A catheter including a proximal section, a distal tip, an elongate shaft, and an inflation subassembly, the elongate shaft extending from the proximal section to the distal tip and defining a longitudinally extending delivery lumen, the inflation subassembly including a compliant sleeve member and an elongate tube, the sleeve member extending around an exterior surface of the shaft, in proximity to the distal tip, the sleeve member including a proximal end, a distal end and an inflatable section extending between the proximal and distal ends, the proximal and distal ends being secured to the shaft, and the elongate tube defining an inflation lumen that extends within the shaft from a first opening in the proximal section to a second opening that communicates between the exterior surface of the shaft and an interior surface of the inflatable section of the sleeve, and the proximal section of the catheter comprising: a proximal terminal end defining a perimeter of a proximal opening of the delivery lumen; a proximal port portion extending distally from the proximal opening of the delivery lumen and along a longitudinal axis of the proximal opening; and a seal zone portion for the delivery lumen, the seal zone portion extending distally from the proximal port portion; a perimeter of the proximal port portion being divided into a first portion and a second portion, the first and second portions extending along a length of the proximal port portion and being located on opposite sides of the longitudinal axis, the first portion having a relatively soft inner surface, the second portion having a relatively hard inner surface, and the second portion including a relatively thin wall section that extends distally from a proximal edge thereof, the proximal edge defining part of the perimeter of the proximal opening; and wherein the proximal terminal end of the proximal section has a tapered profile; the first portion of the proximal port portion of the proximal section protrudes proximally from the second portion and includes an exposed sealing area at the proximal terminal end, the exposed sealing area being exposed by virtue of the tapered profile; and wherein the exposed sealing area, relatively soft inner surface and seal zone are formed from a single bulk of relatively soft material; said catheter further comprising: a handle portion comprising a connector port for the inflation lumen, the handle portion projecting laterally from the seal zone portion on an opposite side of the longitudinal axis from the relatively thin wall section of the proximal port portion, and the connector port being configured for coupling of an inflation fluid source thereto; wherein the tube of the inflation subassembly includes a section extending laterally from the shaft and into the handle portion such that the first opening of the inflation lumen is located in the connector port; characterized in that the handle portion of the proximal section further comprises at least one slot being sized to receive and grip a segment of a guide wire. a proximal terminal end defining a perimeter of a proximal opening of the delivery lumen; a proximal port portion extending distally from the proximal opening of the delivery lumen and along a longitudinal axis of the proximal opening; and a seal zone portion for the delivery lumen, the seal zone portion extending distally from the proximal port portion; a perimeter of the proximal port portion being divided into a first portion and a second portion, the first and second portions extending along a length of the proximal port portion and being located on opposite sides of the longitudinal axis, the first portion having a relatively soft inner surface, the second portion having a relatively hard inner surface, and the second portion including a relatively thin wall section that extends distally from a proximal edge thereof, the proximal edge defining part of the perimeter of the proximal opening; and wherein the proximal terminal end of the proximal section has a tapered profile; the first portion of the proximal port portion of the proximal section protrudes proximally from the second portion and includes an exposed sealing area at the proximal terminal end, the exposed sealing area being exposed by virtue of the tapered profile; and wherein the exposed sealing area, relatively soft inner surface and seal zone are formed from a single bulk of relatively soft material; said catheter further comprising: a handle portion comprising a connector port for the inflation lumen, the handle portion projecting laterally from the seal zone portion on an opposite side of the longitudinal axis from the relatively thin wall section of the proximal port portion, and the connector port being configured for coupling of an inflation fluid source thereto;