Systems and methods for transeptal cardiac procedures are disclosed. A patient treatment device in accordance with a particular embodiment includes an elongated first intravenous guidewire that includes a first branch and a second branch fixably secured relative to the first branch at a first location. The device can further include an elongated second intravenous guidewire that is movable relative to at least one of the first and second branches between a first position in which the first and second branches are releasably secured relative to each other by the second guidewire at a second location, and a second position in which the first and second branches are separated from each other at the second location.
