Electrophysiological correlates of transmural linear ablation

Area of Science:

• Cardiology
• Electrophysiology
• Medical Devices

Background:

• Atrial flutter ablation requires effective methods for targeting the tricuspid annulus-inferior vena cava (TA-IVC) isthmus.
• Radiofrequency (RF) ablation efficiency can be enhanced by cooled catheter systems, leading to larger lesions.
• Novel catheter designs are explored to improve the practicality and efficacy of TA-IVC isthmus ablation.

Purpose of the Study:

• To characterize lesions created by a saline/foam electrode RF ablation system for TA-IVC isthmus ablation.
• To compare electrophysiological parameters with histological findings post-ablation.
• To evaluate the practicality of this system for atrial flutter ablation.

Main Methods:

• A linear ablation catheter with saline bipole electrodes was used in sheep models.
• Radiofrequency energy was applied at 50 watts for 90 seconds with a specific saline flow rate.
• Bipolar atrial signal amplitude and pacing thresholds were measured before and after ablation; histological analysis was performed.

Main Results:

• Atrial signal amplitude decreased by an average of 76%, and pacing thresholds increased by 617%.
• Transmural lesions measuring 8-20 mm in length, 4-10 mm in width, and 1.5-2.0 mm in depth were consistently produced.
• No charring, coagulum, or remote damage was observed, and electrophysiological changes correlated with complete necrosis.

Conclusions:

• Stationary RF linear ablation using the saline/foam electrode catheter system can create continuous transmural TA-IVC isthmus lesions.
• The system allows for electrophysiological assessment that correlates with complete tissue necrosis.
• This approach offers a practical method for TA-IVC isthmus ablation in atrial flutter treatment.