EPS Tracing
Interpretation 1
D r Ali Vasheghani Farahani
Electrophysiology Department
Tehran Heart Center
Tehran University of Medical
Sciences
EPS TRACINGS INTERPRITATION
Dr Vasheghani Farahani
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ECG Interpretation





Narrow QRS tachycardia
Rate= 180 bpm
Inferior/normal axis
long RP- Short PR
P waves are positive in leads II, III, aVF, and V6
and positive in V1.
 Diagnosis/Impression :
 AT
 Differential Diagnosis :
 Atypical AVNRT
 PJRT
EPS TRACINGS INTERPRITATION
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EPS TRACINGS INTERPRITATION
Dr Vasheghani Farahani
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EP Tracing
Interpretation
 Narrow QRS tachycardia
 Ventricular CL=Atrial CL =400ms
 Ventricular HR =Atrial HR=150
 Inferior /normal axis
 1:1 AV association
 VA>AV
 1:1 antegrade conduction via AVN-HIS, normal HV
 Earliest atrial activation in ablation catheter
 Diagnosis :
 AT originating from right atrium (interatrial septum /definite diagnosis in EPS)
 Orthodromic AVRT Via right free wall AP
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Steps
in EP recordings interpretation
‫حرفهای‬
‫تعامل‬
‫بحث پیرامون‬
Basic
Knowledge
‫با همکاران‬
EPS TRACINGS INTERPRITATION
Dr Vasheghani Farahani
Oblique View of Right Atrium
Superior
Vena
Cava
Crista
Terminalis
Fossa Ovalis
Pectinate
Muscle
Eustachian
Ridge
Orifice of
Coronary
Sinus
Inferior Vena
Cava
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Diagnostic Catheters
Quaderipolar diagnostic Catheter (RA,RV,HIS)
Decapolar catheter (CS)
dodecapolar Halo Catheter
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Quaderipolar diagnostic Catheter
Proximal
Distal
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Decapolar catheter (CS)
CS3-4
CS1-2
CS5-6
CS7-8
CS9-10
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EPS TRACINGS INTERPRITATION
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CATHETER PLACEMENT
HIGH RA
HIS
CS
RV APEX
LV
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AP
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RAO
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LAO
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Steps
in EP recordings interpretation
‫حرفهای‬Line
‫تعامل‬
‫بحث پیرامون‬
of signals
‫با همکاران‬
EPS TRACINGS INTERPRITATION
Dr Vasheghani Farahani
Look and see how each line of signals on the page you see
is labeled
 Usually the labels are located on the left side of the paper.
 There are often two or three surface leads at the top of the page.
 The first intracardiac channels are usually from the high right atrium as this is
where the signal is first seen when a patient is in normal sinus rhythm.
 Below the atrial channels I usually place the HIS recordings,
 followed by the CS
 then the right ventricular channels.
 Proximal is placed above distal in most of my setups.
 When configured this way, you will see a natural progression of atrial and
ventricular signals in normal sinus rhythm.
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Choices of Surface and Intracardiac Signals
 A classic display would include three to five surface
ECG leads (more common to use leads I, II, aVF, V1,
and V6), which provide most of the information,
 high RA recording,
 HB recording,
 CS recording,
 and RV apex recording .
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Look and see how each line of signals on the page you
see is labeled
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Dr Vasheghani Farahani
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EP TRACINGS INTERPRITATION
Dr Vasheghani Farahani
Steps
in EP recordings interpretation
‫بحث پیرامون تعامل حرفهای‬
‫با همکاران‬
Intracardiac Electrograms
EPS TRACINGS INTERPRITATION
Dr Vasheghani Farahani
Unipolar and bipolar recordings

