(885.3) Home-Based Leg Heat Therapy Does Not Improve Vascular Function in Patients with Symptomatic Peripheral Artery Disease

Poster Board Number: E301

Jacob Monroe (Indiana University School of Medicine , Purdue University), Jason Parker (Indiana University School of Medicine), Susan Perkins (Indiana University School of Medicine), Yan Han (Indiana University School of Medicine), Byung Joon Pae (Purdue University), Janet Klein (Indiana University School of Medicine), Raghu Motaganahalli (Indiana University School of Medicine), Bruno Roseguini (Purdue University)

INTRODUCTION

Patients with peripheral artery disease (PAD) suffer from severe exercise intolerance and accelerated rates of functional decline, resulting, in part, from significant endothelial cell dysfunction and the consequent impairment in leg blood flow. Unfortunately, few non-invasive therapeutic interventions have been shown to ameliorate the microvascular dysfunction in patients with PAD. Repeated exposure to heat therapy (HT) improves endothelial function in sedentary young individuals, but the effects of this therapy on vascular function in patients with PAD remain poorly defined. The objective of the present study was to test the hypothesis that 8 weeks of home-based leg HT would improve leg vascular function in patients with symptomatic PAD.

METHODS

Thirty-four patients with symptomatic PAD (66 ± 8 years, ankle-brachial index: 0.68 ± 0.12) were randomized into one of two groups: home-based leg HT (HT, n=18) or a control treatment (CON, n=16). Patients in both groups were provided with identical water-circulating trousers and a portable heating pump and were asked to apply the therapy daily (7 days/week, 90 min per session) for 8 consecutive weeks. The pump issued to participants circulated water through the trousers at 43ºC in the HT group and 33ºC in the control group. Laser-Doppler flowmetry was used  to measure red blood cell flux, an index of skin blood flow, during local skin heating to 39°C for 40 min, followed by 43ºC for 20 min. Cutaneous vascular conductance (CVC) was calculated as red blood cell flux divided by mean arterial pressure and expressed as a percentage of maximal vasodilation (%CVCmax). Calf skeletal muscle perfusion was assessed using arterial spin labeling magnetic resonance imaging (MRI) following circulatory occlusion of the thigh for 5 min.

RESULTS

Five participants were either withdrawn prior to study completion or failed to complete the 8-week follow-up visit. The remaining 29 participants were included in the final analysis (CON: n=14, HT: n=15). Two participants from CON and 4 from HT were unable to undergo the MRI scans.  At baseline, local skin heating to 39ºC increased %CVCmax to 55.8 ± 12.9% in CON and 52.5 ± 18.7% in the HT group. The change from baseline to 8 weeks in %CVCmax was similar between CON and HT (CON: -2.6 ± 13.9%, HT: -0.7 ± 16.3%, p=0.74). Peak calf blood flow during reactive hyperemia was comparable between groups at baseline (CON: 48.0 ± 24.6 ml/min/100g, HT: 43.8 ± 20.4 ml/min/100g, p=0.76). The change from baseline to 8 weeks in peak calf perfusion was also similar between CON and HT (CON: -4.8±21.9 ml/min/100g, HT: -2.8±11.0 ml/min/100g, p=0.84).

CONCLUSION

Eight weeks of home-based leg HT does not improve leg vascular function in patients with symptomatic PAD.

Support: NIH/NIA amp;ndash; 5R21AG053687