During ablation, tissue directly under the catheter experiences which heating, and the surrounding myocardium experiences which heating?

• A. Resistive heating inside and conductive heating outside
• B. Conductive heating inside and resistive heating outside
• C. Radiofrequency heating only
• D. Convective heating

Answer: (A)

During radiofrequency ablation, heat generation starts at the tissue directly under the catheter tip because the electrical current encounters tissue resistance there, causing resistive heating in that immediate area. The heat then spreads outward to the surrounding myocardium by conduction, so the nearby tissue heats up more slowly as heat diffuses from the hot zone. So the tissue under the catheter experiences resistive heating, while the surrounding myocardium experiences conductive heating. Convection from blood flow mainly cools tissue rather than causing heating, so it doesn’t describe the heating pattern here.