Analytic and Holistic Thinkers: Differences in the Dynamics of Heart Rate Complexity When Solving a Cognitive Task in Field-Dependent and Field-Independent Conditions

Analytic and holistic thinking styles are known to be associated with individual differences in various aspects of behavior and brain activity. In this study, we tested a hypothesis that differences in thinking styles may also be manifested at the level of neuro-visceral coordination. Heart rate variability (HRV) was compared between analytic and holistic thinkers at rest, during a simple motor choice reaction time task and when solving cognitive choice reaction time tasks in conditions with varying instructions contrasting the role of the field when evaluating objects. Participants (N = 52) with analytic and holistic thinking styles were equally successful at solving the cognitive tasks but response times were longer in the analytic group, compared to the holistic group. Heart rate complexity, as measured by sample entropy, was higher in the analytic group during the cognitive tasks but did not differ from the holistic group at rest or during the simple motor task. Analytic participants had longer response times and higher heart rate complexity when evaluating objects in relation to the field than when evaluating objects irrespective to the field. No difference in response times or heart rate complexity between tasks was observed in the holistic group. Our findings demonstrate that differences in individual behavior, including those related to holistic and analytic thinking styles, can be reflected not only in brain activity, as shown previously using fMRI and EEG methods, but also at the level of neuro-visceral coordination, as manifested in heart rate complexity.

Cardiac Autonomic Dysfunction and Incidence of de novo Atrial Fibrillation: Heart Rate Variability vs. Heart Rate Complexity

BackgroundThe REACT DX registry evaluates standard therapies to episodes of long-lasting atrial tachyarrhythmias and assesses the quality of sensing and stability of the lead and the implantable cardioverter-defibrillator (ICD) (BIOTRONIK Lumax VR-T DX and successors) over at least a 1-year follow-up period.ObjectiveTo study the association between the risk of de novo device-detected atrial fibrillation (AF), the autonomic perturbations before the onset of paroxysmal AF and a 7-days heart rate variability (7dHRV) 1 month after ICD implantation.MethodsThe registry consists of 234 patients implanted with an ICD, including 10 with de novo long-lasting atrial tachyarrhythmias with no prior history of AF. The patients were matched via the propensity-score methodology as well as for properties directly influencing the ECGs recorded using GE CardioMem CM 3000. Heart rate variability (HRV) analysis was performed using standard parameters from time- and frequency-domains, and from non-linear dynamics.ResultsNo linear HRV was associated with an increased risk of AF (p = n.s.). The only significant approach was derived from symbolic dynamics with the parameter “forbidden words” which distinguished both groups on all 7 days of measurements (p < 0.05), thereby quantifying the heart rate complexity (HRC) as drastically lower in the de novo AF group.ConclusionCardiac autonomic dysfunction denoted by low HRC may be associated with higher AF incidence. For patients with mild to moderate heart failure, standard HRV parameters are not appropriate to quantify cardiac autonomic perturbations before the onset of AF. Further studies are needed to determine the individual risk for AF that would enable interventions to restore autonomic balance in the general population.

Heart Rate Complexity in US Army Forward Surgical Teams During Pre Deployment Training

Introduction For trauma triage, the US Army has developed a portable heart rate complexity (HRC) monitor, which estimates cardiac autonomic input and the activity of the hypothalamic-pituitary-adrenal (HPA) axis. We hypothesize that autonomic/HPA stress associated with predeployment training in U.S. Army Forward Surgical Teams will cause changes in HRC. Materials and Methods A prospective observational study was conducted in 80 soldiers and 10 civilians at the U.S. Army Trauma Training Detachment. Heart rate (HR, b/min), cardiac output (CO, L/min), HR variability (HRV, ms), and HRC (Sample Entropy, unitless), were measured using a portable non-invasive hemodynamic monitor during postural changes, a mass casualty (MASCAL) situational training exercise (STX) using live tissue, a mock trauma (MT) STX using moulaged humans, and/or physical exercise. Results Baseline HR, CO, HRV, and HRC averaged 72 ± 11b/min, 5.6 ± 1.2 L/min, 48 ± 24 ms, and 1.9 ± 0.5 (unitless), respectively. Supine to sitting to standing caused minimal changes. Before the MASCAL or MT, HR and CO both increased to ~125% baseline, whereas HRV and HRC both decreased to ~75% baseline. Those values all changed an additional ~5% during the MASCAL, but an additional 10 to 30% during the MT. With physical exercise, HR and CO increased to >200% baseline, while HRV and HRC both decreased to 40 to 60% baseline; these changes were comparable to those caused by the MT. All the changes were P < 0.05. Conclusions Various forms of HPA stress during Forward Surgical Team STXs can be objectively quantitated continuously in real time with a portable non-invasive monitor. Differences from resting baseline indicate stress anticipating an impending STX whereas differences between average and peak responses indicate the relative stress between STXs. Monitoring HRC could prove useful to field commanders to rapidly and objectively assess the readiness status of troops during STXs or repeated operational missions. In the future, health care systems and regulatory bodies will likely be held accountable for stress in their trainees and/or obliged to develop wellness options and standardize efforts to ameliorate burnout, so HRC metrics might have a role, as well.

Exercise-Induced Changes in Compensatory Reserve and Heart Rate Complexity

BACKGROUND: Portable noninvasive Heart Rate Complexity (HRC) and Compensatory Reserve Measurement (CRM) monitors have been developed to triage supine combat casualties. Neither monitor has been tested in upright individuals during physical exercise. This study tests the hypothesis that exercise evokes proportional changes in HRC and CRM.METHODS: Two instruments monitored volunteers (9 civilian and 11 soldiers) from the Army Trauma Training Department (ATTD) before, during, and following physical exercise. One recorded heart rate (HR, bpm), cardiac output (CO, L · min−1), heart rate variability (HRV, root mean square of successive differences, ms), and HRC (Sample Entropy, unitless). The other recorded HR, pulse oximetry (Spo2, %), and CRM (%).RESULTS: Baseline HR, CO, HRV, HRC, and CRM averaged 72 ± 1 bpm, 5.6 ± 1.2 L · min−1, 48 ± 24 ms, 1.9 ± 0.5, and 85 ± 10% in seated individuals. Exercise evoked peak HR and CO at > 200% of baseline, while HRC and CRM were simultaneously decreased to minimums that were ≤ 50% of baseline (all P < 0.001). HRV changes were variable and unreliable. Spo2 remained consistently above 95%. During a 60 min recovery, HR and CRM returned to baseline on parallel tracks (t1/2=11 ± 8 and 18 ± 14 min), whereas HRC recovery was slower than either CRM or HR (t1/2=40 ± 18 min, both P < 0.05).DISCUSSION: Exercise evoked qualitatively similar changes in CRM and HRC. CRM recovered incrementally faster than HRC, suggesting that vasodilation, muscle pump, and respiration compensate faster than cardiac autonomic control in young, healthy volunteers. Both HRC and CRM appear to provide reliable, objective, and noninvasive metrics of human performance in upright exercising individuals.Mulder MB, Eidelson SA, Buzzelli MD, Gross KR, Batchinsky AI, Convertino VA, Schulman CI, Namias N, Proctor KG. Exercise-induced changes in compensatory reserve and heart rate complexity. Aerosp Med Hum Perform. 2019; 90(12):1009–1015.