4 ECG Monitoring Recording of Electrical Activity Uses Bipolar or Unipolar leadsThe ECG DOES NOT provide a recording or evaluation of Mechanical Activity!!!
5 ECG Monitoring Bipolar Leads 1 positive and 1 negative electrode RA always negativeLL always positiveTraditional limb leads are examples of theseLead ILead IILead IIIProvide a view from a vertical plane
6 ECG Monitoring Unipolar Leads 1 positive electrode 1 negative “reference point”calculated by using summation of 2 negative leadsAugmented Limb LeadsaVR, aVF, aVLvertical planePrecordial or Chest LeadsV1-V6horizontal plane
7 ECG Monitoring Einthoven’s Triangle Each lead “looks” from a different perspectiveCan determine the direction of electrical impulsesUpright electrical recording indicates electricity flowing towards the + electrodepositive deflection
9 Standardized Methods & Devices ECG PaperDevice Paper SpeedDevice CalibrationElectrode PlacementVariations Do Exist!
10 Standardized Methods & Devices ECG Graph PaperVertical axis- voltage1 small box = 1 mm = 0.1 mVHorizontal axis - time1 small box = 1 mm = 0.04 sec.Every 5 lines (boxes) are boldedHorizontal axis - 1 and 3 sec marks
11 Standardized Methods & Devices ECG Paper ExamplesVertical AxisNo. of mm in 10 small boxes?No. of small boxes in 2 mm?Horizontal AxisNo. of seconds in 5 small boxes?No. of small boxes in 0.2 second?No. of small boxes in 1 second?
12 Standardized Methods & Devices Paper Speed & CalibrationPaper Speed - 25 mm/sec standardCalibration of Voltage is AutomaticBoth Speed and voltage calibration can be changed on most devices
13 Standardized Methods & Devices Electrode PlacementStandardization improves accuracy of comparison ECGs3 Lead and 12 Lead Placement are most commonAssure good conduction gelPrep area with alcohol prepAvoidBoneLarge muscles or hairy areasLimb vs. Chest placement
14 Standardized Methods & Devices Electrode PlacementPoor placement or preparationOften results in artifactStray energy from other sources can also lead to poor ECG tracings (noise)60 cycle interference
16 Components of the ECG Complex Components & Their RepresentationP, Q , R, S, T WavesPR IntervalQRS IntervalST Segment
17 Components of the ECG Complex P Wavefirst upward deflectionrepresents atrial depolarizationusually 0.10 seconds or lessusually followed by QRS complex
18 Components of the ECG Complex QRS ComplexComposition of 3 WavesQ, R & Srepresents ventricular depolarizationmuch variabilityusually < 0.12 sec
19 Components of the ECG Complex Q Wavefirst negative deflection after P wavedepolarization of septumnot always seen
20 Components of the ECG Complex R Wavefirst positive deflection following P or Q wavessubsequent positive deflections are R’, R”, etc
21 Components of the ECG Complex S WaveNegative deflection following R wavesubsequent negative deflections are S’, S”, etcmay be part of QS complexabsent R wave in aberrant conduction
22 Components of the ECG Complex PR Intervaltime impulse takes to move through atria and AV nodefrom beginning of P wave to next deflection on baseline (beginning of QRS complex)normally secmay be shorter with faster rates
23 Components of the ECG Complex QRS Intervaltime impulse takes to depolarize ventriclesfrom beginning of Q wave to beginning of ST segmentusually < 0.12 sec
24 Components of the ECG Complex J Pointpoint where QRS complex returns to isoelectric linebeginning of ST segmentcritical in measuring ST segment elevation
25 Components of the ECG Complex ST Segmentearly repolarization of ventriclesmeasured from J point to onset of T waveelevation or depression may indicate abnormality
26 Components of the ECG Complex T Waverepolarization of ventriclesconcurrent with end of ventricular systole
29 ECG Analysis Ventricular Rate Triplicate method R-R method R-R methoddivide 300 by # of large squares between consecutive R waves6 Second methodmultiply # of R waves in a 6 second strip by 10Rate meter unreliable!!!
30 ECG Analysis Rhythm Measure R-R intervals across strip Should find regular distance between R wavesClassificationRegularIrregularRegularly irregularIrregularly irregular
31 ECG Analysis QRS Complex Narrow Wide < 0.12 seconds (3 small boxes) is normalindicates supraventricular origin (AV node or above) of pacemakerWide> 0.12 seconds is wideindicates ventricular or supraventricular w/aberrant conduction
32 ECG Analysis P Waves Present? Do they all look alike? Regular interval Upright or inverted in Lead II?Upright = atria depolarized from top to bottomInverted = atria depolarized from bottom to top
33 ECG Analysis Relationships/Measurements PR Interval Constant?Less than 0.20 seconds (1 large bx)P to QRS RelationshipP wave before, during or after QRS?1 P wave for each 1 QRS?Regular relationship?
34 ECG Analysis A monitoring lead can tell you: How often the myocardium is depolarizingHow regular the depolarization isHow long conduction takes in various areas of the heartThe origin of the impulses that are depolarizing the myocardium
35 ECG Analysis A monitoring lead can not tell you: Presence or absence of a myocardial infarctionAxis deviationChamber enlargementRight vs. Left bundle branch blocksQuality of pumping actionWhether the heart is beating!!!
36 ECG Analysis An ECG is a diagnostic tool, NOT a treatment No one was ever cured by an ECG!!Treat the PATIENT not the Monitor!!!