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... Palpitations WPW Known or suspected arrhythmia Unexplained syncope Medication intolerance VPB s/apb s Don t do if... Known indications for pacemaker or ICD implant Recent MI Asymptomatic
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 Haematoma Haemorrhage Vascular injury Systemic emboli Acute cardiac tamponade Pneumothorax 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 HRA Quad in HRA (e.g. JSN) Dec in CS Quad at His (e.g. CRD-2) Quad in RV (e.g. CRD) CS His RV
ELE CTRODE POS ITIONS Electrode (R positions AO P ROJ ECTION) - RAO HRA CS HIS R VA
Electrode positions - RAO SVC RA IVC RV
ELE CTRODE POS ITIONS (LAO PR OJ EC 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 V A
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 (S 1 ) and a variable number of extrastimuli (S 2, S 3 and S 4 ) 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 (S 2 ), decrease by 20ms until refractory. Stage 2 S 2 refractory + 20ms plus S 3, decrease by 20ms until refractory Stage 3 Drive train (S 1 ) of 100bpm (600ms) + S 2 Stage 4 As stage 3 + S 3
Wellens protocol Stage 5 As stage 3 with drive train of 120bpm (500ms) Stage 6 As stage 5 + S 3 Stage 7 As stage 3 with drive train of 140bpm (428ms) Stage 8 As stage 7 + S 3
Wellens protocol Stage 9 SR with S 2 refractory + 20ms and S 3 refractory + 20ms plus S 4 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)