the positive lead to the negative lead and gives a
different view of the heart
▪ The exact portion of the heart being visualized depends on lead placement
▪ This allows for observation of electrical activity in many different parts of the heart
3 Lead EKGUsed for continuous patient monitoring
▪ A 3 lead ECG is considered non-diagnostic so it does not provide a clear
view of the entire heart, but instead a basic view of the electrical
pathway of the heart triangulated between the 3 leads.
▪ 3-lead is usually used on transport monitors, and monitors two different
areas of the heart (one lateral, two inferior).
▪ The 3 lead ECG is usually simple to use and most have standardized
color coded placement of the 3 electrode leads. These are the most
common 3 lead ECG placements:
▪ 3-electrode system
- Uses 3 electrodes (RA, LA and LL).
- Monitor displays the bipolar leads (I, II and III)
- To get best results – Place electrodes on the chest wall equidistant
from the heart
Will give us a view of the top, lateral, and inferior portion of
the heart
EKG Leads I,II, III
▪ Lead I
▪ is the voltage between the (positive) left arm (LA) electrode and
right arm (RA) electrode:
▪ Lead II
▪ is the voltage between the (positive) left leg (LL) electrode and the
right arm (RA) electrode:
▪ Lead III
▪ is the voltage between the (positive) left leg (LL) electrode and the
left arm (LA) electrode:
AUGMENTED LEADS: LIMB LEADS
PLEASE NOTE THE FOLLOWING:
Definition: electrocardiogram recorded between one limb
and two other limbs. The augmented leads are designated
aVF, aVL, and aVR for recordings made between the foot
(left), left arm, and right arm, respectively, and the other
two limbs
▪ The same three leads that form the standard leads also
form the three unipolar leads known as the augmented
leads. These three leads are referred to as aVR (right
arm), aVL (left arm) and aVF (left leg) and also record a
change in electric potential in the frontal plane.
▪ These leads are unipolar in that they measure the electric
potential at one point
5 Lead EKG
▪ This configuration refers to the standard Holter
monitor or the 5 lead rhythm setup
White lead=right sternum/clavicle area
Black lead=left sternum/clavicle area
Red lead=left lower thoracic area
Green lead=right lower thoracic area
Brown lead= just below and to the right of the
bottom of the sternum
12 LEAD EKG
▪ Definition- A representation of the heart’s electrical activity recorded
from 10 electrodes placed in standard positions on the body surface.
▪ Analogy- Envision the heart as an object placed on a pedestal around
which a person can move while taking photographs (different views)
from all angles.
12 Lead EKG
Provides a Cross Sectional View of the Heart
▪ 12-lead ECG
- 10 electrodes required to produce 12lead ECG.
- Electrodes on all 4 limbs (RA, LL, LA,
RL)
- Electrodes on precordium (V1–6)
V1 @4th IC right of sternum
V2 @ 4th IC left of sternum
Leads I,II,II are bipolar= this means
they have one positive and one
negative electrode ( limb leads)
-Allows the best interpretation of
specific areas of the heart
V3@ between V2/V4
- Inferior (II, III, aVF)
- High Lateral Wall(I, aVL)
V4 @ 5th IC midclavicular
-Lower Lateral Wall( V5, V6)
V5 5th IC between V4/V6
-Septal View (V1-V2)
V6 @ 5th IC midaxillary
-Anterior View (V3-V4)
Precordial LEAD Placement
of the 12 lead EKG
V1 @4th IC right of sternum
V2 @ 4th IC left of sternum
V4 @ 5th IC midclavicular
V3 @ between V2/V4
V6 @ 5th IC midaxillary
V5 5th IC between V4/V6
Lead Placement
Visual
12 Lead EKG
12 LEAD EKG
PLACEMENT VIDEO
Lead Placement and Heart Views
EKG Graph Paper
▪ Arranged in a series of horizontal and vertical lines and squares
▪ Standard in all health care settings
▪ Moves at a constant speed of 25 millimeters per second
▪ Both time and amplitude are measured on EKG graph paper
▪ Time is measured on the HORIZONTAL line
▪ Amplitude is measured on the VERTICAL line
▪ Divided into small squares, each of which is 1 mm in width and equals a time
interval of 0.04 second
▪ Darker lines further divide every 5th square, both vertically and horizontally
▪ Each larger square measures 5 mm in height and 5 mm in width and represents
a time interval of 0.20 second
EKG Paper and Markings
▪ Divided into small squares, each of which is 1 mm in width and equals a time
interval of 0.04 second
▪ Darker lines further divide every 5th square, both vertically and horizontally
▪ Each larger square measures 5 mm in height and 5 mm in width and represents a
time interval of 0.20 second
▪ 5 of the large squares all equal one second noted by the small line on the
very top of the paper
▪ Most practitioners will print a 6 second strip to interpret a patients rhythm
▪ The squares of on the EKG paper represent the measurement of the length of
time required for the electrical impulse to traverse a specific time in the
heart
EKG Paper and Markings
EKG Paper and Markings
EKG Waveforms
P Wave
▪ P wave
▪
▪
▪
▪
Impulse fired by the SA node
The p wave is a smooth rounded upward deflection
Represents depolarization of the atria
It is 0.1 second in duration
PR Interval
 Represents the time interval for the impulse to travel for the SA
node through the internodal pathway toward the ventricle
 Normal PR interval is 3-5 small boxes or 0.12 – 0.20 second in
length
QRS Complex
▪ Represents the conduction of the impulse from the Bundle of His
through the ventricle muscle or ventricle depolarization
▪ QRS measures less than 0.12 second or less than 3 small boxes
on the EKG graph paper
ST Segment
▪ Represents the time interval which the ventricles are depolarized
and ventricular repolarization
▪ ST segment is ISOELECTRIC or at baseline
T Wave
▪ Represents ventricular repolarization
▪ Resting phase of the cardiac cycle
U Wave
▪ The U wave is a wave on an electrocardiogram that is not always seen
▪ typically small, and, by definition, follows the T wave
▪ U waves are thought to represent repolarization of the Purkinje
fibers.[1]
How is an EKG Interpreted?
