ECG BASIC dr. fikri Taufiq, M.Si.Med
Physiology Department
Hp: 08122519992
email: [email protected]
Cardiac Conduction Pathway
SA Node
Intra-atrial conduction Internodal tract: SA Node AV Node Bachman bundle: Right Atrium Left Atrium
AV Node
Bundle of His
Bundle branch Left Bundle Branch Left anterior fasicular branch
Left ponterior fasicular branch
Right Bundle Branch
Purkinje Fibers
Impulse Conduction & the ECG Sinoatrial node
AV node
Bundle of His
Bundle Branches
Purkinje fibers
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Electrical Measurement
-Single Cell Model- In the resting state the surface of the cell is
positive charged relative to the inside because the surface is homogeneously charged the voltmeter electrodes outside the cell do not record any electrical potential different
If depolarization current is directed toward the (+) electrode of the voltmeter an upward deflection is recorded
If depolarization current is directed away from the
(+) electrode of the voltmeter a downward deflection is recorded
Electrocardiographic Lead Bipolar limb lead
Lead I
Lead II
Lead III
Unipolar limb lead
aVR
aVL
aVF
Precordial lead
V1
V2
V3
V4
V5
V6
Position of ECG Limb Leads
Lead (+) Electrode (-) Electrode
Bipolar Lead
I LA RA
II LL RA
III LL LA
Unipolar lead
aVR RA
aVL LA
aVF LL
Position of ECG Chest Electrodes
V1 4th ICS, 2 cm to the right of sternum
V2 4th ICS, 2 cm to the left of sternum
V3 Midway between V2 and V4
V4 5th ICS, left midclavicular line
V5 5th ICS, left anterior axillary line
V6 5th ICS, left midaxillary line
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The axial reference system
Hexadensial System
The ECG Paper
The ECG Paper
Horizontally
One small box - 0.04 s
One large box - 0.20 s
Vertically
One large box - 0.5 mV
Every 3 seconds (15 large boxes) is
marked by a vertical line.
This helps when calculating the heart rate.
NOTE: the following strips are not marked
but all are 6 seconds long.
3 sec 3 sec
Sequence of Normal Cardiac
Activation
The PQRST
P wave - Atrial depolarization
T wave Ventricular repolarization
QRS Ventricular depolarization
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The PR Interval
Atrial depolarization
+
delay in AV junction
(AV node/Bundle of His)
(delay allows time for the
atria to contract before
the ventricles contract)
Interpretation of The
Electrocardiogram Calibration
Heart Rhytm
Regularity
Heart Rate
P wave
PR interval
QRS wave QRS interval Axis Transition zone Atrium Abnormality Ventricular hipertrophy
Pathologic Q wave
ST Segment
T wave
Calibration
Check 1.0 mV vertical box inscription (normal standard = 10 mm)
25 mm/second speed
Heart Rhytm
Sinus rhytm is present if
Each P wave is followed by a QRS complex
Each QRS is preceded by P wave
P wave is upright in lead I, II, and III
PR interval is >0.12 sec (3 small boxes)
Atrial rhytm
Junctional rhytm
Ventricular rhytm
Regularity
Regular
Regular-Irregular
Irregular-Irregular
Heart Rate
Use one of three methode:
1500/(number of mm between beat)
Count-off methode: 300-150-100-75-60-50
Number of beat in 6 sec x 10
If regular
If irregular
Find a R wave that lands on a bold line.
Count total of large boxes to the next R wave. If the second R wave is
1 large box away the rate is 300,
2 boxes - 150,
3 boxes - 100,
4 boxes - 75, etc.
R wave
Example to count Heart Rate
Memorize the sequence:
300 - 150 - 100 - 75 - 60 - 50
Interpretation?
3
0
0
1
5
0
1
0
0
7
5
6
0
5
0
Approx. 1 box less than 100 = 95 bpm
Example to count Heart Rate
Count total of R waves in a 6 second
rhythm strip, then multiply by 10.
Interpretation?
9 x 10 = 90 bpm
3 sec 3 sec
Example to count Heart Rate
P wave
Inspect P in lead II and V1 for:
Right atrial enlargment (P pulmonal)?
Left atrial enlargment (Pmitral)?
PR interval
Normal PR interval = 0.12-0.20 sec (3-5 small
boxes)
QRS Wave
QRS interval?
Normal QRS interval 0.10 sec (2.5 small boxes)
Axis look at lead I and aVF
NAD?
LAD?
RAD?
Transition zone?
Normal in V3 and V4 V1 and V2 counter clockwise
V5 and V6 clockwise
Inspect for left and right ventricular hypertrophy
Inspect for pathologic Q wave: what anatomic distribution?
QRS Axis
ST segment or T wave abnormalities
Inspect for ST elevation
Myocard Infartion STEMI
what anatomic distribution?
Inspect for ST depressions or T wave
inversion:
Myocardial ischemia or Non-ST elevation MI
what anatomic distribution?
Abnormalities of the P Wave
P wave Represent depolarization of the right atrium followed quickly by the depolarization of the left atrium
The two components are nearly superimposed on one another
Right atrial enlargment best observed in lead II
Left atrial enlargment best observed in lead V1.
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Right atrial abnormality
P wave amplitude
> 2.5 mm in leads II
Left atrial abnormality
Negative P in V1
> 1 mm wide
> 1 mm deep
Abnormalities of the QRS Complex
For this Modul, we will discuse:
1. Ventricular hypertrophy
2. Pathologic Q wave
Right ventricular hypertrophy V1 & V2 record greater
than normal upward deflections
The R wave becomes taller than the S wave in V1 & V2
The increased right ventricular mass shifts the mean axis of the heart RAD (mean axis > +900)
Left ventricular hypertrophy
V5 & V6 show taller
than normal R waves
V1 & V2 demonstrate the opposite deeper than normal
S waves
Pathologic Q Wave In Myocardial Infarction Irreversible necrosis of the heart muscle
Width 1 small box and depth > 25% of total height of QRS
Necrotic muscle does not generate electrical force.
The ECG electrode over that region detects electrical currents from the healthy tissue on opposite regions of the ventricle inscribing the downward deflection
Do not differentiated between acute event and an MI that ocured week or years earlier
ST Segment and T Wave
Abnormalities Acute ST Segment Elevation MI
The initial abnormality is elevation of the ST segment, often with a peaked appearance of the T wave.
Abnormality of injured myocardial cell The diastolic current theory Capable of depolarization but abnormally leaky Allowing ionic flow that prevents the cells from fully
repolarization
The systolic current theory
Acute Non-ST Segment Elevation MI Result from an acute partially occlusive coronary
thrombus ST segmen depression and T wave inversion
The diastolic current theory
MI Locations
First, take a look again at this picture of the heart.
Anterior portion
of the heart
Lateral portion
of the heart
Inferior portion
of the heart
MI location
Resource Pathophysiology of Heart Disease, Leonard S. Lilly
Lange Instant Access EKGs and CARDIAC STUDIES, Anil M. Patel
Kursus Elektrokardiografi, Perki