Influence of Transcutaneous Electrical Nerve Stimulation on Clinical Measures and Functional Capacity in Patients with Peripheral Artery Disease

Abstract

Peripheral Arterial Disease (PAD), which is characterized by occlusive plaques in the arteries perfusing the legs, often manifests in intermittent claudication. Home‐based exercise is commonly suggested for individuals with PAD, but adherence to such programs is often poor, resulting in limited clinical benefits. Therefore, this patient population would benefit from low‐risk, inexpensive, and simple to use therapeutic interventions that can improve exercise tolerance and capacity. One such potentially beneficial intervention is transcutaneous electrical nerve stimulation (TENS), which may induce transient increases in leg blood flow sufficient to improve the matching of oxygen supply and demand distal to the site of stenosis in patients with peripheral artery disease (PAD). Thus, the purpose of this study was to test the hypothesis that a single bout of TENS applied to the lower leg (for 15 or 45 minutes) will increase resting popliteal artery blood flow and 6‐minute walk distance (6MWD) in patients with PAD. Five subjects with PAD (67–81 yrs.; Intermittent Claudication, Fontaine stage II) participated in the protocol. Four subjects attended the laboratory for three randomized visits during which bilateral lower leg TENS (burst mode; 3Hz burst rate; 100Hz freq.; 250 μs pulse duration) sufficient to evoke skeletal muscle contraction was carried out for either 15 or 45 minutes or subjects participated in a control visit. One subject completed only the control and 15 minute TENS trials. Clinical and cardiovascular measures including resting single leg popliteal artery blood flow (Doppler ultrasound), ankle‐brachial index (ABI), and toe oxygen saturation (pulse oximetry) were carried out prior to and beginning 10 minutes following TENS. Popliteal vascular conductance (PVC) was calculated as flow/mean arterial pressure. 6MWD and time/distance to claudication onset were measured on the control day and each experimental day 35 minutes post‐TENS. The 15‐minute TENS trial increased popliteal artery blood flow from 63.5 ± 10.9 to 89.8 ± 21.8 mL min−1 (42.2%; P < 0.05; n=5), PVC from 0.70 ± 0.12 to 0.92 ± 0.21 mL min−1 mmHg−1 (31.5%; P < 0.05; n=5), and 6MWD from 1018.0 ± 133.8 to 1141.6 ± 149.2 feet (12.1%; P < 0.05; n=5). The 45‐minute TENS trial increased popliteal artery blood flow from 56.4 ± 9.3 to 74.4 ± 15.9 mL min−1 (32.1%; P = 0.056; n=4), PVC from 0.66 ± 0.15 to 0.81 ± 0.20 mL min−1 mmHg−1 (23.2%; P < 0.05; n=4), and 6MWD from 943.8 ± 128.5 to 1096.3 ± 146.9 feet (14.9%; P < 0.05; n=4). Furthermore, the subjects reported onset of claudication at 573.8 ± 84.4 feet of the control visit 6MW, which was compared to 810.0 ± 199.2 feet after the 15 minute TENS trial and 690.0 ± 60.1 feet after the 45 minute TENS trial (both P > 0.05). Neither of the TENS trials evoked changes in ABI or toe oxygen saturation. These preliminary findings suggest that acute lower leg TENS in patients with PAD may increase leg perfusion and exercise tolerance which, if undertaken routinely, could increase either patient adherence to or efficacy of exercise prescription in this population.Support or Funding InformationSupported by the Salisbury University Faculty Mini‐Grant