NORMAL Electrocardiogram, ECK/EKG PPT....

1. ELECTRICAL CONDUCTION SYSTEM OF HEART
And
Electro cardio graphy
VENBA.E
M.Sc., NURSING II YEAR,
COLLEGE OF NURSING,
MMC,CHENNAI -03.

2. INTRODUCTION
• The cardiac conduction system is a network of specialized cardiac muscle
cells that initiate and transmit the electrical impulses responsible for the
coordinated contractions of each cardiac cycle.
• These special cells are able to generate an action potential on their own
(self-excitation) and pass it on to other nearby cells (conduction),
including cardiomyocytes.

3. The conduction system of the heart consists of the following structures,
 Sinoatrial node
Atrioventricular node
 Bundle of HIS
 Bundle branches
 Purkinje fibers

4. SA NODE
The sinoatrial node (SA node) is a flat, elliptical collection of specialized nodal
tissue with dimensions of up to 25 millimeters (mm) in length.
The node is nestled in the superior posterolateral wall of the right atrium near the
opening of the superior vena cava.
The pale-staining cells(P) populated centrally and decrease towards the periphery
of the SA Node.
The ‘P’ cells contain both cholinergic and adrenergic receptors to respond to the
neuro transmitters.
BLOOD SUPPLY _Sinoatrial nodal branch of the coronary artery.

6. INTERNODAL PATHWAYS
The internodal pathway is divided into anterior, middle and posterior
branches.
Anterior (Bachmann’s bundle)
Middle
Posterior

7. AV NODE
The secondary pacemaker of the heart.
Smaller than SA node and is located in the posteroinferior part of
interatrial septum.
There are fewer P cells and more transition cells.
BLOOD SUPPLY
Atrioventricular nodal branch of inferior interventricular branch of right
coronary artery
It also has adrenergic and cholinergic receptors.

8. BUNDLE OF HIS
The bundle of HIS is a short bundle of fibers at bottom of the AV node
leading to the bundle branches
A unique and important features of the AV bundle is that it only allows the
‘Forward’ movement of action potentials.
It is supplied by the anterior and inferior interventricular branches of the
coronary artery.

9. RIGHT BUNDLE BRANCH
Emerges from the AV bundle in the membranous interventricular septum.
It travels to the right side of the interventricular septum. Where it gives of
branches to the ventricular walls before going on toward the ventricular apex.
The terminal arborization of the right branch supplies the papillary muscle
and recurs to supply the rest of the ventricular wall.

10. LEFT BUNDLE BRANCH
Emerges from the AV bundle at the start of the muscular interventricular
septum.
It travels to the left side of the interventricular septum and towards the
ventricular apex.
Here it trifurcates into
Posterior
Septal and
Anterior divisions

11. PURKINJIE FIBERS
The right and left bundles are populated with subendocardial branches (Purkinje
fibers)
Subendocardial branches are found throughout the entire length of both bundles in the
subendocardial layer.
They extend toward the cardiac apex, then curve upward and backward through the
walls of the ventricles
They are able to transmit impulses 6 times faster than ventricular muscles and 150
times faster than AV nodal fibers
The increased number of gap junctions allow more ions to pace from one cell to the
next, thus increasing the rule of conduction.

12. KEY FACTS ABOUT CONDUCTION SYSTEM
Parts Nodal tissue: sinuatrial (SA) and atrioventricular (AV) nodes
Conducting fibers: internodal and interatrial conduction pathways, bundle of His,
bundle branches, subendocardiac branches
Sinuatrial node Contains cardiac pacemaker (P) cells
Pacemaker of the heart
Supplied by the SA nodal branch of the right coronary artery
Internodal conduction
pathway
Anterior, middle, posterior
Interatrial conduction
pathway
Conducts impulses to the left atrium
Supplied by the SA nodal artery
Atrioventricular node Secondary pacemaker
Supplied by AV nodal artery
Bundles Atrioventricular (AV) bundle (of His) – oval, quadrangular, or triangular
Right and left bundles
Sub endocardiac branches (Purkinje fibers)

13. CARDIAC ELECTROPHYSIOLOGY
Cardiac Electrophysiology
The study of elucidating, diagnosing and treating the electrical activities
of the heart.
To assess arrhythmias,
Elucidate symptoms,
Evaluate abnormal electrocardiograms
Assess risk of developing arrhythmias in the future
Plan treatment.

