Digital signal analysis of blood flow in patients on a total artificial heart
Abstract
The physiological condition of patients with chronic heart diseases is vastly different and likely more compromised than patients with acute heart disease. Therefore, a method that would better assess a patient's response to the total artificial heart (TAH) may enhance that patient's prospect of survival. One possible approach would be to examine the condition of the vascular system of the patients on a TAH and correlate variations to clinical changes in the patient. This could greatly enhance the effectiveness of a control system for a TAH, and this information could also be used as an indicator for appropriate drug therapy. Between 1986 and 1989, eight patients received the Jarvik 7-70 TAH as a bridge to transplantation at St. Luke's Hospital of Milwaukee. The data recorded on these patients was examined to determine sampling methods and storage techniques. It was then analyzed using digital signal processing (DSP) techniques. Both a parametric and a non-parametric correlation coefficient, between the power spectrum and a physiological condition such as tamponade or increased pulmonary vascular resistance, were calculated. A physiological model of the venous return was also developed and the correlation between the model's coefficients and the power density spectrum (PDS) of the venous return blood flow was determined. The results of this research clearly demonstrated that there are recognizable changes in the PDS of the venous return blood flow that can be correlated to clinical changes. A high degree of correlation between the model's coefficients and the PDS of the venous return blood flow was also found. Both findings suggest that either the PDS or the model's coefficients could be used as possible predictors of clinical complications in patients supported by a TAH. These findings clearly meet the objective of this research, which was to develop a method that could be used to predict physiological system changes in patients on the TAH. It is very likely that either technique could provide a more precise method of assessing a patient's response to the TAH and enhance the patient's prospect of survival.
This paper has been withdrawn.