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ECG made easy
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ECG INTERPRETATIONPart 2
ECG INTERPRETATIONPart 2
Coronal plane (Limb Leads)1. Bipolar leads - l , l l , l l l2.Unipolar leads - aVL,Avr aVF
Transverse planeV1 — V6 (Chest Leads)
10 electrodes
LIMB LEADS
Augmented limb leads
How to READ??
Standardization
Calibrate to 10mm/mV Rate at 25mm/s
Rhythm
“Constant Ps & Rs interval”. Every QRS must be preceded by a
P wave.
Heart rate
Regular: 300/RRbig or 1500/RR
For irregular Rhythm: 15 cm scalenumber of R waves in a 6-second
(30 big square) X 10.
AXIS
Neonate & infant: 90-150 child: 60-120 elder: “>12 years” 30-90
Left leaves
Right reaches
ECG INTERPRETATION PART 2
WAVES INTERVALS CHAMBER HYPERTROPHY
Waves
Physiological waves:P-wave:Best seen in Lead II Normally 2-3 small squares (0.08-
0.12 sec) duration & height “Simple 2.5X2.5”.
Height A tall P wave
(over 2.5mm) can be called P pulmonale
Occurs due to right atrial hypertrophy
Length A P wave with a
length >0.08 seconds (2 small squares) and a bifid shape is called P mitrale
It is caused by left atrial hypertrophy
QRS-waves
Q - First downward R - first upward R’ - 2nd upward S - first downward after 1st
upward QS
QRS-waves
QRS-waves
Duration: <3 small squares ( 0.12 secs )
Amplitude: Variable <2.0 mV or 4 big sq
Q wave: <3 small squares depth in “right leads” V1 , v2
QRS
Progression:A. Right to left: From mainly S in
V1 to mainly R in V6B. Age: From RV dominance in
neonates to LV dominance after age of 3 years.
R wave Progression
QRS
Narrow QRS Broad QRS RSR’ LVH vs RVH Delta slurring
T wave Repolarization begins in the last area of
the heart to have been depolarized, and then travels backward, in a direction opposite that of the wave of depolarization
both an approaching wave of depolarization and a receding wave of repolarization generate a positive deflection on the EKG,
T-wave:
V6 T - always upright. ( If inverted indicate LVH )
The amplitude, of T wave is one third to two thirds that of the corresponding R wave
V1 it is inverted from age of 1 week up to puberty “16 years”; upright after birth & after puberty.
T wave
Tall T wave Flat (< 0.5 mm negative ) Inverted (> 0.5 mm negative )
Pathological waves
1. Delta-wave2. J-wave (Osborne wave)3. R’ -wave4. U-wave
???
Interval /segment
Interval / segment
Intervals
PR Interval Normally, 2-5 small squares
(average 0.08-0.2 sec)
Long PR >5 Short PR <2
Q-T Interval
The duration of the QT interval is proportionate to the heart rate.
Q-T IntervalCount the number of small squares, then multiply by 0.04 seconds, that the QT in seconds.
Bazett Formula.
QTc = QT/square root of RR“RR: are the small squares between 2 R waves”
Crude normal value: 0.35-0.45 at rate between 60-100
Short Q-T: Hypercalcemia
Long Q-T: 5 Hypos “Thermia, Thyroidism,
Calcemia, Magnisemia & Kalemia” 2 Syndromes: Romano–Ward & Jervell
and Lange–Nielson “+Deafness” Drugs: e.g. Tricyclic Antidepressant
S-T segment
Elevated ST segment: Pericarditis / MI
Depressed ST segment: Ischemia ( Angina ) Hypokalemia.
Chamber size
RAE vs LAE RVH vs LVH
Chamber size
Right Atrial Enlargement: Tall P- wave “P pulmonale” ( >3 small squares )Lead II & V2
Left Atrial Enlargement:
Wide P- wave “P mitrale” >3 small squares (> 0.12 sec)Lead II & V6
RVH vs LVH
R wave Progression
Right Ventricular Hypertrophy
In lead V1, the R wave is larger than the S wave.
In lead V6, the S wave is larger than the R wave
With Right axis deviation
Left Ventricular Hypertrophy
R wave in V5 + S wave in > 35 mm.
R in V5 is 26mm, S in V1 in 15mm. The sum is 41 mm
Bi-Ventricular Hypertrophy
Sum of RS in V3 & V4 > 60
ECG INTERPRETATION PART 3
Arrythmias Heart block Myocardial infarction
Acute myocardial infarction
Three stages:
1. T wave peaking followed by T wave inversion
2. ST segment elevation3. Appearance of new Q waves
3 stages
Pathologic Q wave
The Q wave must be greater than 0.04 seconds in duration.
The depth of the Q wave must be at least one third the height of the R wave in the same QRS complex.
Lead AVR should not be considered when assessing possible infarction.
T wave inversion --- not diagnostic ST segment elevation is a reliable sign Appearance of new Q waves indicates
irreversible myocardial cell death has occurred
Reciprocal Changes --- at lead distant from an infarct ( ST segment depression )
Inferior infarction- inferior leads Lateral infarction - the left lateral
leads Anterior infarction - Any of the
precordial leads (V1 through V6) Posterior infarction- reciprocal
changes in the anterior leads, especially V1.
Arrythmia
Sinus arrythmia