Introduction to Electrophysiology - Pennsylvania · Introduction to Electrophysiology Wm. W....
Transcript of Introduction to Electrophysiology - Pennsylvania · Introduction to Electrophysiology Wm. W....
Introduction to
Electrophysiology
Wm. W. Barrington, MD, FACC
University of Pittsburgh Medical
Center
Objectives
• Indications for EP Study
• How do we do the study
• Normal recordings
• Abnormal Recordings
• Limitations of EP Study
Indications for EP Study
• Characterization of an arrhythmia with the intent of performing ablation therapy.
• Characterization of the conduction system to determine the need for permanent pacing.
• Stratify the patient’s risk of developing a symptomatic or life threatening arrhythmia.
• Characterization of the effectiveness of therapy.
"Guidelines for Clinical Intracardiac Electrophysiological and Catheter Ablation
Procedures“ Circulation. 1995;92:673-691.)
Ablation is a large part of the current indications
for EP Study
Am J Cardiol (2009)104:671-77
The authors examined published results from
1990 to 2007 that were cited in Medline or
EMBASE:
• 18 Primary Studies of Atrial Flutter ablation
• 39 Primary Studies of SVT ablation
Study examined reentrant SVT’s
Am J Cardiol (2009)104:671-77
Atrial Flutter
Ablation Line
Ablation site
AV Node Reentry
Accessory Pathways
Ablation
Site
Meta-Analysis of Ablation of Atrial Flutter and SVT’s
Atrial Flutter
Single procedure success
Am J Cardiol (2009)104:671-77
Accessory Pathways
AV Node Reentry
91.7% 90.9% 94.3%
Multi-procedure success 97.0% 93.3% 96.0%
Repeat ablation procedure 8.0% 8.0% 5.6%
Procedure related mortality 0.0% 0.1% 0.0%
Hematoma 0.0% 0.3% 0.3%
Cardiac Tamponade 0.0% 0.4 % 0.1%
Need for Pacemaker 0.2% 0.3 % 0.7%
Complications
1. Am J Cardiol (2009)104:671-77
• “studies of RFA for treatment of patients with atrial flutter
and SVT report high efficacy rates and low rates of
complications1.”
• “the 2003 consensus guidelines for SVT management2
recommend radiofrequency ablation as a class I
intervention in all cases except:
• First episode of well tolerated atrial flutter
• SVT patients who do not desire ablation or
• Asymptomatic patients with WPW.”
Meta-Analysis of Ablation of Atrial Flutter and SVT’s
2. J Am Coll Card (2003) also available at www.acc.org
The authors concluded:
Furthermore:
• Electrophysiologist will place 1, 2, 3 or more catheters into the heart.
• Access will be from femoral vein, antecubital vein, subclavian vein or internal jugular vein.
• Catheters generally at least “quadrapolar” (4 electrodes) in configuration.
• Pacing and recording usually done in “bipolar” configuration (one electrode + and the other -)
How to do an EP Study
High Right Atrial
Location
HRA
His Bundle
Location
His
Right Ventricular Apical
Location
RVA
How to do an EP Study
Typical Catheter
Locations
• Intracardiac recordings are “filtered” to
allow visualization of signals
• Band pass filter from 30 or 40 Hz to
400 or 500 Hz
• Gain settings to optimize viewing
• Clipping as needed
• Screen display shows surface ECG and
appropriate intracardiac channels
How to do an EP Study
• Sinus cycle length (SCL or AA
interval)
• PR interval (120 – 200 ms)
• QRS duration (< 100 ms)
• QT interval (QTc < 440)
• AH interval (60 – 125 ms)
• HV interval (35 – 55 ms)
How to do an EP Study
Baseline Measurements
AA = 880 ms
PR = 140 ms
QRS = 140 ms
AH = 100 ms HV = -30 ms
Ventricular Pre-excitation
(Wolff- Parkinson-White)
• Pace HRA at fixed rate for at least 30
seconds.
• Measure interval from last paced atrial
signal to first sinus atrial signal – this is
the sinus node recovery time (SNRT).
• Generally this is repeated for a variety of
pacing cycle lengths.
How to do an EP Study
Atrial pacing – examining SA nodal function or
Sinus Node Recovery Time (SNRT)
Sinus Node Recovery Times
(SNRT)
• Normal is < 1.3 x sinus cycle length
(<1600 ms)
• Can “correct” by several methods:
• CSNRT = SNRT – SCL
( Normal <525 ms)
• Ratio of SNRT/SCL (Normal < 1.5)
• Limitation of SNRT is that while it is very
specific – it is not very sensitive!
