Effect of Hyperventilation on Periodic Repolarization Dynamics.

Dominik Schüttler,Konstantinos D Rizas,Lukas Von Stülpnagel,Wolfgang Hamm,Stefan Brunner,Axel Bauer

doi:10.3389/fphys.2020.542183

Abstract

Heart and lung functions are closely connected, and the interaction is mediated by the autonomic nervous system. Hyperventilation has been demonstrated to especially activate its sympathetic branch. However, there is still a lack of methods to assess autonomic activity within this cardiorespiratory coupling. Periodic repolarization dynamics (PRD) is an ECG-based biomarker mirroring the effect of efferent cardiac sympathetic activity on the ventricular myocardium. Its calculation is based on beat-to-beat variations of the T wave vector (dT°). In the present study, we investigated the effects of a standardized hyperventilation maneuver on changes of PRD and its underlying dT° signal in 11 healthy subjects. In response to hyperventilation, dT° revealed a characteristic pattern and normalized dT° values increased significantly compared to baseline [0.063 (IQR 0.032) vs. 0.376 (IQR 0.093), p < 0.001] and recovery [0.082 (IQR 0.029) vs. 0.376 (IQR 0.093), p < 0.001]. During recovery, dT° remained on a higher level compared to baseline (p = 0.019). When calculating PRD, we found significantly increased PRD values after hyperventilation compared to baseline [3.30 (IQR 2.29) deg2 vs. 2.76 (IQR 1.43) deg2, p = 0.018]. Linear regression analysis revealed that the increase in PRD level was independent of heart rate (p = 0.63). Our pilot data provide further insights in the effect of hyperventilation on sympathetic activity associated repolarization instability.

Highlights

Our breathing and heart rate as well as heart function are linked and controlled by the autonomic nervous system. This close connection has been described earlier with heart rates slowing during expiration and a relative tachycardia evolving during inspiration due to vagolytic effects, the so called respiratory sinus arrhythmia (RSA; Yasuma and Hayano, 2004)
During hyperventilation, normalized dT° signals significantly increased compared to baseline [0.376 (IQR 0.093) vs. 0.063 (IQR 0.032), p < 0.001] and recovery [0.376 (IQR 0.093) vs. 0.082 (IQR 0.029), p < 0.001]
We detected significantly increased values of Periodic repolarization dynamics (PRD) after hyperventilation compared to baseline levels [3.30 (IQR 2.29) deg2 vs. 2.76 (IQR 1.43) deg2; p = 0.018; Figure 3]

Summary

Introduction

Our breathing and heart rate as well as heart function are linked and controlled by the autonomic nervous system. This close connection has been described earlier with heart rates slowing during expiration and a relative tachycardia evolving during inspiration due to vagolytic effects, the so called respiratory sinus arrhythmia (RSA; Yasuma and Hayano, 2004). It is hypothesized that the RSA facilitates efficient respiratory gas exchanges and decreases the workload of the heart while maintaining blood gases in physiological levels (Ben-Tal et al, 2012). Breathing disorders and pulmonary diseases are tightly linked to autonomic dysfunction (van Gestel and Steier, 2010; Milagro et al, 2019). It has been demonstrated that the maintenance of correct cardiorespiratory coupling exerts beneficial cardiovascular effects in patients with an attenuated RSA (Ben-Tal et al, 2012)

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Results

Conclusion