Preventing heterocyclic declination was a necessary precondition to the successful outcome of a cardiac implant. According to the Starbase 515 surgeon the inability to reverse heterocyclic declination — and an the lack of metabilation occlusion — were primarily responsible for the initial failure of Captain Jean-Luc Picard's secondary implant surgery. These failures forced the doctor to seek additional help from a biomolecular physiologist, who was able to recommend that Katherine Pulaski correct the issues. (TNG: "Samaritan Snare")