▪ Read strip from left to right
▪ Apply the 5 step approach that you will learn
▪ Ask and answer each question in the 5 step
approach
▪ You must master the accepted parameters for
each dysrhythmia and then then apply those
parameters to each of the 5 steps when analyzing
the strip.
FIVE STEP APPROACH
▪ Step 1: What is the rate?
▪ Step 2: Is it regular?
▪ Step 3 : Is the complex narrow?
▪ Step 4: Is there a P WAVE?
▪ Step 5: Do all the complexes look the same?
STEP ONE & the 6 Second Method
▪ What is the rate?
▪ Count the number of QRS complexes or number of
ventricular beats in one minute -▪ Normal heart rate is 60-100 bpm
▪ 6 second method
▪Simply count the number of QRS complexes in either
3 or 6 second strip
▪If a 3 second strip is used– X by 20
▪If a 6 second strip is used – X by 10
6 Second Strip
3 And 6 second Illustrations
STEP 2
▪ Asks if the rhythm is regular?
▪ Rhythms that originate from the normal pacemakers in the heart will be regular
▪ IRREGULAR rhythms indicate extra or abnormal beats
▪ Looks at the patterns of your QRS complexes
▪ All heart rhythms are classified as regular or irregular
▪ You should use EKG calipers or use a piece of paper and mark r-r wave distance
1. Measure your R-R interval to determine Ventricular regularity
2. Measure your P-P waves for atrial regularity
STEP 3
▪ Is the complex narrow?
▪ Narrow complexes are normal
▪ Wide QRS complexes indicated a conduction abnormality
▪ Normal QRS width is 0.12 second or less than 3 small boxes
▪ Wide QRS or greater than 0.12 second or more than 3 small
boxes ( ventricular in origin)
▪ Narrow QRS less than 0.12 second may indicate a
supraventricular rhythm
NARROW & WIDE QRS Complexes
Step 4
▪ ASK– IS THERE A P WAVE????????? Preceding the QRS complex?
▪ A P-wave before the QRS represent normal conduction from the atria
to the ventricles
▪ If there is NO P wave---- the impulse is being generated from
ELSEWHERE IN THE HEART AND IS NOT A SINUS RHYTHM
Step 5
▪ Do all the complexes look the same?
5 STEP APPROACH to EKG Interpretation
1. What is the rate?
2. Is it regular?
3. Are the QRS complexes narrow?
4. Is there a P WAVE? ( Is there a P WAVE before each
complex?) Is the PRI normal ?
5. Do all the QRS complexes look the same?
Normal P wave, Absence of P wave, Abnormal
P Wave
Step 5
▪ Do all the complexes look the same?
▪ Normal conductions follows the same pathway with each
beat
▪ Different looking complexes indicate that some impulses
are following alternative or aberrant pathways
Conclusion of the 5 STEP METHOD
▪If you can answer affirmatively to
all of the 5 steps then your patient
has a Normal Sinus Rhythm or
NSR
Normal Sinus RHYTHMS
▪Normal Sinus Rhythm or NSR
▪ Rate 60-100
▪Sinus Bradycardia--▪ Rate is LESS THAN 60
▪Sinus Tachycardia–
▪ Rate is GREATER THAN 100 but not more
than 140
Atrial
RHYTHMS
ATRIAL
FIBRILLATION
ATRIAL FLUTTER
SVT/PSVT
Rhythms That Originate in the Atria
▪ Atrial Fibrillation
▪ Atrial Fibrillation with Rapid Ventricular
Response
▪ Atrial Flutter
▪ Supraventricular Tachycardia
EKG Findings Common to ATRIAL RHYTHMS
▪ P wave absent or has an abnormal shape
▪ Fibrillatory waves present– commonly
called f waves
▪ Flutter waves present
▪ QRS is narrow
Atrial Fibrillation
▪ Atrial fibrillation produces a rapid and irregular heartbeat
▪ The atria (the upper two chambers of the heart that receive
blood) quiver, or fibrillate, instead of beating normally
▪ impulses come from all over the atria, triggering 300 to 500
contractions per minute within the heart’s upper chambers
▪ the atrioventricular node becomes overwhelmed by impulses
▪ the result is an irregular and rapid heartbeat (80 to 160
beats per minute versus normal 60 to 100 beats per minute).
