An interventional system is used to treat a lesion in a target anatomy. The interventional system includes a balloon catheter and a guidewire. The balloon catheter includes a balloon coupled to a catheter shaft. The catheter shaft includes a guidewire lumen having a lumen diameter. The guidewire includes a coil tip coupled to a guidewire shaft at a proximal joint. A coil diameter of the coil tip at the proximal joint is larger than the lumen diameter of the catheter shaft. The interventional system can be used to access and treat the lesion in the target anatomy. Other embodiments are also described and claimed.