Guide For Arrhythmia Recognition

Cheryl Sabin, MSN, ANPAnd other ANP faculty, Indiana University

Objectives

Recognize and explain the basic conduction system of the heart

Able to accurately measure:PR intervalQRS durationQT intervalAnalyze 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 & roundNo 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 = PRIRepresents 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 QRSThe 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)

QTc (sec) &

Normal range

40 1.5 0.46(0.41-0.51)

50 1.2 0.42(0.38-0.46)

60 1.0 0.39(0.35-0.43)

70 0.86 0.37(0.33-0.41)

80 0.75 0.35(0.32-0.39)

90 0.76 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 Method: 30 large boxes = 6 sec.

Ventricular Rate: count the number of QRS complexes in the 6 sec. strip and multiply that number by 10.

Large 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 aVRP-R interval: Normal 0.10-0.20 seconds and

constantQRS 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 ArrhythmiasPremature 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 TachycardiaParoxysmal 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

AHA

Class I Benefit >>> Risk

Procedure/ Treatment SHOULD be performed/ administered

Class IIa Benefit >> RiskAdditional studies with focused objectives needed

IT IS REASONABLE to perform procedure/administer treatment

Class IIb Benefit ≥ RiskAdditional studies with broad objectives needed; Additional registry data would be helpful

Procedure/Treatment MAY BE CONSIDERED

Class III Risk ≥ BenefitNo additional studies needed

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