A system is described for assisting a wire guide (32) to cross obstructed ducts in a mammalian body. The system can be used for applying pulsed energy to an occlusion obstructing the duct. The pulsed energy is applied by means of an auxiliary probe (12). The auxiliary probe (12) is relatively displaceable with respect to the wire guide (32) along a lumen provided within the probe. The distal region (28) of the probe (12) is provided with enhanced flexibility compared with the reminder portion of the probe (12).
