Introduction to Electrophysiology

Karen Bain
James Cook University Hospital
Middlesbrough
Electrophysiology
 Electrophysiology...
 Is the study of the heart’s electrical system
 Assesses the function of each component of cardiac
conduction
 Determines the potential for a patient to have an
arrhythmia
 Determines the mechanism of an arrhythmia
 Evaluates the need for treatment/ therapy
The role of EPS in the diagnosis and
treatment of cardiac arrhythmias
 To characterise physiological and pathological properties of the
atria, ventricles and the atrioventricular conduction system, identify
accessory pathways, and determine the sites and mechanisms of
arrhythmias
 To correlate patient symptoms with arrhythmias and evaluate risks
for life threatening events and/or differentiate arrhythmias.
 To define arrhythmia induction and termination methods for EPS
guided interventions: i.e. Medications, anti-tachycardia pacing, antiarrhythmic surgery, ICD’s, ablation or modification.
Indications
 Class I – an EP study is indicated
 Class II – an EP study may be indicated
 Class III – an EP study is not indicated
Indications – class I
 Patients not tolerating or not responding to medications
for narrow complex tachycardia in whom the study would
alter their therapy
 Narrow QRS tachycardia preferring ablative therapy
 Sustained wide QRS complex tachycardia
 An accessory pathway tachycardia that is symptomatic
and may require ablative therapy
Indications – class I
 Unexplained syncope and known structural heart disease.
 Palpitations and documented inappropriate rapid pulse rates
without apparent cause.
 Survival of cardiac arrest with NQWMI or surviving cardiac
arrest occurring >48 hrs after AMI.
 Candidates for implantation of an electrical device to treat
their arrhythmias or those who have an implanted device and
require therapy changes that may alter the safety or efficacy of
their device.
Indications – class II
 Sinus node dysfunction - to exclude other arrhythmic causes or
assess the severity or mechanism of dysfunction and drug
response to direct therapy.
 Second or third degree AV block to determine the site or
mechanism of the block in order to direct therapy.
 Symptomatic patients with bundle branch block to assess the
site and severity of the conduction delay in order to direct
therapy and evaluate prognosis.
 Patients with premature ventricular complexes and
unexplained pre-syncope or syncope.
Indications – class II
 Asymptomatic patients with ECG evidence of WPW syndrome
to evaluate the accessory pathway in high-risk activities, a
family history of premature sudden death, or unexplained
syncope
 Patients with clinically significant cardiac palpitations thought
to be of cardiac origin but not documented by non-invasive
testing in order to diagnose, treat, and assess prognosis
 Risk stratify post MI patients with reduced LV function having
frequent PVC’s, NSVT, or both, particularly if the signal
averaged ECG shows late potentials.
Indications – class III
 Symptomatic patients with sinus node dysfunction with
ECG documentation of a bradyarrhythmic cause
 Asymptomatic patients with nocturnal bradycardia
 Patients with congenital or acquired long QT syndrome
with symptoms related to an identifiable cause or
mechanism
 Patients with a known cause of syncope
 Patients with cardiac arrest occurring only within the first
48 hrs of AMI
Newer indications
 AF
 Paroxysmal
 Persistent
 Permanent?
 Complex VT
 Fascicular VT/Idiopathic LVVT
 BB Re-entry
 VT associated with RVD
 Ischaemic VT
In other words...
Do it if...
Don’t do if...
 Palpitations
 Known indications for
 WPW
pacemaker or ICD implant
 Recent MI
 Asymptomatic
 Known or suspected
arrhythmia
 Unexplained syncope
 Medication intolerance
 VPB’s/APB’s
National Service Framework chapter for arrhythmias
and sudden cardiac death – Chapter 8; March 2005
Contraindications
 Bleeding disorder
 Unstable angina
 Uncontrolled congestive heart failure
 Uncooperative patient
 Severe peripheral vascular disease
 Valvular or sub valvular stenosis (LV access)
 Thrombophlebitis (femoral access)
 Groin infection
 Bilateral amputee (femoral access)
Possible complications
 Hypotension
 Systemic emboli
 Haematoma
 Acute cardiac tamponade
 Haemorrhage
 Pneumothorax
 Vascular injury
 Death
 Thrombophlebitis
Before we start...
 Patient preparation
 Informed consent
 Drugs stopped
 Bloods
 INR if on warfarin
 Results of investigations
 ECG of tachycardia is very useful
What we need...
 Equipment
 Fluoroscopy unit
 Radiographic table
 Physiologic recorder and
oscilloscopes
 Instrumentation for vascular
access
 Crash trolley
 Personnel
 Electrophysiologist
 Cardiac physiologists
 Nursing staff
 Radiographer
 EP equipment
 Programmable stimulator
 Multichannel lead switching
box (junction box)
 Electrode catheters
 Ablation system





Generator
Irrigation Pump
Remote Panel
Cables
Tubing
 3D Navigational Mapping
System (optional)
Lab set up
Lab set up
Patient
Junction
box
Signal
amplifier
Recorder
Oscilloscope
Stimulator
Catheters and sheaths
Electrodes
 Tip and ring
 99% Platinum
 Good conductor of electricity
 1% Iridium
 Radio-opaque
 Binds to copper connecting wire
Curves
 Josephson
 Dr Mark E Josephson
 Cournand
 Cournand, André Frédéric 1895-1988.
