The use of irrigation of the ablation electrode has a positive effect in all the following aspects of the energy delivery except:

• A. Accurate Measure of Tissue Temperature
• B. Improved Lesion Depth
• C. Reduced Char Formation
• D. Stable Catheter Temperature

Answer: (A)

Irrigation cools the electrode-tissue interface during energy delivery, which helps prevent overheating, reduces char and thrombus formation at the contact surface, and allows higher power with longer energy delivery. This cooling also helps keep the catheter temperature stable, avoiding temperature spikes that can occur with dry ablation and supporting more consistent lesion formation, including greater lesion depth.

But this same cooling makes tissue temperature harder to measure accurately. The sensor at the catheter tip mainly tracks the electrode surface temperature, and when saline irrigation is flowing, convective cooling decouples that reading from the actual tissue temperature. The tissue right at the ablation site can reach higher temperatures than the sensor indicates because the cooling effect carries heat away, creating a heat-sink situation. So while irrigation improves several aspects of energy delivery, it does not improve, and in fact can diminish, the accuracy of tissue temperature measurements.