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9/18/2013
1
Challenging Cardiac
Arrhythmias:
A Case-Based Approach
Critical Care Symposium 2013 Mary G Carey, PhD, RN, CNS, FAHA
Associate Director, Clinical Nursing Research Center, Strong
Memorial Hospital
Associate Professor, School of Nursing
© 2013 Mary G. Carey, PhD, RN, CNS, FAHA
Recommendations vary regarding initial
competency
It is unknown what is necessary to maintain
competency
Major interpretation errors are common (4% to
33%) but adverse patient outcomes resulting
from these errors are rare (<1%).
Computer analyses of ECGs are useful adjuncts
but should not replace a qualified clinician in
making patient decisions.
Evidence-Based Knowledge
9/18/2013
2
The best way to avoid errors in
interpreting ECGs, is to analyze an
ECG systematically, step by step.
• Rate?
• Regularity?
• P waves?
• PR interval?
• QRS duration?
Calculate heart rate
Regular or irregular
Normal or absent
Narrow or wide
Fixed or variable
Interpretation?
The ECG Paper Horizontally (measure of time)
One small box - 0.04 seconds
One large box - 0.20 seconds
Vertically (amplitude)
One little box 1mm
One large box 5 mm or 0.5 mV
9/18/2013
3
Calculating Heart Rate
Option 1
Count the # of R waves in a 6 second rhythm
strip, then multiply by 10.
Best used with irregular rhythms
Interpretation?
3
sec
3
sec
Option 2
Find an R wave that lands on a bold line.
Count the # of large boxes to the next R wave.
Best used with regular rhythms
R wave
Calculating Heart Rate
9/18/2013
4
Marriott's Practical Electrocardiography
GS Wagner & HJL Marriott
0.12-0.20 (3-5 boxes)
<0.12seconds (3 boxes)
Rhythm
• Rate?
• Regularity?
• P waves?
• PR interval?
• QRS duration?
Interpretation?
9/18/2013
5
Rhythm
• Rate?
• Regularity?
• P waves?
• PR interval?
• QRS duration?
Interpretation?
Rhythm
• Rate?
• Regularity?
• P waves?
• PR interval?
• QRS duration?
Interpretation?
9/18/2013
6
Rhythm
• Rate?
• Regularity?
• P waves?
• PR interval?
• QRS duration?
Interpretation?
Is the PR interval
fixed or variable?
Fixed
Does every P
wave cause a
QRS complex?
1st degree
Are some QRS
complexes
dropped?
2nd degree,
Type II
Variable
Is the PR interval
lengthening?
2nd degree,
Type I
Is the PR interval
random?
3rd degree
Flow Chart for Heart Blocks
9/18/2013
7
• Rate?
• Regularity?
• P waves?
• PR interval?
• QRS duration?
Interpretation?
24 year old trauma patient (lead I)
• Rate?
• Regularity?
• P waves?
• PR interval?
• QRS duration?
Tri- athlete
9/18/2013
8
12 Lead ECG Limb leads
Precordial leads
Rhythm strip
72 yo male, routine resting 12-lead ECG
9/18/2013
9
Pathological Q waves 0.04s wide (one little box) and ¼ of R amplitude
Fragmented QRS complexes
(fQRS)
• Improved sensitivity and negative predictive value
(Das, et al. 2006)
• Associated with adverse cardiac events (Pietrasik
et al. 2007)
• Regional fQRS patterns predict regional infarction
in the absence of Q waves (Mahenthiran, et al. 2007)
9/18/2013
10
I
aVR
II
III
aVF
ECG Methodology
V1
V3
V5
V4
V6
V2
Characteristics of the 12-lead
Holter ECG in Professional
Firefighters
National Institutes of Health Grants R21 NR011077
9/18/2013
11
9/18/2013
12
Recognizing ST Deviation
Normal Ischemia, ST depression Injury, ST elevation
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13
Single Lead Monitoring Lead II
Interpretation?
• Rate?
• Regularity?
• P waves?
• PR interval?
• QRS duration?
Injury is regional, not global
Interpretation?
9/18/2013
14
Challenging Cardiac
Arrhythmias:
A Case-Based Approach
Critical Care Symposium 2013 Mary G Carey, PhD, RN, CNS, FAHA
Associate Director, Clinical Nursing Research Center, Strong
Memorial Hospital
Associate Professor, School of Nursing
© 2013 Mary G. Carey, PhD, RN, CNS, FAHA
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