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8/19/2016
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12 Lead ECG Interpretation: The Basics and Beyond
Cindy Weston, DNP, RN, CCRN, CNS-CC, FNP-BC
Assistant Professor
Texas A&M Health Science Center
Objectives
• Review the basics of 12 lead electrocardiogram
• Review when to order an ECG
• Identify the 12 most common rhythms and their treatment
• Identify and initiate treatment for acute myocardial infarction
Disclosures
• No Conflicts
“I struggled with everything cardiac in nursing school.”
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My Tips
• Understand Anatomy
• Take a Systematic Approach
• Ask yourself “Is this clinically significant?”
• Know common arrhythmias
• Know what to do about them
Conduction System
Willem Einthoven
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Action Potential
Intrinsic Rates
SA Node _______ beats/min
AV Node _______ beats/min
Bundle of HIS ____ beats/min
Purkinje Fibers ____ beats/min
60-100
40-60
20-40
20-40
Basic Rhythm
Depolarization
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Waves & Intervals
• P wave– Atrial depolarization (right then left)
– Usually upright (positive)
• PR interval– 0.12-0.20 seconds
– Measures start of atrial depolarization to start of ventricular depolarization
Waves & intervals
• QRS wave/interval– Q not always present, R first positive, S negative
after R
– Ventricular depolarization
– < 0.10-0.12
• T wave– Ventricular repolarization
– Usually upright
– May vary based on perfusion, electrolytes, meds
Waves and Intervals
• QT interval– < 0.40 seconds
– Corrected QTc (0.34-0.43)
– Men <0.47; women < 0.48
– > 0.50 DANGER!!!
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Waves and Intervals
• U wave– Repolarization of Purkinje fibers
– Electrolyte imbalance: hypokalemia, hypercalcemia, digoxin toxicity, use of some antiarrhythmics, congenital long QTc
ST segment
ECG Graph paperhorizontalSm box 0.04 secLg box 0.20 secverticalLg box 0.5mVSm box 0.1mV
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My Systematic Approach
• Rate
• Regularity
• Waves: p,q,r,s,t,u
• Intervals: PR, QRS, QTc
• ST segments
• R wave progression
• Axis: lead I & AVF
RATE
• # QRS 6 second strip x 10
• Memorize: 300, 150, 100, 75, 60, 50 rule
• 1500 / #small boxes between R-R waves
Regularity
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PQRST(U) waves
Intervals: PR, QRS, QTc
ST Segments
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12 LEAD ECG
12 snapshots of the electrical conduction in the heart
12 Views
• Limb leads give 6 views– I,II,III (Bipolar)
– AVR, AVL, AVF (unipolar, augmented vector)
• Precordial leads give 6 views– V1, V2, V3, V4, V5, V6
InferiorInferior
Late
raL
ate
ral
Einthoven’s Triangle
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Precordial chest leads “v” leads
12 Lead ECG
• 3 limb leads (I, II, III)
• 3 Augmented Vector leads (AVR, AVL, AVF)
• 6 Precordial leads (V1-V6)
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R wave progression
AXIS
Direction of electrical vector during ventricular depolarization
AXIS- NORMAL
Left- Wedding RingLead I
Right- Aggie RingLead AVF
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AXIS- LEFT Deviation
Left- Wedding RingLead I
Right- NO Aggie RingLead AVF
AXIS- RIGHT Deviation
Left- NO Wedding RingLead I
Right- Aggie RingLead AVF
AXIS- Extreme Right “no man’s land”
Left- NO Wedding RingLead I
Right- NO Aggie RingLead AVF
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Hypertrophy: LVH
• Left Axis Deviation
• R wave in AVL exceeds 13 mm
• R wave in V5 or V6 PLUS S wave in V1 or V2 exceeds 35 mm
• “eye ball test” QRS touch…
RVH
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RVH
BBB: Left
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BBB: Right
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BREAK TIME!!!
