Download Anterior MI

EKG
Normal Impulse Conduction
Sinoatrial node
AV node
Bundle of His
Bundle Branches
Purkinje fibers
Pacemakers of the Heart
• SA Node - Dominant pacemaker with an
intrinsic rate of 60 - 100 beats/minute.
• AV Node - Back-up pacemaker with an
intrinsic rate of 40 - 60 beats/minute.
• Ventricular cells - Back-up pacemaker with an
intrinsic rate of 20 - 45 bpm.
Advanced Cardiac Life Support,
Guideline CPR ECC2005
American Heart Association
Impulse Conduction & the ECG
Sinoatrial node
AV node
Bundle of His
Bundle Branches
Purkinje fibers
Advanced Cardiac Life Support,
Guideline CPR ECC2005
American Heart Association
The “PQRST”
• P wave - Atrial
depolarization
• QRS - Ventricular
depolarization
• T wave - Ventricular
repolarization
Advanced Cardiac Life Support,
Guideline CPR ECC2005
American Heart Association
The PR Interval
Atrial depolarization
+
delay in AV junction
(AV node/Bundle of His)
(delay allows time for the
atria to contract before
the ventricles contract)
Advanced Cardiac Life Support,
Guideline CPR ECC2005
American Heart Association
The PR Interval
Atrial depolarization
+
delay in AV junction
(AV node/Bundle of His)
(delay allows time for the
atria to contract before
the ventricles contract)
Advanced Cardiac Life Support,
Guideline CPR ECC2005
American Heart Association
Normal Intervals
• PR
– 0.20 sec (less than one
large box)
• QRS
– 0.08 – 0.10 sec (1-2 small
boxes)
• QT
– 450 ms in men, 460 ms in
women
– Based on sex / heart rate
– Half the R-R interval with
normal HR
Lead Placement
aVF
All Limb Leads
Precordial Leads
2004 Anna Story
11
Precordial Leads
What to look for
•
•
•
•
Rate
Rhythm
Axis
ST segment changes
– Elevations or depressions
Rate
• This one is easy
• Too fast or too slow
• Remember treatment is based not on the
number but the clinical scenario
• A heart rate of 40 is fine if the BP and mental
status is good
The ECG Paper (cont)
3 sec
3 sec
• Every 3 seconds (15 large boxes) is marked by
a vertical line.
• This helps when calculating the heart rate.
• 300 / จำนวนช่องใหญ่
Advanced Cardiac Life Support,
Guideline CPR ECC2005
American Heart Association
Rhythm
• Normal sinus rhythm
– A p wave for every QRS and a QRS for every p
Rate 60-100
Rate < 60
Rate > 100
Axis
•
The
Quadrant
Approach
QRS up in I and up in aVF = Normal
Rhythm
•
•
•
•
•
Rate?
Regularity?
P waves?
PR interval?
QRS duration?
Interpretation?
70 bpm
occasionally irreg.
2/7 different contour
0.14 s (except 2/7)
0.08 s
NSR with Premature Atrial
Contractions
Normal Impulse Conduction
Sinoatrial node
AV node
Bundle of His
Bundle Branches
Purkinje fibers
Normal Impulse Conduction
Sinoatrial node
AV node
Bundle of His
Bundle Branches
Purkinje fibers
Premature Atrial Contractions
• Deviation from NSR
– These ectopic beats originate in the atria
(but not in the SA node), therefore the
contour of the P wave, the PR interval, and
the timing are different than a normally
generated pulse from the SA node.
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Rhythm
•
•
•
•
•
Rate?
Regularity?
P waves?
PR interval?
QRS duration?
60 bpm
occasionally irreg.
none for 7th QRS
0.14 s
0.08 s (7th wide)
Interpretation? Sinus Rhythm with 1 PVC
Teaching Moment
• When an impulse originates in a ventricle,
conduction through the ventricles will be
inefficient and the QRS will be wide and
bizarre.
Ventricular Conduction
Normal
Abnormal
Signal moves rapidly
through the ventricles
Signal moves slowly
through the ventricles
Rhythm
•
•
•
•
•
Rate?
Regularity?
P waves?
PR interval?
QRS duration?
100 bpm
irregularly irregular
none
none
0.06 s
Interpretation? Atrial Fibrillation
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Atrial Fibrillation
• Etiology: Recent theories suggest that it is due
to multiple re-entrant wavelets conducted
between the R & L atria. Either way, impulses
are formed in a totally unpredictable fashion.
The AV node allows some of the impulses to
pass through at variable intervals (so rhythm is
irregularly irregular).
Impulse Conduction
Sinoatrial node
AV node
Bundle of His
Bundle Branches
Purkinje fibers
Rhythm
•
•
•
•
•
Rate?
Regularity?
P waves?
PR interval?
QRS duration?
74 148 bpm
Regular  regular
Normal  none
0.16 s  none
0.08 s
Interpretation? Paroxysmal Supraventricular
Tachycardia (PSVT)
PSVT
• Deviation from NSR
– The heart rate suddenly speeds up, often
triggered by a PAC (not seen here) and the
P waves are lost.
PSVT
• Etiology: There are several types of PSVT but
all originate above the ventricles (therefore
the QRS is narrow).
• Most common: abnormal conduction in the
AV node (reentrant circuit looping in the AV
node).
Normal Impulse Conduction
Special track
AV node
Bundle of His
Bundle Branches
Purkinje fibers
Rhythm
•
•
•
•
•
Rate?
Regularity?
P waves?
PR interval?
QRS duration?
60 bpm
regular
normal
0.36 s
0.08 s
Interpretation? 1st Degree AV Block
1st Degree AV Block
• Deviation from NSR
– PR Interval
> 0.20 s
Normal Impulse Conduction
Sinoatrial node
AV node
Bundle of His
Bundle Branches
Purkinje fibers
Rhythm
•
•
•
•
•
Rate?
Regularity?
P waves?
PR interval?
QRS duration?
50 bpm
regularly irregular
nl, but 4th no QRS
lengthens
0.08 s
