Functional electrical stimulation of lower limbs in patients with chronic heart failure

Post-operative electrical muscle stimulation attenuates loss of muscle mass and function following major abdominal surgery in older adults: a split body randomised control trial

INTRODUCTION

Significant losses of muscle mass and function occur after major abdominal surgery. Neuromuscular electrical stimulation (NMES) has been shown to reduce muscle atrophy in some patient groups, but evidence in post-operative patients is limited. This study assesses the efficacy of NMES for attenuating muscle atrophy and functional declines following major abdominal surgery in older adults.

METHODS

Fifteen patients undergoing open colorectal resection completed a split body randomised control trial. Patients' lower limbs were randomised to control (CON) or NMES (STIM). The STIM limb underwent 15 minutes of quadriceps NMES twice daily on post-operative days (PODs) 1-4. Ultrasound measurements of Vastus Lateralis cross-sectional area (CSA) and muscle thickness (MT) were made preoperatively and on POD 5, as was dynamometry to determine knee extensor strength (KES). Change in CSA was the primary outcome. All outcomes were statistically analysed using linear mixed models.

RESULTS

NMES significantly reduced the loss of CSA (-2.52 versus -9.16%, P < 0.001), MT (-2.76 versus -8.145, P = 0.001) and KES (-10.35 versus -19.69%, P = 0.03) compared to CON. No adverse events occurred, and patients reported that NMES caused minimal or no discomfort and felt that ~90-minutes of NMES daily would be tolerable.

DISCUSSION

NMES reduces losses of muscle mass and function following major abdominal surgery, and as such, may be the promising tool for post-operative recovery. This is important in preventing long-term post-operative dependency, especially in the increasingly frail older patients undergoing major abdominal surgery. Further studies should establish the efficacy of bilateral NMES for improving patient-centred outcomes.

In-hospital electrical muscle stimulation for patients early after heart failure decompensation: results from a prospective randomised controlled pilot trial

BACKGROUND

Electrical muscle stimulation (EMS) is being evaluated as a possible alternative to exercise training to improve functional capacity in severely deconditioned patients with heart failure (HF). However, there is insufficient data on delayed effects of EMS starting early after decompensation. The aim of this study was to determine the impact of a short inpatient EMS intervention in severely deconditioned patients with HF on functional capacity and quality of life (QoL) over a follow-up period of 1 month.

METHODS

This is a prospective randomised sham-controlled pilot study. 45 patients hospitalised for decompensated systolic HF (58% men, mean age 66.4±10.2 years) were randomised to EMS (n=22) or sham stimulation (n=23) of lower limbs starting within 3 days after admission. The intervention included 7-10 sessions lasting from 30 to 90 min. The 6-minute walking test distance (6-MWTD), Duke Activity Status Index (DASI) and Minnesota Living with Heart Failure Questionnaire (MLHFQ) were evaluated at baseline, discharge and after 1 month.

RESULTS

All patients completed the programme with good EMS tolerance. 37 patients were included in the final analysis. At discharge, 6-MWTD improved from 206,1±61,3 to 299.5±91 m, DASI from 12.1±5.6 to 18.3±7.2 and MLHFQ from 55.6±8.5 to 34.2±9 with EMS compared with smaller improvements in the sham group (p<0.05 for all). One month after discharge, improvements in the EMS group remained significant for MLHFQ (p=0.004) and DASI (p=0.042) and statistically non-significant for 6-MWTD compared with the sham group.

CONCLUSIONS

Short-term in-hospital EMS leads to improvements in functional capacity and QoL in selected patients early after HF decompensation that are retained over 1 month after discharge and therefore may serve as initial intervention to improve physical capacity or as a bridge to further conventional exercise training. Larger studies are required to evaluate individual responses to an early initiation of EMS in decompensated HF as well as long-term effects.

Real-world experience of feasibility and efficacy of electrical muscle stimulation in elderly patients with acute heart failure: A randomized controlled study

BACKGROUND

Reduced aerobic capacity and deconditioning contributes to morbidity and mortality in elderly acute heart failure (AHF) patients. Electrical muscle stimulation (EMS) has shown to be a suitable alternative to exercise in AHF. However, feasibility and efficacy are unknown in a real-world setting.

METHODS

This is a prospective, open label blinded, randomized, controlled study, investigating feasibility and efficacy of high-intensity versus low-intensity EMS versus controls in elderly AHF patients. Patients and investigators were blinded to the intervention. EMS was offered to > 60 years old AHF patients, initiated during hospitalization and continued at home. Outcome measures included changes in 6-min walking test distance (6-MWTD), functional capacity and quality-of-life at 3 and 6 weeks.

