MLG TURNED TO WRONG HEADING AND CAUSED A CONFLICT.

Narrative

INITIAL CONTACT WITH MSP DEP CTL WAS BLOCKED BY ANOTHER ACFT AFTER TKOF ON RWY 22 AT MSP. WE SEEMED TO BE CLOSING ON PREVIOUS DEP; TURBO-PROP ACFT IN OUR MLG AT THIS TIME. DEP CTLR'S SECOND XMISSION INSTRUCTED A TURN TO WHAT I UNDERSTOOD TO BE X DEGS. I INITIATED A RAPID LEFT TURN TO X DEGS IN ORDER TO GAIN SEP FROM PREVIOUS DEP ACFT. ABOUT 45 SECS LATER WE SAW A NE BOUND LGT AT ABOUT 5000'; AT OUR 3 O'CLOCK POS; AT ABOUT 2 MI. I LEVELED AT 4200' AS THE CTLR ALSO POINTED OUT THIS TFC AND TOLD US TO MAINTAIN OUR ALT. WE PASSED BEHIND AND BELOW THE 5000' TFC; AND NO EVASIVE ACTION WAS REQUIRED. IT IS ENTIRELY POSSIBLE THAT I MISUNDERSTOOD THE CTLR'S HDG INSTRUCTIONS; ALTHOUGH THERE DID NOT SEEM TO BE ANY DOUBT IN MY MIND AT THE TIME. OUR CALL SIGN WAS X AND THE HDG TO OUR INITIAL FIX; ODI; IS X DEGS. I AM CERTAIN THAT I WAS DISTRACTED BY THE FREQ CONGESTION; AND THE PROX OF THE PREVIOUS DEP. I MAY HAVE PREPROGRAMMED MYSELF FOR THE X DEG HDG; AND IN MY HASTE TO GAIN SEP FROM THE ACFT AT MY 12 O'CLOCK; TURNED TO X DEGS.