14. NORMAL HEART
An electrical impulse stimulates the heart muscle to contract.
The normal electrical conduction starts in the Sino-atrial (SA) node
sending, an impulse through the atria to the atrio-ventricular (AV) node,
which is the relay station of the heart and sends the electrical impulses to
the ventricles.

15. THE CARDIAC ACTION POTENTIAL
 The cardiac action potential, the basic unit of electrical activity in the heart,
produces cardiac contractions.
 Cardiac myocytes, like other types of muscle cells have a negative have a
negative potential difference (-90mv) at rest between the cell membrane and
extra-cellular space(i.e they are polarized).
 Under the influence of trigger events, potassium, sodium, and calcium ions
cross the cell membrane, thereby generating discrete ion currents.

16. PHASES OF CARDIAC ACTION POTENTIAL
Divided into ‘FIVE’
Phases 0 (Opening of Na’+ channels)
Phases 1(Opening of K’+ channels)
Phases 2 (Opening of Ca’++channels)
Phases 3 (Opening of K’+channels)
Phases 4 (Return to resting membrane potential)

20. PHASE 0: Rapid depolarization phase
Resting membrane potential in a myocardial cell is -90 mv
With opening of Na’+ channels rapid influx of sodium ions into
myocardial cells – depolarization occurs and phase 0 begins.
PHASE 1:
Inactivation of sodium channels.
Activation/opening of potassium channels
Action potential reduces
Slight downward deflection of action potential.

21. PHASE 2:
Calcium channels get opened
In this phase
Inward movement of calcium ions, Outward movement of K+ ions.
Since there is a balance between inward movement of calcium & outward
movement of potassium.
PHASE 3:
Calcium channels close
Potassium channels still remain open
Due to above changes – repolarization occurs
When membrane potential reaches -80 to -85 will leads to k+ channels
close.

22. PHASE 4: RESTING MEMBRANE POTENTIAL(RMP)
Associated with diastole
Certain myocardial cells have potential to undergo spontaneous
depolarization to generate action potential without any stimulus.
Spontaneous depolarization is fast in SA node hence it is also known
as “pacemaker”.
From SA node the electrical activity begins and propagates to the rest
of the heart.

23. VELOCITY OF CONDUCTION OF IMPULSES

24. ELECTROCARDIOGRAPHY
DEFINITION
Electrocardiography is the process of producing an
electrocardiogram, a recording of the heart's electrical activity. It is an
electrogram of the heart which is a graph of voltage versus time of the
electrical activity of the heart using electrodes placed on the skin.
-BRUNNER AND SUDDHARTH.
Electrocardiography, method of graphic tracing
(electrocardiogram; ECG or EKG) of the electric current generated by
the heart muscle during a heartbeat.
-LEUWIS.

25. PURPOSES
Ischemia/ infarct
Arrythmias Ventricular and atrial enlargement
Conduction defects
Pericarditis
Effects of some drugs and electrolytes
Vital in cardio pulmonary resuscitation
Monitoring in anesthesia during surgery, as well as in pre-operative,
Intraoperative and post operative monitoring.
Assessment in a sports physical exam to rule out cardiomyopathy.

26. INDICATION FOR ECG
Chest pain/ Epigastric pain
Shortness of breath
Palpitation
Syncope
Hypertension
Pre operative assessment
Monitoring cardiac conditions
Screening

27. Cont….
Evaluation of symptoms suggestive of cardiac ischemia
Electrolyte abnormalities
Pulmonary edema
Exertional dyspnoea
Weakness
Diabetic keto acidosis
Excessive diaphoresis

28. ECG PAPER
ECG paper consists of horizontal and vertical lines.
Horizontal lines represent time and vertical lines represent amplitude
in electrical voltage.
Horizontal- Each small square horizontally is equal to 0.04 seconds
and each large box horizontally equal to 0.20 second.
Vertical axis- Small box measures 1mm and is equal to 0.1mV and
each large box measure 5mm and is equal to 0.5mV.

