Guide For Arrhythmia
Recognition
Cheryl Sabin, MSN, ANP
And other ANP faculty, Indiana University
Objectives
Recognize and explain the basic
conduction system of the heart
 Able to accurately measure:

 PR
interval
 QRS duration
 QT interval
 Analyze the rate and rhythm of EKG strips
Objectives

Recognize and distinguish what area of
the conduction system is pacing the heart

Able to state appropriate treatment
responses to various identified rhythm
strips
The ECG
Electrodes on the skins surface records
the electrical activity of the heart.
 Monitoring cables are connected to the
skin electrodes and attached to the
monitor or ECG machine
 The horizontal axis corresponds with time.
 The vertical axis = voltage or amplitude.

ECG Paper

ECG paper normally
records at 25mm/se

Each horizontal 1mm
box represents 0.04
sec. (25mm/sec x
0.04 sec = 1mm).
ECG Paper
The lines between every 5 boxes are
heavier indicating one large box. Each
large horizontal box is 0.20 sec
 5 large boxes = 1 sec.
 Thirty large boxes = 6 sec.
 A small box is 1 mm high, a large box is
5mm high.

Paper
Waveform
Movement away from the baseline in
either a positive or negative direction
Segment
A line between waveforms; named by
the waveform that precedes or follows it
Interval
A waveform and a segment
Complex
Several waveforms
*Waveform*
P Wave: represents atrial depolarization
and the spread of the electrical impulse
throughout the right and left atria.
 P Wave Characteristics:

 Smooth
& round
 No more than 2.5 mm in height or 0.11 sec in
duration
PR

PR Segment: horizontal line between the
end of the P wave and the beginning of
the QRS complex.
 Normally

isoelectric
PR Interval: P wave + PR segment = PRI
 Represents
the interval between the onset of
atrial depolarization and ventricular
depolarization.
PRI
Time from impulse from SA to AV node
PR Cont.

PR Interval cont.
 Measured
from the point where the P wave
leaves the baseline to the beginning of the
QRS.
 Normally measures 0.12 to 0.20 sec.
 Normally
shortens as heart rate increases.
QRS


QRS Complex: consists of the Q, R, & S waves
and represents the spread of electrical impulse
through the ventricles. Ventricular
depolarization.
Q Wave: is always a negative waveform.
 It
represents depolarization of the
interventricular septum
 Measures less than 0.04 sec in duration and
less than 25% of the amplitude of the R wave.
Waveforms

R Wave: is the first positive deflection of
the QRS

S Wave: is a negative deflection following
a R wave.
Waveforms

The R & S wave represents the
simultaneous depolarization of the R & L
ventricles.

The QRS complex typically represents the
electrical activity which occurs within the
Left ventricle due to it’s greater muscle
mass.
QRS

Measuring of QRS
 The
width of the QRS is taken from the point
where the first wave of the complex leaves
the baseline. The point at which the last wave
form returns to the baseline marks the end of
the QRS complex.
 Duration of the QRS varies between 0.06 and
0.10 sec.
ST

ST Segments: portion between the QRS
complex and the T wave.
 Is
the term used regardless of the final wave
of the QRS.
 Represents the early part of repolarization of
the R&L ventricles.
 Normal ST segment is isoelectric
Waveforms

T Wave: Represents ventricle
repolarization.
 The
absolute refractory period ends at the
peak of the T wave and the relatively
refractory period begins.
Waveform

T Wave Characteristics:
 The
T wave is typically oriented in the same
direction as the preceding QRS complex.
 The
T wave is slightly asymmetric
QT

QT Interval: Represents the time from
ventricular depolarization to repolarization.
 QT
is measured from the beginning of the
QRS complex to the end of the T wave.
 To determine if the QT is WNL: measure
between R-R waves. If the QT interval is less
than ½ the R-R interval it is considered
normal.
QTc Interval Table
HR/min
R-R Interval
(sec)
40
1.5
QTc (sec) &
Normal range
0.46(0.41-0.51)
50
60
70
80
90
1.2
1.0
0.86
0.75
0.76
0.42(0.38-0.46)
0.39(0.35-0.43)
0.37(0.33-0.41)
0.35(0.32-0.39)
0.33(0.30-0.36)
QTc Interval Table
HR/min
R-R Interval
(sec)
QTc (sec) &
Normal range
100
0.60
0.31(0.28-0.34)
120
0.50
0.29(0.26-0.32)
150
0.40
0.25(0.23-0.28)
180
0.33
0.23(0.21-0.25)
200
0.30
0.22(0.20-0.24)
Calculating Rate

Assess the Rate:
 Six-second

Ventricular Rate: count the number of QRS
complexes in the 6 sec. strip and multiply that
number by 10.
 Large

