A medical device for ablation of a target tissue is disclosed. The medical device includes a catheter assembly attached to a balloon for the ablation of the target tissue. The catheter assembly includes a proximal end and a distal end. The catheter assembly includes a plurality of individual shafts placed concentrically or adjacent to each other. Further, the plurality of individual shafts includes a respective lumen, wherein the lumens of the plurality of individual shafts can be configured to supply radio frequency (RF) energy to an RF transmitter placed inside the balloon and also to serve as the passageway for a fluid to travel within the balloon. The fluid flowing within the lumens of the catheter assembly can further help in expanding the balloon and transferring energy from the RF transmitter within the balloon to the ablation site via a plurality of windows attached.