Affera Module 3/4: Model Mode/NSR/Customer Experience & Biophysics of Ablation

when both are programmed, which two triggers have to have a consistent relationship for affera to collect a point?

stim and V triggers

what aspects does orient to temperature adjust on the ablation tag?

shape, location, orientation

geomtry can be collected in treat mode T/F

False but editing tools still work and switching to model mode click F4 key

what visual cues are provided to inform the physician that the catheter is posterior?

posterior mask

p distance measurement

plan view

what items can you change retrospectively?

trigger

respiration

WOI

cycle length

WOI

cycle length

how is a trigger sensed?

absolute peak

what detection algorithm is used for point annotation

-dV/dT

what is the difference between remap and clone

remap keeps the geometry but not the electrograms, clone keeps both

how does RF create heat

when the current from the catheter passes through tissue, the resistance it faces results in heat generation, raising the tissue temp

how does RF create lesions

electrode-tissue interface must be at least 50 degrees C

resistive heating

direct thermal energy from the ablation electrode to the endocardial tissue

conductive heating

transfer of thermal energy from surface tissue to deeper tissue and this heating continues after RF energy delivery stops

what type of heating determines lesion width and depth

conductive heatin

downsides of irrigated catheter

higher risk of collateral damage and increase in fluid intake to the pt

in affera, where is the RF energy returned to

dispersive electrodes on pt’s torso

what does the affera system control to make it temp controlled and current limited

the current being delivered

what is the indication of a current limited system

the X between temp and current

current density

flow of current over cross section

current density x electrode-tissue contact relationship

tissue contact increases current density and lesion size

current p is proportional to the square of the distance from the ablation electrode

current density x electrode size relationship

larger electrodes disperse power across a larger area, resulting in lower current density

current density equation

how does sphere 9 avoid steam pop and maintain a large current

large surface area of sphere 9 allows for greater amount of current to be pushed through the cath while maintaining a low current p and a lower risk of steam pop

impedance in RF/PFA

measured between lattice tip and the return electrode

flow rate in RF

2 seconds of pre cooling at 30ml/min and flow rate persists until 5s after therapy completion

temp in RF

temp growth in RF

consistent increase in temp throughout ablation

what affect current density

electrode size

electrode tissue contact

resistance

4.65mm

F

1,2,5

flow rate in PFA

1s of pre cooling at 30ml/min and lowers to 15ml/min once therapy starts and remains there until temp reads below 40 C

temp in PFA

hottest temp measured from the 9 thermocouples

T/F PFA can be biphasic and monophasic

True

what is the PULSE3 preset

4s; 95% current limit; no temp target, 15ml/min flow rate

role of calcium in PFA

the pores generate change in calcium concentration between membrane, inhibiting the cell’s response to pacing. if the pores heal, the cell can respond to pacing and continue with arrythmia

tissue proximity study findings

they found that even at 4mm tissue proximity, the cardiac tissue still had a lesion

although, the most effective lesion is 0mm tissue proximity

phrenic nerve injury study results

PF did not result in acute phrenic paralysis

RF did result in phrenic nerve paralysis

although after RF and PFA, histology saw intact phrenic nerve bundle structures with both

rec RF ant and MI ablation settings

optimal PFA ablation

slight rise in temp and consistent current

what do spikes in temp indicate for RF ablation

intermittent tip tissue contact

flutter ablation with RF exception to temp and current relationship

on the valvular end of the CTI, there may be a sawtooth pattern to temp across the cath lattice but overall an inverse relationship

decrease in temp in PFA

catheter movement

spike in temp from PFA

intermittent tissue tip contact

what happens at septal regions of the LA during PFA

area of high blood flow so temp feedback is not reliable → Fluro, local impedance monitoring, and ICE should be used to asses cath position and stability

train of four

quantifiable method of measuring the degree of neuromuscular blockade using a peripheral nerve stimulator

done by counting the number of twitches elicited through electrodes placed on nerve pathway

hot spots for TOF

facial nerve, ulnar nerve, posterior tibial nerve

what do the number of twitches indicate for a TOF monitoring session?

pt’s level of paralysis

4 twitches =

70-75% receptors blocked

1 twitch =

95% receptors blocked

main differences between general anesthesia and sedation

level of consciousness

required equipment to support ventilation

adverse effects

spont ventilation

ability for pt to breathe independently

determine amount of paralytics/twitches expected

prior to pacing for phrenic nerve capture, if TOF stimulation testing was undertaken, how many twitches would u see?

3-4 to allow the diaphfragm to innervate