RESULTS

Among 97 consecutive AHF patients (78.1 ± 9.4 years, 42.3% females), 60 (61.9%) were eligible for EMS. Of these, 27 provided written informed consent and were randomly assigned to high-intensity (n = 10), low-intensity EMS (n = 9) and controls (n = 8). 13/27 completed the intervention. Main reason for dropouts was intolerance of the overall intervention burden. MACE occurred in 5 and were not associated with the study. EMS groups showed significant improvement of 6-MWTD (controls vs low-intensity p = 0.018) and of independence in daily living (for both p < 0.05).

CONCLUSIONS

Changes in 6-MWTD suggest efficacy of EMS. Whereas all tolerated EMS well, the burden of study intervention was too high and resulted in a consent rate of <50% and high dropouts, which limit the interpretability of our data. Less demanding EMS protocols are required to evaluate the full potential of EMS in elderly AHF patients.

Improvement in Physical Function After Coronary Artery Bypass Graft Surgery Using a Novel Rehabilitation Intervention: A RANDOMIZED CONTROLLED TRIAL

PURPOSE

Cardiorespiratory and skeletal muscle deconditioning occurs following coronary artery bypass graft surgery and hospitalization. Outpatient, phase 2 cardiac rehabilitation (CR) is designed to remediate this deconditioning but typically does not begin until several weeks following hospital discharge. Although an exercise program between discharge and the start of CR could improve functional recovery, implementation of exercise at this time is complicated by postoperative physical limitations and restrictions. Our objective was to assess the utility of neuromuscular electrical stimulation (NMES) as an adjunct to current rehabilitative care following postsurgical discharge and prior to entry into CR on indices of physical function in patients undergoing coronary artery bypass graft surgery.

METHODS

Patients were randomized to 4 wk of bilateral, NMES (5 d/wk) to their quadriceps muscles or no intervention (control). Physical function testing was performed at hospital discharge and 4 wk post-discharge using the Short Physical Performance Battery and the 6-min walk tests. Data from 37 patients (19 control/18 NMES) who completed the trial were analyzed. The trial was registered at ClinicalTrials.gov (NCT03892460).

RESULTS

Physical function measures improved from discharge to 4 wk post-surgery across our entire cohort (P < .001). Patients randomized to NMES, however, showed greater improvements in 6-min walk test distance and power output compared with controls (P < .01).

CONCLUSION

Our results provide evidence supporting the utility of NMES to accelerate recovery of physical function after coronary artery bypass graft surgery.

The ergoreflex: how the skeletal muscle modulates ventilation and cardiovascular function in health and disease

The control of ventilation and cardiovascular function during physical activity is partially regulated by the ergoreflex, a cardiorespiratory reflex activated by physical activity. Two components of the ergoreflex have been identified: the mechanoreflex, which is activated early by muscle contraction and tendon stretch, and the metaboreflex, which responds to the accumulation of metabolites in the exercising muscles. Patients with heart failure (HF) often develop a skeletal myopathy with varying degrees of severity, from a subclinical disease to cardiac cachexia. HF‐related myopathy has been associated with increased ergoreflex sensitivity, which is believed to contribute to dyspnoea on effort, fatigue and sympatho‐vagal imbalance, which are hallmarks of HF. Ergoreflex sensitivity increases significantly also in patients with neuromuscular disorders. Exercise training is a valuable therapeutic option for both HF and neuromuscular disorders to blunt ergoreflex sensitivity, restore the sympatho‐vagal balance, and increase tolerance to physical exercise. A deeper knowledge of the mechanisms mediating ergoreflex sensitivity might enable a drug or device modulation of this reflex when patients cannot exercise because of advanced skeletal myopathy.

Respiratory, cardiac and metabolic responses during electrical muscle stimulation in quadriceps muscle versus comparable voluntary muscle contractions

