Leg heat therapy improves perceived physical function but does not enhance walking capacity or vascular function in patients with peripheral artery disease

Abstract

A single session of leg heat therapy (HT) has been shown to elicit increases in leg blood flow and reduce blood pressure (BP) and the circulating levels of endothelin-1 (ET-1) in patients with symptomatic peripheral artery disease (PAD). We assessed whether 6 weeks of supervised leg HT (3 times/wk) using water-circulating trousers perfused with water at 48ºC improved 6-minute walk distance in people with PAD, compared to a sham treatment. Secondary outcomes included the assessment of leg vascular function, BP, quality of life and the serum ET-1 and nitrite plus nitrate (NOx) levels. Of thirty-two PAD patients randomized, thirty (age: 68±8 yrs; ankle-brachial index (ABI): 0.6±0.1) completed the 3 and 6-week follow ups. Participants completed 98.7% of the treatment sessions. When compared to the sham treatment, exposure to HT did not improve 6-minute walk distance, BP, popliteal artery reactive hyperemia, cutaneous microvascular reactivity, resting ABI or the serum NOx levels. The change from baseline to 6 weeks in scores of the physical functioning subscale of the 36-item Short Form Health Survey was significantly higher in the HT group (Control: -6.9±10 versus HT: 6.8±15; 95% confidence interval: 2.5-24.3, p=0.017). Similarly, the change in ET-1 levels after 6 weeks was different between groups, with the HT group experiencing a 0.4 decrease (95% confidence interval: -0.8,-0.0, p=0.03). These preliminary results indicate that leg HT may improve perceived physical function in symptomatic PAD patients. Additional, larger studies are needed to confirm these findings and determine the optimal treatment regimen for symptomatic PAD patients.

Acute effects of leg heat therapy on walking performance and cardiovascular and inflammatory responses to exercise in patients with peripheral artery disease

“…The pillars of the medical management of PAD are to reduce cardiovascular morbidity and mortality and to reduce limb morbidity (Bonaca & Creager, 2015). Our current findings, as well as other recent studies (Akerman et al., 2019; Kim et al., 2017; Monroe et al., 2020; Pellinger et al., 2019), indicate that HT may be a practical adjunctive therapy that fulfills both therapeutic goals. First, by reducing resting and exercise BP as well as the circulating levels of ET‐1, HT may improve cardiovascular health and consequently diminish the risk of MI, stroke, and death in patients with PAD.…”

“…The goal of the present study was to examine the effects of pre-treatment with leg HT or a sham intervention on the cardiovascular responses and tolerance to a symptom-limited exercise test on the treadmill in patients with symptomatic PAD. Building on our previous findings (Monroe et al, 2020;Neff et al, 2016), we hypothesized that a single 90-min session of leg HT would: 1) improve calf muscle oxygenation, 2) enhance pain-free and maximal walking time, and 3) reduce blood pressure and the levels of ET-1 at rest and during exercise. Based upon the observations in cultured cells (Brunt et al, 2018), rodents (Chen et al, 2004), and patients with ankylosing spondylitis (Tarner et al, 2009) of reduced inflammation after exposure to heat stress, we further hypothesized that leg HT would reduce the plasma levels of interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF alpha).…”

“…We first demonstrated that a single session of leg HT using customized, liquid-circulating trousers perfused with warm water increases leg blood flow by ~100% and reduces blood pressure (BP) and the circulating levels of ET-1 in symptomatic PAD patients (Neff et al, 2016). Further, we recently reported that repeated exposure to leg HT for 6 weeks improved perceived physical functioning and reduced the levels of ET-1 by 13% when compared to a sham treatment (Monroe et al, 2020). Other HT modalities, including sauna and water bath immersion, have also been shown to elicit beneficial adaptations in PAD patients, including an improvement in walking tolerance (Akerman et al, 2019;Pellinger et al, 2019;Shinsato et al, 2010;Tei et al, 2007).…”

A systematic review of the role of heat therapy for patients with intermittent claudication due to peripheral artery disease

“…17 All three studies measured ABPI. 17,22,23 Means difference testing demonstrated a statistically significant improvement in ABPI (p = 0.01; large ES 1.10, 95% CI: 0.20-1.99) favouring whole-body immersion compared to SEP. 17 Shinsato et al…”

“…Three studies met the inclusion criteria for intervention analysis. 17,22,23 Akerman et al compared heat therapy to a SEP, Shinsato et al compared heat therapy to usual care (best medical therapy) and Monroe et al compared heat therapy to a sham treatment. None of the heat therapy treatments (including duration, frequency and type) in the studies were the same ( Table 1).…”