Final answer:
Code 33508 is an add-on code for cardiovascular surgical procedures that must be used in conjunction with primary procedure codes ranging from 33510 to 33530.
Step-by-step explanation:
The add-on code 33508 is used in conjunction with a specific range of primary procedure codes. Code 33508 must be used in conjunction with procedure codes that range from 33510 to 33530. This means that whenever code 33508 is billed, it should be accompanied by another procedure code that falls within the specified range. These codes are related to cardiovascular surgical procedures, and code 33508 is not a standalone code; it represents an additional service that is only performed in conjunction with primary cardiovascular procedures.