Conduction transfers heat through solids , Convection transfers heat through liquids or gasses, and Radiation occurs through a solid, liquid, or gas.
The answer i believe is a gel
After the depolarization wave front passes through the atria, it enters that AV node which is located at the apex of the triangle of Koch. It would be the AV node that <span>collects the depolarization wave from the atria to pass it onto the ventricles. Hope this answers the question.</span>