 French-born American physician. He shared a 1956 Nobel
Prize for developing cardiac catheterisation
 D’Amato
 Anthony N. D’Amato: 1930–2001
Curls and sweeps
Terminology
 Quadripolar - Quad
 Four poles
 Decapolar - Dec
 Ten poles
 Duo Dec
 Twenty poles
Spacing
 Spacing indicates the space in mm between electrodes on
the catheter.
 First number is spacing between electrodes 1 and 2
 Second number is spacing between electrodes 2 and 3
etc…
 Only one number indicates that all inter electrode
spacings are equal
Spacing
Spacing
 Smaller spacing to map complex or small localised
electrograms i.e. 2-2-2
 His bundle
 Para-Hisian
 Bundle branch potentials
 Larger spacing to map larger areas of myocardium or
cross chamber i.e. 2-8-2
 CS (LA&LV)
 H-Curve (or duo-dec, Halo) for RA whole chamber mapping
Catheter size
 French gauge scale
 Abbreviated to FR, Fr or F
 Measurement of outer diameter of cylindrical objects
i.e. catheters
 D (mm) = Fr/3
 Fr = D (mm)x3
Catheter French
Advantages of 6F over 5F
 More stability
 More Torque
 More Pushability
Advantages of 5F over 6F
 Smaller introducers
 Reduced risk of
complications, damage
and healing time due to
smaller size
 Preserve vessel access in
younger patients
 Less chance of
compromising circulation
Catheter uses
 Visualise intracardiac electrograms
 Fluoroscopy visualisation
 Measurement of electrograms
 Pacing
 Geometry creation for navigational mapping
 Ablation
 Internal Cardioversion
Catheter placement
 Access route is commonly
the femoral vein
 Other routes include:
 External jugular vein
 Internal jugular vein
 Subclavian vein
Catheter placement
 Quad in HRA (e.g. JSN)
 Dec in CS
HRA
 Quad at His (e.g. CRD-2)
 Quad in RV (e.g. CRD)
CS
His
RV
E L E CTRODE P OS ITIONS
(R AO P ROJ E CTION)
Electrode positions - RAO
HRA
CS
HIS
R VA
Electrode positions - RAO
SVC
RA
RV
IVC
E L E CTRODE P OS ITIONS
(L AO P R OJ E C TION)
Electrode positions - LAO
HRA
CS
HIS
R VA
Electrode positions - LAO
Anterior
TV
MV
CS
Posterior
Sheaths
 Short or long
 Short – cannulation of arteries or veins at access point i.e.
femoral vein
 Lockable or standard
 Long
 for intracardiac use
 Offer stability
 Transseptal
 Various curves for different chambers and locations
Sinus rhythm
Sinus rhythm
Sinus rhythm
Sinus rhythm
Basic intervals
 AH interval
 Time taken to travel over the AVN
 Measured from the atrial EGM recorded at the HIS bundle
to the onset of the HIS EGM
 Normal = 55 – 125ms
 HV interval
 Time taken to travel through the His-Purkinje system
 Measured from the onset of the HIS EGM to the earliest
ventricular activation in any lead (inc. surface)
 Normal = 35 – 55ms
Pacing in EP
 Programmed electrical stimulation is used:
 To assess refractory periods, conduction properties and
automaticity
 To evaluate inducibility of those patients who have an
indication for EPS
 To characterise arrhythmia and assist in choice of therapy
 For the purpose of mapping and ablation
 To evaluate efficacy of treatment
 To evaluate success of treatment
Drive train with extrastimuli
S1
S1
S1
S1
S1
S1
S1
S1
S2
A
H V
A
H V
A
H VA
A
H
V
V
A
V
A
V
A
V
V
A
Initiation and termination of
tachycardia
 Antegrade and retrograde curves
 Burst atrial/ventricular pacing
 His synchronous VPB
VT stim protocols
 Programmed electrical stimulation (PES) of the RV
 Usually two pacing sites: RVA and RVOT/RV septum
 Drive train of eight paced impulses (S1) and a variable
number of extrastimuli (S2, S3 and S4)
 Progressively shortened coupling intervals between the
drive and extrastimuli
 Extrastimuli induce VT or cause ventricular refractoriness
 Isoprenaline may be used during VT stimulation
Wellens protocol
 Stage 1
 SR with one extra stimulus (S2), decrease by 20ms until
refractory.
 Stage 2
 S2 refractory + 20ms plus S3, decrease by 20ms until
refractory
 Stage 3
 Drive train (S1) of 100bpm (600ms) + S2
 Stage 4
 As stage 3 + S3
Wellens protocol
 Stage 5
 As stage 3 with drive train of 120bpm (500ms)
 Stage 6
 As stage 5 + S3
 Stage 7
 As stage 3 with drive train of 140bpm (428ms)
 Stage 8
 As stage 7 + S3
Wellens protocol
 Stage 9
 SR with S2 refractory + 20ms and S3 refractory + 20ms plus
S4
 Stage 10
 As stage 9 with drive train at 100bpm (600ms)
 Stage 11
 As stage 9 with drive train at 120bpm (500ms)
 Stage 12
 As stage 9 with drive train at 140bpm (428ms)