Physical capacity increase in patients with heart failure is associated with improvement in muscle sympathetic nerve activity.

BACKGROUND: Exercise training improves physical capacity in patients with heart failure with reduced ejection fraction (HFrEF), but the mechanisms involved in this response is not fully understood. The aim of this study was to determine if physical capacity increase in patients HFrEF is associated with muscle sympathetic nerve activity (MSNA) reduction and muscle blood flow (MBF) increase. METHODS: The study included 124 patients from a 17-year database, divided according to exercise training status: 1) exercise-trained (ET, n = 83) and 2) untrained (UNT, n = 41). MSNA and MBF were obtained using microneurography and venous occlusion plethysmography, respectively. Physical capacity was evaluated by cardiopulmonary exercise test. Moderate aerobic exercise was performed 3 times/wk. for 4 months. RESULTS: Exercise training increased peak oxygen consumption (V̇O2, 16.1 ± 0.4 vs 18.9 ± 0.5 mL·kg-1·min-1, P < 0.001), LVEF (28 ± 1 vs 30 ± 1%, P = 0.027), MBF (1.57 ± 0.06 vs 2.05 ± 0.09 mL.min-1.100 ml-1, P < 0.001) and muscle vascular conductance (MVC, 1.82 ± 0.07 vs 2.45 ± 0.11 units, P < 0.001). Exercise training significantly decreased MSNA (45 ± 1 vs 32 ± 1 bursts/min, P < 0.001). The logistic regression analyses showed that MSNA [(OR) 0.921, 95% CI 0.883-0.962, P < 0.001] was independently associated with peak V̇O2. CONCLUSIONS: The increase in physical capacity provoked by aerobic exercise in patients with HFrEF is associated with the improvement in MSNA.

Exaggerated Exercise Blood Pressure as a Marker of Baroreflex Dysfunction in Normotensive Metabolic Syndrome Patients.

INTRODUCTION: Exaggerated blood pressure response to exercise (EEBP = SBP ≥ 190 mmHg for women and ≥210 mmHg for men) during cardiopulmonary exercise test (CPET) is a predictor of cardiovascular risk. Sympathetic hyperactivation and decreased baroreflex sensitivity (BRS) seem to be involved in the progression of metabolic syndrome (MetS) to cardiovascular disease. OBJECTIVE: To test the hypotheses: (1) MetS patients within normal clinical blood pressure (BP) may present EEBP response to maximal exercise and (2) increased muscle sympathetic nerve activity (MSNA) and reduced BRS are associated with this impairment. METHODS: We selected MetS (ATP III) patients with normal BP (MetS_NT, n = 27, 59.3% males, 46.1 ± 7.2 years) and a control group without MetS (C, n = 19, 48.4 ± 7.4 years). We evaluated BRS for increases (BRS+) and decreases (BRS-) in spontaneous BP and HR fluctuations, MSNA (microneurography), BP from ambulatory blood pressure monitoring (ABPM), and auscultatory BP during CPET. RESULTS: Normotensive MetS (MetS_NT) had higher body mass index and impairment in all MetS risk factors when compared to the C group. MetS_NT had higher peak systolic BP (SBP) (195 ± 17 vs. 177 ± 24 mmHg, P = 0.007) and diastolic BP (91 ± 11 vs. 79 ± 10 mmHg, P = 0.001) during CPET than C. Additionally, we found that MetS patients with normal BP had lower spontaneous BRS- (9.6 ± 3.3 vs. 12.2 ± 4.9 ms/mmHg, P = 0.044) and higher levels of MSNA (29 ± 6 vs. 18 ± 4 bursts/min, P < 0.001) compared to C. Interestingly, 10 out of 27 MetS_NT (37%) showed EEBP (MetS_NT+), whereas 2 out of 19 C (10.5%) presented (P = 0.044). The subgroup of MetS_NT with EEBP (MetS_NT+, n = 10) had similar MSNA (P = 0.437), but lower BRS+ (P = 0.039) and BRS- (P = 0.039) compared with the subgroup without EEBP (MetS_NT-, n = 17). Either office BP or BP from ABPM was similar between subgroups MetS_NT+ and MetS_NT-, regardless of EEBP response. In the MetS_NT+ subgroup, there was an association of peak SBP with BRS- (R = -0.70; P = 0.02), triglycerides with peak SBP during CPET (R = 0.66; P = 0.039), and of triglycerides with BRS- (R = 0.71; P = 0.022). CONCLUSION: Normotensive MetS patients already presented higher peak systolic and diastolic BP during maximal exercise, in addition to sympathetic hyperactivation and decreased baroreflex sensitivity. The EEBP in MetS_NT with apparent well-controlled BP may indicate a potential depressed neural baroreflex function, predisposing these patients to increased cardiovascular risk.

