A systematic review of lower extremity electrical stimulation for treatment of walking impairment in peripheral artery disease

Literature review of transcutaneous electrical nerve stimulation in peripheral arterial occlusive disease of the lower limbs

The therapeutic challenge in peripheral arterial occlusive disease (PAD) is often to increase walking distance, improve pain or heal a wound when PAD is symptomatic. Walking rehabilitation or surgical revascularization techniques are limited. Others strategies as alternatives and/or complementary treatments are needed. Among alternative options, Transcutaneous Electrical Nerve Stimulations (TENS) could be of interest, both for improved walking distance or pain reduction. The Transcutaneous Electrical Nerve Stimulation (TENS) is a non-pharmacological, mini-invasive technique involving transcutaneous electrical stimulation. However, there are other transcutaneous electrical nerve stimulation techniques based on the principle of vagus nerve stimulation with different mechanistics. Trans-auricular Vagus nerve stimulation (Ta-VNS) is another TENS technique (electrode on the external ear) which relies on the anti-inflammatory pathways of efferent and afferent vagal fibers. We propose here to review the literature of mini-invasive electrical stimulations, whatever the anatomical zone concerned, in PAD.

METHOD

The aim was to evaluate the use of non-invasive transcutaneous electrical stimulation therapies (regardless of location) in PAD of the lower limbs, whatever the disease grade. A review of the literature was carried out via a search of the MEDLINE/PubMed database from 1975 to 2023. The articles were selected via abstracts by checking (1) medical indications: PAD patients with claudication were retained, excluding neurological or venous claudication, PAD whatever the disease grade (intermittent claudication or critical limb ischemia [CLI]) and (2) non invasive electrical stimulations were considered (neuromuscular electrical stimulation and spinal cord stimulation were excluded) whatever the anatomical site. Non-electrical stimuli such as acupuncture and reflexotherapy were excluded.

RESULTS

Only 9 items were selected, including 7 studies with TENS treatment on the calf, one with trans-auricular vagus nerve stimulation and one with electro-acupuncture points of stimulation.

CONCLUSION

Even if the mechanisms involved are different, TENS on the calves or in the external ears show an improvement of walking distance in PAD patients with intermittent claudication. The results of the studies show few positive effects in arteriopathy but we should keep vigilant in the technics used since mechanisms are different and not fully understood. Electro-stimulation of the calf and external ear appears to be an easy-to-use and accessible therapeutic option, especially since some PAD patients are still failing to be released from pain, despite the rise of endovascular interventional techniques.

A Multicenter, Investigator-Blinded, Randomized Controlled Trial to Assess the Efficacy of Calf Neuromuscular Electrical Stimulation Program on Walking Performance in Peripheral Artery Disease: The ELECTRO-PAD Study Protocol

This paper describes a currently on-going multicenter, randomized controlled trial designed to assess the efficacy of calf neuromuscular electrical stimulation (NMES) on changes in maximal walking distance in people with lower extremity peripheral artery disease (PAD), compared with a non-intervention control-group. This study (NCT03795103) encompasses five participating centers in France. PAD participants with a predominant claudication at the calf level and a maximal treadmill walking distance ≤300 m are randomized into one of the two groups: NMES group or Control group. The NMES program consists of a 12-week program of electrical stimulations at the calf-muscle level. The primary outcome of the study is the change in maximal treadmill walking distance at 12 weeks. Main secondary outcomes include changes in the pain-free treadmill walking distance; 6 min total walking distance; global positioning system (GPS)-measured outdoor walking capacity; daily physical activity level by accelerometry; self-reported walking impairment; self-reported quality of life; ankle-brachial index; and skin microvascular function, both at the forearm and calf levels. Recruitment started in September 2019 and data collection is expected to end in November 2022.

Powering Implantable and Ingestible Electronics

Implantable and ingestible biomedical electronic devices can be useful tools for detecting physiological and pathophysiological signals, and providing treatments that cannot be done externally. However, one major challenge in the development of these devices is the limited lifetime of their power sources. The state-of-the-art of powering technologies for implantable and ingestible electronics is reviewed here. The structure and power requirements of implantable and ingestible biomedical electronics are described to guide the development of powering technologies. These powering technologies include novel batteries that can be used as both power sources and for energy storage, devices that can harvest energy from the human body, and devices that can receive and operate with energy transferred from exogenous sources. Furthermore, potential sources of mechanical, chemical, and electromagnetic energy present around common target locations of implantable and ingestible electronics are thoroughly analyzed; energy harvesting and transfer methods befitting each energy source are also discussed. Developing power sources that are safe, compact, and have high volumetric energy densities is essential for realizing long-term in-body biomedical electronics and for enabling a new era of personalized healthcare.