Co-Author(s):
Raju Viswanathan, PhD - Vice President of Research and Development,
Farapulse
Vivek Reddy, MD - Director of Cardiac Arrhythmia Services, Mount Sinai
MPMC/CPMC Sutter Health
1501 Trousdale Drive, Burlingame, CA, 94010
Introduction | Objectives: Endocardial pulsed field ablation (PFA) has electrolytic effects that
are echogenic and can be altered via device and delivery parameters.
Quantification of PFA-generated ,in comparison with radiofrequency (RF),
bubbles can inform PFA’s embolic safety profile.
Methods: The PFA system was described previously1. A bubble
trap described previously was used2. Room temperature
saline (4.5 g/L NaCl to mimic clinical impedance) flowing at a rate of
0.8 L/min was used. PFA was delivered and quantification of gas burden
was made with a bubble counter (Gampt BCC300). Gas emission was
qualified via ICE echocardiography (RF and PFA). RF applications were
made using a commercial system (Boston Scientific Maestro 4000/Blazer
Model 9620). The data was compared with published values from an in-vivo
RF model3.
Results: 6 scenarios for PFA delivery were investigated (figure 1):
free-floating vs in contact with porcine myocardium (tissue), 2.0 vs
1.8kV amplitudes and two catheter shapes. A total of 8 applications were
delivered per session per clinical studies1. Average
gas volume and maximal bubble diameter was 1.52±1.44nL and 85 mm,
respectively, across all PFA scenarios. RF applications to tissue
(excluding steam pops) created an average gas volume (nl) of 177±134 or
59.3±44.7 when adjusted for flow rate2 (factor 0.33),
similar to previous data. Saline vs tissue PFA values were similar.
Median bubble diameter was smaller with PFA than RF (18 vs 30µm,
respectively). PFA bubbles were visible only on ICE and only during the
few seconds of delivery. RF bubbles were visible via ICE, persisting up
to one minute after end of delivery.
Conclusions: Total volume and maximal diameter of bubbles produced with a clinical
PFA system were lower when compared with RF values. The density of
small-sized bubbles occurring in a short PFA delivery duration
contribute to the echogenicity of PFA delivery. Similar results between
PFA deliveries to tissue and saline support electrolytic rather than
heat-related bubble formation. References
- Takami et al, Circ. Arrythm. Electrophysiol. 9:e003226, 2016.
- Vivek Reddy et al, Am. Coll. Cardiol . 74(3) (2019 Jul 23) 315
– 326.
- van Es et al, Cardiovasc. Electrophysiol. 30 (2019) 2071 –
2079.
AFS 2021-42