EP Signal and Recording

Where is HRA catheter placed?

- SVC, used to evaluate sinus node

Where is the His bundle catheter placed?

- Over tricuspid valve, time to go through atrium and AV node

Where is CS catheter placed?

- In AV groove, records A and V signals, atrial activation sequence proximal to distal

Bipolar Signals

- Sum of positive and negative end

- Electrodes are so close together most noise is measured equally

- Unaffected by FF signals

- Sees higher frequency

Unipolar Signals

- Reference is far away

- Can see FF signals

- Propagation towards electrode results in positive deflection and away in negative deflection

- Provides directionality information

Bipolar Blindness

- EGMs diminish in amplitude when catheter perpendicular to wavefront

HD Grid ] Bipolar Blindness solution

Signal amplitudes remain unchanged regardless of catheter

Double potential

3 shows the double potential; the high frequency signal in between resulting from the gap in the line of block

Signal Processing: Gain

Increases amplitude of all signals

Signal Processing: High pass filters

Filters out signals below a certain frequency (30 Hz)

Signal Processing: Low pass filters

filters out signals above a certain frequency (500 Hz)

Signal Processing: Band pass filter

Filters out signals outside of range of frequencies (30-500hz)

Signal Processing: Notch pass filter

Filters out a specificity frequency (60hz b/c we have 60hz electrical system in USA)

Label Waveforms

P-A Interval

- 1st evidence of SA node depol

- Conduction time from SA node to AVN 20-60ms

A-H Interval

- Atrial deflection HB EGM to his

- AVN conduction time 50-120ms

- Sympathetic stimulation = shorter A-H conduction time

H-V Interval

- His potential to earliest ventricular activation

- 35-55ms

Overdrive Pacing

- Stimuli delivered at constant rate (PCL), must be faster than intrinsic rhythm

Burst pacing

- Stimuli delivered at constant rate for short duration, but successively faster rates with each burst

Stepwise decremental pacing

- Pace at a given rate for number of stimuli or seconds

- Intervening pauses between each rate increase

Ramp pacing

- Gradual decrease of PCL every several paced complexes

Extrastimulus pacing

- Drive train of paced complexes followed by a extrastimulus at a shorter cycle length

- To find refractory periods

SA Recovery

- SA node resumes discharge at a slower rate and gradually speeds up in reponse to overdrive pacing

Response to decremental atrial pacing

- Find AVN refractory times

- Find atrial refractory period

AV Connections during atrial pacing

- Fast pathway

How to identify if person has dual nodal pathway

- Faster pacing occurs in longer A-H interval times

- A-H interval jump >35ms

Echo beat

Occurs when fast pathway is completely out of refractory by the time the slow pathway reaches it

Ventricular pacing purpose

- To find VERP, VAERP

- To find retrograde conduction

Ventricular fast pathway

Ventricular slow pathway

>150ms

SVTs involve retrograde or antegrade pathways?

Both