The development of a control method for a total artificial heart using mixed venous oxygen saturation

For physiological control of a total artificial heart (TAH), applying mixed venous oxygen saturation (Svo₂) as a parameter for TAH control is a promising approach regarding sensitivity to the recipient's oxygen demand and the practical possibility of continuous monitoring using near infrared rays through transparent blood pump housings. To develop a control method for the TAH using Svo₂, the relationship between Svo₂ and cardiac output (CO) was investigated in a normal calf, and a control algorithm was developed based on this correlation. Then the feasibility of this method (Svo₂ mode) was evaluated in a calf implanted with a pneumatic TAH and compared with the fixed drive control mode (fixed mode) in which the drive parameters were unchanged. The calf performed a graded exercise test in both modes. The CO was effectively increased from 7.3 to 13.0 L/min in the Svo₂ mode, and the capacity for exercise was augmented compared to the fixed mode. We conclude that this Svo₂ mode is feasible and may be effectively applied in TAH control.