Popping phenomena in temperature-controlled radiofrequency ablation: when and why do they occur?

Area of Science:

• Cardiovascular Interventions
• Medical Device Engineering
• Electrophysiology

Background:

• Popping sounds during temperature-controlled radiofrequency (RF) ablation indicate adverse events like blood boiling and tissue rupture.
• Understanding factors influencing these phenomena is crucial for improving ablation safety.

Purpose of the Study:

• To investigate the impact of cooling (fluid flow), electrode-tissue contact force, and tip temperature on RF ablation popping.
• To identify conditions that increase the risk of popping phenomena and associated complications.

Main Methods:

• In vitro study using porcine ventricle tissue immersed in saline.
• Forty-two RF ablations performed with varying contact forces (0.0-0.44 N) and tip temperature control (70°C setpoint).
• Ablations conducted with (Group I) and without (Group II) fluid flow (0.1 m/s).

Main Results:

• Popping phenomena occurred in 10/21 ablations in Group I (fluid flow) versus 0/21 in Group II (no flow).
• Pops were associated with poor contact force (<0.1 N) and lower tip temperatures (<60°C).
• Two endocardial ruptures occurred, both linked to popping events.

Conclusions:

• Fluid flow and poor electrode-tissue contact significantly increase the risk of popping during RF ablation.
• Under these conditions, intramyocardial temperatures can reach boiling point, causing steam formation and pops.
• Optimizing electrode contact and managing fluid flow are critical for preventing adverse events during RF ablation.