Download ECG Leads

ECG
Electrocardiography
It is a voltage
difference, record
the electrical activity
of the heart as well
as valuable
information about
the heart function
and structure.
Willem Einthoven 1924
Leads (lead x electrode)

LIMB LEADS
I
II
III
AVF
AVL
AVR
bipolar
unipolar
CHEST LEADS
V1
V2
V3
V4
V5
V6

Limb leads
Limb leads
Both limb leads
Chest leads
What chest lead represent ?
ECG Leads - Views of the Heart
einthoven's triangle :
ECG Paper
ECG Speed 25mm/sec

See video
ECG Cardiac Cycle

What is the isoelectric line‫؟‬
P wave


Represent
the
electrical activity of
both atria ( atrial
depolarization)
The
depolarization
slow within the AV
node, there is a brief
delay or PAUSE before
the
depolarization
conducted to the
ventricles
Normal duration <0.12 sec
Absent P wave:
Atrial fibrillation
SA Block
AV Rhythm
Peak P wave:
Atrial hypertrophy
PR interval

Normally :0.12-0.2sec

Prolonged in : heart block.

Short in : W-P-W syndrome.
QRS Complex

Represent the
electrical activity of
both ventricles.

Ventricular
depolarization(
initiation of the
ventricular
contraction
QRS Complex

Q wave

R wave:

S wave :

:Normal QRS duration < 0.12 sec
QRS Complex

Q wave

first downward
deflection .

septal
depolarization.

0.04sec.

R wave :first upward deflection.
height: 5-8 mm.
early ventricular depolarization

S wave : late ventricular depolarization,
Large QRS indicate Ventricular
hypertrophy.
ST - Segment

ST segment: the
plateau phase of
ventricular
repolarization.

Isoelectric or>
or<1mm.

If the ST segment
elevated or depressed
beyond the normal
baseline this usually
sign of serious
pathology. (MI)
T- Wave
T-wave :represent rapid
phase of ventricular
repolarization.
peaked T wave:




early MI
hyperkalemia
Black races
Inverted :




MI .
Ventricular hypertrophy.
Hypokalemia
Digoxin
Q-T interval

0.4 sec in HR 70

Prolonged in :
1.
Hypocalcemia
hypomagnesemia
2.
U wave
repolarization of the interventricular septum.
 low amplitude
 Prominent: suspect hypokalemia, hypercalcemia
or hyperthyroidism

J wave

represents the approximate end of depolarization and
the beginning of repolarization

camel-hump sign

Hypothermia
hypocalcemia.

.
Low voltage ECG
Obesity
 Emphysema
 COPD
 Severe hypothyroidism

Rate
Normal heart rate 60-100/ min
 < 60 called bradycardia
 >100 called tachycardia

How To Calculate Heart Rate ?
HR=
HR=
300
No. of Large box btw R-R
1500
No. of Small box btw R-R
RHYTHM

Look For The Distance between Identical
waves.

Most commonly used R-R
AXIS
At any point during depolarization and
repolarization electrical potential are
being propagated in different directions.
Most of these cancel each other out and
only the net force is recorded. This net is
called AXIS or cardiac VECTOR
How To Check Axis in ECG
Principles of ECG recording
Explain the indication and the procedure for the
patient. (assurance )
 Ask the patient to take off any metals he/she
wears.
 Expose the wanted sites.
 Cleaning of skin and shaving if necessary.
 Place the electrodes in the correct positions .
 Instruct the patient to remain still (should not talk
during the test ) and relax their shoulders and legs
while the recording takes place (1 min)


See video
How to comment on ECG
Name.Age ,Date and time.
 Calibration and Speed of paper
 RAWIHI :

RAWIHI
R: rate, regularity,rhythm(sinus or asinus),
 A: axis.
 W:waves.
 I :intervals.
 H: hypertrophy.
 I: ischemia

Normal Sinus Rhythm








Rate = 60-100 beat / minute.
The rhythm is regular
All intervals are within normal limits
There is a P for every QRS and a QRS for every
P.
P : QRS ratio = 1 : 1.
The P waves all look the same
Presence of P, QRS, T in each cycle.
Normal shape, time of waves, segments and
intervals
Interfering factors

Inaccurate placement of the electrodes

Electrolyte imbalances

Poor contact between the skin and the electrodes

Movement or muscle twitching during the test

Drugs that can affect results include digitalis,
quinidine, and barbiturates
MI
When myocardial blood supply is abruptly reduced to
a region of the heart, a sequence of injurious events
occur :
Ischemia ( subendocardial or
transmural)
 Injury
 Necrosis, and eventual fibrosis
(scarring) if the blood supply isn't
restored in an appropriate period of time


Hyperacute T wave is the earliest
sign of acute myocardial
infarction
Precordial Septal Leads
◦ V1 – V2
– Look at the
Septum of the
heart
– The septal
branch of the
LAD
Precordial
Anterior Leads
◦ V3 – V4
–anterior wall of
the left ventricle
–The LAD
diagonal
branch)
Anterior-Septal Terminology
Lateral Precordial Leads
◦ I,AVL,V5 – V6
◦ lateral of the left
ventricle
◦ The left circumflex
Inferior border leads
◦ II, III and aVF
◦ the Inferior wall of
the RV
◦ Posterior Descending
Branch of the RCA.
Posterior MI

No leads look at the posterior wall.

usually associated with inferior and/or lateral wall MI.


The changes of posterior myocardial infarction are seen
indirectly in the anterior precordial leads. Leads V1 to V3 face
the endocardial surface of the posterior wall of the left
ventricle. As these leads record from the opposite side of the
heart instead of directly over the infarct, the changes of
posterior infarction are reversed in these leads. The R waves
increase in size, becoming broader and dominant, and are
associated with ST depression and upright T waves. This
contrasts with the Q waves, ST segment elevation, and T wave
inversion seen in acute anterior myocardial infarction.
ST depression is considered reciprocal ECG changes in what
should be ST elevation for acute posterior wall injury.
ECG Leads - Views of the Heart
lead
border
V3 & V4
anterior Right RCA
Ventricle
Septum
LAD
V1 & V2
a VL,V5 & V6
II+III+AVF
Arterial
supply
Lateral Left
LCX
Ventricle
inferior
RCA
borderof right
ventricle
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