Flávia Cristina Rossi Caruso

Heart rate autonomic responses during deep breathing and walking in hospitalised patients with chronic heart failure

Objective. To evaluate the acute effect of physiotherapy (deep breathing exercises and walking) on heart rate variability in patients hospitalised with chronic heart failure (CHF). Design. Ten males with CHF (57 ± 7 years) and 10 healthy controls (59 ± 9 years) were included. Heart rate and RR intervals were recorded in the following conditions: supine, seated, during deep breathing exercises and during and after walking. Heart rate variability was analysed by linear and non-linear methods (α2, Mean HR, rMSSD, SDNN and ApEn). Results. Patients presented significantly lower SDNN (12.4 ± 4 versus 26 ± 8 ms), rMSSD (18.2 ± 16.2 versus 25 ± 19.5 ms) and ApEn (9.9 ± 10 versus 16.68 ± 22.6) during the walking compared to controls (p < 0.05). In addition, mean HR was significantly higher during and after walking for patients with CHF compared to controls (103 ± 8 versus 80 ± 2 bpm and 90 ± 9 versus 68 ± 2 bpm, respectively). Patients with CHF demonstrated a significant reduction of α2 during deep breathing (0.78 ± 0.1) when compared to the seated position (1.08 ± 0.1) and walking (1.15 ± 0.2, p < 0.05). Additionally, rMSSD index increased during deep breathing when compared to walking in both groups. Conclusion. Deep breathing exercises and walking are safe and promote beneficial effects on heart rate variability in patients hospitalised for CHF.

Hemodynamic, Autonomic, Ventilatory, and Metabolic Alterations After Resistance Training in Patients With Coronary Artery Disease: A Randomized Controlled Trial

Objective The aim of this work was to evaluate the hemodynamic, autonomic, and metabolic responses during resistance and dynamic exercise before and after an 8-week resistance training program using a low-intensity (30% of 1 repetitium maximum), high-repetition (3 sets of 20 repetitions) model, added to an aerobic training program, in a coronary artery disease cohort. Design Twenty male subjects with coronary artery disease (61.1 ± 4.7 years) were randomly assigned to a combined training group (resistance + aerobic) or aerobic training group (AG). Heart rate, stroke volume, cardiac output, minute ventilation, blood lactate, and parasympathetic modulation indices of heart rate (square root of the mean squared differences of successive RR intervals [RMSSD] and dispersion of points perpendicular to the line of identity that provides information about the instantaneous beat-to-beat variability [SD1]) were obtained before and after an 8-week RT program while performing exercise on a cycle ergometer and a 45-degree leg press. Results Resistance training resulted in an increase in maximal and submaximal load tolerance (P < 0.01), a decreased hemodynamic response (P < 0.01), and a reduction in blood lactate in the combined training group compared to the aerobic training group during the 45-degree leg press. During exercise on a cycle ergometer, there was a decreased hemodynamic response and increased minute ventilation (P < 0.01). The 8-week RT program resulted in greater parasympathetic tone (RMSSD and SD1) and an increase in the SDNN index during exercise on a cycle ergometer and 45-degree leg press (P < 0.05). Conclusions An 8-week resistance training program associated with aerobic training may attenuate hemodynamic stress, and modify metabolic and autonomic responses during resistance exercise. The training program also appeared to elicit beneficial cardiovascular and autonomic effects during exercise.

Is heart rate variability a feasible method to determine anaerobic threshold in progressive resistance exercise in coronary artery disease

