An assembly (100, 300) for a transseptal puncture procedure and enhancing procedural efficiency by facilitating exchange and positioning, the assembly comprising: a puncture device (110, 112, 10, 114) for puncturing tissue, the puncture device comprising an electrically conductive mandrel; and at least one distal end marker which is visible under an imaging system; and a supporting member for supporting the puncture device comprising a lumen for receiving the puncture device and a distal tip marker which is visible under the imaging system; wherein the puncture device is capable of being insertable within the lumen of the supporting member and being selectively usable in co-operation therewith during a portion of a procedure for puncturing tissue and wherein the puncture device is usable independently therefrom during another portion of the procedure, characterized in that the assembly further comprises at least one proximal marker (116,117) positioned at a proximal end of the puncture device, the at least one proximal marker (116,117) covering a proximal portion of the mandrel; and a clear or translucent layer of insulation covering the mandrel, and the at least one proximal marker, the clear layer not covering the distal end of the mandrel such that the distal end of the mandrel is electrically exposed to define a distal tip electrode (114d,10d), wherein a diameter of the puncture device is constant at and adjacent the at least one proximal marker and wherein when the puncture device is inserted within the lumen, the at least one proximal marker allows the puncture device to be positioned relative to a proximal end of the supporting member, and the at least one distal tip marker and the at least one distal end marker allows the puncture device to be positioned relative to the supporting member by using the imaging system. a puncture device (110, 112, 10, 114) for puncturing tissue, the puncture device comprising an electrically conductive mandrel; and at least one distal end marker which is visible under an imaging system; and a supporting member for supporting the puncture device comprising a lumen for receiving the puncture device and a distal tip marker which is visible under the imaging system; wherein the puncture device is capable of being insertable within the lumen of the supporting member and being selectively usable in co-operation therewith during a portion of a procedure for puncturing tissue and wherein the puncture device is usable independently therefrom during another portion of the procedure, characterized in that the assembly further comprises at least one proximal marker (116,117) positioned at a proximal end of the puncture device, the at least one proximal marker (116,117) covering a proximal portion of the mandrel; and a clear or translucent layer of insulation covering the mandrel, and the at least one proximal marker, the clear layer not covering the distal end of the mandrel such that the distal end of the mandrel is electrically exposed to define a distal tip electrode (114d,10d), wherein a diameter of the puncture device is constant at and adjacent the at least one proximal marker and the assembly further comprises at least one proximal marker (116,117) positioned at a proximal end of the puncture device, the at least one proximal marker (116,117) covering a proximal portion of the mandrel; and a clear or translucent layer of insulation covering the mandrel, and the at least one proximal marker, the clear layer not covering the distal end of the mandrel such that the distal end of the mandrel is electrically exposed to define a distal tip electrode (114d,10d), wherein a diameter of the puncture device is constant at and adjacent the at least one proximal marker and wherein when the puncture device is inserted within the lumen, the at least one proximal marker allows the puncture device to be positioned relative to a proximal end of the supporting member, and the at least one distal tip marker and the at least one distal end marker allows the puncture device to be positioned relative to the supporting member by using the imaging system.