ECG
ontents :1 ) Introduction 2 ) Medical View 3 ) Principles of operation 4 ) Block diagram
ntroduction :-
aphy or ECG is a important diagnostic tool for Veter
he electrical activity of the heart.
device had 10 electrodes separated in two gro 1) (LA , RA , LL , Physical ground). 2) (v1 , v2 ,v3 ,v4 , v5 ,v6)
ontents :1 ) Introduction 2 ) Medical View 3 ) Principles of operation 4 ) Block diagram
Medical View: - of The Anatomy Heart
Body Circulations
ary ( lesser ) circulation .
ood circulates between the heart and lungs oxygenated ).
ic ( greater ) circulation .
ood circulates between the heart and the body eliver oxygen and nutrients to all body cells
Pulmonary ( lesser ) circulation .
Systemic ( greater ) circulation .
Initiation & Conduction of electric Impulse In The Heart
n the right atrium of the heart called sinoatrial no
1) The left atrium. SAN
Atrioventricular node (AVD) ch conduct the impulse very slowly.
AVN
3) Atrioventricular bundle
es which conduct the impulses to the right & left v
ontents :1 ) Introduction 2 ) Medical View 3 ) Principles of operation 4 ) Block diagram
inciples of operation : 12 parameters (12 lead) by using 10 electrodes are s -
LL , Physical ground). 3 ,v4 , v5 ,v6). are put in the body like in the next figure:
2 lead) is measured using 10 electrodes are shown
ECG waveform
3 distinct waves are produced during cardiac cycle P wave caused by atrial depolarization QRS complex caused by ventricular depolarization T wave results from ventricular repolarization
lements of the ECG ( 6 PARTS
arization of both atria; hip between P and QRS helps distinguish various card duration of P may indicate atrial enlargement.
13-63
interval : from onset of P wave to onset of QRS
mal duration = 0.12-2.0 sec.
resents atria to ventricular conduction time.
longed PR interval may indicate a 1st degree heart bl b
depolarization
of greater muscle mass of ventricles.
seconds.
morphology are useful in diagnosing cardiac arrhyth
rization or recovery of ventricles inning of QRS to apex of T is referred to as the abs
ST segment : - Connects the QRS complex and T wave - Duration of 0.08-0.12 sec (80-120 msec)
nterval •Measured from beginning of QRS to the end of the T •Normal QT is usually about 0.40 sec •QT interval varies based on heart rate
Types of ECG Recordings Leads
ipolar Leads
Unipolar Leads
LEAD I LEAD II AUGMENTED LEAD III LEADS
CHEST LEADS
ipolar Leads Lead Lead Lead
I records between right arm & left arm II : right arm & left leg III : left arm & left leg
nipolar Leads 1 ) AUGMENTED LEADS :-
nipolar Leads 2 ) CHEST LEADS :-
ontents :1 ) Introduction 2 ) Medical View 3 ) Principles of operation 4 ) Block diagram
lock diagram: -
SENSING ELECTRODES sensing the signal from the body to the E
PROTECTION CIRCUIT protect the human body from the electric
LEAD SELECTOR
select the wanted leads that we want to show there si s
multiplexers that has multi input and one output is
MULTIINPUT S
LA LL LL
OUTPUT
MULTIPLEXE R RA LA RA
OPAMP
PRE AMPLIFIER
the signal is amplifiered to be available to the nex
UNAMPLIFIED SIGNAL
AMPLIFIED SIGNAL