Method: 30 large boxes = 6 sec.
Box Method:
Count the number of large boxes between 2
consecutive R waves and divide into 300. May
also calculate the Atrial rate the same way.
Calculating Rate
 Sequence

Method:
Select an R wave that falls on a dark vertical line.
Number the next 6 consecutive dark vertical lines
as follows: 300, 150, 100, 75, 60, and 50.
Sinus Rhythms

Normal Sinus Rhythm or Regular Sinus
Rhythm(NSR,RSR)
 Rate:
60-100.
 Rhythm: regular.
 P waves Configuration: All look alike; upright
in standard leads I,II, aVF, inverted in aVR
 P-R interval: Normal 0.10-0.20 seconds and
constant
 QRS duration: Normal 0.04-0.12 seconds.
NSR
Sinus Bradycardia
Rate: less than 60 beats per minute.
 Rhythm: Regular.
 P waves: Configuration: all look alike(see
NSR) one P before each QRS.
 P-R interval: Normal 0.10-0.20 seconds
and constant.
 QRS duration: Normal 0.04-0.12
seconds.

Sinus Brady



What drugs induce SB?
When do you treat SB?
Why do they have symptoms?
Sinus Tachycardia (Sinus Tach)





Rate: 100-150( maybe 180, depends on who’s
book you read!)
Rhythm: Regular
P waves: All look alike( see NSR). One P wave
before each QRS
PRI: Normally shortens as heart rate increases.
QRS duration: Normal 0.04-0.12 sec.
Sinus Tach
Sinus Arrhythmia
(happens to all of us!)
Rate: 60-100 but it is variable. Rate
increases with inspiration and decreases
with expiration.
 Rhythm: Irregular; varies with respiratory
cycle

Sinus Arrest

Rate: Variable; often slow

Rhythm: Interrupted by pauses when the
SA node “fails to fire.” Regular until
absence of a P wave; duration of the
pause is not a multiple of the P-P interval
or the underlying rhythm
Sinus Arrest
Sinus Block(SA Exit Block)

Impulse originates in pacemaker cells of
SA node but is blocked as it exits.

Rate: Variable; often slow

Rhythm: Regular except for pause
periods; overall the rhythm is not
interrupted.
SA block
Atrial Arrhythmias
Premature Atrial Contractions

P waves: Shape of premature P wave often differs. One
P wave for each QRS. PAC occurs early; no
compensatory pause(usually).

P-R interval: Interval for PAC usually different than is
sinus cycles.

QRS duration: Normal duration; QRS of premature
beat usually the same as the sinus conducted QRS

Rhythm: Interrupted by premature contraction
NSR PAC
Atrial Tachycardia
Paroxysmal Atrial Tach-PAT





Rate: 180-250
Rate is the only difference from Sinus Tach.
Rhythm: Regular unless associated with AV
block-PAT marked by sudden onset and sudden
cessation.
P waves: Often buried in preceding T wave-tent
like appearance.One P for each QRS
P-R interval: Not measurable because of rapid
rate.
Atrial Flutter





Rate: Ventricular rate varies depending upon
the degree of AV block( 250-350).It is Regular.
Rhythm: Dependent on block; regular if block is
constant
P Waves: Flutter waves are saw tooth pattern
or undulating atrial waves.
P-R interval: Not measured.
QRS duration: Normal
A. Flutter pathways
A. Flutter
A. Flutter
???

What if the rate is so fast you can’t tell
what they are in????

What is SVT?

What does this do to CO?
SVT vs. A.Flutter
Rhythm strip
following
Adenosine

Atrial Fibrillation

Ventricular rate
>
100 = uncontrolled <100 = controlled
Atrial rate: 350-500
 Rhythm: Usually Irregular !
 P waves: Not identifiable
 P-R interval: Can’t be determined
 QRS duration: Normal

A. Fib. Electrical Pathways
A. Fib
A. Fib
Class I
Class IIa
Class IIb
Class III
Benefit >>> Risk
Benefit >> Risk
Additional studies with
focused objectives
needed
Benefit ≥ Risk
Additional studies with
broad objectives needed;
Additional registry data
would be helpful
Risk ≥ Benefit
No additional studies
needed
Procedure/ Treatment
SHOULD be
performed/
administered
IT IS REASONABLE to
perform
procedure/administer
treatment
Procedure/Treatment
MAY BE CONSIDERED
AHA
Procedure/Treatment
should NOT be
performed/administered
SINCE IT IS NOT
HELPFUL AND MAY BE
HARMFUL
AHA
Wandering Pacemaker

Rate: usually slow, but may be 60-100

Rhythm: usually regular, but there is no
reason it has to be!
Wandering Pacemaker
P waves: May vary depending on the
origin of the impulse. One P for each QRS
(maybe)
 P-R interval: Varies as pacemaker
wanders between SA node, atrial tissue,
and AV node.
 QRS duration: Normal

WAP