BACKGROUND Recent studies have shown that the magnitude of the metabolic and autonomic responses during progressive resistance exercise (PRE) is associated with the determination of the anaerobic threshold (AT). AT is an important parameter to determine intensity in dynamic exercise. OBJECTIVES To investigate the metabolic and cardiac autonomic responses during dynamic resistance exercise in patients with Coronary Artery Disease (CAD). METHOD Twenty men (age = 63±7 years) with CAD [Left Ventricular Ejection Fraction (LVEF) = 60±10%] underwent a PRE protocol on a leg press until maximal exertion. The protocol began at 10% of One Repetition Maximum Test (1-RM), with subsequent increases of 10% until maximal exhaustion. Heart Rate Variability (HRV) indices from Poincaré plots (SD1, SD2, SD1/SD2) and time domain (rMSSD and RMSM), and blood lactate were determined at rest and during PRE. RESULTS Significant alterations in HRV and blood lactate were observed starting at 30% of 1-RM (p<0.05). Bland-Altman plots revealed a consistent agreement between blood lactate threshold (LT) and rMSSD threshold (rMSSDT) and between LT and SD1 threshold (SD1T). Relative values of 1-RM in all LT, rMSSDT and SD1T did not differ (29%±5 vs 28%±5 vs 29%±5 Kg, respectively). CONCLUSION HRV during PRE could be a feasible noninvasive method of determining AT in CAD patients to plan intensities during cardiac rehabilitation.ABSTRACT Background Recent studies have shown that the magnitude of the metabolic and autonomic responses during progressive resistance exercise (PRE) is associated with the determination of the anaerobic threshold (AT). AT is an important parameter to determine intensity in dynamic exercise. Objectives To investigate the metabolic and cardiac autonomic responses during dynamic resistance exercise in patients with Coronary Artery Disease (CAD). Method Twenty men (age = 63±7 years) with CAD [Left Ventricular Ejection Fraction (LVEF) = 60±10%] underwent a PRE protocol on a leg press until maximal exertion. The protocol began at 10% of One Repetition Maximum Test (1-RM), with subsequent increases of 10% until maximal exhaustion. Heart Rate Variability (HRV) indices from Poincaré plots (SD1, SD2, SD1/SD2) and time domain (rMSSD and RMSM), and blood lactate were determined at rest and during PRE. Results Significant alterations in HRV and blood lactate were observed starting at 30% of 1-RM (p<0.05). Bland-Altman plots revealed a consistent agreement between blood lactate threshold (LT) and rMSSD threshold (rMSSDT) and between LT and SD1 threshold (SD1T). Relative values of 1-RM in all LT, rMSSDT and SD1T did not differ (29%±5 vs 28%±5 vs 29%±5 Kg, respectively). Conclusion HRV during PRE could be a feasible noninvasive method of determining AT in CAD patients to plan intensities during cardiac rehabilitation.

High-Intensity Inspiratory Protocol Increases Heart Rate Variability in Myocardial Revascularization Patients

Objective: To evaluate heart rate variability during an inspiratory muscle endurance protocol at three different load levels [30%, 60% and 80% of maximal inspiratory pressure], in patients who had previously undergone coronary artery bypass grafting. Methods: Nineteen late postoperative myocardial revascularization patients participating in a cardiovascular rehabilitation program were studied. Maximal inspiratory pressure maneuvers were performed. An inspiratory muscle endurance protocol at 30%, 60% and 80% of maximal inspiratory pressure was applied for four minutes each, in random order. Heart rate and RR intervals were recorded and heart rate variability was analyzed by time (RMSSD-the mean of the standard deviations for all R-R intervals, and RMSM-root-mean square differences of successive R-R intervals) and frequency domains indices (high and low frequency) in normalized units. ANOVA for repeated measurements was used to compare heart rate variability indices and Student t-test was used to compare the maximal inspiratory pressure and maximal expiratory pressure values. Results: Heart rate increased during performance of maximal respiratory pressures maneuvers, and the maximal inspiratory pressure and maximal expiratory pressure mean values were significantly lower than predicted values (P<0.05). RMSSD increased significantly at 80% in relation to rest and 30% of maximal inspiratory pressure and RMSM decreased at 30% and 60% of maximal inspiratory pressure in relation to rest (P<0.05). Additionally, there was significant and progressive decrease in low frequency and increase in high frequency at 30%, 60% and 80% of maximal inspiratory pressure in relation to the resting condition. Conclusion: These results suggest that respiratory muscle training at high intensities can promote greater parasympathetic activity and it may confer important benefits during a rehabilitation program in post-coronary artery bypass grafting.

Poor glycemic control impacts linear and non-linear dynamics of heart rate in DM type 2

