ECG BASICS
Depolarization
Repolarization
Placement of electrocardiogram (ECG)
electrodes
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
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
The axial reference
system
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
The ECG Paper
The ECG Paper
Horizontally
One small box - 0.04 s
One large box - 0.20 s
Vertically
One small box – 0.1 mv
One large box - 0.5 mV
Sequence of Normal Cardiac
Activation
The “PQRST”
P wave - Atrial depolarization
• T wave – Ventricular repolarization
• QRS – Ventricular depolarization
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
Atrium Abnormality
PR interval
QRS wave
QRS interval
Axis
Transition zone
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:
1.
1500/(number of mm between beat)
2.
Count-off methode: 300-150-100-75-60-50
3.
Number of beat in 6 sec x 10
If regular If irregular Irregular
P wave
Inspect P in lead II and V
1for:
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?
Atrial and Ventricular Hipertrophy
Ischemia and Infarct
&
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 V
1.
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
V
5& V
6show taller than normal R
waves
V
1& V
2demonstrate 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
Anterior portion of the heart
Lateral portion of the heart
Inferior portion
of the heart
Miniaturized 12-lead ECG schematic
ARITMIA
Gangguan Pembentukan
Impuls Gangguan Pembentukan
Impuls
Gangguan Penghantaran
Impuls
Sinus
Atrial
Junctiona l
Ventrikular
Sinus Bradikardi Sinus Takikardi Atrial Fibrilasi
Atrial Flutter Atrial Ektrasistole Supraventrikula
r Takikardi (SVT) Ventrikel Ekstrasistole Ventrikel Takikardi
Torsade De Pointes
Ventrikel Fibrilasi
AV BLOCK
-HR >
100 -QRS
Sempit (<0,10s )
-HR >
100 -QRS
Lebar (>0,10s )
HR < 80
HR < 80
