Multiscale Entropy Analysis of Heart Rate Regularity Changes in Older People with Orthostatic Intolerance

Orthostatic hypotension (OH) is an excessive fall in blood pressure when an upright position is assumed. It is related symptoms associated with the occurrence of syncope. It presents as a heterogeneous group of diseases but commonly is manifested itself as symptoms of orthostatic intolerance (OI). Heart Rate (HR) variability is the output of multiple physiologic control mechanisms that operate over a wide range of time scales. This study is focused to quantify the regularity changes in the HR dynamics in different time scales by Multiscale entropy (MSE) measures in older people, with and without symptoms of OI. We analyzed 65 elderly people. There was no significant differences in age and gender between symptomatic and asymptomatic OI participants, 44.6% (n=29) had symptoms of OI and 55.4% (n=36) did not. The main differences were observed in the ascent phase and descent phase between symptomatic and asymptomatic OI patients. In both cases, the symptomatic OI group presents higher levels of entropy in all time scales. Moreover, it is possible to observe that male group showed higher differences between symptomatic and asymptomatic OI participants than female group. The main conclusion is that the MSE features capture differences in heart rate regularity providing hemodynamic changes that occur in symptomatic OI patients.