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� The first half of the P wave reflects stimulationof the right atrium
� The downslope of the P wave reflectsstimulation of the left atrium.
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� One P wave normally precedes each QRScomplex.
�
Smooth and rounded
� No more than 2.5 mm in height
� No more than 0.11 sec in duration
� Positive in leads I, II, aVF, and V2 through V6
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Represents ventricular depolarization
A Q wave is always a negative waveform
Not every QRS complex contains a Q wave, Rwave, and S wave
Normal duration of the QRS complex in an adultvaries between 0.06 and 0.10 sec.
A normal Q wave is less than 0.04 sec in durationand less than one-third of the amplitude of the Rwave in that lead
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�May appear in various forms
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Examples of T waves
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� Normally measures 0.12 to 0.20 sec in adults
� Normally shortens as heart rate increases
� Normally lengthens as heart rate decreases
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� We will use a 5 step approach to identify arhythm. The steps will include«
1. Rate
2. Rhythm
3. P-wave
4. P - R interval
5. QRS
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the simplest, quickest, and most commonly usedmethod of rate measurement is the Six-SecondMethod
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� Is the rhythm regular?
� Are the R-R intervals or the P-P intervals the same?
� A variation of plus or minus 10% is acceptable
Various terms may be used to describe an irregularrhythm- essentially regular, irregular, regularlyirregular or irregularly irregular
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� Are P waves present?
� Do P waves have a normal shape?
� Are all the P waves similar in size and shape?
� Do all the P waves point in the same direction?
� Do you have one P wave for each QRScomplex?
� Is each P wave the same distance from it's QRScomplex?
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� What is the duration of the PR interval?(Normal 0.12 to 0.20 seconds)
� Is the PR interval constant?
Dysrhythmias such as AV blocks are associated
with abnormal PR intervals
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� Are all the complexes the same size and shape?
� What is the duration of the QRS complex?(Normal duration is no more than 0.10
seconds)
� Are all the QRS complexes the same distancefrom the T waves that follow them?
�
Do all the QRS complexes point in the samedirection?
� Are any QRS complexes that appear differentfrom the other QRS complexes?
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x Rate- 60-100 bpm
x Rhythm- P-P interval regular, R-R interval regular
x P waves- Positive (upright) in lead II, one precedes each
QRS complex, P waves look alike
x PR interval- 0.12-0.20 second and constant from beat to beat
x QRS duration- 0.10 second or less unless an intraventricular
conduction delay exists
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� Rate-Less than 60 bpm
� Rhythm-P-P interval regular, R-R interval regular
� P waves-Positive (upright) in lead II, one precedes eachQRS complex, P waves look alike
� PR interval-0.12-0.20 second and constant from beat to beat
� QRS duration-0.10 second or less unless an intraventricularconduction delay exists
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� Rate-101-180 bpm
� Rhythm-P-P interval regular, R-R interval regular
�
P waves-Positive (upright) in lead II, one precedes eachQRS complex, P waves look alike At a very fast rate itmay be difficult to distinguish between a P or a T wave
� PR interval-0.12-0.20 second (may shorten with faster
rates) and constant from beat to beat� QRS duration-0.10 second or less unless an
intraventricular conduction delay exists
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x Rate- Usually 60-100 bpm, may be slower or faster
x Rhythm- Irregular, phasic with respiration: heart rateincreases gradually during inspiration (R-R intervalsshorten) and decreases with expiration (R-R intervalslengthen)
x P waves- Positive (upright) in lead II, one precedes eachQRS complex, P waves look alike
x PR interval- 0.12-0.20 second and constant from beat to
beat
x QRS duration- 0.10 second or less unless anintraventricular conduction delay exists
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x Rate- Usually normal but varies because of the pause
x Rhythm- Irregular due to the pause(s) caused by theSA block- the pause is the same as (or an exact multiple
of) the distance between two other P-P intervalsx P waves- Positive (upright) in lead II, P waves look
alike.When present, one precedes each QRS complex.
x PR interval- 0.12-0.20 second and constant from beat to
beat
x QRS duration- 0.10 second or less unless anintraventricular conduction delay exists
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x Rate- Usually normal but varies because of the pause
x Rhythm- Irregular ² the pause is of undeterminedlength (more than one PQRST complex is missing) and
is not the same distance as other P-P intervalsx P waves- Positive (upright) in lead II, P waves look
alike.When present, one precedes each QRS complex.
x PR interval- 0.12-0.20 second and constant from beat to
beatx QRS duration- 0.10 second or less unless an
intraventricular conduction delay exists
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