How to do an EP Study
• Pace the HRA at gradually increasing
rates.
• Look for gradual prolongation in the AH
interval (“decremental” conduction).
• Determine the AV nodal wenkebach
cycle length.
How to do an EP Study
Incremental atrial pacing – examining AV nodal
function
A A H
V
A
PCL = 410 ms
Wenkebach CL = 410 ms
AH = 220 ms
Wenkebach Block – Mobitz type I (above His bundle)
No V
No H
Atrial PCL = 500 ms or 120 bpm
A H V A H
Mobitz type II block
(below the bundle of His)
A H V A H V A H V A H A H A H
• Pace the atrium at a fixed CL (typically
600, 500, 400 ms) for 8 beats then
introduce 1,2 or 3 extrastimuli
• Useful in determining:
• Refractory periods
• Change in conduction
• Dual AV nodal physiology
• Initiation of an arrhythmia
How to do an EP Study
Atrial extra stimulus techniques
Drive Train of 8 beats at 500 ms (S1)
and one premature S2 310 ms after S1
S1 S2 310 ms
A H V
Drive Train of 8 beats at 500 ms (S1)
and one premature S2 300 ms after S1
AH=160 ms
S1 S2
300 ms
A H V
AH=280 ms
AH
In
terv
al
S1S2 Interval
Dual AV Nodal
Physiology
• AH Interval “jumps” suggest
conduction moved from one
conduction pathway to another.
• A > 50 msec jump in AH
interval with a 10 msec
decrease in S1S2 interval is
called
More Premature
AV Nodal Function Curve
Right Atrial Anatomy
Superior Input Inferior
Input
Left Atrial
Input
Atrial depolarization
can reach the AV
node by several
“paths.”
When activation
changes from the
“fast” conducting
Superior input to
the “slower” Inferior
input – we see an
AH interval jump.
• Pace the RVA at gradually increasing
rates.
• Look for gradual prolongation in the VA
interval (decremental conduction)
• Concentric activation (via AV node)
• Eccentric activation (via AP).
• Determine the VA wenkebach cycle length.
How to do an EP Study
Incremental Ventricular pacing – examining
retrograde AV nodal function
Concentric (AV nodal) retrograde Activation
V A
Earliest A
In His
V A
Earliest A
In CS
(left side)
Eccentric (AP) retrograde Activation
• Pace the ventricle at a fixed CL (typically
600, 500, 400 ms) for 8 beats then
introduce 1,2 or 3 extrastimuli
• Useful in determining:
• Refractory periods
• Change in conduction
• Dual retrograde AV nodal physiology
• Initiation of an arrhythmia
How to do an EP Study
Ventricular extra stimulus techniques
S1 = 600 ms S1S2 = 260 ms
Single Ventricular extra stimuli
No retrograde conduction No repetitive
response
• EP Study has not been widely used in
patients with nonischemic
cardiomyopathy
• Sensitivity and specificity is likely
decreased
Limitations of the EP Study
• EP study may not be able to “reproduce” a
non-reentrant arrhythmia
• The EP study tries to cause “block” in
one limb while exciting the other limb to
induce the arrhythmia
• Pharmacologic maneuvers may help
induce non reentrant arrhythmias
Limitations of the EP Study
• Electro-anatomic mapping (CARTO)
• Catheter mapping
• Pacing maneuvers
Allow us to localize the arrhythmia circuit to facilitate diagnosis and treatment with ablation.
How to do an EP Study
These techniques along with
Successful RF Ablation
Wide QRS
(130 ms)
AV = 50 ms AV = 180 ms
QRS = 80 ms
Loss of antegrade
AP function
I
aVF
V1
V6
hRA
His p
His m
His d
Abl d
Abl p
Cs 4
Cs 3
Cs 2
Cs d
RVa
Stim
Intracardiac in SVT
Eccentric Activation
Concentric Activation
Ventricular Pacing
Why are these
different?
I
aVF
V1
V6
hRA
His p
His m
His d
Abl d
Abl p
Cs 4
Cs 3
Cs 2
Cs d
RVa
Stim
Eccentric
Activation
In SVT
Concentric
Activation
RV pacing
Termination of SVT with RF
I
aVF
V1
V6
hRA
His p
His m
His d
Abl d
Abl p
Cs 4
Cs 3
Cs 2
Cs d
RVa
Stim
Termination with
Block in AP
SVT