Effect of exercise training on cardiovascular autonomic and muscular function in subclinical Chagas cardiomyopathy: a randomized controlled trial.

PURPOSE: Patients with chronic chagasic cardiomyopathy with preserved ventricular function present with autonomic imbalance. This study evaluated the effects of exercise training (ET) in restoring peripheral and cardiac autonomic control and skeletal muscle phenotype in patients with subclinical chronic chagasic cardiomyopathy. METHODS: This controlled trial (NCT02295215) included 24 chronic chagasic cardiomyopathy patients who were randomized www.random.org/lists/ into two groups: those who underwent exercise training (n = 12) and those who continued their usual activities (n = 12). Eight patients completed the exercise training protocol, and 10 patients were clinically followed up for 4 months. Muscular sympathetic nerve activity was measured by microneurography and muscle blood flow (MBF) using venous occlusion plethysmography. The low-frequency component of heart rate variability in normalized units (LFnuHR) reflects sympathetic activity in the heart, and the low-frequency component of systolic blood pressure variability in normalized units reflects sympathetic activity in the vessels. The infusion of vasoactive drugs (phenylephrine and sodium nitroprusside) was used to evaluate cardiac baroreflex sensitivity, and a vastus lateralis muscle biopsy was performed to evaluate atrogin-1 and MuRF-1 gene expression. RESULTS: The baroreflex sensitivity for increases (p = 0.002) and decreases (p = 0.02) in systolic blood pressure increased in the ET group. Muscle blood flow also increased only in the ET group (p = 0.004). Only the ET group had reduced resting muscular sympathetic nerve activity levels (p = 0.008) and sympathetic activity in the heart (LFnu; p = 0.004) and vessels (p = 0.04) after 4 months. Regarding skeletal muscle, after 4 months, participants in the exercise training group presented with lower atrogin-1 gene expression than participants who continued their activities as usual (p = 0.001). The reduction in muscular sympathetic nerve activity was positively associated with reduced atrogin-1 (r = 0.86; p = 0.02) and MuRF-1 gene expression (r = 0.64; p = 0.06); it was negatively associated with improved baroreflex sensitivity both for increases (r = -0.72; p = 0.020) and decreases (r = -0.82; p = 0.001) in blood pressure. CONCLUSIONS: ET improved cardiac and peripheral autonomic function in patients with subclinical chagasic cardiomyopathy. ET reduced MSNA and sympathetic activity in the heart and vessels and increased cardiac parasympathetic tone and baroreflex sensitivity. Regarding peripheral muscle, after 4 months, patients who underwent exercise training had an increased cross-sectional area of type I fibers and oxidative metabolism of muscle fibers, and decreased atrogin-1 gene expression, compared to participants who continued their activities as usual. In addition, the reduction in MSNA was associated with improved cardiac baroreflex sensitivity, reduced sympathetic cardiovascular tone, and reduced atrogin-1 and MuRF-1 gene expression. TRIAL REGISTRATION: ID: NCT02295215. Registered in June 2013.

Exercise Rehabilitation Improves Cardiac Volumes and Functional Capacity in Patients With Endomyocardial Fibrosis: A RANDOMIZED CONTROLLED TRIAL.