INTRODUCAO: E de conhecimento geral que o diabetes mellitus tipo 2 (DM2) produz neuropatia autonomica cardiovascular (NAC), que pode afetar a modulacao autonomica cardiaca. Entretanto, nao e claro se a falta de controle glicemico em diabeticos tipo 2 sem NAC, poderia impactar negativamente na modulacao autonomica cardiaca. Objetivo: Avaliar a relacao entre controle glicemico e modulacao autonomica cardiaca em individuos com DM2 sem neuropatia autonomica cardiovascular. Estudo descritivo, prospectivo e transversal. METODOS: Quarenta e nove pacientes com DM2 (51±7 anos) foram divididos em dois grupos de acordo com a hemoglobina glicosilada (HbA1c): G1: ≤ 7% e G2: >7,0%. A frequencia cardiaca de repouso (FC) e intervalo RR (iRR) foram obtidos e calculados por metodos lineares (media iRR; media FC; rMSSD; STD RR; LF; HF; LF/HF, TINN e RR Tri) e nao lineares (SD1; SD2; DFα1; DFα2, Entropia de Shannon; ApEn; SampEn e CD) de variabilidade de frequencia cardiaca. Insulina, HOMA-IR, glicemia de jejum e HbA1c foram obtidas por analises sanguineas. RESULTADOS: G2 (HbA1c ≤ 7%) mostrou valores menores para media de iRR; STD RR; RR Tri, TINN, SD2, CD e maiores para media de FR quando comparado com G1 (HbA1c > 7%). Adicionalmente, HbA1c correlacionou-se negativamente com media iRR (r=0,28, p=0,044); STD RR (r=0,33, p=0,017); RR Tri (r=-0,35, p=0,013), SD2 (r=-0,39, p=0,004) e positivamente com media FC (r=0,28, p=0,045). Finalmente, a glicemia de jejum correlacionou-se negativamente com STD RR (r=-0,36, p=0,010); RR Tri (r=-0,36, p=0,010); TINN (r=-0,33, p=0,019) e SD2 (r=-0,42, p=0,002). CONCLUSAO: Conclui que o controle glicemico deficiente relaciona-se com indices de modulacao autonomica cardiaca em individuos com DM2, ainda que nao apresentem neuropatia autonomica cardiovascular.INTRODUCCION: Es de conocimiento general que la diabetes mellitus tipo 2 (DM2) produce neuropatia autonomica cardiovascular (NAC), que puede afectar la modulacion autonomica cardiaca. Entretanto, no es claro si la falta de control glucemico en diabeticos tipo 2 sin NAC, podria impactar negativamente en la modulacion autonomica cardiaca. Objetivo: Evaluar la relacion entre control glucemico y modulacion autonomica cardiaca en individuos con DM2 sin neuropatia autonomica cardiovascular. Estudio descriptivo, prospectivo y transversal. METODOS: Cuarenta y nueve pacientes con DM2 (51±7 anos) fueron divididos en dos grupos de acuerdo con la hemoglobina glucosilada (HbA1c): G1: ≤ 7% y G2: >7,0%. La frecuencia cardiaca de reposo (FC) e intervalo RR (iRR) fueron obtenidos y calculados por metodos lineales (promedio iRR; promedio FC; rMSSD; STD RR; LF; HF; LF/HF, TINN y RR Tri) y no lineales (SD1; SD2; DFα1; DFα2, Entropia de Shannon; ApEn; SampEn y CD) de variabilidad de frecuencia cardiaca. Fueron obtenidas insulina, HOMA-IR, glucemia en ayunas y HbA1c a traves de analisis sanguineos. RESULTADOS: G2 (HbA1c ≤ 7%) mostro valores menores para el promedio de iRR; STD RR; RR Tri, TINN, SD2, CD y mayores para el promedio de FR al ser comparado con G1 (HbA1c > 7%). Adicionalmente, HbA1c se correlaciono negativamente con el promedio iRR (r=0,28, p=0,044); STD RR (r=0,33, p=0,017); RR Tri (r=-0,35, p=0,013), SD2 (r=-0,39, p=0,004) y positivamente con el promedio FC (r=0,28, p=0,045). Finalmente, la glucemia en ayunas se correlaciono negativamente con STD RR (r=-0,36, p=0,010); RR Tri (r=-0,36, p=0,010); TINN (r=-0,33, p=0,019) e SD2 (r=-0,42, p=0,002). CONCLUSION: Concluimos que el control glucemico deficiente se relaciona con indices de modulacion autonomica cardiaca en individuos con DM2, aunque no presenten neuropatia autonomica cardiovascular.

Exploring vascular function biomarkers: Implications for rehabilitation

The endothelium plays an important role in maintaining vascular homeostasis and regulating blood vessel function. Endothelial function is considered an independent predictor for risk of future cardiovascular events in cardiovascular and non-cardiovascular patients, as well as a predictor for postoperative complications in cardiovascular surgery patients. Brachial artery flow-mediated dilation by high-resolution ultrasound is widely used to evaluate endothelium-dependent vasodilation, which is mainly mediated by nitric oxide release. Physical exercise exerts beneficial effects on endothelial function and can be used in both primary and secondary prevention of cardiac and peripheral artery diseases, even in the postoperative period of cardiovascular surgery.

