Hello everyone. In today's topic we are going to discuss about the basic information about the Electro cardiogram (ECG).
The content is available in video forms in Tamil and English. If you have any doubts please post in the comment section .
ENGLISH : https://youtu.be/DQNFPnDpbxA
TAMIL :https://youtu.be/1RgN1gnOJ60
INTRODUCTION:
- ECG is the tool used to visualize the electricity that flows through the heart
- In the body ,tissues and fluids conduct electricity well. That’s why the electrical activity in the heart can be recorded on the skin surface using electrodes which are positioned on the limbs and the chest.
- This recording is called an electrocardiogram(ECG) which shows the spread of the electrical signal which are generated by the SA node as it travels through the atria, the AV node and the ventricles.
- The normal ECG shows five waves which, are P, Q, R, S and T.
PQRST WAVES:
- The P wave arises when the impulse from the SA node travels over the atria in the atrial depolarization.
- The QRS complex represents the very rapid / speedy spread of the impulse from the AV node through the AV bundle and the Purkinje fibers to the ventricles and the electrical activity of the ventricular muscle happens is called as ventricular depolarization.
- There is a delay between the completion of the P wave and the onset of the QRS complex. This represents the conduction of the impulse through the AV node which is slower and allows atrial contraction to finish completely before the ventricular contraction starts.
- The T wave represents the relaxation of the ventricular muscle is known as the ventricular repolarization.
- Atrial repolarization which is the relaxation of the atrium occurs during ventricular contraction, and it is not seen because of the larger QRS complex.
- The ECG originates from the SA node and is called sinus rhythm.
- The rate of sinus rhythm = 60–100 b.p.m.
- A faster heart rate is tachycardia and a slower heart rate is bradycardia
- By examining the pattern of waves and the time interval between cycles and parts of cycles, the state of the myocardium and the cardiac conduction system is obtained.
- BASICS OF THE DIPOLE ELECTRODE:
The cells are negatively charged and its
slightly positive in the outside environment.
- When depolarization occurs (contraction) the cells become slightly positive inside and negative at the outside environment.
- The electrodes detect the charge outside the cells.
- Usually the dipole will be more towards the positive electrode.
- The bigger the dipole bigger the deflection.
- When resting the charge will be negative and there is no dipole so no deflection.
- When the vector dipole goes to the opposite electrode there will be negative deflection.
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