Computer Modeling for Radiofrequency Bipolar Ablation Inside Ducts and Vessels: Relation Between Pullback Speed and...

Area of Science:

• Medical Devices
• Biomedical Engineering
• Minimally Invasive Surgery

Background:

• Radiofrequency (RF) ablation is used for tissue removal within ducts and vessels.
• Simultaneous catheter pullback and RF power application are key procedural elements.
• Understanding the interplay between pullback speed, impedance, and temperature is essential for procedural control.

Purpose of the Study:

• To characterize the relationship between catheter pullback speed, impedance changes, and temperature distribution during RF ablation.
• To investigate how varying pullback speeds affect lesion characteristics and procedural safety.

Main Methods:

• A numerical model simulating a bipolar catheter within a duct was developed.
• The model solved coupled electrical, thermal, and mechanical equations.
• Lesion assessment utilized an Arrhenius model, with model parameters calibrated to experimental impedance values.

Main Results:

• Slow pullback speeds (<0.4 mm/s) resulted in impedance drop, deep lesions, and overheating.
• Faster speeds (0.4-1.0 mm/s) led to initial impedance rise followed by a plateau.
• A strong inverse relationship was observed between pullback speed and lesion depth; the hottest point was near the second electrode.

Conclusions:

• Pullback speed significantly influences impedance progression during RF ablation.
• Impedance monitoring can serve as a guide for achieving effective and safe ablations.
• This research provides insights for optimizing RF ablation techniques in luminal structures.