The effects of low frequency electrical muscle stimulation in advanced heart failure
Aims: To investigate Low Frequency Electrical Muscle Stimulation (LF-EMS) in the advanced Chronic Heart Failure (CHF) population: 1) Characterise the physiological stimulus of LF-EMS, 2) Determine the feasibility of a Randomised Controlled Trial (RCT) in the CHF population, 3) Investigate effect of LF-EMS on vascular function.Methods and Results: Study one: Nine healthy males (mean age: 24.0 ±3.1 yrs) and 6 male patients with CHF (New York Heart Association class III- IV, mean age: 67.7 ± 14.1
... n age: 67.7 ± 14.1 yrs) undertook a 45-minute bout of LF-EMS (4Hz, continuous) of the legs. Oxygen uptake (VO2), was measured at 5-minute intervals along with multiple haemodynamic variables. VO2 increased in both groups (P<0.001), although patients with CHF demonstrated higher percentage of their maximal VO2 (5.8% [95%CI: 2.6, 7.9% :P<0.001]). Haemodynamic variables increased in both groups consistent with moderate exercise.Study two: Sixty participants with CHF were randomised to 8-weeks (5 x 60 minute per week) of LF-EMS (n=30) or 'sham' placebo (n=30). Recruitment, dropout and adherence were measured in addition to Six-Minute Walk Distance (6MWD) and quality of life (QoL). Sixty of 171 eligible participants (35.08%) were recruited, 12 (20%) patients withdrew. Forty-one patients (68.3%), adhered to the protocol (<70% of sessions). There were nosignificant differences between groups in 6MWD(P=0.13) and QoL (P=0.55). Study three: This study measured endothelial function using Flow Mediated Dilation (FMD) and maximal VO2 in a smaller cohort (LF-EMS n=20, 'sham' n=15). There was some evidence of enhanced FMD following LF-EMSiicompared to 'sham'.Conclusions: Study one: LF-EMS can elicit a significantly greater cardiovascular response in patients with CHF compared to healthy individuals. Study two: People with CHF can be recruited to and tolerate LF-EMS studies; a larger RCT in this population is technically feasible.Study three: Patients with CHF using LF-EMS could gain prognostically significant improvements in endothelial function.