Two complexes from different sites are
shown in a patient with Wolff-ParkinsonWhites syndrome.
 The dashed line denotes onset of the delta
wave.
 A, At this site, the unfiltered unipolar
recording shows a somewhat blunted “QS”
complex and small atrial component, but
the filtered (30- to 300-Hz)bipolar signal
shows a very large atrial signal and very
small ventricular signal (arrow), suggesting
a poor choice for ablation site.
 B, This site shows a sharper “QS” in the
unipolar signal, with a larger ventricular
than atrial electrogram, and the initial nadir
of bipolar recording coincides with the
maximal negative dV/dt of the unipolar
recording.
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Coronary Sinus Electrogram
Because the CS lies in the AV groove, in close
contact to both the LA and LV, the CS catheter
records both atrial and ventricular electrograms.
However, the CS has a variable relationship to the
mitral annulus.
The CS lies 2 cm superior to the annulus as it crosses
from the RA to the LA. More distally, the CS
frequently over rides the LV.
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Dr Vasheghani Farahani
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Coronary Sinus Electrogram
Consequently, the most proximal CS electrodes
(located at the CS os) are closer to the atrium and
typically show a local sharp, large atrial electrogram
and a smaller, farfield ventricular electrogram.
The more distal CS electrodes, lying closer to the LV
than the LA, will record progressively smaller, less
sharp, farfield atrial electrograms and larger, sharper,
near field ventricular electrograms
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Dr Vasheghani Farahani
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His bundle–ventricular (HV) intervals
It is important that the HV interval be measured from
the onset of the His potential in the recording
showing the most proximal (rather than the most
prominent) His potential (His prox) to the onset of the
QRS on the surface ECG (rather than the ventricular
electrogram on the His bundle [HB] recording).
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HIS BUNDLE ELECTROGRAM
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His bundle–ventricular (HV) intervals
 Even if a large His potential is recorded in association with a
small atrial electrogram, the catheter should be withdrawn to
obtain a His potential associated with a larger atrial
electrogram.
 Using a multipolar (three or more) electrode catheter to record
simultaneously proximal and distal HB electrogram (e.g., a
quadripolar catheter records three bipolar electrograms over a
1.5-cm distance) can help evaluate intra-His conduction.
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His bundle–ventricular (HV) intervals
 Anatomically, the proximal portion of the HB originates in
the atrial side of the tricuspid annulus; thus, the most
proximal HB deflection is the one associated with the largest
atrial electrogram.
 Recording of His potential associated with a small atrial
electrogram can reflect recording of the distal HB or RB, and
therefore might miss important intra-His conduction
abnormalities and falsely shorten the measured His bundle
ventricular (HV) interval .
EPS TRACINGS INTERPRITATION
Dr Vasheghani Farahani
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Steps
in EP recordings interpretation
‫بحث پیرامون تعامل حرفهای‬
‫با همکاران‬
Intracardiac Stimulation
EPS TRACINGS INTERPRITATION
Dr Vasheghani Farahani
Extra stimulus Technique
S1-S1 Drive Stimuli:
 The heart is paced, or driven, at a specified rate and
duration (typically eight beats) after which a
premature extrastimulus is delivered.
 The eight drive beats are each termed S1 stimulus.
The S1-S1 drive stimuli are sometimes called trains.
These S1 drive stimuli can be followed by first,
second, third, and Nth premature extrastimuli, which
are designated as S2, S3, S4, and SN.
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Extra stimulus Technique
simple sequential method:
 the S1-S2 coupling interval is decreased until it fails to
capture, at which time the coupling interval is increased until it
captures (usually within 10 to 20 milliseconds).

