CVTs are CardioVascular Turbopumps, a more flexible, distributed replacement for the heart. The system consists of a suite of turbopumps installed in all the major arteries, and linked to a body-wide communications network. The pumps are cylindrical, and slightly larger in diameter than the vessels in which they are installed. The installation of the pumps is invasive, so as few as possible are usually installed (three for non-military systems, as many as a dozen if military).
The system draws its power from metabolism of carbohydrates in the blood stream, using standard mechano-metabolic modules. The turbopumps themselves are able to operate at a range of speeds, providing fine control over the blood supply to various organs and regions; oscillatory variation in pump speeds allows a pulse to be simulated. The pumps respond to hormonal messaging (which can be selectively blocked) and the inter-pump commnet is patched in to the autonomous nervous system. A front-end accessed through a neural interface allows manual control of the pumping rate within safe limits and integration with related cybersystems.
The distributed nature of the system makes it considerably more robust than the biological heart that it replaces. In case of damage or malfunction affecting a limited number of the pumps, the others increase in power to compensate. The turbopumps may be powered down to reduce bloodflow to injured sections of the body to prevent blood loss through haemorrhaging. The system is usually installed with further flow-control mechanisms such as vessel-blockers.
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