29. ECG PAPER

31. ECG LEADS

32. ECG LEADS

33. DEXTROCARDIA

35. 6 limb leads (Frontal plane)
Records the electrical activity in the Frontal plane-traveling up/ down anf
right/ left I the heart.
Bipolar leads
A bipolar lead has a positive and negative pole; with each contributing
equally to the recording.
Lead I, II, III are bipolar leads.
Unipolar leads / Augmented limb leads
A unipolar lead has one positive pole and a reference pole in the center of
the chest/ center of the electrical field of the heart and has a zero potential.
aVR, aVL, aVF are called as augmented limb leads.

36. 6 Precardial leads( Horizontal plane)
V1 to V6- leads records electrical activity in the horizontal plane,
travelling anterior/ posterior and right/ left.
They are also unipolar leads.

37. Chest leads Electrode placement View of heart
V1 4th ICS to the right of the sternum Septum
V2 4th ICS to the left of the sternum Septum
V3 Directly between the leads V2 and V4 Anterior
V4 5th ICS at midclavicular line Anterior
V5 5th ICS at left anterior axillary line Lateral
V6 5th ICS at left midaxillary line Lateral
RV1 5th ICS at right midclavicular line
RV2 5th ICS at right anterior axillary line
RV3 5th ICS at right mid axillary line

38. Cont…
Chest leads Electrode placement View of the heart
V7 5th ICS Posterior axillary line 5 Ritht Ventricle
V8 5th ICS Posterior mid scapular line Posterior
V9 5th ICS Posterior Directly between V8 to the left
border of spine
Posterior

39. ECG WAVES
Deflection and its description
P WAVE
First seen wave
Small upright wave indicating atrial depolarization
(0.1 seconds)
QRS COMPLEX
Represents ventricular depolarization
Q-Wave _First negative deflection
R-Wave_First positive deflection
S-Wave_First negative deflection after R wave.
0.08to 0.1 seconds

40. T WAVE
Rounded upright wave(positive)
Following QRS complex indicating ventricular repolarization
0.2 seconds
U WAVE
Small rounded,upright( positive) wave
Following ‘T’ wave repolarization of Purkinjie muscle
P-R INTERVAL
Distance between beginning of ‘P’ wave and beginning of QRS
complex , indicating the duration of depolarization wave travelling
from the atria to ventricles its duration is 0.12 – 0.2 seconds.

41. Q-T INTERVAL
Measured from beginning of QRS complex to end of T wave.
It represents the total ventricular activity.
Duration 0.4_0.42 seconds.
ST SEGMENT
Measured as a distance between S wave and beginning of T wave.
Represents the time between the ventricular depolarization and
beginning of ventricular repolarization.
Duration_0.08 seconds.

44. AXIS DETERMINATION
Perpendicular leads taken for determination
Lead I and Lead aVF
Lead II and Lead aVL
Lead III and Lead aVR
METHODS
Simple method
Classical method
Equiphasic method

48. SIMPLE METHOD
 Compare the QRS complex
in lead I and aVF.
 If QRS complex is negative or
positive this methods can be
applied.

49. CLASSICAL METHOD
 If QRS complex is biphasic this method can be applied
 Look at the QRS complex in Lead I and count the number of positive
and negative boxes.
 Mark the net vector along the appropriate end of lead I on the axis
wheel.
 Look at the QRS complex in aVF and follow the same method.
 Draw a perpendicular line from lead I axis and also draw a
perpendicular line from aVF axis ,so that two perpendicular lines meet
each other.
 Draw a line from the center of the axis to the point where these two
perpendicular lines meet that line gives the mean QRS axis.

