Examples presented herein generally include a catheter and a system configured to deliver electrical pulses for ablation by IRE and methods for constructing and using the same. The catheter and system can further be configured to delivery RF electrical current for thermal ablation interleaved with ablation by IRE, simultaneously with ablation by IRE, and/or separately from ablation by IRE. The catheter can have a linear distal portion with a tip electrode, a middle ring electrode, and a proximal ring electrode. The electrodes be configured in several combinations to provide unipolar ablation, bipolar ablation, and/or a combination thereof.