A transseptal system includes a needle, a guidewire, a handle, and a dilator. The handle defines a needle passage to slidably receive the needle, and a guidewire passage to slidably receive the guidewire. The dilator defines a lumen having a distal region and a proximal region. The dilator is coupled to the handle such that the lumen is open to the needle passage and the guidewire passage. The proximal region of the lumen is sized to simultaneously receive the needle body and the guidewire. The distal region is sized to slidably receive one of the needle and the guidewire on an individual basis. A transseptal puncture and access procedure can be performed, including puncturing tissue with the needle followed by immediate advancement of the guidewire into the accessed area, eliminating the need for multiple instrument exchanges during the procedure.