Interpretation? 2nd Degree AV Block, Type I
2nd Degree AV Block, Type I
• Etiology: Each successive atrial impulse
encounters a longer and longer delay in the
AV node until one impulse (usually the 3rd or
4th) fails to make it through the AV node.
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Rhythm
•
•
•
•
•
Rate?
Regularity?
P waves?
PR interval?
QRS duration?
40 bpm
regular
nl, 2 of 3 no QRS
0.14 s
0.08 s
Interpretation? 2nd Degree AV Block, Type II
2nd Degree AV Block, Type II
• Deviation from NSR
– Occasional P waves are completely blocked
(P wave not followed by QRS).
2nd Degree AV Block, Type II
• Etiology: Conduction is all or nothing (no
prolongation of PR interval); typically block
occurs in the Bundle of His.
Rhythm
•
•
•
•
•
Rate?
Regularity?
P waves?
PR interval?
QRS duration?
40 bpm
regular
no relation to QRS
none
wide (> 0.12 s)
Interpretation? 3rd Degree AV Block
3rd Degree AV Block
• Etiology: There is complete block of
conduction in the AV junction, so the atria and
ventricles form impulses independently of
each other. Without impulses from the atria,
the ventricles own intrinsic pacemaker kicks in
at around 30 - 45 beats/minute.
Remember
• When an impulse originates in a ventricle,
conduction through the ventricles will be
inefficient and the QRS will be wide and
bizarre.
For more presentations
www.medicalppt.blogspot.com
Impulse Conduction
Sinoatrial node
AV node
Bundle of His
Bundle Branches
Purkinje fibers
Impulse Conduction
Sinoatrial node
AV node
Bundle of His
Bundle Branches
Purkinje fibers
EKG
12 leads
Rule 1
1.0
Millivolts
0.5
R
PR
interval
PR interval should be 120
to 200 milliseconds or 3 to
5 little squares
T
P
Q
0
S
-0.5
0
200
400
Milliseconds
600
Rule 2
1.0
R
The width of the QRS
complex should not exceed
110 ms, less than 3 little
squares
Millivolts
0.5
T
P
Q
0
S
-0.5
QRS
0
200
400
Milliseconds
600
Rule 3
I II III
aVR aVL aVF
The QRS complex should be
dominantly upright in leads I
and II
Rule 4
I II III
aVR aVL aVF
QRS and T waves tend to have
the same general direction in
the limb leads
Rule 5
All waves are negative in lead aVR
P
T
Q
S
Rule 6
V1
V2
V3
V4
V5
V6
The R wave in the precordial leads must grow from V1 to at
least V4
Rule 7
I II III
aVR aVL aVF
V1 V2 V3
V4 V5 V6
The ST segment should start isoelectric except in V1
and V2 where it may be elevated
Rule 8
I II III
aVR aVL aVF
V1 V2 V3
V4 V5 V6
The P waves should be upright in I, II, and V2 to V6
Rule 9
I II III
aVR aVL aVF
V1 V2 V3
V4 V5 V6
There should be no Q wave or only a small q less
than 0.04 seconds in width in I, II, V2 to V6
Rule 10
I II III
aVR aVL aVF
V1 V2 V3
V4 V5 V6
The T wave must be upright in I, II, V2 to V6
All Limb Leads
EKG Distributions
•
•
•
•
•
•
Anteroseptal: V1, V2, V3, V4
Anterior: V1–V4
Anterolateral: V4–V6, I, aVL
Lateral: I and aVL
Inferior: II, III, and aVF
Inferolateral: II, III, aVF, and V5
and V6
Views of the Heart
Some leads get a good
view of the heart
Anterior portion
of the heart
Inferior portion
of the heart
Lateral portion
of the heart
Anterior MI
Remember the anterior portion of the heart is best
viewed using leads V1- V4.
Limb Leads
Augmented Leads
Precordial
Leads
Lateral MI
So what leads do you think the
lateral portion of the heart is
best viewed?
Limb Leads
Leads I, aVL, and V5V6
Augmented Leads
Precordial
Leads
Inferior MI
Now how about the inferior
portion of the heart?
Limb Leads
Leads II, III and aVF
Augmented Leads
Precordial
Leads
Characteristic changes in AMI
 ST segment elevation over area of damage
 ST depression in leads opposite infarction
 Pathological Q waves
 Reduced R waves
 Inverted T waves
ST elevation
R
ST
P
Q
• Occurs in the early stages
• Occurs in the leads facing the
infarction
• Slight ST elevation may be
normal in V1 or V2
ECG Changes: STEMI
 ST segment elevation of greater than 0.5 mm in at least
2 contiguous leads
 Heightened or peaked T waves
 Directly related to portions of myocardium rendered
electrically inactive
 New LBBB
Baseline
70
2004 Anna Story
Deep Q wave
R
ST
P
T
Q
• Only diagnostic change of
myocardial infarction
• At least 0.04 seconds in
duration
• Depth of more than 25% of
ensuing R wave
T wave changes
• Late change
• Occurs as ST elevation is
returning to normal
• Apparent in many leads
R
ST
P
T
Q
Bundle branch block
Anterior wall MI
I II III
aVR aVL aVF
V1 V2 V3
Left bundle branch block
V4 V5 V6
I II III
aVR aVL aVF
V1 V2 V3
V4 V5 V6
ECG Changes : NSTEMI
 T-wave inversion ( flipped T)
 ST segment depression
 T wave flattening
 Biphasic T-waves
Baseline
74
2004 Anna Story
Sequence of changes in evolving AMI
Anterior infarction
Anterior infarction
I II III
Left
coronary
artery
aVR aVL aVF
V1 V2 V3
V4 V5 V6
Inferior infarction
Inferior infarction
I II III
Right
coronary
artery
aVR aVL aVF
V1 V2 V3
V4 V5 V6
Lateral infarction
Lateral infarction
I II III
Left
circumflex
coronary
artery
aVR aVL aVF
V1 V2 V3
V4 V5 V6
Location of infarct combinations
I
aVR
ANT
POST
LATERAL
aVL
II
V1
V2
V3
III
INFERIOR
aVF
V4
ANT
SEPTAL
V5
ANT
V6 LAT
Mirror image
Reciprocal change
A Normal 12 Lead ECG
81
Color Coding ECG’s Anterior
 Yellow indicates V1, V2, V3, V4
 Anterior infarct with ST elevation
 Left Anterior Descending Artery