▪ Atrial Fibrillation
Atrial Fibrillation
Atrial Fibrillation
▪ P wave---none or fibrillation waves
▪ PR interval—none
▪ QRS—less than 0.12 seconds
▪ Ventricular rate—60-100 bpm
▪ Atrial rate( if different than the ventricular rate)– 300-600/min
▪ Complexes look similar
▪ RHYTHM__ IS IRREGULAR
▪ FYI- if the rate is less than 100 = controlled
▪ If the rate is greater than 100= rapid ventricular response or RVR
TREATMENT
▪ Medications
▪ Cardioversion
▪ Ablation surgical procedures
Atrial FLUTTER
▪ Typical atrial flutter results from a single “short-circuit” in the right atrium.
▪ This short-circuit causes the atria to beat at about 300 beats per minute
while the lower chamber of the heart (the ventricles) beat at a slower rate
(often 75 to 150 beats per minute
▪ Atrial flutter is similar to Atrial fibrillation
▪ It differs from atrial fibrillation (AF) in that the heartbeat is regular, not
irregular.
▪ Will see characteristic FLUTTER waves that are saw-tooth in shape
Atrial Flutter
▪ P wave- none– Flutter waves
▪ PR interval– NONE
▪ QRS -- less than 0.12 seconds
▪ Ventricular rate– 60-100 – but can be as high as
130-160
▪ Atrial rate– 240-320/ min
▪ Complexes will look similar
▪ RHYTHM is REGULAR
Atrial Flutter
Atrial FLUTTER Treatment
▪ Medications
▪ Ablation Therapy
Supraventricular Tachycardia - PSVT
( Paroxysmal SVT)
▪ Most episodes of SVT are caused by faulty electrical connections in
the heart
▪ Supraventricular tachycardia (SVT) is a rapid heart rhythm
originating at or above the AV node.
▪ SVT rates are above 100 beats per minute and are typically 150250 bpm.
▪ SVT’s rapid heart rate does not allow the ventricles to completely
fill with blood, decreasing cardiac output.
SVT/PSVT
▪ P-wave- hard to find– if present there is one
per QRS
▪ PR interval-usually not measurable
▪ QRS- 0.04-0.10 seconds NARROW
▪ All complexes look the same
▪ Ventricular rate- 150-240/min
▪ RHYTHM is REGULAR
SVT/ PSVT
Treatments for SVT/PSVT
▪ Carotid Massage
▪ Vagal Maneuvers
▪ Valsalver maneuver & Holding breath, Cold
immersion, coughing
▪ Innervated by parasympathetic NS
▪ Medications
▪ Synchronized Cardioversion
▪ Ablation interventions
VIDEO on SVT/ A FIB & A Flutter
▪ THE Atrial and SVT RHYTHMS
JUNCTIONAL RHYTHMS
Junctional RHYTHMS
▪ Junctional rhythms are named such because their
impulse originates from the AV node (AV junction)
instead of the SA node.
▪ ▪The SA node may be impaired secondary to drug
toxicity or underlying cardiac disease.
▪ ▪When the AV node does not sense an impulse
coming down from the SA node, it will become the
pacemaker of the heart
Junctional RHYTHM
▪Rate- 40-60 bpm
▪ RHYTHM is REGULAR
▪ P wave are ABSENT OR INVERTED
▪ ▪PR interval of <0.12 seconds (remember normal
is 0.12-0.2)
▪ Narrow complexes ( 0.06 seconds on average)
▪ All complexes look the same
Junctional RHYTHM
Junctional RHYTHM
▪ Junctional Bradycardia
▪ Rate=less than 40
▪ Accelerated Junctional RHYTHM
▪ Rate=greater than 60
▪ Junctional Tachycardia
▪ rate= greater than 100
Junctional Treatment
▪ If the patient has NO symptoms--- they will just will
observe the patient
▪ If symptomatic ----a permanent pacemaker may be
needed
▪ If the junctional rhythm is due to digitalis toxicity, then the
medication atropine, digoxin immune Fab (Digibind), or
both may be necessary.
