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Electrocardiographs ECG

Electrocardiographs ECG. OUTLINES :. Introducing what is meant by Biopotential signals. what is Electrocardiograph (ECG). The conduction system. The standard Lead system. The ECG machine Construction. . Introduction to Biopotential Signals. I. Electrocardiograph (ECG). I.

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Electrocardiographs ECG

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  1. ElectrocardiographsECG

  2. OUTLINES : • Introducing what is meant by Biopotential signals. • what is Electrocardiograph (ECG). • The conduction system. • The standard Lead system. • The ECG machine Construction.

  3. Introduction to Biopotential Signals I

  4. Electrocardiograph (ECG). I

  5. The ECG is a graph showing the electrical activity due to the systole and diastole of the heart muscle • Which Records : 1-Amount of electrical activity of the heart. 2-The time required for the electrical activity to travel through the heart . 3-The rate and rhythm of the heart.

  6. The heart acts as a blood pump. • Heart contracts generating action potential. • This potential creates electrical currents that spread from the heart throughout the body. • The spreading electrical currents create potentials differences which can be detected through surface electrodes • The waveform produced is called the electrocardiogram (ECG)

  7. Electrocardiogram (ECG) • Is a recording of electrical activity of heart conducted through ions in body to surface 13-60

  8. ECG Graph Paper • Runs at a paper speed of 25 mm/sec • Each small block of ECG paper is 1 mm2 • At a paper speed of 25 mm/s, one small block equals 0.04 s • Five small blocks make up 1 large block which translates into 0.20 s (200 msec) • Hence, there are 5 large blocks per second • Voltage: 1 mm = 0.1 mV between each individual block vertically

  9. (SA node) (AV node)

  10. Normal conduction pathway: SA node -> atrial muscle -> AV node -> bundle of His -> Left and Right Bundle Branches -> Ventricular muscle

  11. Recording of the ECG: • Leads used: • Limb leads are I, II, II. • Each of the leads are bipolar; i.e., it requires two sensors on the skin to make a lead. • If one connects a line between two sensors, one has a vector. • There will be a positive end at one electrode and negative at the other. • The positioning for leads I, II, and • III were first given by Einthoven. • Form the basis of Einthoven’s triangle.

  12. Types of ECG Recordings • Bipolar leads record voltage between electrodes placed on wrists & legs (right leg is ground) • Lead I records between right arm & left arm • Lead II: right arm & left leg • Lead III: left arm & left leg 13-61

  13. ECG • 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 13-63

  14. Normal ECG Waveform

  15. ECG Readout devices 1- Medical Oscilloscope: vertical output is severely limited. • CRT persistence is very long . • ECG use a horizontal sweep speed 25 mm/s. 2- strip chart recorder (speed 25 mm/s) and has a grid pattern that is 50 mm wide. The small grid are 1 mm apart. The vertical scale is calibrated at 0.1 mV/mm

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