ELECTROCARDIOGRAM

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ELECTROCARDIOGRAM

• YINGMIN-CHEN
• Renji Hospital affiliated to Shanghai Second
  Medical University

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WPW Diagram
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ECG Intervals and Waves
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ECG Components Diagram
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RV vs LV PVC's
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Diagram AV Nodal Reentrant Tachycardia
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Diagram Type I vs. Type II 2nd Degree AV Block
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QRS Axis 90 degrees
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QRS Axis -30 degrees
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Normal ECG
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Wandering Atrial Pacemaker
Wandering atrial pacemaker is a benign rhythm
change where the pacemaker site shifts from the
sinus node into the atrial tissues. P-wave
morphology varies with the pacemaker site.
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Junctional Escape Rhythm
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PAC's with RBBB Aberrant Conduction
PAC's are identified by the arrows. Note that the
PP interval surrounding the PAC is less than 2x
the basic sinus cycle indicating that the sinus
node has been reset by the ectopic P wave. The
pause after the PAC, therefore, is incomplete
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Long QT Mischief
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Atrial Parasystole
In atrial parasystole non-fixed coupled PACs,
shown by arrows, occur at a common inter-ectopic
interval or at multiples of this interval. Atrial
fusions, not shown here, may also occur when the
PAC occurs in close temporal proximity to the
sinus impulse
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In ventricular parasystole, non-fixed coupled
PVC's occur at a common inter-ectopic interval.
Fusion beats, indicated by arrows, are often
seen. Fusions occur when the sinus impulse
entering the ventricles find the ventricles
already partially depolarized by the parasystolic
focus
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Ventricular Fusion Beats
Fusion beats occur when two or more activation
fronts contribute to the electrical event. These
may occur in the atria or in the ventricles. In
this example the ventricular fusions are the
result of simultaneous activation of the
ventricles from two foci, the sinus node and a
ventricular ectopic focus
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PVC With Venticular Echo
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Nonconducted PACs and Junctional Escapes
Although at first glance this looks like 2nd
degree AV block, the P waves indicated by the
arrows are premature and not sinus P waves. The
pause is long enough to encourage a junctional
escape focus to take over. Note the sinus P waves
just before the escape beats. Had the escapes not
occurred, the sinus impulses would have captured
the ventricles
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Nonconducted And Conducted PAC's
The pause in this example is the result of a
nonconducted PAC, as indicated by the first
arrow. The second arrow points to a conducted
PAC. The most common cause of an unexpected pause
in rhythm is a nonconducted PAC
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PAC and PVC Complete vs. Incomplete Pause
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Identification of PVC's and PAC's
PVC's usually stick out like sore thumbs PAC's
are often difficult to see because they are
hidden in the preceding ST-T wave. The PVC in
this example is mostly negative in lead V1
suggesting RV origin i.e., most of activation is
moving in posterior dirction towards the left
ventricle
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Nonconducted PAC's An Unusual Bigeminy
Occasionally nonconducted PAC's can create
interesting rhythms. In this example every other
sinus beat is followed by an early, nonconducted
PAC. The resulting pause sets up a bigeminal
rhythm. Note the distortion of the T waves caused
by the nonconducted PAC's
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An Interpolated PAC
Although most PAC's reset the sinus node
producing an "incomplete compensatory pause",
this PAC, indicated by the black arrow, is
interpolated, i.e., sandwiched between two sinus
beats. Note that the subsequent sinus P wave
conducts with prolonged PR interval due to the
relative refractoriness of the AV junction left
by the PAC. Auscultation of the heart during this
single PAC event would reveal three rapid beats
in a row, suggesting a brief tachycardia
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These PAC's, indicated by arrows, enter the
ventricles and find the right bundle refractory.
They therefore conduct with RBBB aberrancy. In
most normal hearts the right bundle recovery time
is longer than the left bundle's most aberrancy,
therefore, has a RBBB morphology. In some
diseased hearts the left bundle may have a longer
refractory period resulting in LBBB aberration.
Aberrant conduction may also involve the fasicles
of the left bundle
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The Three Fates Of PAC's
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Sore Thumbs
Two funny looking premature beats are seen in
this rhythm strip. Beat 'A' is preceded by a PAC
which distorts the T wave, making this an
aberrantly conducted PAC. Beat 'B' is a PVC. The
notch on the downslope of the QRS complex clearly
dentifies this as a PVC and not aberrancy
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Premature Junctional Complexes With Retrograde P
Waves
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PAC's With and Without Aberrant Conduction
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Ventricular Bigeminy
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PVC Couplet
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PAC Couplet
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PVC with R-on-T
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PVC Triplet
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Atrial Flutter With 21 AV Conduction
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Atrial Flutter With 32 AV Conduction
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Multifocal Atrial Tachycardia (MAT)
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Atrial Flutter With Variable AV Block And
Rate-Dependent LBBB
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Atrial Fibrillation in Patient with WPW Syndrome
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Atrial Flutter With Variable AV Block
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Retrograde atrial captures from an accelerated
ventricular focus are occurring with increasing
R-P intervals, When the longer R-P occurs, the
impulse traversing the AV junction finds a route
back to the ventricles, and the result is a
ventriclar echo
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Approximately 50 percent of ventricular
tachycardias are associated with AV dissociation.
The other 50 percent have retrograde atrial
capture. This example shows ventricular
tachycardia with retrograde Wenchebach. The
retrograde P waves are hard to find, but the
arrows are of some help
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Left Ventricular Tachycardia
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Ventricular Tachycardia
The main features of this wide QRS tachycardia
that indicate its ventricular origin is the
condordance of QRS's in the precordial leads (all
QRS's are in the same direction).
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Right Ventricular Tachycardia
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If the sinus node slows too much a junctional
escape pacemaker may take over as indicated by
arrows. AV dissociation is incomplete, since the
sinus node speeds up and recaptures the entricles
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Mobitz II 2nd Degree AV Block With LBBB
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Left Anterior Fascicular Block (LAFB)
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Left Bundle Branch Block (LBBB)
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Right Bundle Branch Block (RBBB)
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Bifascicular Block RBBB LAFB
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WPW Type Preexcitation
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WPW with a Pseudo-inferior MI
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Ventricular Pacemaker Rhythm
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Atrial Pacemaker Rhythm
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AV Sequential Pacing
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left lateral pathway
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anteroseptal pathway
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AV Sequential Pacing