Download Electrocardiography (ECG)

Lab-2-
Anatomy and physiology
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Electrocardiography ECG(EKG)
Electrocardiography (ECG):-the machine which recorded the electrical
activities of the heart on moving strip of paper by amplify electrical signals from the
heart
Purpose : ECG help in diagnosis of the following :1- Primary induction abnormalities
2- Electrolytes imbalance
3-Heart attack (Myocardial infarction)
The electrocardiography assists in the diagnosis of specific cardiac abnormalities
by detecting transmission of electrical impulses through the heart’s conductive
tissues. This is accomplished by means of leads (or electrodes), attached to a
patient’s limbs and chest, which transmit electrical impulses to the recording device.
Different types of ECGs can be referred to by the number of leads that are recorded,
for example 3-lead, 5-lead or 12-lead ECGs (sometimes simply "a 12-lead").
A 12-lead ECG is one in which 12 different electrical signals are recorded at
approximately the same time and will often be used as a one-off recording of an
ECG, traditionally printed out as a paper copy.
1. Of the 12 leads, the 4 limbs electrodes
provide six leads( I,II,III, aVF, aVR, and aVL)
measure electrical activity in the vertical
plane.
2.
Lab-2-
Anatomy and physiology
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2. While the six precordial electrodes provide six leads( V1,V2,V3,V4,V5, and V6)
through the horizontal plane of the chest, which help determine the extent and
location of myocardial damage.
The precordial leads, designated as leads V1,
V2, V3, V4, V5, and V6, are placed at different angles in specific regions of the chest
to register cardiac electrical activity in the horizontal plane and to reveal valuable
information about specific regions of the heart. As shown above, the precordial leads
are placed on the anterior chest in the following manner:
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V1 - is placed on the fourth intercostal space at the right sternal border
V2 - is placed on the fourth intercostal space at the left sternal border
V3 - is placed halfway between V2 and V4
V4 - is placed on the fifth intercostal space at the left midclavicular line
V5 - is placed on the same level as V4 at the left anterior axillary line
V6 - is placed on the same level as V4 at the left midaxillary line
The precordial leads are also classified based on the region of the heart they are
monitoring:
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V1 and V2 are called the septal leads. Electrical activity of the inter-ventricular
septum is best measured in these leads.
V3 and V4 are called the anterior leads. Electrical activity of the anterior (front)
wall of the left ventricle is best measured in these leads.
V5 and V6 are called the left precordial or lateral precordial leads. Electrical
activity of the lateral (left) wall of the left ventricle is best measured in these
leads (together with leads I and aVL).
Lab-2-
Anatomy and physiology
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Each of the different electrodes (the six limb leads and the six precordial leads)
monitors heart activity from its own specific angle and position. As a result specific
areas of the heart are best analyzed through a particular set of leads.