Dysrhythmias
– Part 1
Chapter 35
Content Objectives
• Review the heart and cardiovascular system, electrical and
mechanical components of the cardiac cycle, and cardiac output.
• Describe the cardiovascular diagnostics.
• Apply nursing considerations for diagnostics relevant to
cardiovascular function.
• Examine the nursing care of patients needing continuous
electrocardiographic (ECG) monitoring including rhythm
interpretation.
Nervous System Control
of Heart
• Autonomic Nervous System
• Parasympathetic Nervous System – vagus nerve fibers (rest &
digest)
• ↓ rate of SA node
• Slows impulse conduction of AV node
• Sympathetic Nervous System –nerve fibers (flight & fight)
• ↑ rate of SA node
• ↑ impulse conduction of AV node
• ↑ cardiac contractility
Conduction System of the Heart
Dysrhythmias
Disorder of impulse formation, conduction of
impulses, or both
SA node normal pacemaker of heart (60–100
beats/minute)
AV node (40–60 beats/minute)
Secondary pacemakers
His-Purkinje fibers (20–40
beats/minute)
Electrocardiogram
Monitoring
• Graphic tracing of electrical
impulses produced by heart
• Waveforms of ECG/EKG
represent activity of charged
ions across membranes of
myocardial cells
Electrocardiogram
Monitoring
12-Lead ECG
Clip excessive hair
on chest
Patient
Preparation for
Lead
Placement
Rub skin with dry
gauze
May need to use
alcohol for oily skin
Apply electrode pad
12 –EKG Lead
Placement
5-Lead Placement
Resting ECG
Monitoring
• Observation of HR & rhythm at a distant
site
Ambulatory ECG
Monitoring
• Event monitor
• Loop recorder
• Holter monitoring
Artifact
ECG Time and Voltage
ECG
• Three Principal Waveforms
•
•
•
•
P Wave
QRS Complex
T Wave
U Wave-advanced interpretation
• Segments & Intervals
• PR interval
• ST segment
• QT interval
Assessment of
Heart Rhythm
• Interpret the rhythm
AND assess the clinical
status of the patient
• Is the patient
hemodynamically stable?
• Determine cause of
dysrhythmia
• Assess & treat the patient,
not the monitor!
5-Step Method to
ECG/EKG Interpretation
• Step One –regular or not/irregular
• Start with measuring the first two RR intervals then measure across the
tracing
• If the shortest and longest vary by
more than 0.12 (3 squares) then
irregular
• Step Two
• Step Three
• Step Four
• Step Five
5-Step Method to ECG/EKG Interpretation
• Step One
• Step Two – determine the rate
• First Method
• Count the number of R waves in a 6-second strip and multiple by 10
• Step Three
• Step Four
• Step Five
• Step Two – determine the rate
• Second Method
5-Step Method
to ECG/EKG
Interpretation
• Find an R wave that falls on a thick vertical line
•
•
•
•
•
•
1 Box = 300 beats per minute (bpm)
2 Boxes = 150 beats per minute (bpm)
3 Boxes = 100 beats per minute (bpm)
4 Boxes = 75 beats per minute (bpm)
5 Boxes = 60 beats per minute (bpm)
6 Boxes = 50 beats per minute (bpm)
• The rate becomes a guestimate of whatever 2 numbers the R
wave falls between
• What is the approximate rate?
5-Step Method to ECG/EKG Interpretation
Regular/irregular? What is the rate?
5-Step Method to ECG/EKG Interpretation
• Step Three – identify the P wave
• Should be near identical, one P to one QRS
• Normal P wave is indicated as Sinus aka sinus
rhythm
• As long as there is a normal or biphasic
appearance and the rate is 60-100 it is
normal sinus rhythm
• If the P wave is normal and the rate is above
100 then sinus tachycardia; below 60 sinus
bradycardia
• In the second example, the P wave is inverted
which is not a normal biphasic appearance
• The P wave that is inverted, or not normal in
shape, is coming from somewhere else
besides the SA node so it is not a sinus
rhythm
• This is considered an ectopic morphology
• Hint: atrial rate = count the # of P waves
5-Step Method to
ECG/EKG Interpretation
• Step One
• Step Two
• Step Three
• Step Four – measure the PR interval
• Count the number of small squares
and multiple by 0.04
• Is it normal duration or longer or
shorter
• Normal PR interval=0.12 to 0.20 sec
• Step Five
5-Step Method to
ECG/EKG Interpretation
• Step One
• Step Two
• Step Three
• Step Four
• Step Five – evaluate the ventricular
rhythm
• Measure the QRS Complex
• Count the small squares and times by
0.04
• Normal QRS Complex < 0.12 sec
Other questions to
ask…..
• Assess the ST segment
• Is it isoelectric (flat), elevated,
or depressed?
• This may indicate electrolyte
issues, ischemia, or infarction
Other questions to ask…..
• Measure the duration of the QT interval
• Is it normal duration or prolonged?
• 0.34-0.43
• Certain medications impact the QT as well as
electrolytes
• Note the T wave
• Is it upright or inverted?
• This may indicate electrolyte issues
• What is the dominant or underlying rhythm
and/or dysrhythmia?
• What is the clinical significance of your
findings?
• What is the treatment for that rhythm?
Copyright © 2017, Elsevier Inc. All Rights Reserved.
Hot-Spot
Answer Options:
• Apex
• Atrioventricular (AV)
bundle/Bundle of
HIS
• Atrioventricular (AV)
node
• Left and right bundle
branches
• Left atrium
• Left ventricle
• Purkinje fibers
• Sinoatrial (SA) node
Hot-Spot
Copyright © 2017, Elsevier Inc. All Rights Reserved.
Hot-Spot
• HESI NCLEX book – p. 45 – incorrect rate
• Steps:
• #1 – Regular/irregular?
• #2 – Rate?
• #3 – P-wave?
• #4 – PR interval?
• #5 – QRS interval?
Steps:
•
•
•
•
•
#1 – Regular/irregular?
#2 – Rate?
#3 – P-wave?
#4 – PR interval?
#5 – QRS interval?