A medical guidewire , comprising: a core wire having a longitudinal axis, the core wire including: a distal constant diameter section having a distal end and a proximal end, the distal end of the distal constant diameter section defining a distal end of the core wire ; a first tapered section having a distal end and a proximal end, the distal end of the first tapered section being attached to the proximal end of the distal constant diameter section such that a first inflection point is defined where the distal end of the first tapered section and the proximal end of the distal constant diameter section meet; an intermediate constant diameter section having a proximal end and a distal end, the distal end of the intermediate constant diameter section being attached to the proximal end of the first tapered section ; a second tapered section having a proximal end and a distal end, the distal end of the second tapered section being attached to the proximal end of the intermediate constant diameter section such that a second inflection point is defined where the distal end of the second tapered section and the proximal end of the intermediate constant diameter section meet; and a proximal constant diameter section having a proximal end and a distal end, the distal end of the proximal constant diameter section being attached to the proximal end of the second tapered section ; wherein the core wire is configured such that when a first predetermined longitudinal force is applied to the distal end of the distal constant diameter section along the longitudinal axis, the distal constant diameter section prolapses such that a first loop is defined about the first inflection point . a distal constant diameter section having a distal end and a proximal end, the distal end of the distal constant diameter section defining a distal end of the core wire ; a first tapered section having a distal end and a proximal end, the distal end of the first tapered section being attached to the proximal end of the distal constant diameter section such that a first inflection point is defined where the distal end of the first tapered section and the proximal end of the distal constant diameter section meet; an intermediate constant diameter section having a proximal end and a distal end, the distal end of the intermediate constant diameter section being attached to the proximal end of the first tapered section ; a second tapered section having a proximal end and a distal end, the distal end of the second tapered section being attached to the proximal end of the intermediate constant diameter section such that a second inflection point is defined where the distal end of the second tapered section and the proximal end of the intermediate constant diameter section meet; and a proximal constant diameter section having a proximal end and a distal end, the distal end of the proximal constant diameter section being attached to the proximal end of the second tapered section ; wherein the core wire is configured such that when a first predetermined longitudinal force is applied to the distal end of the distal constant diameter section along the longitudinal axis, the distal constant diameter section prolapses such that a first loop is defined about the first inflection point . <EOS>