TAILIEUCHUNG - Ebook ECG workbook (3rd edition): Part 2

(BQ) Part 2 book "ECG workbook" presents the following contents: Axis deviation, ischaemia, injury and necrosis, sites of infarction, bundle branch blocks, chamber enlargement, hemiblocks, bifascicular blocks and trifascicular blocks, paced rhythms, a systematic approach to ECG interpretation. | Chapter 8 Axis deviation We have already learned about the normal pathway of the impulse as it travels through the conducting system. We have also seen how the direction of this impulse and the position of electrodes around the heart affect the polarity of the limb leads. However there may be times when the normal pathway of the impulse is disrupted . by a piece of damaged tissue as the result of a heart attack. Such a disruption may cause the pathway of the impulse to deviate to the left or the right or in extreme cases back up to the direction from which it came. This is known as axis deviation. This disruption will affect the polarity of the limb leads. If something is causing the impulse to travel back from where it came the aVR may be positive on the ECG rather than negative because the impulse is now travelling towards the aVR. Meanwhile Lead II may be negative as the impulse is now travelling away from the lead. One way of working out axis deviation is therefore by looking at the polarity of two of the limb leads. This can be most easily done by assessing Lead I and the aVF. In a normal ECG as we know all the limb leads should be positive except aVR. Therefore if the ECG shows a normal axis deviation meaning that there is no disruption of the normal pathway of electrical activity both Lead I and the aVF should look positive see fig . Figure Normal cardiac axis demonstrated by both Lead I and the aVF being positive. 47 The ECG workbook If there is an extreme axis deviation severe disruption of the electrical pathway the opposite will occur - Lead I and the aVF will look negative see fig . Figure Extreme axis deviation. Lead I and the aVF lead are negative. Note that the aVR is positive the electrical impulses are therefore moving in the opposite direction from normal. If the impulse deviates to the left there is left axis deviation Lead I is positive and the aVF is negative. This can be easily remembered by thinking about the tips of the .

• Y khoa - Dược
• ECG workbook
• Axis deviation
• Injury and necrosis
• Sites of infarction
• Bundle branch blocks
• Chamber enlargement
• Cifascicular blocks
• Trifascicular block
• Paced rhythms
• Recording a readable electrocardiogram
• A systematic approach to rhythm strip analysis
• Heart blocks
• common arrhythmias
• Ectopics and extrasystoles
• The 12 lead ECG