51. EQUIPHASIC METHOD
Find the limb lead with smallest or most equiphasic QRS complex (net
charge is zero as per classical method).
Locate the perpendicular lead,look at the QRS complex is positive or
negative in that lead.
If it is positive, the axis is directed toward the positive end of the lead
and it is negative, the axis is directed toward the negative end of the
lead.

52. NINE-STEP PROCESS
1. Determine the rate. (Is it normal, fast, or slow?)
2. Determine the regularity. (Is it regular or irregular?)
3. Assess the P waves. (Is there a uniform P wave preceding each QRS
complex?)
4. Assess the QRS complexes. (Are the QRS complexes within normal
limits? Do they appear normal?)
5. Assess the PR intervals. (Are the PR intervals identifiable? Within
normal limits? Constant in duration?)

53. Cont….
6. Assess the ST segment. (Is it a flat line? Is it elevated or depressed?)
7. Assess the T waves. (Is it slightly asymmetrical? Is it of normal
height? Is it oriented in the same direction as the preceding QRS
complex?)
8. Look for U waves. (Are they present?)
9. Assess the QT interval. (Is it within normal limits?)

54. 1.DETERMINE THE RATE
10 TIMES METHOD
Using the 6-second10 method
 Multiply by 10 the number of QRS complexes (for the ventricular
rate) and the P waves (for the atrial rate) found in a 6-second portion
of ECG tracing. The rate in the ECG below is approximately 70 beats
per minute

55. USING THE 1500 METHOD
Begin by counting number of small squares between two consecutive
R waves and divide 1500 by that number.
Remember, this method cannot be used with irregular rhythms.

56. 300 METHOD
Rhythm regular
Largebox=0.2 sec
0.2x 300= 60 seconds
Heart rate =300/ Number of large boxes.

57. SEQUENCE METHOD
Begin by finding an R wave (or P wave) located on a bold line (the
start point).
Then find the next consecutive R wave.
The bold line it falls on (or is closest to) is the end point and
represents the heart rate.
If the second R wave does not fall on a bold line the heart rate must
be approximated.

58. SEQUENCE METHOD

59. 2.DETERMINING REGULARITY :
Equal R-R and P-P intervals
Normally the heart beats in a regular, rhythmic fashion. If the distance
of the R-R intervals and P-P intervals is the same, the rhythm is regular.

60. Unequal R-R and P-P intervals
If the distance differs, the rhythm is irregular
 Irregular rhythms are considered abnormal.
Use the R wave to measure the distance between QRS complexes as it
is typically the tallest waveform of the QRS complex.
Remember, an irregular rhythm is considered abnormal.
A variety of conditions can produce irregularities of the heartbeat.

61. METHODS OF DETERMINING REGULARITY
Using calipers
Place ECG tracing on a flat surface.
Place one point of the caliper on a starting point, either the peak of an
R wave or P wave.
Open the calipers by pulling the other leg until the point is positioned
on the next R wave or P wave.
With the calipers open in that position, and keeping the point
positioned over the second P wave or R wave, rotate the calipers
across to the peak of the next consecutive (the third) P wave or R
wave.

62. USING CALIPERS

63. Using paper and pen
Place the ECG tracing on a flat surface.
Position the straight edge of a piece of paper above the ECG tracing
so that the intervals are still visible.
Identify a starting point, the peak of an R wave or P wave, and place a
mark on the paper in the corresponding position above it.
Find the peak of the next consecutive R wave or P wave, and place a
mark on the paper in the corresponding position above it.
Move the paper across the ECG tracing, aligning the two marks with
succeeding R-R intervals or P-P intervals

64. USING PAPER AND PEN

65. Counting the small squares between each R-R interval
Count the number of small squares between the peaks of two
consecutive R waves (or P waves) and then compare that to the other
R-R (or P-P) intervals to reveal regularity.

66. 3. ASSESS THE P WAVE
Are P waves present?
Do they all have normal configurations?
Do they all have a similar size and shape?
Is there one P wave for every QRS complex?