Heart
BLOCKS
FIRST DEGREE
SECOND DEGREE
THIRD DEGREE
Heart Blocks
▪ Heart blocks are arrhythmias caused by an
interruption in the conduction of impulses
between the atria and the ventricles.
▪ ♥The AV block can be total or partial or it may
simply delay conduction.
The Heart Block Rhythms
First Degree AV Block
▪♥Second Degree AV Block
▪ ♥Type I (Wenckebach) -----also called Mobitz I
▪ ♥Type II---- also called Mobitz II
▪♥Third Degree AV Block
First Degree Heart Block
▪ First Degree AV Block
▪ ♥Is the most common form of heart block
▪ ♥Looks similar to sinus rhythm
▪ ♥Impulse conduction between the atria and the Bundle of His is delayed at the
level of the AV node
▪ ♥The PR interval will be prolonged (> 0.20)
5 STEPS to Interpret First Degree HB
▪ 1.What is the rate?
60-100 bpm
▪ 2. What is the rhythm?
Usually regular
▪ 3. Is there a P wave before each QRS? YES
Are P waves upright and uniform? Yes
▪ 4. What is the length of the PR interval?
>0.20 seconds
▪ 5. Do all QRS complexes look alike?
Yes
▪ What is the length of the QRS complexes?
squares)
Less than 0.12 seconds (3 small
Causes and S/S of First Degree AV Block
▪ ▪Can occur in healthy hearts
▪ ▪May be temporary
▪ ▪Myocardial infarction or ischemia
▪ ▪Medications – digitalis, calcium channel blockers, beta
blockers
▪ ▪Myocarditis
▪ ▪Degenerative changes in the heart
Medical Tx of First Degree AV Block
▪ ▪No treatment is usually necessary if the patient
is asymptomatic
▪ ▪Treat the underlying cause
▪ ▪Monitor closely to detect progression to a more
serious form of block
2nd Degree AV Block Mobitz Type I
(Wenckebach)
▪ ♥The delay of the electrical impulse at the AV node
produces a progressive increase in the length of the PR
interval (> 0.20 seconds)
▪ ♥The
PR interval continues to increase in
length until the impulse is not conducted or
the QRS complex is “dropped”
2nd Degree AV Block Mobitz Type I (Wenckebach)
The PR interval continues to increase in length
until the impulse is not conducted or the QRS
complex is “dropped”
5 Steps to Identify 2nd Degree AV Block
Mobitz Type I
(Wenckebach)
▪ 1. What is the rate?
Varies
▪ 2. What is the rhythm?
Ventricular: irregular
▪ 3. Is there a P wave before each QRS? ----------------------------Yes
▪ Are P waves upright and uniform? ------------------------------- Yes, for conducted beats
▪ 4. What is the length of the PR interval?
▪ Progressively prolongs until a QRS is not conducted
▪ 5. Do all QRS complexes look alike? ---------------------------------YES
▪ What is the length of the QRS complexes?
▪ Less than 0.12 seconds (3 small squares)
Causes of 2nd Degree AV Block Mobitz Type I
(Wenckebach)
▪ ▪May occur normally in an otherwise healthy
person
▪ ▪Coronary artery disease
▪ ▪Inferior wall MI
▪ ▪Rheumatic fever
▪ ▪Medications – propanolol, digitalis, verapamil
▪ ▪Increased vagal stimulation
Medical Tx of 2nd Degree AV Block Mobitz Type I
(Wenckebach)
No treatment is usually necessary if the patient is
asymptomatic
▪ ▪Treat the underlying cause
▪ ▪Monitor closely to detect progression to a more serious
form of block, especially if the block occurs during an MI
▪ ▪If symptomatic
▪ ▪Atropine may improve AV node conduction
▪ ▪Temporary pacemaker may help with symptom relief
until the rhythm resolves itself
BIGGEST RISK WITH 2nd Degree AV Block Mobitz
Type I (Wenckebach )
▪▪Reduced cardiac output, although
this is uncommon
▪▪Progression to 3rd degree block
2nd Degree AV Block Mobitz Type II
▪ Occurs when there is intermittent interruption of
conduction
▪ ♥Less common that a 2nd Degree Type 1 block, but more
dangerous
▪ ♥PR intervals are regular for conducted beats
▪ ♥The atrial rhythm is regular
▪ ♥The ventricular rhythm is irregular due to dropped or
nonconducted (blocked) beats
2nd Degree AV Block Mobitz Type II
FIXED PR interval with randomly
dropped QRS complexes
5 Steps to Identify 2nd Degree AV Block Mobitz Type II
▪ 1.What is the rate? Varies
