Felipe X Cepeda1, Matthew Lapointe2, Can Ozan Tan3, J Andrew Taylor4. 1. Heart Institute (InCor-HCFMUSP) do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil; Cardiovascular Research Laboratory, Spaulding Rehabilitation Hospital, Cambridge, MA, United States. 2. Cardiovascular Research Laboratory, Spaulding Rehabilitation Hospital, Cambridge, MA, United States. 3. Cardiovascular Research Laboratory, Spaulding Rehabilitation Hospital, Cambridge, MA, United States; Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA, United States. 4. Cardiovascular Research Laboratory, Spaulding Rehabilitation Hospital, Cambridge, MA, United States; Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA, United States. Electronic address: jandrew_taylor@hms.harvard.edu.
Abstract
BACKGROUND: Prior work has found that linear heart rate variability (HRV) indices do not accurately reflect cardiac vagal control, and nonlinear indices of HRV have been proposed as alternative tools that may better capture cardiac vagal effects. We used progressive low dose atropine to induce changes in cardiac vagal tone to test the hypotheses that nonlinear HRV indices accurately reflect cardiac vagal control, and that their changes in response to low dose atropine correlate with those in RR interval. METHODS: Changes in RR interval and HRV indices during intravenous injections of saline (control) and 6 cumulative doses of atropine (from 1.4 to 7.2 μg/kg) during controlled breathing at 15 breaths per minute were assessed in 14 young healthy individuals. RESULTS: As expected, low dose atropine increased average RR interval (vagotonic effect). There was no strong association between vagotonic changes in RR interval and the majority of nonlinear HRV indices, either within or among subjects. CONCLUSIONS: These data suggest an inconsistent relationship between responses of nonlinear HRV indices and RR interval to changes in cardiac vagal tone. Therefore, nonlinear HRV indices may not be reliable indices of cardiac vagal control in healthy humans.
BACKGROUND: Prior work has found that linear heart rate variability (HRV) indices do not accurately reflect cardiac vagal control, and nonlinear indices of HRV have been proposed as alternative tools that may better capture cardiac vagal effects. We used progressive low dose atropine to induce changes in cardiac vagal tone to test the hypotheses that nonlinear HRV indices accurately reflect cardiac vagal control, and that their changes in response to low dose atropine correlate with those in RR interval. METHODS: Changes in RR interval and HRV indices during intravenous injections of saline (control) and 6 cumulative doses of atropine (from 1.4 to 7.2 μg/kg) during controlled breathing at 15 breaths per minute were assessed in 14 young healthy individuals. RESULTS: As expected, low dose atropine increased average RR interval (vagotonic effect). There was no strong association between vagotonic changes in RR interval and the majority of nonlinear HRV indices, either within or among subjects. CONCLUSIONS: These data suggest an inconsistent relationship between responses of nonlinear HRV indices and RR interval to changes in cardiac vagal tone. Therefore, nonlinear HRV indices may not be reliable indices of cardiac vagal control in healthy humans.
Authors: Carmen Schiweck; Ali Gholamrezaei; Maxim Hellyn; Thomas Vaessen; Elske Vrieze; Stephan Claes Journal: Front Psychiatry Date: 2022-04-18 Impact factor: 5.435