Download ECG Case Review

Update in Electrocardiography & Arrhythmias, 2011
ECG Case Review
Basic
10:45 - 12:00 pm
Prof. Barbara J. Drew
University of California, San Francisco
Standard 12-Lead ECG
Frontal Plane
_
_
Horizontal Plane
_
+
aVR
+ aVL
LV
V6
_
+I
V5
_
_
+
III + aVF + II
Limb Leads
V1 V2
V3
V4
Precordial
Leads
1
Three things you have to know to
figure out what the waveforms
should look like in a given ECG lead:
1.  How the heart is positioned in the
chest
2.  Where the positive and negative
poles of the lead are
3.  How the cardiac impulse is moving
through the heart (i.e., sinus vs.
ectopic rhythm)
-
V
+
2
-
+
V
-
V
V
+
3
Right-Left & Superior-Inferior
Limb Leads in the
Frontal Plane
S
R
L
I
What direction would limb leads be blind to?
Answer: Anterior-Posterior
What would the limb leads record if a current of
myocardial injury flowed anteriorly?
Frontal Plane
_
_
_
+
aVR
+ aVL
_
+I
_
_
+
III + aVF + II
Limb Leads
Limb leads are blind to this acute
anterior myocardial infarction
4
Precordial Leads in
the Horizontal Plane
Right - Left & Anterior - Posterior
P
L
R
V6
A
V5
V1 V2
V3
V4
What direction would precordial leads be blind to?
Answer: Superior-Inferior
What would the precordial leads record if a
current flowed inferior, then superior?
Horizontal Plane
V6
V5
LV
V1 V2
V3
V4
Precordial leads are blind
to superior-inferior atrial
motion in atrial flutter
5
Limb Leads
Lead I
─
RA
Lead II
LA
RL
+ ─ RA
Lead aVR
+
RA
LA
RL
LL
LA
LL
RA
+
LL
RA
LA
LA
RL
Lead aVL
LL
─
+
Lead aVF
+
RA
─
LA
─
─
RL
Lead III
RL
LL
RL
LL
+
For resting “diagnostic” 12-lead ECGs, limb electrodes go on the extremity (not the torso)
6
7
8
Hexaxial System in the Frontal Plane
_
_
_
+
aVR
+ aVL
_
+I
_
_
+
III
+ aVF + II
9
-
Lead II
+
Determination of QRS Axis
If patient is in sinus rhythm, assume
lead wire reversal; repeat ECG
Left
Left
Extreme
Left
Left
Extreme
Normal
Right
Right
Normal
Right
10
Determination of QRS Axis
Step One:
Determine whether normal, left,
right, or extreme by checking
QRS polarity in leads I and II
-
-
-
-Normal Axis
11
Left Axis
Right Axis
12
Extreme Axis
Summary of “Quick-Look” Method
Lead I
Lead II
Normal
Axis
LAD
RAD
Right Superior
Axis
Indeterminate
Axis
13
Practice ECGs for
axis calculation
Determination of QRS Axis
Step Two:
Determine degrees by checking
polarity of the lead 90° from the
lead with an isoelectric (or
smallest) QRS
14
WNL
+60°
15
+40°
LAD
16
-70°
RAD
17
+100°
Right
superior
axis
18
±180°
RA-LA Lead-Wire Reversal
+
LA
RA
─
Lead I
Would RA-LA reversal alter precordial leads?
19
V6
─
+
V5
V1
+
V2
+
V3
+
V4
+
+
PRECORDIAL LEADS
The negative pole for precordial leads is the
Wilson Central Terminal (combination of 3 limb
leads into the negative pole)
Negative pole
located within
the heart
20
RA-LA Lead-Wire Reversal
+
LA
RA
─
Lead I
NO
Would RA-LA reversal alter precordial leads?
Lead I
-
_
+I
Dextrocardia
21
V6
V5
V1
V2
V3
V4
Dextrocardia alters the precordial
leads as well as the limb leads
Learn this “drill”
Whenever you see a negative QRS in
lead I, examine the P wave to see if it is
also negative. If it is normal (positive), the
patient just has an abnormal QRS axis.
However, if the P wave is also negative,
one of 2 things is possible: 1) RA-LA leadwire reversal, or 2) dextrocardia (heart is
in a mirror-image position in the chest)
22
Determining Lead-Wire Reversal
versus Dextrocardia
RA-LA Lead
Wire Reversal
Dextrocardia
Lead V6
Full 12-lead ECG in the same patient
What is the diagnosis?
Answer: Dextrocardia
23
Confirming Dextrocardia with Right
Precordial Leads
Standard Precordial Leads
Right Precordial Leads
Same patient with right ventricular leads recorded
24
Happy Halloween!
25