PURPOSE: Endomyocardial fibrosis (EMF) is a restrictive cardiomyopathy associated with low functional capacity and high mortality rates. Exercise training has been proved to be a nonpharmacological treatment of cardiovascular diseases. Therefore, the purpose of this study was to determine the effects of exercise rehabilitation in EMF patients. METHODS: Twenty-two EMF patients, functional classes II and III (New York Heart Association [NYHA]), were randomized to the control (C-EMF) or exercise rehabilitation (Rehab-EMF) group. Patients in the Rehab-EMF group underwent 4 mo of exercise rehabilitation, whereas patients in the C-EMF group were instructed to maintain their usual daily routine. Peak oxygen uptake ((Equation is included in full-text article.)O2), cardiac function, and quality of life were evaluated. All assessments were performed at baseline and after 4 mo. RESULTS: After 4 mo of rehabilitation, peak (Equation is included in full-text article.)O2 increased in the Rehab-EMF group (17.4 ± 3.0 to 19.7 ± 4.4 mL/kg/min, P < .001), whereas the C-EMF group showed no difference (15.3 ± 3.0 to 15.0 ± 2.0 mL/kg/min, P = .87). Also, post-intervention, peak (Equation is included in full-text article.)O2 in the Rehab-EMF group was greater than that in the C-EMF group (P < .001). Furthermore, the Rehab-EMF group, when compared to the C-EMF group, showed an increase in left ventricular end-diastolic volume (102.1 ± 64.6 to 136.2 ± 75.8 mL vs 114.4 ± 55.0 to 100.4 ± 49.9 mL, P < .001, respectively) and decrease in left atrial diastolic volume (69.0 ± 33.0 to 34.9 ± 15.0 mL vs 44.6 ± 21.0 to 45.6 ± 23.0 mL, P < .001, respectively). Quality-of-life scores also improved in the Rehab-EMF group, whereas the C-EMF group showed no change (45 ± 23 to 27 ± 15 vs 47 ± 15 to 45 ± 17, P < .001, respectively). CONCLUSION: Exercise rehabilitation is a nonpharmacological intervention that improves functional capacity, cardiac volumes, and quality of life in EMF patients after endocardial resection surgery. In addition, exercise rehabilitation should be prescribed to EMF patients to improve their clinical condition.

Characterization of Cardiopulmonary Exercise Testing Variables in Patients with Endomyocardial Fibrosis after Endocardial Resection / Caracterização das Variáveis do Teste de Esforço Cardiopulmonar em Pacientes com Endomiocardiofibrose após Cirurgia de Ressecção Endocárdica

Abstract Background: Endomyocardial fibrosis (EMF) is a rare disease, characterized by diastolic dysfunction which leads to reduced peak oxygen consumption (VO2). Cardiopulmonary exercise testing (CPET) has been proved to be a fundamental tool to identify central and peripheral alterations. However, most studies prioritize peak VO2 as the main variable, leaving aside other important CPET variables that can specify the severity of the disease and guide the clinical treatment. Objective: The aim of this study was to evaluate central and peripheral limitations in symptomatic patients with EMF by different CPET variables. Methods: Twenty-six EMF patients (functional class III, NYHA) were compared with 15 healthy subjects (HS). Functional capacity was evaluated using CPET and diastolic and systolic functions were evaluated by echocardiography. Results: Age and gender were similar between EMF patients and HS. Left ventricular ejection fraction was normal in EMF patients, but decreased compared to HS. Peak heart rate, peak workload, peak VO2, peak oxygen (O2) pulse and peak pulmonary ventilation (VE) were decreased in EMF compared to HS. Also, EMF patients showed increased Δ heart rate /Δ oxygen uptake and Δ oxygen uptake /Δ work rate compared to HS. Conclusion: Determination of the aerobic capacity by noninvasive respiratory gas exchange during incremental exercise provides additional information about the exercise tolerance in patients with EMF. The analysis of different CPET variables is necessary to help us understand more about the central and peripheral alterations cause by both diastolic dysfunction and restrictive pattern.

Resumo Fundamento: A endomiocardiofibrose (EMF) é uma doença rara, caracterizada por disfunção diastólica que leva à redução consumo de oxigênio (VO2) pico. O teste de esforço cardiopulmonar (TECP) tem se mostrado uma ferramenta fundamental na identificação de alterações centrais e periféricas. No entanto, a maioria dos estudos prioriza o VO2 pico como a variável principal, em detrimento de outras importantes variáveis do TECP que poderiam identificar a gravidade da doença e direcionar o tratamento clínico. Objetivo: O objetivo deste estudo foi avaliar limitações centrais e periféricas em pacientes com EMF sintomáticos por meio de variáveis do TECP. Métodos: Vinte e seis pacientes com EMF (classe funcional III, NYHA) foram comparados com 15 indivíduos controle saudáveis (CS). A capacidade funcional foi avaliada por TECP e funções sistólicas e diastólicas por ecocardiografia. Resultados: A idade e o gênero foram similares entre pacientes com EMF e CS. A fração de ejeção do ventrículo esquerdo foi normal em pacientes com EMF, porém diminuída em comparação aos CS. Os picos de frequência cardíaca, carga de trabalho, VO2, pulso de oxigênio (O2) e da ventilação pulmonar (VE) estavam diminuídos em pacientes com EMF em comparação aos CS. Ainda, os pacientes com EMF apresentaram Δ frequência cardíaca /Δ consumo de oxigênio e Δ consumo de oxigênio /Δ taxa de trabalho aumentados em comparação aos CS. Conclusão: A determinação da capacidade aeróbica por troca respiratória não invasiva durante exercício progressivo fornece informações sobre a tolerância ao exercício em pacientes com EMF. É necessária uma análise das diferentes variáveis do TECP para nos ajudar a compreender mais acerca das alterações centrais e periféricas causadas tanto pela disfunção diastólica como pelo padrão restritivo.

