12-10-2012, 04:30 PM
STUDY OF ECG
STUDY OF ECG.docx (Size: 92.95 KB / Downloads: 101)
THEORY:
The Electro Cardio Graphy (ECG) deals with the study of the electrical activity of the heart muscles. The potentials originated in the individual fibers of heart muscle are added to produce the ECG waveform. Electro cardiogram is recorded ECG wave pattern. ECG sometimes called EKG, which is derived from the German electrocardiogram. The electro cardiogram reflects the rhythmic electrical depolarization and repolarization of the myocardium (heart muscle) associated with the contractions of the atria and ventricles. The shape, time interval and amplitude of the ECG give the details of the state of the heart. Any form of arrhythmia (disturbances in the heart rhythm) can be easily diagnosed using electrocardiogram.
The heart is divided into four chambers. The top two champers are atria and lower two chambers are ventricles. The right atrium receives blood from the veins and pumps it into right ventricle. The right ventricle pumps the blood into the lungs where it is purified and oxygenated. The oxygen-enriched blood enters the left atrium from which it is pumped into the left ventricles. Then the left ventricle pumps the blood into arteries through aortic valve for circulation throughout the body. For circulation, blood requires proper pressure. Sufficient pressure is delivered by the ventricular muscle’s contraction, which is achieved through the cardiac action potential.
Each action potential in the heart originates at the sinoatrial (SA) node which is situated in the wall of the right atrium and near the entry of the vena cava. It is also called cardiac pacemaker and generates impulse at the normal rate of the heart, about 70 beats per minute at rest. The rate is governed by the autonomic nervous system, being increased by the sympathetic nerves and decreased by the parasympathetic nerves. These are connected with brain through the spinal cord. The action potential contracts the atrial muscle and the impulse spread through the atrial wall during a period of about 0.04 second to the atrio- ventricular (AV) node. The node is located in the lower part of the wall between the two atria. The AV node delays the spread of excitation for about 0.11 second. Thus the AV node acts as a “delay line” to provide
PROCEDURE:
1. Give the connection as per the position of photoelectric sensors to bio signal input.
2. Switch on the power supply.
3. Initialize the buzzer switch in off position.
4. Connect the test point TP2 to one channel and note the blood volume variation for each digital pulse in oscilloscope.
5. Reset the counter, for every 30 sec, and the normal pulse rate is noted per minute (60- 110).
6. Turn on the buzzer switch now can hear the pressure pulse as per the blood density variation.