▪ 2. What is the rhythm? Ventricular: irregular
▪ 3. Is there a P wave before each QRS? More than one can precede the QRS
▪ Are P waves upright and uniform? Yes, some not followed by a QRS -----Yes, for conducted beats
▪ 4. What is the length of the PR interval? ------------ Constant for conducted beats
▪ 5. Do all QRS complexes look alike? -----------------------Yes, but may be intermittently absent
▪
What is the length of the QRS complexes? --------Less than or greater than 0.12 seconds
Causes and S/S of 2nd Degree AV Block
Mobitz Type II
▪ Anterior wall MI
▪ ▪Degenerative changes in the conduction system
▪ ▪Severe coronary artery disease
▪ uses and S/S of 2nd Degree AV Block Mobitz Type II
Medical Tx of 2nd Degree AV Block Mobitz
Type II
▪ May choose to just observe an asymptomatic patient
▪ ▪Bedrest to reduce myocardial oxygen demands
▪ ▪Oxygen therapy
▪ ▪Focus on raising the heart rate to improve cardiac output
▪ ▪Medication
▪ ▪Permanent pacemaker
▪ RISK:
▪ Reduced cardiac output
▪ ▪Progression to 3rd degree AV block (complete)
3rd Degree AV Block Complete heart block,
AV dissociation
Is the most serious type of heart block
▪ ♥May progress to asystole, because ventricular rate is
usually very slow and ineffective
▪ ♥Impulses from the atria are completely blocked at the AV
node and can’t be conducted to the ventricles
▪ P waves are usually march consistently through….NO
correlation between P’s & QRS’s
▪ Loss of all communcation between atria & ventricles
3rd Degree AV Block Complete heart block, AV
dissociation
P waves are usually march consistently through….NO
correlation between P’s & QRS’s
5 Steps to Identify 3rd Degree AV Block
1.What is the rate?----------------------less than 60
▪ 2. What is the rhythm?------------Regular
▪ 3. Is there a P wave before each QRS?--- NO --No relationship to QRS complexes
▪ Are P waves upright and uniform?----Yes What is the length of the PR interval?-Totally
variable, no pattern
4. Is the complex narrow?– No- they are WIDE
▪ 5. Do all QRS complexes look alike? -------------------Yes
Causes and S/S of 3rd Degree AV Block
▪ ▪Congenital condition
▪ ▪Coronary artery disease
▪ ▪Anterior or inferior wall MI
▪ ▪Degenerative changes in the heart
▪ ▪Digitalis toxicity
▪ ▪Surgical injury
Medical Tx of 3rd Degree AV Block
▪ ▪Aim
to improve the ventricular rate
▪ ▪Atropine
▪ Isopreterenol
▪ ▪Permanent pacemaker
Heart Block Video
▪Heart Blocks
Heart Blocks Made EASY- GOLDEN RULES
▪ Perform a normal interpretation on the tracing
▪ If you find more P waves than QRS complexes do the following:
1. Measure your R-R interval
2. Measure your PR interval
If the R-R interval is CONSTANT, the block must be second degree type 2
or third degree. If the PR interval VARIES– HOW DOES IT VARY??
• If it elongates , the block must be second degree type 1
• If there is NO association, the block must be third degree
Ventricular Rhythms
▪ Objective
▪ Recognize ventricular dysrhythmias on EKG and
relate cause, significance, symptoms, and
treatment
Ventricular Rhythms
♥
▪ When the sinoatrial (SA) node and the AV Junctional tissues fails to
generate an impulse the ventricles will assume the role of pacing the
heart
▪ ♥ There is an absence of P waves because there is no atrial activity or
depolarization
▪ ♥Ventricular rhythms will display QRS complexes that are wide (greater
than or equal to 0.12 seconds) and bizarre in appearance
Ventricular Rhythms
▪ These 8 rhythms are the lethal ones: KNOW THESE
▪ ♥Idioventricular rhythm (ventricular escape rhythm; rate usually >20 – <40 bpm)
▪ ♥Accelerated Idioventricular rhythm (>40 bpm)
▪ ♥Agonal rhythm (20 or less bpm)
▪ ♥Ventricular tachycardia (>150 bpm)
▪ ♥Ventricular fibrillation
▪ ♥Torsades de Pointes
▪ ♥Pulseless Electrical Activity (PEA)
▪ ♥Asystole - Cardiac Standstill
Ventricular Rhythms
Premature Ventricular Contractions
▪ A PVC is not a rhythm, but an ectopic beat that arises from an
irritable site in the ventricles.
