Method and apparatus for the dialysis of blood

A catheter, comprising:

• a body comprising a body side wall, a proximal end and a distal end;
• a septum extending from the proximal end to the distal end, wherein the body and the septum terminating in a substantially flat distal end surface substantially perpendicular to a longitudinal axis of the body wherein;
• a first lumen and a second lumen separated by the septum, the first lumen forming a first mouth at the distal end, and the second lumen forming a second mouth at the distal end;
• a first slot formed in a portion of the body side wall at the distal end and in fluid communication with the first lumen;
• and
• a second-slot formed in a portion of the body side wall at the distal end and in fluid communication with the second lumen;
• wherein
• each of the first and second slots has a substantially constant width that extends linearly along a direction parallel to the longitudinal axis of the body;
• the first and second slots are centered on a plane substantially perpendicular to the septum,
• the distal end of the body has a substantially round cross section, and each of the first and second lumens has a substantially D-shaped cross-section at the distal end;
• and
• each of the first and second slots has a width that is between 30% and 60% of a longer dimension of the D-shaped cross-section of a corresponding one of the first and second lumen.