82
(LAD)
V1 and V2 may also indicate septal
involvement which extends from
front to the back of the heart along
the septum
Left bundle branch block
Right bundle branch block
2nd Degree Type2
Complete Heart Block
2004 Anna Story
83
2004 Anna Story
Color Coding ECG- Inferior
 Blue indicates leads II, III, AVF
 Inferior Infarct with ST
elevations
 Right Coronary Artery (RCA)
 1st degree Heart Block
 2nd degree Type 1, 2
 3rd degree Block
 N/V common, Brady
84
85
Right Sided EKG????
 RVI occurs around 40% in inferior
MI’s
 Significance
 Larger area of infarct
 Both ventricles
 Different treatment
 Right leads “look” directly at Right
Ventricle and can show ST elevations
in leads II. III. AVF, V4R , V5R and
The single most accurate tool V6R
 Occlusion in RCA and proximal
used in measuring RVI.
enough to involve the RV
90% sensitive and specific
86
Clinical Triad of RVI
 Hypotension
 Jugular vein distention
 Dry lung sounds
87
Color Coding ECG- Posterior
 Green indicates leads V1, V2
 Posterior Infarct with ST
Depressions and/ tall R wave
 RCA and/or LCX Artery
 Understand Reciprocal changes
 The posterior aspect of the
heart is viewed as a mirror
image and therefore
depressions versus elevations
indicate MI
 Rarely by itself usually in
combo
88
89
2004 Anna Story
Color Coding ECG- Lateral
 Red indicates leads I,
AVL, V5, V6
 Lateral Infarct with ST
elevations
 Left Circumflex Artery
 Rarely by itself
 Usually in combo
90
2004 Anna Story
91
2004 Anna Story
NSTEMI
92
More than one color shows
abnormality
 A combination of infarcts such as:
 Anterolateral yellow and red
 Inferoposterior blue and green
 Anteroseptal yellow and green
93
Putting it ALL together
94
95
2004 Anna Story
Practice 1
Click
for
answer
96