Characterization of Cardiopulmonary Exercise Testing Variables in Patients with Endomyocardial Fibrosis after Endocardial Resection.

BACKGROUND: Endomyocardial fibrosis (EMF) is a rare disease, characterized by diastolic dysfunction which leads to reduced peak oxygen consumption (VO2). Cardiopulmonary exercise testing (CPET) has been proved to be a fundamental tool to identify central and peripheral alterations. However, most studies prioritize peak VO2 as the main variable, leaving aside other important CPET variables that can specify the severity of the disease and guide the clinical treatment. OBJECTIVE: The aim of this study was to evaluate central and peripheral limitations in symptomatic patients with EMF by different CPET variables. METHODS: Twenty-six EMF patients (functional class III, NYHA) were compared with 15 healthy subjects (HS). Functional capacity was evaluated using CPET and diastolic and systolic functions were evaluated by echocardiography. RESULTS: Age and gender were similar between EMF patients and HS. Left ventricular ejection fraction was normal in EMF patients, but decreased compared to HS. Peak heart rate, peak workload, peak VO2, peak oxygen (O2) pulse and peak pulmonary ventilation (VE) were decreased in EMF compared to HS. Also, EMF patients showed increased Δ heart rate /Δ oxygen uptake and Δ oxygen uptake /Δ work rate compared to HS. CONCLUSION: Determination of the aerobic capacity by noninvasive respiratory gas exchange during incremental exercise provides additional information about the exercise tolerance in patients with EMF. The analysis of different CPET variables is necessary to help us understand more about the central and peripheral alterations cause by both diastolic dysfunction and restrictive pattern.

Exercise training improves aortic depressor nerve sensitivity in rats with ischemia-induced heart failure.

Exercise training improves arterial baroreflex control in heart failure (HF) rabbits. However, the mechanisms involved in the amelioration of baroreflex control are unknown. We tested the hypothesis that exercise training would increase the afferent aortic depressor nerve activity (AODN) sensitivity in ischemic-induced HF rats. Twenty ischemic-induced HF rats were divided into trained (n = 11) and untrained (n = 9) groups. Nine normal control rats were also studied. Power spectral analysis of pulse interval, systolic blood pressure, renal sympathetic nerve activity (RSNA), and AODN were analyzed by means of autoregressive parametric spectral and cross-spectral algorithms. Spontaneous baroreflex sensitivity of heart rate (HR) and RSNA were analyzed during spontaneous variation of systolic blood pressure. Left ventricular end-diastolic pressure was higher in HF rats compared with that in the normal control group (P = 0.0001). Trained HF rats had a peak oxygen uptake higher than untrained rats and similar to normal controls (P = 0.01). Trained HF rats had lower low-frequency [1.8 +/- 0.2 vs. 14.6 +/- 3 normalized units (nu), P = 0.0003] and higher high-frequency (97.9 +/- 0.2 vs. 85.0 +/- 3 nu, P = 0.0005) components of pulse interval than untrained rats. Trained HF rats had higher spontaneous baroreceptor sensitivity of HR (1.19 +/- 0.2 vs. 0.51 +/- 0.1 ms/mmHg, P = 0.003) and RSNA [2.69 +/- 0.4 vs. 1.29 +/- 0.3 arbitrary units (au)/mmHg, P = 0.04] than untrained rats. In HF rats, exercise training increased spontaneous AODN sensitivity toward normal levels (trained HF rats, 1,791 +/- 215; untrained HF rats, 1,150 +/- 158; and normal control rats, 2,064 +/- 327 au/mmHg, P = 0.05). In conclusion, exercise training improves AODN sensitivity in HF rats.