Non‐invasive monitoring of cardiac contractility: Trans‐radial electrical bioimpedance velocimetry (TREV)

• Published in: Psychophysiology 2024-01, Vol.61 (1), p.e14411-n/a
• Main Authors: Stump, Alexandra, Gregory, Caitlin, Babenko, Viktoriya, Rizor, Elizabeth, Bullock, Tom, Macy, Alan, Giesbrecht, Barry, Grafton, Scott T., Dundon, Neil M.
• Format: Article
• Language: English
• Subjects: allostasis; analysis/statistical methods < methods; autonomic < methods; cardiovascular < methods; Computers; effort and mobilization; Grasping; Heart rate; Measurement techniques; motor control < content/topics; Muscle contraction; Psychophysics; Software; stress; unconscious processes < content/topics; young adults < groups studied
• ISSN: 0048-5772; 1469-8986; 1540-5958
• DOI: 10.1111/psyp.14411

We describe methods and software resources for a bioimpedance measurement technique, ‘trans‐radial electrical bioimpedance velocimetry’ (TREV) that allows for the non‐invasive monitoring of relative cardiac contractility and stroke volume. After reviewing the relationship between the measurement and cardiac contractility, we describe the general recording methodology, which requires impedance measurements of the forearm. We provide open‐source Jupyter‐based software (operable on most computers) for deriving cardiac contractility from the impedance measurements. The software includes tools for removing variance associated with heart rate and respiration. We demonstrate the ability of this bioimpedance measurement for tracking beat‐to‐beat changes of contractility in a maximal grip force production task. Critically, the results demonstrate both a reactive increase in contractility with force production, and suggest there is a learned increase in contractility prior to grip onset, consistent with anticipatory allostatic autonomic regulation mediated by sympathetic inotropy. The method and software should be of broad utility for investigations of event‐related cardiac dynamics in psychophysical studies. Our novel bioimpedance measurement technique, trans‐radial bioimpedance velocimetry (TREV) and open‐source analysis software provides a simplified approach to reliably capture perturbations of cardiac contractility. TREV electrode recordings of impedance along the forearm can be used to quantify peak flow acceleration after aortic valve opening, an indicator of contractility. When heart rate and respiration influences are accounted for, the relative changes in contractility are indicative of sympathetic inotropy. The method is demonstrated in an isometric force task, where there is evidence of sympathetic associated effort mobilization prior to grip onset. We provide software operable on most computers to analyse TREV time series.