Multiscale Entropy Analysis of Blood Pressure Variability in Dahl Salt-sensitive Rats

The blood pressure variability (BPV) is considered a physiological indicator of the autonomic nervous system and may be related to the increased cardiovascular risk in hypertensive patients. We performed BPV analysis on the systolic blood pressure sequence and diastolic blood pressure sequence of 9 salt-sensitive (SS) rats and 6 salt-protected rats on both high-salt and low-salt diets. We use standard deviation (SD), coefficient of variation (CV), average real variability (ARV), and mainly multi-scale entropy (MSE) analysis to measure BPV in rats quantitatively. Results of the traditional time-domain indexes (SD, CV, and ARV) have little difference under different rats and diets. Meanwhile, MSE analysis show that salt intake will affect the dynamics of blood pressure in rats, and the effect on SS rats is more prominent. There was no significant difference in BPV between the two rats under the low-salt diet, indicating that the low-salt diet helps regulate blood pressure and cardiovascular system. Our results also verified that MSE analysis could be a new method to explain BPV in salt-sensitive hypertension patients.