An infusion system includes an infusion catheter defining a fluid passage extending between a proximal catheter end and a distal catheter end, and having a plurality of infusion ports in communication with the fluid passage and defining an infusion zone. A filtration device is provided which may be retrofitted upon the infusion catheter and includes a filter sleeve coupled to a slidable control sleeve. The filter sleeve is deformable between a first configuration having a radially contracted footprint and a second configuration having a radially expanded footprint, responsive to sliding the control sleeve over the infusion catheter such that the deformable filter sleeve buckles outwardly from the infusion catheter.

Multi-lumen catheters with improved tip configurations, including a triple-lumen catheter which may be useful for apheresis. In one variation, the catheter has three lumens with distal openings angularly spaced apart and staggered axially with respect to one another. In another variation, the catheter has two lumens exiting distally and one centrally positioned lumen exiting proximally. A third variation is a catheter with a single distal opening and two proximal openings. The staggered lumen openings along the axial length of the catheter may decrease recirculation while maximizing flow rates.