The S1-S2 coupling interval is then held constant while the
S2-S3 interval is decreased similarly to that used for S1-S2,
and then the same for S3-S4.
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Extra stimulus Technique
The tandem method:
 the S1-S2 coupling interval is decreased until S2 fails to
capture, and then the S1-S2 coupling interval is increased by
40 to 50 milliseconds and held there. S3 is then introduced and
the S2-S3 interval decreased until S3 fails to capture.
 At that point, the S1-S2 interval is decreased, and S3 retested
to see whether it captures. From that point on, the S1-S2 and
S2-S3 are decreased in tandem until refractory.
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Extra stimulus Technique
 As compared with the simple sequential method, the tandem
method allows relatively longer intervals and provides a larger
number of stimulation runs before moving on to the next
extrastimulus.
 Prospective studies comparing the two methods have shown
no differences between the two methods in any of the
outcomes assessed.
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Dr Vasheghani Farahani
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Steps
in EP recordings interpretation
‫بحث پیرامون تعامل حرفهای‬
‫با همکاران‬
Intracardiac Mesurments
EPS TRACINGS INTERPRITATION
Dr Vasheghani Farahani
Effective Refractory Period
The effective refractory period (ERP) is the longest
premature coupling interval (S1-S2) at a designated
stimulus amplitude (usually 2× diastolic threshold)
that results in failure of propagation of the premature
impulse through a tissue.
ERP, therefore, must be measured proximal to the
refractory tissue.
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Functional Refractory Period
 The minimum interval between two consecutively conducted
impulses through a tissue is known as the functional refractory
period (FRP).
 Because the FRP is a measure of output from a tissue, it is
described by measuring points distal to that tissue.
 FRP is a response-to-response measurement in contrast, the
ERP is a stimulus-to-stimulus measurement.
 Therefore, the FRP is a measure of refractoriness and
conduction velocity of a tissue.
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Definition of Refractory Periods
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Steps
in EP recordings interpretation
Normal values
‫بحث پیرامون تعامل حرفهای‬
‫با همکاران‬
EPS TRACINGS INTERPRITATION
Dr Vasheghani Farahani
Normal values of AH & HV intervals
Normal AH interval
60- 125 msec
Normal HV interval:
35- 55 msec
AH<60 msec--- Enhanced AV nodal conduction
Normal value of HV in the presence of LBBB
Up to 60 msec
Normal SNRT:
Up to 1500 msec
Normal CSNRT
Up to 525 msec
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AH &HV intervals
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Basic EP Recording
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Normal AH &prolonged HV intervals
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Steps
in EP recordings interpretation
‫بحث پیرامون تعامل حرفهای‬
‫با همکاران‬
EPS TRACINGS INTERPRITATION
Dr Vasheghani Farahani
Step One:
Find out what kinds of intracardiac electrograms are there:
 Spontaneous rhythm

Tachycardia
 Wide QRS tachycardia (pattern and axis)
 narrow QRS tachycardia

Bradycardia
 Wide QRS rhythm
 narrow QRS rhythm
 Pace rhythm
 Overdrive




atrial
Ventricular
CS
parahisian
 Extra stimulation
 Atrial
 Ventricular
 CS
 parahisian
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Step two:
Look at tracing speed ( at the bottom)
Define the CL
The HR is equal to: 60000 / CL
( when the speed is 100 mm/sec)
For example , if the CL is 400, the HR is 150 bpm
EPS TRACINGS INTERPRITATION
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Step Three:
If it is a spontaneous rhythm:
 Look at HRA and RV to find any association:
Compare HRA with ventricular electrogram
 VA –AV relationship(RP-PR )
 VA>AV
 VA<AV
 VA=AV
VA association:
1:1 VA/AV association
2:1 VA/AV association
VA/AV dissociation
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Dr Vasheghani Farahani
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Step Four:
 Look at HBE to find out:
Is HIS involved?
Is HV positive or negative?
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Step Five:
look at retrograde atrial activation:
 Concentric Retrograde Atrial Activation /
Earliest retrograde atrial activation in His
 Orthodromic AVRT via anteroseptal AP
 Typical AVNRT
 Concentric Retrograde Atrial Activation /
Earliest retrograde atrial activation in CS9-10 (proximal CS).
 Atypical AVNRT
 Orthodromic AVRT via Posteroseptal AP
 PJRT
 Concentric Retrograde Atrial Activation /
Earliest Retrograde Atrial Activation in HRA
 Orthodromic AVRT via RV free wall AP
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Step Five:
 Eccentric Retrograde Atrial activation /
Earliest Retrograde Atrial activation in CS1-2(distal CS).
 Orthodromic AVRT via left lateral AP
 Eccentric Retrograde Atrial activation /
Earliest Retrograde Atrial activation in CS3-4(distal CS).
 Orthodromic AVRT via left posterolateral AP
 Eccentric Retrograde Atrial activation /
Earliest Retrograde Atrial activation in CS5-6(distal CS).
 Orthodromic AVRT via left posterior AP
 Eccentric Retrograde Atrial activation /
Earliest Retrograde Atrial activation in CS7-8(distal CS).
 Orthodromic AVRT via left posteroseptal AP
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Final Steps:
 Mention EP maneuvers




AH jump
PPI
His synchronous PVC
Parahisian Pacing
 Mention Events or other findings




Echo beat
BBB
AV blocks
Arrhythmia induction/termination
 Mention the most appropriate impression/diagnosis
 Mention differential diagnosis
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