Maladaptive Cardiac Autonomic Control during a Stress Reactivity Assessment Among Primary Care Patients with Metabolic Syndrome

Abstract

Metabolic syndrome (MetS) comprises a constellation of metabolic abnormalities that substantially increase risk for chronic illnesses. Autonomic dysregulation is closely linked to MetS, and while pathophysiological models often address chronic stress exposure, none have examined how such physiological contributions operate situationally, in a clinical setting. We used ambulatory impedance cardiography to examine indicators of cardiac autonomic control (CAC) in a sample of 50 adult primary care patients with and without MetS. Indices of independent sympathetic and parasympathetic cardiovascular control in primary care outpatients were measured during a brief stress reactivity assessment. We compared interdependent CAC features, including cardiac autonomic balance (i.e., sympathovagal reciprocity) and cardiac autonomic regulation (i.e., sympathovagal coactivation) and found significant differences among MetS participants as compared to healthy controls. In particular, cardiac autonomic regulation scores were higher among MetS patients when discussing medication concerns, and cardiac autonomic balance scores were lower among MetS patients when discussing daily stressors. These results suggest that patients meeting criteria for MetS demonstrate momentary variations in CAC depending on personally relevant health topics. The potential for future research is discussed with a focus on prospective data collection to enhance diagnostic procedures and treatment monitoring.

A Close Examination of the Use of Systolic Time Intervals in the Calculation of Impedance Derived Cardiac Autonomic Balance and Regulation

“…Autonomic nervous system imbalance, or an increase in sympathetic activity coupled with a decrease in parasympathetic activity, has been associated with poorer physiological health outcomes including metabolic abnormalities (Licht et al, 2013) and cardiovascular disease risk factors (i.e., hypertension, diabetes) (Thayer et al, 2010b), as well as worse psychological outcomes, including anxiety (Friedman and Thayer, 1998), depression (Stone et al, 2020), and increased levels of daily stress (Mitchell et al, 2017). Due to its importance in health research, there have been several attempts to accurately measure cardiac autonomic balance and regulation over the years using various physiological measures.…”

“…CAB and CAR can be calculated using indices of parasympathetically mediated HRV (e.g., the root mean square of successive differences [RMSSD], HF-HRV) and impedance derived systolic time intervals (i.e., pre-ejection period [PEP]) as an index of sympathetic activity (Berntson et al, 2008;Williams et al, 2017). Both CAB and CAR have been used as indices of autonomic balance and activity in a myriad of studies, showing associations with affective responses (Kreibig et al, 2012), psychopathologies (Bylsma et al, 2015;Stone et al, 2020), stress (Gump et al, 2011;Mitchell et al, 2017), inflammatory markers (Singh et al, 2009;Alen et al, 2020), and physiological health (Berntson et al, 2008;Vrijkotte et al, 2015). For example, a history of myocardial infarctions and type 2 diabetes diagnoses are more likely to be linked to low levels of CAR and CAB, respectively (Berntson et al, 2008), while lower CAB has also been shown to be associated with increased levels of inflammatory cytokines such as interleukin-6 and tumor necrosis factor alpha (Alen et al, 2020).…”

Multilevel analysis: Integrating multiple levels of neurobehavioral systems

“…As in the retrospective cases, these subjects had lower CAR scores prior to the MI, indicating that low CAR may be a prospective predictor as well. Subsequent work has supported the view that patterns of CAR and CAB, beyond simply the individual metrics of sympathetic and parasympathetic control, may be predicting of metabolic and cardiovascular disease (Licht et al, 2010(Licht et al, , 2013Mitchell et al, 2017). These results suggest that distinct patterns of autonomic control may be associated with distinct health dimensions.…”

RZ Interval as an Impedance Cardiography Indicator of Effort-Related Cardiac Sympathetic Activity

“…Finally, the present experiments are limited to a particular population and paradigm: seated young women in good cardiac health working on a mental effort task for cash rewards. It would be valuable to compare PEP and RZ in other contexts where sympathetic cardiac activity is commonly assessed, such as paradigms using physical exercise, pharmacological blockades, and mental and physical stressors (e.g., Lackner et al, 2015;Meyer et al, 2016;Mitchell et al, 2017). To date, there's some evidence that RZ's similarity to PEP is general beyond mental effort, such as physical exertion (van Eijnatten et al, 2014;Wilde et al, 1981), Valsalva maneuvers (Meijer et al, 2010), and dobutamine infusion (van der Meer et al, 1999).…”