Submyocardial Pacing Threshold Distribution During Cold Saline Application; Exploring Reversible Arrhythmia...

Area of Science:

• Cardiac Electrophysiology
• Minimally Invasive Cardiac Surgery
• Medical Device Technology

Background:

• Radiofrequency (RF) ablation is a key treatment for cardiac arrhythmias.
• Precise targeting of ablation sites is crucial, especially near delicate cardiac structures.
• Current methods for identifying optimal ablation sites may require further refinement.

Purpose of the Study:

• To investigate the potential of cold saline application via an irrigation catheter to reversibly inhibit submyocardial excitation.
• To determine if this method can aid in identifying ideal radiofrequency (RF) energy delivery sites around sensitive cardiac areas.
• To assess the depth-dependent effects of cold saline on myocardial excitability.

Main Methods:

• An open irrigation catheter was used to apply 4°C saline (20 mL/min) to porcine hearts.
• Myocardial temperature 2 mm below the surface (Temp-BS) and pacing threshold increase (%increase-PT) were measured.
• Pacing thresholds were assessed at varying depths using an electrode plunge needle near the ablation catheter.

Main Results:

• Cold saline application reversibly inhibited submyocardial excitation, interrupting ventricular pacing capture.
• The increase in pacing threshold was greatest at the myocardial surface and decreased with depth.
• Significant pacing threshold increases (>150%) were observed at 2-3 mm depth, and (>120%) at 6-7 mm depth.

Conclusions:

• Cold saline irrigation is a simple, reversible method to inhibit submyocardial excitation.
• This technique shows potential for pre-determining optimal ablation sites in sensitive cardiac regions.
• Further research and technological development are needed for clinical application.