▪ ▪PVCs appear in many different patterns and shapes, but are always
wide and bizarre compared to a “normal” beat
PVC Patterns
Ventricular
▪ Ventricular bigeminy
PVC occurs every other beat
▪ Ventricular trigeminy
PVC occurs every third beat
▪ Ventricular quadrigeminy
PVC occurs every fourth beat
▪ Couplets
Two PVC’s together
▪ Runs of ventricular tachycardia (VT)
PVC’s in a row
Three or more
PVC Patterns
COUPLETS and 3 or More PVC’s= RUN OF VTACH
Causes and S/S of PVC’s
▪ Causes
▪ ▪Exercise
▪ ▪Stress
▪ ▪Caffeine
▪ ▪Heart disease: MI, CHF, Cardiomyopathy, Mitral valve prolapse
▪ ▪Electrolyte imbalances
▪ ▪Hypoxia
▪ ▪Tricyclic antidepressants
▪ ▪Digitalis toxicity
Keys to
identifying:
Idioventricular Rhythm
rhythm is
Idioventricular arrhythmia is also termed ventricular escape rhythm. It is SLOW, no P
considered a last-ditch effort of the ventricles to try to prevent cardiac wave, wide
standstill.
& bizarre
QRS!
▪ ▪The SA node and AV node have failed
▪ ▪Rate usually between 20 to 40 beats per minute (bpm)
▪ ▪Cardiac output is compromised!!
5 Steps to Identify Idioventricular Rhythm
▪ What is the rate?
▪ 2. What is the rhythm?
Ventricular: 20-40 bpm
Usually regular
▪ 3. Is there a P wave before each QRS?
Absent
▪ Are P waves upright and uniform?
Absent
▪ 4. What is the length of the PR interval?
Not measureable
▪ 5. Do all QRS complexes look alike?
▪ What is the length of the QRS complexes?
(>0.12 sec), with T wave deflection
Wide and bizarre
Causes and S/S of Idioventricular Rhythm Causes
•
▪ Causes
▪ •Drugs- Digitalis
▪ •MI
▪ •Metabolic imbalances
▪ •Hyperkalemia
▪ •Cardiomyopathy
Treatment
▪ Medical Treatment
▪ ▪Atropine
▪ ▪Pacing
▪ ▪Dopamine when hypotensive
▪ ▪CPR
Agonal Rhythm
Agonal rhythm is when the Idioventricular rhythm is 20 beats or
less per minute. Frequently is seen as the last-ordered semblance
of a heart rhythm when resuscitation efforts are unsuccessful
5 Steps to Identify an Agonal Rhythm
▪ What is the rate?
Ventricular: <20 bpm VERY SLOW!!
▪ 2. What is the rhythm?
Usually regular
▪ 3. Is there a P wave before each QRS?
Absent
▪ Are P waves upright and uniform?
Absent
▪ 4. What is the length of the PR interval?
Not measureable
▪ 5. Do all QRS complexes look alike?
▪ What is the length of the QRS complexes? Wide and bizarre (>0.12 sec), with T
wave deflection
Signs and TX of Agonal Rhythm
▪ Signs and Symptoms
▪ ▪Loss of consciousness
▪ ▪No palpable pulse or measurable BP
▪ Medical Treatment
▪ ▪CPR/ACLS Protocol
▪ ▪If life saving efforts have already been attempted no further treatment
Ventricular Tachycardia
▪
▪ Ventricular tachycardia almost always occurs in diseased hearts.
▪ ▪Rhythm in which three or more PVCs arise in sequence at a rate greater
than 100 beats per minute.
▪ ▪V-tach can occur in short bursts lasting less than 30 seconds, causing
few or no symptoms.
▪ ▪Sustained v-tach lasts for more than 30 seconds and requires
immediate treatment to prevent death.
▪ ▪V-tach can quickly deteriorate into ventricular fibrillation.
Ventricular Tachycardia
5 Steps to Identify Ventricular Tachycardia (V-Tach)
▪ 1. What is the rate?
▪ 2. What is the rhythm?
101-250 bpm
Atrial rhythm not distinguishable
Ventricular rhythm usually regular
▪ 3. Is there a P wave before each QRS?
No
▪ 4. What is the length of the PR interval?
Not measureable
▪ 5. Do all QRS complexes look alike?
▪ What is the length of the QRS complexes? Wide and bizarre (>0.12 sec)
Causes of V TACH
▪ ▪Usually occurs with underlying heart disease
▪ ▪Commonly occurs with myocardial ischemia or
infarction
▪ ▪Certain medications may prolong the QT interval
predisposing the patient to ventricular tachycardia
▪ ▪Electrolyte imbalance
▪ ▪Digitalis toxicity
▪ ▪Congestive heart failure
Medical Treatment of V Tach
▪ ▪If there is no pulse, begin CPR and follow ACLS protocol
▪ ▪If there is a pulse and the patient is unstable - cardiovert and begin
drug therapy
▪ ▪Amiodarone or Lidocaine
▪ ▪With chronic or recurrent VT
▪ ▪Give antiarrhythmics
▪ ▪Ablation may be used for reentry
Ventricular Fibrillation
▪ V-Fib (coarse and fine)
▪ ♥Occurs as a result of multiple weak ectopic foci in the ventricles
▪ ♥No coordinated atrial or ventricular contraction
▪ ♥Electrical impulses initiated by multiple ventricular sites; impulses are
not transmitted through normal conduction pathway
Course and Fine V. FIB
5 Steps to Identify Ventricular Fibrillation
▪ 1. What is the rate?
