ECG Normal version 1

Basic ECG Reading : 

Basic ECG Reading Dennis Quijano M.D.

Electrode Placement : 

Electrode Placement

Electrode Placement : 

Electrode Placement Limb leads depict cardiac electrical events from six angles in the frontal or vertical plane Chest leads depict electrical events in the horizontal plane

Electrode Placement : 

Electrode Placement Limb leads are usually labeled but also occasionally color coded so that Right arm — "White is on the right." Right leg — "Green is for go." (Right leg is gas pedal.) Left leg — "Red is for stop." (Some brake with left leg.) Left arm — black lead

Electrode Placement : 

Electrode Placement Limb Leads (I, II, II, aVR, aVL, aVF) The six limb leads are used to determine frontal plane axis. Leads II, III, and aVF "look" at the inferior surface of the heart; leads I and aVL "look" at the left or lateral side of the heart; and aVR "looks" at the right side of the heart.

Electrode Placement : 

Electrode Placement

Slide 7: 

Electrode Placement

Slide 8: 

Time is measured from the L to the R — one large box = 0.20 sec and one small one = 0.04 sec. The rate of the ECG machine is 25 mm/sec. Marks on the upper or lower border of paper fall every 3 sec or 3 inches. Voltage or current strength is determined from the magnitude or height of the various waveforms and is measured in mV or mm one small box normally = 0.1 mV 1 mm and one large box = 0.5 mV or 5 mm.

ECG WAVEFORMS : 

ECG WAVEFORMS P wave Represents atrial depolarization A measure of the time required for depolarization to spread through the atria Normal duration: less than 0.12 secs

ECG WAVEFORMS : 

ECG WAVEFORMS Q wave The initial negative deflection of ventricular depolarization

ECG WAVEFORMS : 

ECG WAVEFORMS R wave The initial positive deflection of ventricular depolarization

ECG WAVEFORMS : 

ECG WAVEFORMS S wave The first negative deflection of ventricular depolarization that follows the first R wave

ECG WAVEFORMS : 

ECG WAVEFORMS QRS Complex Represents ventricular depolarization Duration reflects the intraventricular conduction time Duration of less than 0.11 seconds

ECG WAVEFORMS : 

ECG WAVEFORMS T wave The deflection produced by ventricular repolarization

ECG WAVEFORMS : 

ECG WAVEFORMS U wave The deflection that follows the T wave but precedes the subsequent P wave Represent repolarization of the intramural Purkinje conduction system

ECG WAVEFORMS : 

ECG WAVEFORMS ST segment The isoelectric period between the end of the S wave and the beginning of the T wave Minor deviation from baseline of less than ± 1 mm

ECG WAVEFORMS : 

ECG WAVEFORMS ST segment Represents the early part of myocardial repolarization Reference point for baseline is the isoelectric interval between the end of the T wave and the beginning of the P wave

ECG WAVEFORMS : 

ECG WAVEFORMS QT interval Represents the total duration of electrical systole Measured from the beginning of the QRS complex to the end of T wave Important index of drug and electrolyte effects on the myocardium

ECG WAVEFORMS : 

ECG WAVEFORMS QT Interval measurement of the refractory period or the time during which the myocardium would not respond to a second impulse; measured from the beginning of the QRS complex to the end of the T wave Best leads to measure the QT are V2 or V3 Q-T interval should be roughly less than half the preceding R-R interval. It is longer with slower rates and shorter with faster rates

ECG WAVEFORMS : 

ECG WAVEFORMS The Q-T interval can be corrected for heart rate using Basset's formula: Normal QTc interval = 0.39 ± 0.04 sec

ECG WAVEFORMS : 

ECG WAVEFORMS PR Interval Measures the AV conduction time Measured from the onset of the P wave to the onset of the QRS complex Normal value: 0.12-0.20 secs Duration is inversely related to heart rate

ECG WAVEFORMS : 

ECG WAVEFORMS RR Interval The distance between the two consecutive R waves

ECG WAVEFORMS : 

ECG WAVEFORMS PP Interval The distance between two consecutive P waves Normally should be the same as the RR interval unless certain arrhythmias or AV block are present

Approach to Reading the ECG : 

Approach to Reading the ECG Rate Rhythm P wave: morphology and duration PR interval QRS complex: morphology and duration ST segment T wave U wave QT interval

Estimation of Heart Rate : 

Estimation of Heart Rate

Estimation of Heart Rate : 

Estimation of Heart Rate

Estimation of Heart Rate : 

Estimation of Heart Rate If the rhythm is irregular, the rate can be determined by counting the number of beats in 6 seconds and multiplying by 10

Estimation of Heart Rate : 

Estimation of Heart Rate Method 2 Count 25 large squares (each large square= 0.2 secs) this distance = 0.2 seconds x 25 = 5 seconds Count the number of cardiac cycles in the 5 seconds Multiply the number of cardiac cycles by 12 = heart rate

Estimation of Heart Rate : 

Estimation of Heart Rate Method 3 Each large square = 0.2 seconds = 1/5 second the are 300 fifths of a second per minute divide 300 by the number of fifths in the RR interval = hear rate

Determining Frontal QRS Complex : 

Determining Frontal QRS Complex

Determining Frontal QRS Complex : 

Determining Frontal QRS Complex Vector Method Quadrant Method

Determining Frontal QRS Complex : 

Determining Frontal QRS Complex Left Axis Normal Axis Right Axis Extreme Right /Left Axis -90º 0º +90 º +180 º Lead I = positive Lead AVF = positive Lead I = positive Lead AVF = negative Lead I = negative Lead AVF = positive Lead I = negative Lead AVF = negative

Sinus Rhythm : 

Sinus Rhythm Sinus Rhythm is defined as Regularly recurring P waves of the same morphology A normal P wave axis (15º to 75º) A rate between 60-100 beats per minute Each P wave is followed by a QRS complex

Normal Adult ECG : 

Normal Adult ECG P wave upright in leads I, II, AVF and V5,V6 inverted in lead AVR variable in leads III, AVL, V1, v2 Q wave small (less than 0.045 sec; ¼ of R wave) in leads I, V5 and V6 small or none in leads II, AVF, V3, V4 small, none, or moderately large (0.04 to 0.05 secs) in leads III and AVL large (more than 0.04 sec) in lead AVR

Normal Adult ECG : 

Normal Adult ECG R wave Dominant (10 to 25 mm) in leads I, II, V5 and V6 Small, none or less than S wave in leads AVR, V1, v2 Variable in other leads S wave None or less than R wave in Leads I and II Dominant or none in leads III, AVF and AVL Dominant in Leads AVR, V1, V2 Less than R wave in leads V4-V6

Normal Adult ECG : 

Normal Adult ECG T wave Upright in leads I,II and V5-V6 Inverted in lead AVR Variable in leads II, AVF, AVL, V1 and V2 PR interval Isoelectric in all leads 0.12 to 0.20 secs in more than 99% of normal ECG QT interval Shortens with increased rate i.e from 0.41 secs at 50/min to 0.31 secs at 100/min ST segment Usually isoelectric Vary up to 1 mm in standard leads and up to 2 mm in leads V1-V5

Thank You : 

Thank You