Assessment of linear and non-linear coupling effect on cardiovascular subsystems in stroke

Stroke is a deadly condition. It is a leading cause of death in the world. Even with today´s technologies, stroke detection and prevention is still a difficult and inaccurate task. In order to improve stroke detection, more knowledge about the physiological systems that stroke affects must be better understood. Much has been done in past studies already on how stroke affects each subsystem, such as blood pressure, cerebral blood flow, and heart rate. However, not much is known about the independence and relations between the cardiovascular subsystems and other physiological mechanisms. The purpose of this study is to approach this problem by using the nonlinear coupling analysis technique to study the independence of blood pressure, cerebral blood flow, and heart rate based on chaotic measures, in order to determine the relationships between these parameters. The linear coupling relation between heart rate and blood pressure is analyzed in time and frequency domain for evaluating baroreflex. 10 healthy controls and 10 stroke outpatients were enrolled in this study. The result indicates that stroke outpatients have a less independent chaoticness of the three subsystems. Cardiac-baroreceptor sensitivity (B RS) decreased significantly in stroke patients (p<;0.05).