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 and is related symptoms associated with the occurrence of syncope. It presents as a heterogeneous group of diseases but commonly manifest with symptoms of orthostatic intolerance (OI). This study is focused to quantify the regularity in hemodynamic profile by Shannon Entropy (SE) hemodynamic measures to in older people with symptoms of OI undergoing an active stand and to investigate if their dynamic cardiovascular profile during a six-minute walk would be different to those of controls. The database included a total of 65 participants, aged over 70 years of age, of whom 65% were female. There was no significant differences in age and gender between symptomatic and asymptomatic participants 44.6% (n=29) had symptomatic OI and 55.4% (n=36) did not. SE measurement of HR showed differences during phase 2 in both groups with statistical signification (p=0.03), with 1.73±0.56 in non-symptomatic OI and 2.05±0.62 in symptomatic OI. These differences did not arrive to the statistical signification for the average of diastolic and systolic blood pressure. Moreover, HR entropy measures showed statistical significant differences between phases in the control group with a regularity increase during the physically active phase. The main conclusion is that orthostatic HR regularity response appears impaired during the exercise, especially in the symptomatic OI patients, with more irregular time series during the active phase.