Electrical Muscle Stimulation (EMS) and voluntary muscle contraction (VMC) are both acceptable rehabilitative modalities to preserve muscle strength loss. The study aimed to compare respiratory, metabolic, and cardiac parameters during quadriceps muscle contraction (QMC) using either EMS or VMC with comparable generated low intensity muscle force. Thirty healthy non-smoker males, age 20-58 years with normal BMI and low to moderate physical activity, underwent two 20-min sessions of comparable QMC using EMS vs VMC at the same day. The BIODEX III isokinetic dynamometer was used to assess maximum isometric force and the comparable force generated during each condition (EMS vs VMC), while the METAMAX 3B portable metabolic system was used to measure continuously the physiological parameters. Tolerable EMS was used (mean: 33 ± 1.5 mA, at 75 Hz). Each contraction lasted 10 sec followed by 20 sec rest. Paired t-tests were used for comparisons between sessions. A relatively low proportion of maximum isometric force (EMS: 8.5% vs VMC: 8.6%) and torque (EMS: 16 ± 1.3 vs VMC: 16 ± 1.1 Nm) were generated during each session. Mean minute ventilation (EMS: 10.8 L vs VMC: 9.8 L), tidal volume (EMS: 0.6 L vs VMC: 0.5 L), O₂ uptake (EMS: 0.31 L/min vs VMC: 0.26 L/min) and O₂ pulse (EMS: 3.9 ml/beat vs VMC: 3.6 ml/beat) were different between sessions (p ≤ .05); while heart rate (EMS: 72 beats/min vs VMC: 71 beats/min) was equal. Quadriceps muscle EMS induces higher respiratory and metabolic responses compared to equal magnitude VMC in healthy males.

Efficacy of neuromuscular electric stimulation versus aerobic exercise on uraemic restless legs syndrome

Background

The prevalence of restless legs syndrome in haemodialysis patients is approximately ~30%, and it is significantly higher than in the general population. Restless legs syndrome is a sensory-motor disorder with negative effects on sleep and daytime activities that affect personal, family and occupational life. The overall impact of restless legs syndrome on quality of life is comparable to that of chronic and frustrating conditions such as depression and diabetes. The present study was conducted to compare the effect of neuromuscular electric stimulation with aerobic exercise on cases of uraemic restless legs syndrome.

Methods

A total of 60 chronic renal failure patients with uraemic restless legs syndrome aged 20 to 65 years participated in this study. Participants were allocated to receive neuromuscular electric stimulation or aerobic exercises. All participants were evaluated before the first session of treatment and after 3 months, at the end of the treatment. Normal and fast walk gait speed tests and the Five Times Sit-to-Stand Test and 60 second Sit-to-Stand Test were used to assess participants' physical status. The Restless Legs Syndrome Rating Scale was used to determine the level of restless legs syndrome severity.

Results

Neuromuscular electric stimulation resulted in significant improvements in all measures of physical performance and in Restless Legs Syndrome Rating Scale score when compared to baseline. Aerobic exercise produced significant improvements in all tests. At the end of the study, aerobic exercise had greater responses than neuromuscular electric stimulation in all parameters measured except the Five Times Sit-to-Stand Test.

Conclusions

Neuromuscular electrical stimulation may be used as an alternative to aerobic exercise to improve physical performance in cases of less severe restless legs syndrome in those unable or unwilling to participate in physical training.

Effects of aging on mitochondrial hydrogen peroxide emission and calcium retention capacity in rat heart

Aging is a risk factor for heart disease and heart failure, which result from a progressive impairment of cardiac functions, including stroke volume, cardiac output, blood flow, and oxygen consumption. Age-related cardiac dysfunction is associated with impaired cardiac structures, such as the loss of myocytes, structural remodeling, altered calcium (Ca²⁺) handling, and contractile dysfunction. However, the mechanism by which aging affects mitochondrial function in the heart is poorly understood. The purpose of this study was to determine the effects of aging on mitochondrial function in the rat heart. Male Fischer 344 rats were randomly assigned to very young sedentary (VYS, 1 month), young sedentary (YS, 4 months), middle-aged sedentary (MS, 10 months), and old sedentary (OS, 20 months) groups. mitochondrial complex protein levels and mitochondrial function (e.g., mitochondrial hydrogen peroxide (H₂O₂) emission and Ca²⁺ retention capacity) were analyzed in the left ventricle. Aging was associated with decreased levels of OXPHOS (oxidative phosphorylation) protein expression of complex I to IV in the function of the electron transport chain. Aging increased the mitochondrial H₂O₂ emitting potential in the heart. In contrast, mitochondrial Ca²⁺ retention capacity gradually decreased with age. These data demonstrate that aging impairs mitochondrial function in cardiac muscle, suggesting that mitochondrial dysfunction with aging may be a primary factor for aging-induced cardiac dysfunction in the heart.

