In vivo evaluation of pressure head and flow rate estimation on a continuous-flow artificial heart

For monitoring or control of a fully implantable TAH, we should avoid using special sensors that may lose reliability and biocompatibility. Instead of direct measurement of pressure head and flow rate of a centrifugal blood pump, the authors previously proposed a method of estimating these measurements. The method uses an auto-regressive exogenous (ARX) model whose inputs are supplied power, rotational speed and the gain constant expressing the relationship between the two. The gain constant was introduced to compensate for reduction in accuracy caused by the change in blood viscosity or vascular dynamics. In this study, to ascertain the adequacy of the proposed method, an acute animal experiment was carried out using an adult goat equipped with a TAH consisting of two centrifugal pumps. The results indicated that the ARX model identified even in a mock circulation could estimate flow rate in the recipient accurately enough, although estimation accuracy of pressure head was not high.