1. An implantable medical device (IMD) comprising: a sense circuit; an implantable main processing unit coupled to the sense circuit and adapted to execute general operational functions within the IMD; a memory unit coupled to the implantable main processing unit and adapted to store processed data; and an implantable reconfigurable processor unit coupled to the implantable main processing unit and adapted to receive data, perform a processing function on the data, and return processed data to the memory unit, wherein the implantable main processing unit is adapted to selectively reconfigure the coefficient of the reconfigurable processor unit in response to a programmed instruction.