part II

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ecg part ii

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Simplified ECG part II : 

Simplified ECG part II Sayed Syleem, MSc Cardiologist Kafr Saad central hospital 2010

و في الأرضِ آياتٌ للموقنينَ * و في أنفُسِكم أفلا تُبْصِرونَ * : 

و في الأرضِ آياتٌ للموقنينَ * و في أنفُسِكم أفلا تُبْصِرونَ * الذاريات 20 و 21

ECG Monitoring: 

ECG Monitoring Unipolar Leads 1 positive electrode 1 negative “reference point” calculated by using summation of 2 negative leads Augmented Limb Leads aVR, aVF, aVL vertical plane Precordial or Chest Leads V1-V6 horizontal plane

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P Wave first upward deflection represents atrial depolarization usually 0.10 seconds or less usually followed by QRS complex

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PR Interval time impulse takes to move through atria and AV node from beginning of P wave to next deflection on baseline (beginning of QRS complex) normally 0.12 - 0.2 sec may be shorter with faster rates

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Q Wave first negative deflection after P wave depolarization of septum not always seen R Wave first positive deflection following P or Q waves subsequent positive deflections are R’, R”, etc S Wave Negative deflection following R wave subsequent negative deflections are S’, S”, etc may be part of QS complex absent R wave in aberrant conduction

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QRS Complex Composition of 3 Waves Q, R & S represents ventricular depolarization much variability usually < 0.12 sec

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QRS Interval time impulse takes to depolarize ventricles from beginning of Q wave to beginning of ST segment usually < 0.12 sec J Point point where QRS complex returns to isoelectric line beginning of ST segment critical in measuring ST segment elevation

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T Wave repolarization of ventricles concurrent with end of ventricular systole

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ST Segment early repolarization of ventricles measured from J point to onset of T wave elevation or depression may indicate abnormality

Components of a NSR: 

Components of a NSR

Paper Speed: 

Paper Speed

Determining heart rate: 

Determining heart rate Regular beats Rapid [ 1500 / number of small squares () RR] Slow [ 300 / number of large squares () RR] Irregular beats Rapid [number of QRS in 10 LS x 30 ] Slow [number of QRS in 30 LS x 10 ]

Determine the HR in A, B, & C: 

Determine the HR in A, B, & C

Determining AXIS : 

Determining AXIS Rough method From I & avF Hexagonal method From I & avF

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The normal QRS axis lies between -30 o and +90 o . 0 o 30 o -30 o 60 o -60 o -90 o -120 o 90 o 120 o 150 o 180 o -150 o A QRS axis that falls between -30 o and -90 o is abnormal and called left axis deviation . A QRS axis that falls between +90 o and +150 o is abnormal and called right axis deviation . A QRS axis that falls between +150 o and -90 o is abnormal and called superior right axis deviation .

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Each frontal lead corresponds to a location on the circle. 0 o 30 o -30 o 60 o -60 o -90 o -120 o 90 o 120 o 150 o 180 o -150 o I II avF avL avR Limb leads I = +0 o II = +60 o III = +120 o Augmented leads avL = -30 o avF = +90 o avR = -150 o I II III

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0 o 30 o -30 o 60 o -60 o -90 o -120 o 90 o 120 o 150 o 180 o -150 o Since lead I is orientated at 0 o a wave of depolarization directed towards it will result in a positive QRS axis. Therefore any mean QRS vector between -90 o and +90 o will be positive. I

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0 o 30 o -30 o 60 o -60 o -90 o -120 o 90 o 120 o 150 o 180 o -150 o Since lead I is orientated at 0 o a wave of depolarization directed towards it will result in a positive QRS axis. Therefore any mean QRS vector between -90 o and +90 o will be positive. Similarly, since lead II is orientated at 60 o a wave of depolarization directed towards it will result in a positive QRS axis. Therefore any mean QRS vector between -30 o and +150 o will be positive. I II

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0 o 30 o -30 o 60 o -60 o -90 o -120 o 90 o 120 o 150 o 180 o -150 o Since lead I is orientated at 0 o a wave of depolarization directed towards it will result in a positive QRS axis. Therefore any mean QRS vector between -90 o and +90 o will be positive. Similarly, since lead II is orientated at 60 o a wave of depolarization directed towards it will result in a positive QRS axis. Therefore any mean QRS vector between -30 o and +150 o will be positive. Therefore, if the QRS complex is positive in both leads I and II the QRS axis must be between -30 o and 90 o (where leads I and II overlap) and, as a result, the axis must be normal. I II

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0 o 30 o -30 o 60 o -60 o -90 o -120 o 90 o 120 o 150 o 180 o -150 o 0 o 30 o -30 o 60 o -60 o -90 o -120 o 90 o 120 o 150 o 180 o -150 o Now using what you just learned fill in the following table. For example, if the QRS is positive in lead I and negative in lead II what is the QRS axis? (normal, left, right or right superior axis deviation) QRS Complexes I Axis I II + + + - normal left axis deviation II

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0 o 30 o -30 o 60 o -60 o -90 o -120 o 90 o 120 o 150 o 180 o -150 o 0 o 30 o -30 o 60 o -60 o -90 o -120 o 90 o 120 o 150 o 180 o -150 o … if the QRS is negative in lead I and positive in lead II what is the QRS axis? (normal, left, right or right superior axis deviation) QRS Complexes I Axis I II + + + - - + normal left axis deviation right axis deviation II

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0 o 30 o -30 o 60 o -60 o -90 o -120 o 90 o 120 o 150 o 180 o -150 o … if the QRS is negative in lead I and negative in lead II what is the QRS axis? (normal, left, right or right superior axis deviation) QRS Complexes I Axis I II + + + - - + - - normal left axis deviation right axis deviation right superior axis deviation 0 o 30 o -30 o 60 o -60 o -90 o -120 o 90 o 120 o 150 o 180 o -150 o II

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Is the QRS axis normal in this ECG? No, there is left axis deviation. The QRS is positive in I and negative in II.

Rotation: 

Rotation

The END next..( Part III ): 

The END next..( Part III )