P wave = atrial depolarisation. PR Interval = impulse from atria to ventricles to ventricles. QRS complex = ventricular depolarisation. ST segment = isoelectric -. Objectives. Lead Placement. Hexaxial System. ECG Paper. Systematic Approach to Reading an ECG. Page 3. Lead Placement. Page 4. Hexaxial System. Library of Congress Cataloging-in- Publication Data. ECG interpretation made incredibly easy!. —. 5th ed. p. ; cm. Includes bibliographical references and index .
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General Introduction to ECG. Reading Assignment (p in PDF 'Outline'). Objectives. 1. Practice the 5-step 'Method'. 2. Differential Diagnosis: R & L axis. Introduction. This guide demonstrates how to read an ECG in a systematic and effective manner. Confirm the name and date of birth of the patient matches the. Confidential. 12 Lead ECG Interpretation. Deborah Klein, MSN, RN, ACNS-BC, CCRN, CHFN, FAHA. Clinical Nurse Specialist, Coronary ICU, Heart Failure ICU, .
Despite this controversy, a growing number of state dental boards are requiring ECG monitoring for general anesthesia and all levels of intravenous sedation. Disregarding these legal controversies, there is an intangible reassurance provided by an ECG monitor that adds to that provided by periodic measurement of blood pressure and continuous pulse oximetry. This of course presumes that the operator is comfortable witnessing occasional benign arrhythmias and the subtle mechanical nuances all monitors present during routine use.
The purpose of this Continuing Education article is to provide fundamental concepts of ECG recognition that will enable the dentist to feel more comfortable with the routine use of dynamic ECG monitoring.
General Principles of Cardiac Function The output of the heart per minute cardiac output is the paramount cardiovascular event required to sustain blood flow throughout the body.
In addition to blood volume and contractile strength, the heart must sustain a regular cycle of relaxation and contraction if it is to fulfill its objective. This regularity is predicated on a series of complex electrophysiological events within the cardiac tissues that can be monitored using a device called the electrocardiogram. This could easily lead to misdiagnosis.
The limb leads are labelled: R right , L left , F foot and N neutral. Ideally electrodes should be placed over fleshy surfaces, as flesh conducts electricity much better than bone. It is important to have the leads the right way round, otherwise this could change the polarity of the ECG complexes. What is being measured from these leads is simply the difference in electrical potential between two points, so if these points vary slightly e.
It is vital, however, to get the position of the chest electrodes correct see fig 1. The position of the patient will also make a difference to the ECG recording, as different positions alter the way the heart lies within the chest wall.
The ECG should be recorded with the patient lying flat, with two pillows under their head. Some patients e. In such cases it should be noted on the ECG that the patient was not lying flat, so that the interpreter can take this into account when analysing the ECG. Before the leads are disconnected, the quality of the ECG should be examined.
If there is any distortion of the trace, the source of the distortion must be identified and corrected, and the ECG must then be carried out again. The interpreter of the ECG will also find it useful to know whether the patient was experiencing any symptoms at the time of the recording.
Remember to leave the ECG machine clean, untangled and ready for use at all times, as it is often needed in emergency situations. Chapter 1, Activity 1 page 6 describes the process of recording a cardiac rhythm strip for analysis. Make sure that you have read through the chapter and that you have fully understood the key concepts presented.
Then work through the following activity. Activity 1.
Tell them to relax and rest their arms at their 2 3 4 5 6 7 8 sides and to loosen any items of clothing that are tight or may cause them discomfort. Any items of clothing that will obstruct the application of the chest electrodes should be moved or removed. Identify the important anatomical landmarks required for lead positioning see fig 1.
Identify any potential problems with the lead placement. For example, do any clothes or underwear need to be removed?
Assess the skin areas where the leads will be placed. Is the skin clean and dry? Is the skin excessively hairy? Identify the measures required to ensure that the electrodes will make good contact with the skin. Place the leads on the limbs and the chest in accordance with the diagrams in fig 1.
You should now have a well-recorded 12 lead ECG. Keep this recording and use it for later activities in this book. Soon it will all make sense! Electrical impulses are initiated and conducted from within the heart. These impulses produce myocardial contraction. It is these electrical impulses that are recorded on cardiac monitors and the electrocardiogram.
Figure 2. Confirm the name and date of birth of the patient matches the details on the ECG.
If there are obviously P-waves present, check the ventricular rate and the atrial rate. The rates will be the same if there is 1: Mark out several consecutive R-R intervals on a piece of paper, then move them along the rhythm strip to check if the subsequent intervals are the same. Hint — if you are suspicious that there is some atrioventricular block, map out the atrial rate and the ventricular rhythm separately i.
As you move along the rhythm strip, you can then see if the PR interval changes, if QRS complexes are missing or if there is complete dissociation between the two.
Cardiac axis describes the overall direction of electrical spread within the heart. To get a better understanding of cardiac axis read this article. Hint — If P-waves are absent and there is an irregular rhythm it may suggest atrial fibrillation. Second degree heart block Mobitz II 3.
Complete heart block 3rd degree 4. To help remember these degrees of AV block, it is useful to remember the anatomical location of the block in the conducting system: The early activation then spreads slowly across the myocardium causing the slurred upstroke of the QRS complex.
This requires evidence of tachyarrhythmias AND a delta wave. Isolated Q waves can be normal. Look for R wave progression across the chest leads from small in V1 to large in V6.
Poor progression i. High take off or benign early repolarisation to give its full title is a normal variant that causes a lot of angst and confusion as it LOOKS like ST elevation. In a healthy individual it should be an isoelectric line neither elevated or depressed.
T waves are normally inverted in V1 and inversion in lead III is a normal variant.