Partial or total occlusions can form throughout the cardiovascular system of human patients.  Such occlusions limit normal blood flow, and can cause a variety of health problems.  Medical professionals have developed a wide variety of techniques for treating occlusions such as angioplasty, tissue removal and stents.  To perform such techniques, percutaneous entry is employed in a well known manner to gain access to occlusions or other vascular constrictions within a patient.  Percutaneous entry generally involves the creation of an incision in a patient's skin to enable positioning an intraluminal treatment device within the vasculature of a patient.  Wire guides are typically employed to guide an intraluminal treatment device to a location of interest where a procedure such as angioplasty is performed.  It may be necessary to pass a wire guide along a relatively tortuous path, often a meter or longer, to reach the location where angioplasty or another technique is to be performed. 
Properly positioning a wire guide to enable guiding the intraluminal treatment device may include negotiating turns and branches within the patient's vasculature.  The occlusion to be treated may itself include a constriction in the patient's vasculature which is difficult to pass with the wire guide.  Similarly, other constrictions may lie in the desired travel path of the wire guide to a target location.  Crossing such constrictions may create challenges for clinicians.  While some axial force may be applied to a wire guide to push past a vascular constriction, substantially loading a wire guide in axial compression in an attempt to push through a vascular constriction risks injury to the patient, such as vascular wall puncturing. 
Medical professionals have proposed a variety of techniques for crossing vascular constrictions.  Among these are specialized ways to orient a wire guide tip, or stiffen a wire guide or other device, to enable successful crossing of the constriction without creating an undue risk to the patient.  While certain of these techniques have proven successful, there remains room for improvement.