Research Article

Influence of Acute Lower Limb Heating on Clinical Measures and Functional Capacity in Peripheral Artery Disease

Published: 2016-4

Journal: The FASEB Journal

DOI: 10.1096/fasebj.30.1_supplement.954.8

Abstract

Acute local heating of human limbs produces increases in conduit artery blood flow and shear stress, and these increases are comparable in magnitude to those achieved during both whole body and single limb exercise. Numerous studies have shown that acute exposure to periods of high shear stress; whether by exercise or heating, results in increased conduit artery flow‐mediated vasodilation immediately following exposure. However, it is unknown if these transient increases in conduit artery vascular function are 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 lower limb heating (for 15 or 45 minutes) increases resting popliteal artery blood flow and 6 minute walk distance (6MWD) in patients with PAD. One 71 year old male patient with PAD (Intermittent Claudication, Fontaine stage II) attended the laboratory for a screening visit and two experimental visits during which bilateral lower limb heating was carried out via water bath immersion (42C; 40 cm depth) for either 15 or 45 minutes. Clinical and cardiovascular measures including resting single leg popliteal artery blood flow (Doppler ultrasound), ABI, and toe oxygen saturation (pulse oximetry) were carried out prior to and beginning 10 minutes following limb heating. Popliteal vascular conductance (PVC) was calculated as flow/mean arterial pressure. 6MWD and time/distance to pain onset were measured on the screening day and each experimental day 45 minutes post‐leg immersion. The 15 minute leg heating trial increased popliteal artery blood flow from 113.7 to 169.1 mL min−1(48.6%), PVC from 1.41 to 2.15 mL min−1mmHg−1(52.4%), and 6MWD from 660 to 800 feet (21.2%). The 45 minute leg heating trial increased popliteal artery blood flow from 91.8 to 159.3 mL min−1(73.5%), PVC from 1.17 to 1.99 mL min−1mmHg−1(70.6%), and 6MWD from 660 to 770 feet (16.7%). Furthermore, the subject reported onset of leg pain at 2:45 and 325 feet of the screening visit 6MW, which was delayed until 3:00 and 500 feet after the 15 minute leg heating trial and until 4:00 and 550 feet after the 45 minute leg heating trial. Neither of the heating trials evoked changes in ABI or toe oxygen saturation. Although data collection is ongoing, these initial findings suggest that acute lower limb heating in patients with PAD may increase exercise tolerance which, if undertaken routinely, could increase either patient adherence to or efficacy of exercise prescription in this population. Support or Funding Information Supported by the Salisbury University Faculty Mini‐Grant

Faculty Members

  • Grant H. Simmons - Medical Pharmacology & Physiology University of Missouri School of Medicine Columbia MO
  • Thomas K. Pellinger - Health Sciences Salisbury University Salisbury MD
  • Catherine B. Pearce - Health Sciences Salisbury University Salisbury MD

Themes

  • Vascular function
  • Peripheral artery disease (PAD)
  • Blood flow dynamics
  • Oxygen supply and demand
  • Acute local heating
  • Therapeutic interventions for claudication

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