Setting up the EP Lab

Raja Selvaraj
Cardiac Electrophysiologist
Professor of Cardiology
JIPMER

"A journey of a thousand miles begins with a single step." — Lao Tzu

How many EP / RFA cases have you performed independently ?

A. None
B. Less than 50
C. More than 50

Setup

Heart Rhythm Society Expert Consensus Statement on Electrophysiology Laboratory Standards: Process, Protocols, Equipment, Personnel, and Safety 2014

Lab set up

All EP equipment on ceiling mounted equipment boom
Power and data cables separately
Reduce length of data cables
Dedicated earth

Ceiling mounted boom

Earth

Control room

Procedure

Pre-procedure evaluation

History
Physical examination
Drug history
Anesthesia evaluation
Echo - Ebsteins / ASD / CS

Investigations

Adults - CBC, RFT, PT if on OAC
Children - No consensus on required investigations
Women of childbearing age including girls > 12 yrs - Serum or urine pregnancy testing < 2 weeks

Patients on AAD

Usually stopped 5 half lives before

Time out

Patient identifier
Personnel names
Procedure
Allergies

Nurse administered, physician monitored intravenous sedation

Fentanyl and Midazolam
Continuous SPO2 and NIBP
Avoid - Automatic AT, Idiopathic VT

I use sedation for SVT EP study

A. Never
B. Sometimes
C. Always

Sedation and inducibility

Selvaraj RJ, Dukiya S, Ananthakrishna Pillai A, Satheesh S, Balachander J. Effects of conscious sedation on tachycardia inducibility and patient comfort during ablation of supraventricular tachycardia: a double blind randomized controlled study. Europace. 2019 Jan 1;21(1):142-146. doi: 10.1093/europace/euy146.

Anticoagulation

For all left sided procedures
For right sided procedures
- Routinely ?
- Patent ASD
- Long sheaths

Access

Venous access

3 to 5
Right femoral vein
Left femoral vein
Internal jugular / Axillary vein
USG guided access

Our protocol

5F x 2 - RA and RV
6F - CS
7F - His / Map

Postprocedure hemostasis

Compression if no anticoagulation
Reversal with protamine
Wait for ACT < 200
Z stitch / figure of 8 suture

Imaging

Fluoro

Digital flat panel detector
Bi plane preferable if possible
Integrated data display system

Radiation dose should report

A. Fluoro time
B. Air Kerma
C. Dose Area Product
D. All of the above

Reduce radiation

Fluro loop rather than Cine loop
Tap, not stand on fluoro
Personal shielding
Table shielding

What frame rate is suitable for EP studies ?

A. 3.75 fps
B. 7.5 fps
C. 15 fps
D. 30 fps

Other imaging

Electroanatomic mapping
TEE
ICE

Ergonomics

Non lead aprons (30% less weight)
Floor or ceiling mounted radiation protection
Comfortable table height

Catheters and connectors

Woven dacron / Polyurethane

Catheters

Number of electrodes

Naming of electrodes

Catheter selection

Smaller catheters more flexible, lower axial force, less stable
Smaller spacing - more precise localization, may not pick up signal like His

Ablation catheter

Uni vs bidirectional
Push-pull versus rotational handle
Non irrigated versus irrigated

Right atrium

Quadripolar catheter
Right atrial appendage / lateral RA
AP view
Concealed RFW AP
Atriofascicular AP

Coronary sinus

Deflectable decapolar catheter
Superior / inferior approach
RAO / LAO
Proximal electrodes at os

His

Deflectable quadripolar catheter
2-5-2 spacing
Should record atrial signal

Preferred location for RV catheter is

A. Apex
B. Base
C. Midway between apex and base

RV

Quadripolar catheter
Basal position preferable

Catheters

Junction box

A bird's eye view

Setting up the signals

Which signal shows more noise

A. Unipolar
B. Bipolar

Unipolar shows more noise because

A. Wide antenna attracts more noise
B. Wider filter setting
C. Differential coupling of noise to two electrodes

Bipolar vs Unipolar

Field of view

Filtered Unipolar

Far field lower frequency signal
High pass filter (30Hz) reduces far field component

Unipolar pacing is useful for

A. Checking for phrenic nerve capture
B. Entrainment in scar VT
C. Inducing tachycardia

Amplifier set up

Steps

Digitization
Amplification
Filters
- High pass
- Low pass
- Notch

Digitization

Resolution and sampling

Nyquist limit

Sampling rate should be at least twice the frequency of interest
Lose high frequency information
Aliasing

The challenge of intracardiac electrograms

Very small amplitudes
- His bundle signal 0.5 mV
- Critical regions within scar may have smaller voltages - 0.25 mV
Variation in signal amplitudes
- Surface ECG - 5 mV

Noise

Multiple sources of noise
Patient as antenna - picks up signals from wiring and other devices
Leakage current from devices connected to the patient
RF energy - 70 V RMS
Noise level in bandwidth of interest should be 10 times smaller to give SNR > 10

Principles to reduce noise / interference

Decrease at source rather than reduce afterwards
Radiation shielding also reduces electrical interference
Separate all power cables from signal carrying cables
When close, these should be perpendicular and not parallel
Minimize coiling of cables
Minimize distance between amplifier and source (patient table)

Differential amplifier

Amplifies difference between two inputs
Common signal is not amplified (Common mode rejection)
Can be used to remove interference more effectively by tightly coiling two cables recording bipolar signal
Inputs need to be balanced (ablation tip set for pacing)