Ontents :1 ) Introduction 2 ) Medical View 3 )

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