Presentation on theme: "The Standard 12-ECG System"— Presentation transcript:
1 The Standard 12-ECG System CHAPTER 13The Standard 12-ECG System
2 Consists of four limb electrodes and six chest electrodes Standard 12-ECG SystemConsists of four limb electrodes and six chest electrodesCollectively, view the heart from 12 different positionsSix standard limb leadsSix precordial (chest) leads
4 Standard 12-ECG System Each lead: Views the electrical activity of the heart from a different angleHas a positive and negative componentMonitors specific portions of the heart from the point of view of the positive electrode in that lead
17 ECG Monitoring PaperFig The ECG monitoring paper, with the blocks enlarged to illustrate the minimum units of measurement.
18 Large square = 5 sm. Sq. = 0.20 sec. Speed = 5 lg. Sq./sec. ECG PaperSmall square = 0.04 sec.Large square = 5 sm. Sq. = 0.20 sec.Speed = 5 lg. Sq./sec.Vertical portion of sm. Sq. =Amplitude (voltage) of 0.1 millivolt (mV)1 millimeter (1mm) in distance
19 ECG Monitoring PaperFig The ECG monitoring paper, with the blocks enlarged to illustrate the minimum units of measurement.
20 ECG Monitoring PaperFig ECG monitoring paper showing markers indicating 3- and 6-second intervals. There are 15 blocks in 3 seconds and 30 blocks in 6 seconds.
21 Normal ECG Configurations Fig Normal ECG configurations.
22 ECG ConfigurationFig The duration of the normal ECG configuration.
23 The P WaveRepresents atrial depolarizationUsually symmetrical and upright
24 The PR IntervalRepresents the total atrial electrical activity
25 The QRS ComplexRepresents the ventricular depolarization
26 The QRS ComplexFig (A) Q waveform of the QRS. (B) R waveform of the QRS complex. (C) S waveform of the QRS complex.
27 The ST SegmentRepresents the time between ventricular depolarization and repolarization
28 ST Segment Highlighted within Cardiac Complex Fig (A) The ST segment highlighted within cardiac complex. Note variation. (B) ST above the baseline. (C) Shows 3 mm ST segment increase. (D) shows 3 mm ST segment decrease.
29 The T WaveRepresents ventricular repolarization, rest, and recovery
30 The T WaveFig (A) T wave shows ventricular depolarization. (B) The T wave with ST segment elevation. (C) Measuring an inverted T wave and with ST segment depression.
31 Its origin and mechanism are not known Often prominent in certain The U WaveIts origin and mechanism are not knownOften prominent in certainElectrolyte disturbancesMedicationsHeart diseases
32 The U WaveFig The U wave highlighted (arrow) within the cardiac complex.
33 Summary of Normal ECG Configurations and Heart Activity
34 Summary of Normal ECG Configurations and Heart Activity Table 13-2