A practical approach to assess leg muscle oxygenation during ramp-incremental cycle ergometry in heart failure

Heart failure is characterized by the inability of the cardiovascular system to maintain oxygen (O₂) delivery (i.e., muscle blood flow in non-hypoxemic patients) to meet O₂ demands. The resulting increase in fractional O₂ extraction can be non-invasively tracked by deoxygenated hemoglobin concentration (deoxi-Hb) as measured by near-infrared spectroscopy (NIRS). We aimed to establish a simplified approach to extract deoxi-Hb-based indices of impaired muscle O₂ delivery during rapidly-incrementing exercise in heart failure. We continuously probed the right vastus lateralis muscle with continuous-wave NIRS during a ramp-incremental cardiopulmonary exercise test in 10 patients (left ventricular ejection fraction <35%) and 10 age-matched healthy males. Deoxi-Hb is reported as % of total response (onset to peak exercise) in relation to work rate. Patients showed lower maximum exercise capacity and O₂ uptake-work rate than controls (P<0.05). The deoxi-Hb response profile as a function of work rate was S-shaped in all subjects, i.e., it presented three distinct phases. Increased muscle deoxygenation in patients compared to controls was demonstrated by: i) a steeper mid-exercise deoxi-Hb-work rate slope (2.2±1.3 vs 1.0±0.3% peak/W, respectively; P<0.05), and ii) late-exercise increase in deoxi-Hb, which contrasted with stable or decreasing deoxi-Hb in all controls. Steeper deoxi-Hb-work rate slope was associated with lower peak work rate in patients (r=–0.73; P=0.01). This simplified approach to deoxi-Hb interpretation might prove useful in clinical settings to quantify impairments in O₂ delivery by NIRS during ramp-incremental exercise in individual heart failure patients.

Effects of combined exercise training and electromyostimulation treatments in chronic heart failure: A prospective multicentre study

Background Exercise training as part of a comprehensive cardiac rehabilitation is recommended for patients with cardiac heart failure. It is a valuable method for the improvement of exercise tolerance. Some studies reported a similar improvement with quadricipital electrical myostimulation, but the effect of combined exercise training and electrical myostimulation in cardiac heart failure has not been yet evaluated in a large prospective multicentre study. Purpose The aim of this study was to determine whether the addition of low frequency electrical myostimulation to exercise training may improve exercise capacity and/or muscular strength in cardiac heart failure patients. Methods Ninety-one patients were included (mean age: 58 ± 9 years; New York Heart Association II/III: 52/48%, left ventricular ejection fraction: 30 ± 7%) in a prospective French study. The patients were randomised into two groups: 41 patients in exercise training and 50 in exercise training + electrical myostimulation. All patients underwent 20 exercise training sessions. In addition, in the exercise training + electrical myostimulation group, patients underwent 20 low frequency (10 Hz) quadricipital electrical myostimulation sessions. Each patient underwent a cardiopulmonary exercise test, a six-minute walk test, a muscular function evaluation and a quality of life questionnaire, before and at the end of the study. Results A significant improvement of exercise capacity (Δ peak oxygen uptake+15% in exercise training group and +14% in exercise training + electrical myostimulation group) and of quality of life was observed in both groups without statistically significant differences between the two groups. Mean creatine kinase level increased in the exercise training group whereas it remained stable in the combined group. Conclusions This prospective multicentre study shows that electrical myostimulation on top of exercise training does not demonstrate any significant additional improvement in exercise capacity in cardiac heart failure patients.

Effect of functional electrical stimulation on cardiovascular outcomes in patients with chronic heart failure

Background/design Functional electrical stimulation of lower limb muscles is an alternative method of training in patients with chronic heart failure (CHF). Although it improves exercise capacity in CHF, we performed a randomised, placebo-controlled study to investigate its effects on long-term clinical outcomes. Methods We randomly assigned 120 patients, aged 71 ± 8 years, with stable CHF (New York Heart Association (NYHA) class II/III (63%/37%), mean left ventricular ejection fraction 28 ± 5%), to either a 6-week functional electrical stimulation training programme or placebo. Patients were followed for up to 19 months for death and/or hospitalisation due to CHF decompensation. Results At baseline, there were no significant differences in demographic parameters, CHF severity and medications between groups. During a median follow-up of 383 days, 14 patients died (11 cardiac, three non-cardiac deaths), while 40 patients were hospitalised for CHF decompensation. Mortality did not differ between groups (log rank test P = 0.680), while the heart failure-related hospitalisation rate was significantly lower in the functional electrical stimulation group (hazard ratio (HR) 0.40, 95% confidence interval (CI) 0.21-0.78, P = 0.007). The latter difference remained significant after adjustment for prognostic factors: age, gender, baseline NYHA class and left ventricular ejection fraction (HR 0.22, 95% CI 0.10-0.46, P < 0.001). Compared to placebo, functional electrical stimulation training was associated with a lower occurrence of the composite endpoint (death or heart failure-related hospitalisation) after adjustment for the above-mentioned prognostic factors (HR 0.21, 95% CI 0.103-0.435, P < 0.001). However, that effect was mostly driven by the favourable change in hospitalisation rates. Conclusions In CHF patients, 6 weeks functional electrical stimulation training reduced the risk of heart failure-related hospitalisations, without affecting the mortality rate. The beneficial long-term effects of this alternative method of training require further investigation.

