Guide For Arrhythmia Recognition
-
Upload
donovan-williams -
Category
Documents
-
view
38 -
download
1
description
Transcript of Guide For Arrhythmia Recognition
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.
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.
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.
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 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 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 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.
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
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
???
What if the rate is so fast you can’t tell what they are in????
What is SVT?
What does this do to CO?
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
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
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