Not discernible
▪ 2. What is the rhythm?
Rapid, unorganized, not discernable
▪ 3. Is there a P wave before each QRS?
No
▪ Are P waves upright and uniform?
No
▪ 4. What is the length of the PR interval?
None
▪ 5. Do all QRS complexes look alike?
▪ What is the length of the QRS complexes?
None
Causes of V FIB
▪ ▪AMI
▪ ▪Untreated VT
▪ ▪Electrolyte imbalance
▪ ▪Hypothermia
▪ ▪Myocardial ischemia
▪ ▪Drug toxicity or overdose
▪ ▪Trauma
Medical treatment
▪ ▪CPR with immediate defibrillation
▪ ▪Initiate ACLS algorithm
▪ IF not patient will DIE
Torsades de Pointes Rhythm
▪
▪ Torsades de pointes is associated with a prolonged
QT interval. Torsades usually terminates
spontaneously but frequently recurs and may
degenerate into ventricular fibrillation.
▪ ▪The hallmark of this rhythm is the upward and
downward deflection of the QRS complexes around
the baseline. The term Torsades de Pointes means
“twisting about the points.”
Torsades Rhythms
5 Steps to Identify Torsades de Pointes
▪ 1. What is the rate?
Ventricular: 150-250 bpm
▪ 2. What is the rhythm?
Regular or irregular
▪ 3. Is there a P wave before each QRS?
No
▪ 4. What is the length of the PR interval?
Not measurable
▪ 5. Do all QRS complexes look alike?
▪ What is the length of the QRS complexes?
Wide and bizarre, some
deflecting downward and some deflecting upward
Medical Treatment for Torsades
▪ Treatment
▪ ▪Begin CPR and other code measures
▪ ▪Eliminate predisposing factors - rhythm has tendency
to recur unless precipitating factors are eliminated
▪ ▪Administrate magnesium sulfate bolus
▪ ▪Synchronized cardioversion is indicated when the
patient in unstable if possible or defibrillate
Asystole
Ventricular standstill
5 Steps to Identify Asystole
▪ 1. What is the rate?
none
▪ 2. What is the rhythm?
none
▪ 3. Is there a P wave before each QRS?
▪ Are P waves upright and uniform?
none
▪ 4. What is the length of the PR interval?
none
▪ 5. Do all QRS complexes look alike?
▪ What is the length of the QRS complexes?
none
Treatment of Aysytole
▪▪CPR
▪▪ACLS protocol
Pulseless Electrical Activity (PEA)
Electricity is working, but the mechanics and plumbing are not.
▪The absence of a palpable pulse and absence of myocardial
muscle activity with presence of organized electrical activity on
the cardiac monitor. The patient is clinically dead despite some
type of organized rhythm on monitor.
The H’s
▪ •Hypovolemia #1 cause
▪ •Hypoxia
▪ •Hydrogen ions (acidosis)
▪ •Hypo / Hyperkalemia
▪ •Hypothermia
The T’s
▪ •Toxins
▪ •Tamponade (cardiac)
▪ •Tension pneumothorax
▪ •Thrombosis (coronary or pulmonary)
▪ •Trauma
▪ •Massive MI
▪ •Overdose of tricyclic antidepressants
Medical Treatment
▪ ▪Determine cause & treat
▪ ▪CPR
▪ ▪Initiate ACLS protocol
Ectopic and Escape Beats
Ectopic Beats ----aka
Ectopy or Arrhythmias
▪ A. Any cardiac impulse originating outside the SA node is considered
abnormal and is referred to as an ectopic beat▪ WILL OCCUR EARLIER DUE TO INCREASE AUTOMATICITY
▪ B. Ectopic beats can originate in the atria, the AV junction, or the
ventricles, and are named according to their point of origin
▪ Ectopic beat (or cardiac ectopy) is a disturbance of the cardiac rhythm
frequently related to the electrical conduction system of the heart, in
which beats arise from fiber or group of fibers outside the region in
the heart muscle ordinarily responsible for impulse formation (i.e., the
sinoatrial node).
▪ an ectopic beat can be further classified as either:
Ectopic Beats ----aka
Ectopy or Arrhythmias
▪ a premature ventricular contraction, or
▪ a premature atrial contraction
▪ Premature Junction contraction
Causes for ectopic beats include:
▪ 1. Failure or excessive slowing of the SA node
▪ 2. Premature activation of another cardiac site
▪ 3. Abnormal conduction system
PVC, PAC or APC and a PJC
Escape Beats
▪ An escape beat is a heart beat arising from an ectopic focus in the atria, the AV
junction, or the ventricles
▪ WILL OCCUR LATER DUE TO DELAYED SA NODE FIRING
▪ The usual pacemaker fails, so a slower pacemaker fires at its inherent rate.