67. Characteristics of p wave
Begins with its movement away from the baseline and ends in its
return to the baseline.
Characteristically round and slightly asymmetrical.
There should be one P wave preceding each QRS complex.
In leads I, II, aVF , and V2 through V6, its deflection is
characteristically upright or positive.
In leads III, aVL, and V1, the P wave is usually upright but may be
negative or biphasic (both positive and negative).
In lead aVR, the P wave is negative or inverted.
Amplitude_ 2to 3 mm high
Duration _0.06to 0.12 seconds.

68. 4. QRS COMPLEX ASSESSMENT
When determining QRS duration, be sure to measure straight across
from the end of the PR interval to the end of the S wave, not just to the
peak.
Remember, the QRS has no horizontal components.
To calculate duration, count the number of small squares between the
beginning and end of the QRS complex and multiply this number by
0.04 second.
Characteristics
Follow PR segment.
Amplitude 5 to 30 mm high but differ for each lead used.
Duration_ 0.06 to 0.10seconds, or half the PR interval.

69. Q wave_ first negative deflection following PR segment. It is always
negative. In some cases it is absent. The amplitude is normally less
than 25% of the amplitude of the R wave in that lead.
R wave—first positive triangular deflection following Q wave or PR
segment.
S wave—first negative deflection that extends below the baseline in
the QRS complex following the R wave. In leads I, II, III, aVL, aVF ,
and V4 to V6, the deflection of the QRS complex is characteristically
positive or upright.
In leads aVR and V1 to V3, the QRS complex is usually negative or
inverted.
In leads III and V2 to V4 the QRS complex may also be biphasic.

71. DIFFERING FORMS OF QRS COMPLEXES
QRS complexes can consist of positive (upright) deflections called R waves and
negative (inverted) deflections called Q and S waves: all three waves are not
always seen.
If the R wave is absent, complex is called a QS complex. Likewise, if the Q wave
is absent, complex is called an RS complex.
Waveforms of normal or greater than normal amplitude are denoted with a large
case letter, whereas waveforms less than 5 mm amplitude are denoted with a small
case letter (e.g., “q,” “r,” “s”).

72. MEASURING THE QRS COMPLEX
First identify the QRS complex with the longest duration and most
distinct beginning and ending.
Start by finding the beginning of the QRS complex. This is the point
where the first wave of the complex (where either the Q or R wave)
begins to deviate from the baseline.
Then measure to the point where the last wave of the complex
transitions into the ST segment (referred to as the J point).
Typically, it is where the S wave or R wave (in the absence of an S
wave) begins to level out (flatten) at, above, or below the baseline.
This is considered the end of the QRS complex.

74. 5.ASSESS PR INTERVAL
PR interval
Extends from the beginning of the P wave to
the beginning of the Q wave or R wave.
Consists of a P wave and a flat (isoelectric) line.
It is normally constant for each impulse
conducted from the atria to the ventricles.
The PR segment is the isoelectric line that extends from the end of the P
wave to the beginning of the Q wave or R wave.
Duration – 0.12 to 0.20 seconds.

75. MEASURING THE PR INTERVAL
To measure the width (duration) of a PR interval, first identify the
interval with the longest duration and the most distinct beginning and
ending.
Start by finding the beginning of the interval. This is the point where
the P wave begins to transition from the isoelectric line.
Then measure to the point where the isoelectric line (following the P
wave) transitions into the Q or R wave (in the absence of an S wave).
This is considered the end of the PR interval.

77. 6. ASSESS THE ST SEGMENT
The line that follows the QRS complex and connects it to the T wave.
Begins at the isoelectric line extending from the S wave until it gradually
curves upward to the T wave.
Under normal circumstances, it appears as a flat line (neither positive nor
negative), although it may vary by 0.5 to 1.0 mm in some precordial leads.
The point that marks the end of the QRS and the beginning of the ST
segment is known as the J point.
The PR segment is used as the baseline from which to evaluate the degree
of displacement of the ST segment from the isoelectric line.
Measure at a point 0.04 seconds (one small box) after the J point. The ST
segment is considered elevated if it is above the baseline and considered
depressed if it is below it.

