ABC | Volume 114, Nº4, April 2020

Original Article Controlled Study of Central Hemodynamic Changes in Inspiratory Exercise with Different Loads in Heart Failure Luana de Decco Marchese, 1, 2 S ergio Chermont, 1,3 Danielle Warol, 1 Lucia Brandão de Oliveira, 2 Sabrina Bernardez Pereira, 4 Mônica Quintão, 1,5 Evandro Tinoco Mesquita 1 Universidade Federal Fluminense, 1 Niterói, RJ – Brazil Centro Universitário Serra dos Órgãos – Clínica de Insuficiência Cardíaca (CLIC), 2 Teresópolis, RJ – Brazil Hospital Santa Martha, 3 Niterói, RJ – Brazil Hospital do Coração, 4 São Paulo, SP – Brazil Instituto Nacional do Câncer, 5 Rio de Janeiro, RJ – Brazil Mailing Address: Luana de Decco Marchese • Centro Universitário Serra dos Órgãos - Av. Delfim Moreira, 2799. Postal Code 25964-000, Vale do Paraíso, Teresópolis, RJ – Brazil E-mail: luana_dmarchese@hotmail.com Manuscript received November 23, 2018, revised manuscript February 05, 2019, accepted June 05, 2019 DOI: https://doi.org/10.36660/abc.20180375 Abstract Background: Inspiratory muscle weakness contributes to exercise intolerance and decreased quality of life in patients with heart failure. Studies with inspiratory muscle training show improvement in inspiratory muscle strength, functional capacity and quality of life. However, little is known about the central hemodynamic response (CHR) during inspiratory exercise (IE). Objective: To evaluate CHR in a single IE session with different loads (placebo, 30% and 60%) in heart failure. Methods: Randomized placebo-controlled clinical trial in patients with heart failure with reduced ejection fraction, functional class II and III. Twenty patients aged 65 ± 11 years completed a single session of inspiratory exercise, in 3 cycles of 15 minutes, with a 1-hour washout, involving loads of 30% (C30), 60% (C60) and placebo, using a linear load resistor (PowerBreathe Light). The noninvasive hemodynamic study was performed by cardiothoracic bioimpedance (Niccomo™ CardioScreen®). Statistical analysis was performed with Student’s t-test and Pearson’s correlation, and P≤0.05 was considered significant. Results: An increase in heart rate (HR) was observed with C30 (64 ± 15 vs 69 ± 15 bpm; p = 0.005) and C60 (67 ± 14 vs 73 ± 14 bpm, p = 0.002). A decrease was observed in systolic volume (SV) with C30 (73 ± 26 vs 64 ± 20 ml; p = 0.004). Cardiac output (CO), on its turn, increased only with C60 (4.6 ± 1.5 vs 5.3 ± 1.7 l/min; p = -0.001). Conclusion: When using the 60% load, in a single IE session, changes in CHR were observed. HR and CD increased, as did the Borg scales and subjective sensation of dyspnea. The 30% load reduced the SV. (Arq Bras Cardiol. 2020; 114(4):656-663) Keywords: Heart Failure; Muscle Weaknerss; Breathing Exercises; Hemodynamics; Fatigue Syndrome, Chronic; Fatigue Syndrome, Chronic; Quality of Life; Exercise Therapy; Exercise Movement Techniques. Introduction Most patients with heart failure (HF) have exercise intolerance, mainly due to symptoms such as dyspnea and fatigue. This low tolerance to physical efforts generates a cycle of physical inactivity and a consequent decrease in quality of life. 1 In addition to other mechanisms previously described such as excessive ventilatory need, exacerbated muscle ergoreflex and increased sympathetic activity, inspiratory muscle weakness, present in approximately 30 to 50% of patients with heart failure with reduced ejection fraction (HFREF), has been identified as a factor that can contribute to exercise intolerance 2,3 and has an independent prognostic value. 4.5 Previous studies have shown that inspiratory muscle training (IMT) results in significant improvements in inspiratory muscle strength, functional capacity, dyspnea and ventilatory response during exercise, besides contributing to the improvement in quality of life of patients with HF. 6,7 However, the ideal training intensity to optimize these results is still unclear. A recent systematic review with meta-analysis suggested that high- intensity IMT is superior to lower loads and does not appear to have any adverse effects. 8 Most studies have focused on demonstrating the systemic benefits of IMT, but little is known about the central hemodynamic response (CHR) of these patients during inspiratory exercise (IE). 9 The hypothesis of the present study is that, with higher loads, greater hemodynamic repercussions 656