▪ Causes:
▪ sinus node fails in its role as a pacemaker
▪ when the sinus impulse fails to be conducted to the ventricles as in complete heart block
▪ The ectopic impulse in this instance is always late, appearing only after the next
anticipated sinus beat fails to materialize
Escape Beats
Pacemakers
▪ Pacemakers can be temporary or permanent.
▪ ♥Temporary pacemakers
▪ ♥Used to treat temporary heartbeat problems, such as a slow heartbeat
that's caused by a heart attack, heart surgery, or an overdose of medicine.
▪ ♥Temporary pacemakers are also used during emergencies until a
permanent pacemaker can be implanted or until the temporary condition
goes away.
▪ ♥If the patient has a temporary pacemaker, they will stay in the hospital as
long as the device is in place.
▪ ♥Permanent pacemakers are used to control long-term heart rhythm
problems.
Functions of a Pacemaker
♥
▪ Speeds up a slow heart rate.
▪ ♥Helps control an abnormal rhythm or fast heart rate.
▪ ♥Makes sure the ventricles contract normally if the atria are
quivering instead of beating with a normal rhythm (as in atrial
fibrillation).
▪ ♥Coordinates the electrical signaling between the upper and
lower chambers of the heart.
▪ ♥Coordinates the electrical signaling between the ventricles.
Who needs a Pacemaker?
▪ The most common reasons are bradycardia and heart block.
▪ ♥Bradycardia is a slower than normal heartbeat.
▪ ♥Those with Heart blocks
▪ ♥Is a problem with the heart's electrical system and occurs when an
electrical signal is slowed or disrupted as it moves through the heart.
▪ ♥Can happen as a result of aging, damage to the heart from a heart
attack, or other conditions that interfere with the heart's electrical
activity.
▪ ♥Certain nerve and muscle disorders also can cause heart block,
including muscular dystrophy.
How a Pacemaker Functions
♥
▪ A pacemaker monitors and helps control the heartbeat.
▪ ♥The electrodes detect the heart's electrical activity and
sends data through the wires to the computer in the
generator.
▪ ♥If the heart rhythm is abnormal, the computer will direct
the generator to send electrical pulses to the heart.
▪ ♥The pulses then travel through the wires to reach the heart
Principles of Pacing
▪Modes of Pacing
▪▪Atrial pacing
▪▪Ventricular pacing
▪▪Atrial/Ventricular pacing
Assessing Paced EKG Strips
▪ ▪Identify intrinsic rhythm and clinical condition
▪ ▪Identify pacer spikes
▪ ▪Identify activity following pacer spikes
▪ ▪Failure to capture
▪ ▪Failure to sense
▪ ▪EVERY PACER SPIKE SHOULD HAVE A P-WAVE OR QRS COMPLEX
FOLLOWING IT.
Normal Pacing
▪ Normal Atrial Pacing
▪ ▪Atrial pacing spikes followed by P waves
Normal Ventricular Pacing
▪ Normal Ventricular pacing
▪ ▪Ventricular pacing spikes followed by wide, bizarre QRS
complexes
▪ ▪QRS will look wide and bizarre b/c impulse is generated in
the ventricle…does not follow normal pathways from atria
Normal Ventricular pacing
Normal Atrio-Ventricular Pacing
▪ Normal A-V Pacing
▪ ▪Atrial & Ventricular pacing spikes followed
by atrial & ventricular complexes
Normal A-V Pacing
Abnormal Pacing
▪ Atrial non-capture
▪ ▪Atrial pacing spikes are not followed by P waves
▪ ▪Impulse is sent from the pacer, but is not captured by the
ventricle…therefore no QRS following a pacer spike
Atrial non-capture
Abnormal Pacing
▪
▪ Ventricular non-capture
▪ ▪Ventricular pacing spikes are not followed by QRS complexes
▪ ▪Impulse is sent from the pacer, but is not captured by the
ventricle…therefore no QRS following a pacer spike
Ventricular non-capture
Failure to Capture
▪ Causes
▪ ▪Insufficient energy delivered by pacer
▪ ▪Low pacemaker battery
▪ ▪Dislodged, loose, fibrotic, or fractured electrode
▪ ▪Electrolyte abnormalities
▪ ▪Acidosis
▪ ▪Hypoxemia
▪ ▪Hypokalemia
Danger - poor cardiac output
▪ Solutions
▪ ▪View rhythm in different leads
▪ ▪Change electrodes
▪ ▪Check connections
▪ ▪Increase pacer output (↑mA)
▪ ▪Change battery, cables, pacer
Name that rhythm?
▪Identify the correct
EKG rhythm?
Videos of Heart Rhythms
▪ Heart Rhythms