79. 7. EVALUATE THE T WAVE
Larger, slightly asymmetrical waveform that follows the ST segment.
Peak is closer to the end than the beginning, and the first half has a more
gradual slope than the second half.
Normally not more than 5 mm in height in the limb leads or 10 mm in any
precordial lead.
Normally oriented in the same direction as the preceding QRS complex.
Normally positive in leads I, II, and V2 to V6 and negative in lead aVR.
They are also positive in aVL and aVF but may be negative if the QRS
complex is less that 6 mm in height. In leads III and V1, the T wave may be
positive or negative

80. 8. ASSESSMENT OF QT INTERVAL
Distance from onset of QRS complex until end of T wave.
Measures time of ventricular depolarization and repolarization.
Normal duration of 0.36 to 0.44 seconds.
9.ASSESSMENT OF U WAVE
Small upright (except in lead aVL) waveform
sometimes seen following the T wave,
but before the next P.

81. 5 LEAD ECG MONITORING
5 lead ECGis used when the patients heart rate and rhythm must be
continuously monitored.
Electrode/lead wire position colour
RA Right Arm white
RL Right leg Green
LA Left Arm Black
LL Left leg Red
V1 or C Center of chest Brown

82. Cont…
 RA _ below the clavicle at about 2nd ICS
midclavicular line.
 RL _ lower edge of the rib cage at about 7th or
8th right ICS, midclavicular line.
 LA _ below left clavicle at about 2nd ICS,
midclavicular line.
 LL _ lower edge of the rib cage at about 7th or
8th ICS, midclavicular line.
 V1 _ 4th ICS just right of the sternum.

84. 3 LEAD ECG MONITORING
 R and L _ Adjacent to each clavicle bone on the upper chest
 N_ Adjacent to the patient’s lower left abdomen
 It is a typical bipolar lead form and monitor reads as Lead I, II, III.

85. 6 LEAD ECG
Four limb and two chest electrodes
Helps to monitor bipolar and augmented leads
Ca and Cb should be placed in two of the positions of C1 to C6.
May use
C1 & C3
C2 & C5
C1 & C4
C3 & C6
C1 & C5
C3 & C5

86. TYPES OF ECG
EXERCISE EKG / STRESS TEST
 Called as treamill test
 Given while a patient walks on a treadmill or pedals a stationary
bicycle to monitor the heart during stress or exercise.
 Breathing and blood pressure rates are also monitored
 Used to detect coronary artery disease
 To determine safe levels of exercise following a heart attack or
surgery.

87. HOLTER MONITOR
Used to monitor the ECG tracings continuously for a period of 24 hrs
or longer.
Light,portable,battery-operated recorder should be worn or clipped to
the belt.
Used to evaluate the arrythmias and symptoms.
Contains information on heart rate, ectopic beats and brady
arrythmias.

89. AMBULATORY ECG DEVICES
The traditional Holter monitor
offers 24 to 48 hours of continuous monitoring
with full disclosure through multichannel acquisition.
Event recorders are leadless devices held to
The chest during a symptomatic episode.

90. External loop recorders observe continuously
for up to 30 days and record selected sequences
through multichannel acquisition

91. Implantable loop recorders offer very extended continuous
observation and recording of selected sequences.

92. Mobile cardiac telemetry features multiLead recording and a
portable transmitter to wirelessly send ECG data to a monitoring center
in real time.

93. Leadless and wireless ECG patch monitors incorporate
continuous extended monitoring and full disclosure in a small form.

94. KardiaMobile has a 2-electrode band that allows users to generate
ECG tracings on their smartphones, effectively functioning like a post-
event recorder.

95. The Apple Watch Series 4 is capable of continuously
monitoring heart rhythm and distinguishing between atrial
fibrillation and sinus rhythm.

96. FACTORS INFLUENCING ECG RECORDINGS
Patient movement
Electrode placement
Electromagnetic interference
Muscle activity
Patient skin condition
Lead wires and cables
Patient anxiety or stress
Baseline drift
Electrical Interference
Patient positioning