Rhythm Int I

8/6/2019 Rhythm Int I

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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.



� 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





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



�May appear in various forms



Examples of T waves



� Normally measures 0.12 to 0.20 sec in adults

� Normally shortens as heart rate increases

� Normally lengthens as heart rate decreases



� 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



the simplest, quickest, and most commonly usedmethod of rate measurement is the Six-SecondMethod



� 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



� 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?



� 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



� 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?





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





� 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





� 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





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





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.


beat

x QRS duration- 0.10 second or less unless anintraventricular conduction delay exists





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.


beatx QRS duration- 0.10 second or less unless an

intraventricular conduction delay exists



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Rhythm Int I