IJCS | Volume 33, Nº1, January / February 2019

DOI: 10.5935/2359-4802.20190072 Introduction Cardiac autonomic modulation (CAM) is essential for the preservation of heart function according to metabolic needs, contributing to the maintenance of internal stable conditions. 1,2 Time variation between heart beats is considered normal and is related to greater or lesser activation of sympathetic and parasympathetic systems in response to central and peripheral stimuli. 3-5 Among the events that may interfere with the physiological oscillations of the heart rate (HR), the most prominent are those originating from respiration. 6,7 Therefore, any disease that may impair breathing in some way, such as chronic obstructive pulmonary disease (COPD), tend to interfere with cardiovascular mechanisms 8-10 by affecting the RR intervals (RRi) of the cardiac cycle and, consequently, the CAM. 5,8,11,12 Changes in the CAMcan be detected and quantified by analysis of the heart rate variability (HRV). In studies on spontaneous breathing in patients with COPD, however, HRV analysis has yielded conflicting results. 11-13 Part of this controversy may be due to the use of certain 79 ORIGINAL ARTICLE International Journal of Cardiovascular Sciences. 2020;33(1):79-86 Mailing Address: Mario Paschoal Av. John Boyd Dunlop, s/n. Postal Code: 13060-904, Campus II, Campinas, São Paulo, SP - Brazil. E-mail: mapascka@gmail.com Cardiac Autonomic Modulation of Healthy Individuals and Patients with Chronic Obstructive Pulmonary Disease During Spontaneous and Controlled Breathing Mario Augusto Paschoal, 1 L ivea Gianfrancesco, 1 Luisa Torres Camargo, 1 N áira Bueno Seixas, 1 Ana Beatriz Paschoal 2 Pontifícia Universidade Católica de Campinas, 1 São Paulo, SP - Brazil Faculdade de Ciências Médicas da Santa Casa de São Paulo, 2 SP - Brazil Manuscript received on August 21, 2018; reviewed on January 29,2019; accepted on March 08,2019. Abstract Background: Lung diseases and different forms of breathing may interfere with cardiac autonomic modulation (CAM). Objective: To compare CAM in individuals with chronic obstructive pulmonary disease (COPD) with healthy individuals during spontaneous breathing (SB) and controlled breathing (CB). Methods: Cross-sectional study involving 30 individuals selected by convenience, divided into COPD group (n = 19) and control group (CG; n = 12). All participants were submitted to heart beat recordings during five minutes at rest (SB) and another five minutes during CB performed at six cycles/min. CAM was made by assessment of the heart rate variability (HRV) through time domain (TD) and frequency domain (FD). Comparisons between groups were performed by Mann Whitney test, and significance level was set at p < 0.05. Results: During SB, HRV TD and FD indices were higher in the controls than in the COPD group, respectively – RR intervals (53.2 ms versus 36.6 ms), RMSSD (42.1 ms versus 26.6 ms) (p < 0.05), total power (28322.8 ms²/Hz versus 2011.6 ms²/Hz), and high-frequency band (800.5 ms 2 versus 330.7 ms²). During CB, the CG also showed higher values for the TD parameters pNN50 (11.7% versus 5.1%), RMSSD (48.3 ms versus 26.7 ms), and SD of RRi (64.9 ms versus 44.7 ms), as well as for the low-frequency component of FD analysis (2848.6 ms² versus 1197.9 ms²). Conclusion: COPD patients have different CAM when compared with healthy individuals during spontaneous (SB) and controlled breathing (CB). (Int J Cardiovasc Sci. 2020;33(1):79-86) Keywords: Autonomic Nervous System; Heart Rate; Respiratory Rate.