A concentric guidewire assembly includes a unitary first coil spring, a second coil spring joined to the first coil spring, and a core wire extending through the first and second coil springs. The first coil spring has a longitudinal axis, a first spring portion, a second diameter spring portion adjacent the first spring portion, and a third spring portion adjacent the second spring portion, the inner diameter of the second spring portion being smaller than the inner diameters of the first and third spring portions to fit with the core wire and maintain concentricity between the first coil spring and the core wire. The second coil spring has an inner diameter sized to receive the third spring portion.