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.

Effects of inspiratory muscle training combined with aerobic exercise training on neurovascular control in chronic heart failure patients.

AIMS: We tested the hypothesis that the effects of combined inspiratory muscle training and aerobic exercise training (IMT + AET) on muscle sympathetic nerve activity (MSNA) and forearm blood flow in patients with heart failure with reduced ejection fraction are more pronounced than the effects of AET alone. METHODS AND RESULTS: Patients aged 30-70 years, New York Heart Association Functional Class II-III, and left ventricular ejection fraction ≤40% were randomly assigned to four groups: IMT (n = 11), AET (n = 12), IMT + AET (n = 9), and non-training (NT; n = 10). MSNA was recorded using microneurography. Forearm blood flow was measured by venous occlusion plethysmography and inspiratory muscle strength by maximal inspiratory pressure. IMT consisted of 30 min sessions, five times a week, for 4 months. Moderate AET consisted of 60 min sessions, three times a week for 4 months. AET (-10 ± 2 bursts/min, P = 0.03) and IMT + AET (-13 ± 4 bursts/min, P = 0.007) reduced MSNA. These responses in MSNA were not different between AET and IMT + AET groups. IMT (0.22 ± 0.08 mL/min/100 mL, P = 0.03), AET (0.27 ± 0.09 mL/min/100 mL, P = 0.01), and IMT + AET (0.35 ± 0.12 mL/min/100 mL, P = 0.008) increased forearm blood flow. No differences were found between groups. AET (3 ± 1 mL/kg/min, P = 0.006) and IMT + AET (4 ± 1 mL/kg/min, P = 0.001) increased peak oxygen consumption. These responses were similar between these groups. IMT (20 ± 3 cmH2 O, P = 0.005) and IMT + AET (18 ± 3 cmH2 O, P = 0.01) increased maximal inspiratory pressure. No significant changes were observed in the NT group. CONCLUSIONS: IMT + AET causes no additive effects on neurovascular control in patients with heart failure with reduced ejection fraction compared with AET alone. These findings may be, in part, because few patients had inspiratory muscle weakness.

Effects of aerobic and inspiratory training on skeletal muscle microRNA-1 and downstream-associated pathways in patients with heart failure.

BACKGROUND: The exercise intolerance in chronic heart failure with reduced ejection fraction (HFrEF) is mostly attributed to alterations in skeletal muscle. However, the mechanisms underlying the skeletal myopathy in patients with HFrEF are not completely understood. We hypothesized that (i) aerobic exercise training (AET) and inspiratory muscle training (IMT) would change skeletal muscle microRNA-1 expression and downstream-associated pathways in patients with HFrEF and (ii) AET and IMT would increase leg blood flow (LBF), functional capacity, and quality of life in these patients. METHODS: Patients age 35 to 70 years, left ventricular ejection fraction (LVEF) ≤40%, New York Heart Association functional classes II-III, were randomized into control, IMT, and AET groups. Skeletal muscle changes were examined by vastus lateralis biopsy. LBF was measured by venous occlusion plethysmography, functional capacity by cardiopulmonary exercise test, and quality of life by Minnesota Living with Heart Failure Questionnaire. All patients were evaluated at baseline and after 4 months. RESULTS: Thirty-three patients finished the study protocol: control (n = 10; LVEF = 25 ± 1%; six males), IMT (n = 11; LVEF = 31 ± 2%; three males), and AET (n = 12; LVEF = 26 ± 2%; seven males). AET, but not IMT, increased the expression of microRNA-1 (P = 0.02; percent changes = 53 ± 17%), decreased the expression of PTEN (P = 0.003; percent changes = -15 ± 0.03%), and tended to increase the p-AKTser473 /AKT ratio (P = 0.06). In addition, AET decreased HDAC4 expression (P = 0.03; percent changes = -40 ± 19%) and upregulated follistatin (P = 0.01; percent changes = 174 ± 58%), MEF2C (P = 0.05; percent changes = 34 ± 15%), and MyoD expression (P = 0.05; percent changes = 47 ± 18%). AET also increased muscle cross-sectional area (P = 0.01). AET and IMT increased LBF, functional capacity, and quality of life. Further analyses showed a significant correlation between percent changes in microRNA-1 and percent changes in follistatin mRNA (P = 0.001, rho = 0.58) and between percent changes in follistatin mRNA and percent changes in peak VO2 (P = 0.004, rho = 0.51). CONCLUSIONS: AET upregulates microRNA-1 levels and decreases the protein expression of PTEN, which reduces the inhibitory action on the PI3K-AKT pathway that regulates the skeletal muscle tropism. The increased levels of microRNA-1 also decreased HDAC4 and increased MEF2c, MyoD, and follistatin expression, improving skeletal muscle regeneration. These changes associated with the increase in muscle cross-sectional area and LBF contribute to the attenuation in skeletal myopathy, and the improvement in functional capacity and quality of life in patients with HFrEF. IMT caused no changes in microRNA-1 and in the downstream-associated pathway. The increased functional capacity provoked by IMT seems to be associated with amelioration in the respiratory function instead of changes in skeletal muscle. ClinicalTrials.gov (Identifier: NCT01747395).

Impaired Pulmonary Function is an Additional Potential Mechanism for the Reduction of Functional Capacity in Clinically Stable Fontan Patients.

Central factors negatively affect the functional capacity of Fontan patients (FP), but "non-cardiac" factors, such as pulmonary function, may contribute to their exercise intolerance. We studied the pulmonary function in asymptomatic FP and its correlations with their functional capacity. Pulmonary function and cardiopulmonary exercise tests were performed in a prospective study of 27 FP and 27 healthy controls (HC). Cardiovascular magnetic resonance was used to evaluate the Fontan circulation. The mean age at tests, the mean age at surgery, and the median follow-up time of FP were 20(±6), 8(±3), and 11(8-17) years, respectively. Dominant ventricle ejection fraction was within normal range. The mean of peak VO2 expressed in absolute values (L/min), the relative values to body weight (mL/kg/min), and their predicted values were lower in FP compared with HC: 1.69 (±0.56) vs 2.81 (±0.77) L/min; 29.9 (±6.1) vs 41.5 (±9.3) mL/kg/min p < 0.001 and predicted VO2 Peak [71% (±14) vs 100% (±20) p < 0.001]. The absolute and predicted values of the forced vital capacity (FVC), forced expiratory volume in one second (FEV1), inspiratory capacity (IC), total lung capacity (TLC), diffusion capacity of carbon monoxide of the lung (DLCO), maximum inspiratory pressure (MIP), and sniff nasal inspiratory pressure (SNIP) were also significantly lower in the Fontan population compared to HC. An increased risk of restrictive ventilatory pattern was found in patients with postural deviations (OD:10.0, IC:1.02-97.5, p = 0.042). There was a strong correlation between pulmonary function and absolute peak VO2 [FVC (r = 0.86, p < 0.001); FEV1 (r = 0.83, p < 0.001); IC (r = 0.84, p < 0.001); TLC (r = 0.79, p < 0.001); and DLCO (r = 0.72, p < 0.001). The strength of the inspiratory muscles in absolute and predicted values was also reduced in FP [-79(±28) vs -109(±44) cmH2O (p = 0.004) and 67(±26) vs 89(±36) % (p = 0.016)]. Thus, we concluded that the pulmonary function was impaired in clinically stable Fontan patients and the static and dynamic lung volumes were significantly reduced compared with HC. We also demonstrated a strong correlation between absolute Peak VO2 with the FVC, FEV1, TLC, and DLCO measured by complete pulmonary test.