Anterior MI with lateral involvement

ST elevations V2, V3, V4

ST elevations II, AVL, V5
Practice 2
97
Click
for
2004
answer
Anna Story
Anteroseptal MI

ST elevations V1, V2, V3, V4

Practice 3
98
Click
for
2004
answer
Anna Story
Inferior MI

ST elevation 2,3 AVF

Practice 4
Inferior lateral MI

99
Click
for
2004
answer
Anna Story
ST elevations 2, 3, AVF

ST elevations V5

Practice 5
100
Click
for
answer
•Acute inferior MI
•Lateral ischemia
Additional Practice Strips
101
EXTENSIVE ANTERIOR WALL MI
Additional Practice Strips
102
EXTENSIVE ANTERIOR WALL MI
Additional Practice Strips
103
INFEROPOSTERIORLATERAL WALL MI
Additional Practice Strips
104
POSTERIOR WALL MI
Additional Practice Strips
105
INFERIOR WALL MI
Additional Practice Strips
106
ANTEROLATERAL WALL MI
Cardiac Enzymes Indicating Infarct
 Normals
 CPK- 10-155u/liter
 begin rise 3-6 hours and peaks 12-24 with return to norm 3-
5 days
 CPK-MB < than 5% IU/liter
 LDH 85-200 IU/liter
 Begin rise 12 hours, peaks 36-72 and normal around 10 days
 LDH 1- 18.1% - 29% of total
 LDH 2- 27.4% to 37.5% of total
107
2004 Anna Story
Cardiac Enzymes Indicating Infarct
 Troponins- Now the
Gold Standard!
 Rises after 3-6 hours
 Negative Troponin
within 6 hours of onset
of S&S rules out the MI
 Peaks at about 20 hours
 May be raised for 14
days
108
2004 Anna Story
Cardiac Enzymes Indicating Infarct
 Troponin T
 84% sensitivity for MI 8 hours after onset of
symptoms
 22% for unstable angina
 Advantages
 Highly sensitive for detecting myocardial ischemia
 Levels may help to stratify risks
 Disadvantages
 Less specific than Troponin I
 Increased in angina
 Increased in chronic renal failure
109
2004 Anna Story
Cardiac Enzymes Indicating Infarct
 Troponin I
 90% sensitivity for MI 8 hours after onset of S&S and
95% specificity
 Level greater than 1.2 suggest MI
 Negative rules out MI
 Obtain two negative troponin values 4 hours apart
 Normally exceedingly low
 Even a small elevation indicates
myocardial damage
110
2004 Anna Story