Critical load: A novel approach to determining a sustainable intensity during resistance exercise

BACKGROUND A hyperbolic function as well as a linear relationship between power output and time to exhaustion (Tlim) has been consistently observed during dynamic non-resistive exercises. However, little is known about its concept to resistance exercises (RE), which could be defined as critical load (CL). This study aimed to verify the existence of CL during dynamic RE and to verify the number of workbouts necessary to determine the optimal modeling to achieve it. METHODS Fifteen healthy men (23±2.5 yrs) completed 1 repetition maximum test (1RM) on a leg press and 3 (60%, 75% and 90% of 1RM) or 4 (+ 30% of 1RM) workbouts protocols to obtain the CL by hyperbolic and linear regression models between Tlim and load performed. Blood lactate and leg fatigue were also measured. RESULTS CL was obtained during RE and 3 workbouts protocol estimate it at 53% while 4 tests at 38% of 1 RM. However, based on coefficients of determination, 3 protocols provided a better fit than the 4-parameter model, respectively (R2>0.95 vs. >0.77). Moreover, all intensities increased blood lactate and leg fatigue, however, when corrected by Tlim, were significantly lower at CL. CONCLUSIONS It was possible to determinate CL during dynamic lower limbs RE and that 3 exhaustive workbouts can be used to better estimate the CL, constituting a new concept of determining this threshold during dynamic RE and reducing the physically demanding nature of the protocol. These findings may have important applications for functional performance evaluation and prescription of RE programs.

Chronic obstructive pulmonary disease severity and its association with obstructive sleep apnea syndrome: impact on cardiac autonomic modulation and functional capacity

Background The study was conducted to determine the impact of chronic obstructive pulmonary disease (COPD) in association with obstructive sleep apnea syndrome (OSAS) on cardiac autonomic control and functional capacity. Subjects and methods The study was a cross-sectional prospective controlled clinical study. Heart rate variability indices of 24 COPD (n = 12) and COPD+OSAS (n = 12) patients were evaluated and compared by electrocardiographic recordings acquired during rest, active postural maneuver (APM), respiratory sinus arrhythmia maneuver (RSA-m), and the 6-minute walk test (6MWT). Results The COPD group presented higher parasympathetic modulation during APM when compared to the COPD+OSAS group (P = 0.02). The COPD+OSAS group presented higher sympathetic modulation during RSA-m when compared to the COPD group (P = 0.00). The performance during 6MWT was similarly impaired in both groups, despite the greater severity of the COPD group. Conclusion Subjects with COPD+OSAS present marked sympathetic modulation, and the presence of OSAS in COPD subjects has a negative impact on functional capacity regardless of the severity of lung disease.

Flow-mediated dilation and heart failure: a review with implications to physical rehabilitation

Endothelial dysfunction plays as an important role on mismatch responses that occur during exercise in patients with congestive heart failure (CHF). However, cardiac rehabilitation, a core component of management of CHF patients, can improve endothelial function, contributing to reduce the morbidity and mortality of these patients. The primary aims of this review were to describe the importance of flow-mediated dilatation (FMD) as a non-invasive validation tool to assess endothelial dysfunction and to highlight the relevance of scientific studies that evaluated the effects of exercise interventions on peripheral vascular endothelial function as measured by FMD in patients with CHF with both preserved and reduced ejection fraction.

Efeitos da Coexistência de Diabetes Tipo 2 e Hipertensão sobre a Variabilidade da Frequência Cardíaca e Capacidade Cardiorrespiratória

Background Type 2 diabetes Mellitus (T2DM) is associated with cardiac autonomic dysfunction, which is an independent predictor of mortality in chronic diseases. However, whether the coexistence of systemic arterial hypertension (HTN) with DMT2 alters cardiac autonomic modulation remains unknown. Objective To evaluate the influence of HTN on cardiac autonomic modulation and cardiorespiratory fitness in subjects with DMT2. Methods 60 patients of both genders were evaluated and allocated to two groups: DMT2 patients (n = 32; 51 ± 7.5 years old) and DMT2 + HTN patients (n = 28; 51 ± 6.9 years old). RR intervals were obtained during rest in supine position. Linear and nonlinear indices of heart rate variability (HRV) were computed using Kubios HRV software. Pulmonary gas exchange was measured breath-by-breath, using a portable telemetric system during maximal incremental exercise testing on a cycle ergometer. Statistical analysis included Shapiro-Wilk test followed by Student’s t Test, Pearson correlation and linear regression. Results We found that patients in the DMT2+HTN group showed lower values of mean RR intervals (801.1 vs 871.5 ms), Shannon entropy (3 vs 3.2) and fractal dimension SD 1 (9.5 vs 14.5), when contrasted with patients in the DMT2 group. Negative correlations were found between some HRV nonlinear indices and exercise capacity indices. Conclusion HTN negatively affects the cardiac autonomic function in diabetic patients, who are already prone to develop autonomic dysfunction. Strategies are need to improve cardiac autonomic functionality in this population.