12 Common Issues
• Acute Coronary Syndrome
• STEMI
• NSTEMI/Unstable angina
Contiguous Leads
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STEMI
Brown, H. (2014). Synopsis and review of the American College of Cardiology Foundation/American Heart Association 2013 ST-elevation myocardial infarction guideline. AACN Advanced Critical Care, 25(2), 142-150.
Contiguous leads
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Contiguous Leads
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STEMI
Brown, H. (2014). Synopsis and review of the American College of Cardiology Foundation/American Heart Association 2013 ST-elevation myocardial infarction guideline. AACN Advanced Critical Care, 25(2), 142-150.
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STEMI
Brown, H. (2014). Synopsis and review of the American College of Cardiology Foundation/American Heart Association 2013 ST-elevation myocardial infarction guideline. AACN Advanced Critical Care, 25(2), 142-150.
STEMI
Brown, H. (2014). Synopsis and review of the American College of Cardiology Foundation/American Heart Association 2013 ST-elevation myocardial infarction guideline. AACN Advanced Critical Care, 25(2), 142-150.
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ST depression
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T-wave inversion
Q-waves
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NPs treating suspected Acute Coronary Syndrome
• Give ASA 325 mg x1
• STEMI– If outpatient EMS transport to ED with
notification
– If inpatient- prepare for reperfusion (STEMI protocol)
• ST depression/T-wave inversion/CP– Serial cardiac enzymes
– Serial ECGs
12 Abnormal Rhythms
• Premature Beats
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When to order a 12 lead
• Chest pain (duh!)
• Possibly indigestion, jaw pain, arm pain, anxiety, sense of doom….
• Palpitations
• Transient loss of consciousness
• New diagnosis HTN
• DX: HTN, Diabetes, Smoking, Hyperlipidemia
Routine $8.00 Diagnostic with interpretation $16
What about Routine Screen?
IPPE: Initial Preventative Physical Examination (no deductible or Co-payment!)
• G0403: Electrocardiogram, routine ECG with 12 leads; performed as a screening for the initial preventive physical examination with interpretation and report
• G0404: Electrocardiogram, routine ECG with 12 leads; tracing only, without interpretation and report, performed as a screening for the initial preventive physical examination
• G0405: Electrocardiogram, routine ECG with 12 leads; interpretation and report only, performed as a screening for the initial preventive physical examination
https://www.cms.gov/Outreach-and-Education/Medicare-Learning-Network-MLN/MLNProducts/downloads/MPS_QRI_IPPE001a.pdf
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12 Abnormal Rhythms
• Atrial Fibrillation
Atrial Fibrillation
Treatment Guidelines
• Antiarrhythmic– Rate Control
– Rhythm Control
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Anti-arrhythmics
Top 12 Abnormal RhythmsAtrial Flutter
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12 Abnormal RhythmsSupraventricular Tachycardia
SVT
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Treatment
• Vagal
• Adenosine
• Calcium channel blockers
• Digoxin
• Beta blockers
• Cardioversion
12 Abnormal RhythmsWPW
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12 Abnormal RhythmsSinus Tachycardia
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12 Abnormal RhythmsSinus Bradycardia
Junctional Rhythm
12 Abnormal Rhythms1 degree AV Block
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12 Abnormal Rhythms2nd Degree AV Block Type 1
12 Abnormal Rhythms2nd Degree AV Block Type 2
12 Abnormal RhythmsComplete Heart Block
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QUESTIONS?
References
• Ecgpedia.org
• Thaler, M. (2015). The only EKG book you’ll ever need. 8th Ed. Lippincott Williams & Wilkins.
• Garcia, T. (2015). 12 Lead ECG: The art of interpretation. Burlington, MA: Jones & Bartlett Learning.
• Green, J. & Chiaramida, A. (2015). 12-Lead EKG Confidence: A step by step guide. New York: Springer Publishing Co.