Whole body oxygen uptake and evoked torque during subtetanic isometric electrical stimulation of the quadriceps muscles in a single 30-minute session

OBJECTIVE

To evaluate the time course of fatigue in torque output and oxygen uptake during isometric subtetanic neuromuscular electrical stimulation (NMES) to facilitate the design of NMES-based rehabilitation protocols that can accumulate a defined aerobic exercise volume within a given time period.

DESIGN

Single-arm intervention study with within-subject comparisons.

SETTING

University research laboratory.

PARTICIPANTS

Volunteer sample of healthy men (N=11; mean age, 34.2 ± 11.5 y; range, 19-53 y; body mass, 79.1 ± 11.7 kg; range, 58-100 kg).

INTERVENTION

A single 30-minute session of continuous bilateral isometric quadriceps NMES at 4 Hz evoking a mean twitch amplitude of 12% of the maximum voluntary contraction.

MAIN OUTCOME MEASURES

Whole body oxygen consumption rate (V˙o2), and evoked torque were measured simultaneously throughout.

RESULTS

Mean increment in V˙o2 was 596 ± 238 mL/min, and average exercise intensity during the session was 3 ±.47 metabolic equivalents. The V˙o2 and torque declined slowly at a rate of -.54%±.31% and -.47%±.57% per minute, respectively.

CONCLUSIONS

Despite having a higher incremental V˙o2, the observed fatigue rate was considerably less than that previously reported during intermittent isometric tetanic stimulation, suggesting that subtetanic isometric NMES is more sustainable for exercise interventions aimed at accumulating a therapeutic aerobic exercise volume.

Functional electrical stimulation of peripheral muscles improves endothelial function and clinical and emotional status in heart failure patients with preserved left ventricular ejection fraction

BACKGROUND

Functional electrical stimulation (FES) improves exercise capacity, quality of life, emotional stress, and endothelial function in chronic heart failure with impaired systolic function. We sought to investigate the effects of FES on the above parameters in patients with preserved ejection fraction (HFpEF).

METHODS

Thirty HFpEF patients, 18 female and 12 male, aged 69 ± 8 years, in New York Heart Association class II or III and with mean ejection fraction 63% ± 6%, were randomly (1:1) assigned to a 6-week FES program or placebo. Assessment was performed at baseline and after completion of training protocol and included 6-minute walked distance, quality of life (Kansas City Cardiomyopathy Questionnaire and Minnesota Living with Heart Failure Questionnaire), depressive symptoms (Beck Depression Inventory and Zung self-rated depression scores), B-type natriuretic peptide, endothelial function (flow-mediated dilatation), and left ventricular diastolic function.

RESULTS

A significant improvement in 6-minute walked distance (F = 21.61, P = .001), Kansas City Cardiomyopathy Questionnaire summary (F = 8.68, P = .006), Minnesota Living with Heart Failure Questionnaire (F = 6.43, P = .017), Beck Depression Inventory (F = 6.66, P = .015), Zung (F = 6.25, P = .019), and flow-mediated dilatation diameter (F = 11.98, P = .002) was observed in the FES group compared with placebo group; B-type natriuretic peptide also declined but not significantly (F = 0.249, P = .622), and there was a tendency toward lower mitral E/e' wave ratio (F = 3.066, P = .091).

CONCLUSION

As in heart failure and reduced left ventricular ejection fraction, FES also improves exercise capacity, quality of life, emotional status, and endothelial function in HFpEF. Given the lack of effective evidence-based therapies in these patients, FES warrants further investigation.

Proteomic identification of biomarkers of skeletal muscle disorders

Disease-specific biomarkers play a central diagnostic and therapeutic role in muscle pathology. Serum levels of a variety of muscle-derived enzymes are routinely used for the detection of muscle damage in diagnostic procedures, as well as for the monitoring of physical training status in sports medicine. Over the last few years, the systematic application of mass spectrometry-based proteomics for studying skeletal muscle degeneration has greatly expanded the range of muscle biomarkers, including new fiber-associated proteins involved in muscle transformation, muscular atrophy, muscular dystrophy, motor neuron disease, inclusion body myositis, myotonia, hypoxia, diabetes, obesity and sarcopenia of old age. These mass spectrometric studies have clearly established skeletal muscle proteomics as a reliable method for the identification of novel indicators of neuromuscular diseases.