Cryogenic Open Heart Procedure
From Star Trek : Freedom's Wiki
A Surgical procedure in which the body temperature opf the patient and the replacement heart are both lowered to near cryogenic levels. This is done only in dire situations were there are inadequate supplies to properly drug or provide replacement blood for the patient. the purpose is to significantly decrease the patients metabolic rate during the procedure.
This is a very risky procedure and is only utilized as a last resort.
