A 
catheter includes a 
cryoablation tip with an electrically-driven 
ablation assembly for heating tissue. The 
cryoablation tip may be implemented with a 
cooling chamber through which a controllably injected 
coolant circulates to lower the tip temperature, and having an RF 
electrode at its distal end. The RF 
electrode may be operated to warm cryogenically-cooled tissue, or the 
coolant may be controlled to conductively cool the tissue in coordination with an RF 
treatment regimen, allowing greater versatility of operation and enhancing the 
lesion size, speed or placement of multi-
lesion treatment or single 
lesion re-treatment cycles. In one embodiment a 
microwave energy source operates at a frequency to extend beyond the 
thermal conduction depth, or to penetrate the cryogenic ice ball and be absorbed in tissue beyond an ice boundary, thus extending the depth and / or width of a single treatment locus. In another embodiment, the cooling and the application of RF energy are both controlled to position the 
ablation region away from the surface contacted by the 
electrode, for example to leave surface tissue unharmed while ablating at depth or to provide an 
ablation band of greater uniformity with increasing depth. The driver or RF 
energy source may supply 
microwave energy at a frequency effective to penetrate the ice ball which develops on a cryocatheter, and different frequencies may be selected for preferential absorption in a layer of defined thickness at depth in the nearby tissue. The 
catheter may operate between 70 and minus 70 degrees Celsius for different tissue applications, such as 
angioplasty, 
cardiac ablation and 
tissue remodeling, and may preset the temperature of the tip or adjacent tissue, and otherwise 
overlay or 
delay the two different profiles to tailor the shape or position where ablation occurs or to speed up a treatment cycle.