Heat Therapy to Reduce Pain and Improve Walking Tolerance

Study Overview
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Brief Summary
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The purpose of this study is to investigate whether exposure to heat therapy improves calf muscle oxygenation and enhances walking tolerance in patients with symptomatic Peripheral Arterial Disease (PAD).

Detailed Description
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Heat therapy (HT) is an emerging non-invasive approach that has been shown to enhance vascular function of the leg in old individuals. The objective of this study is to establish evidence to support the validity of HT in improving walking tolerance on PAD patents. Subjects will complete baseline assessments for eligibility, including medical history and ankle-brachial measurement. Eligible participants will be asked to report to the laboratory on 4 different occasions. The purpose of visits 1 and 2 The central hypothesis of this study, based on preliminary data, is that exposure to HT will enhance the oxygenation of calf muscles during exercise and as a result, the onset of pain will be delayed and walking performance will be enhanced. is to familiarize the participants with the treadmill walking test and assess the test-retest reliability of maximal walking time determination. On visits 3 and 4 participants will receive either heat treatment or a control treatment for 80 min prior to undergoing a symptom-limited incremental test on the treadmill.

Official Title
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Heat Therapy to Reduce Leg Pain and Improve Walking Tolerance in Patients With Symptomatic Peripheral Artery Disease

Conditions
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Peripheral Arterial Disease

Intervention / Treatment
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* Device: Control/Sham Treatment
* Device: Heat Therapy (HT)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Men and women with stable symptomatic leg claudication for 6 months or longer. Ankle brachial index < 0.9 Exclusion Criteria: Heart Failure COPD Critical limb ischemia Prior amputation Exercise-limiting co-morbidity Recent infrainguinal revascularization or planned during study period Plans to change medical therapy during duration of the study Active cancer Chronic kidney disease HIV positive, active HBV or HCV disease Presence of any unsuitable comorbid clinical condition in the opinion of the PI Peripheral neuropathy, numbness or paresthesia in the legs Morbid obesity, BMI > 36 or unable to fit in water-circulating pants Open wounds or ulcers on the extremity Unable to walk on the treadmill
Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Sham, then heat therapy<br>Participants were fitted with liquid-circulating trousers. In the sham-treatment session, water at 33℃ was circulated through the trousers for 90 min using a water pump (HTP-1500, Adroit Medical, Louden, Tennessee, United States). At least 72 hrs after completion of the sham treatment session, participants returned to the laboratory and received the heat therapy (HT) treatment. In the HT session, water at 43℃ was circulated through the tube-lined trousers using a heated bath circulator (HT; Aqua Relief Systems, Akron, Ohio, United States) with the goal of increasing leg skin temperature to 37-38ºC. | Device: Control/Sham Treatment<br>* Water at 33ºC was circulated through water-circulating trousers.<br>Device: Heat Therapy (HT)<br>* Water at 42-43ºC was circulated through the water-circulating trousers.<br>|
| Experimental: Heat therapy, then sham<br>Participants were fitted with liquid-circulating trousers. In the HT session, water at 43℃ was circulated through the tube-lined trousers using a heated bath circulator (HT; Aqua Relief Systems, Akron, Ohio, United States) with the goal of increasing leg skin temperature to 37-38ºC. At least 72 hrs after completion of the sham treatment session, participants returned to the laboratory and received the sham treatment. In the sham-treatment session, water at 33℃ was circulated through the trousers for 90 min using a water pump (HTP-1500, Adroit Medical, Louden, Tennessee, United States). | Device: Control/Sham Treatment<br>* Water at 33ºC was circulated through water-circulating trousers.<br>Device: Heat Therapy (HT)<br>* Water at 42-43ºC was circulated through the water-circulating trousers.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Peak Walking Time | Exercise testing was performed in a motorized treadmill (Pro 27, Woodway, St. Paul, Minnesota, United States) following the Gardner-Skinner protocol, which consists of walking at a constant speed (2 mph) with a 2%-grade increase every 2 min (Gardner et al., 1991). Participants received standardized instructions and were asked to indicate when they first began to feel leg pain with a thumbs up signal (defined as COT), and then give a thumbs down signal when they could no longer continue with the test (defined as PWT). | Immediately after exposure to a single session of heat therapy or sham treatment, up to  20 min | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Claudication Onset Time | Exercise testing was performed in a motorized treadmill (Pro 27, Woodway, St. Paul, Minnesota, United States) following the Gardner-Skinner protocol, which consists of walking at a constant speed (2 mph) with a 2%-grade increase every 2 min (Gardner et al., 1991). Participants received standardized instructions and were asked to indicate when they first began to feel leg pain with a thumbs up signal (defined as COT), and then give a thumbs down signal when they could no longer continue with the test (defined as PWT). | The exercise test was performed immediately after exposure to a single session of either heat therapy or sham, up to  20 min | 
| Peak Systolic Blood Pressure | Blood pressure was measured in the left arm using a stethoscope and sphygmomanometer during exercise. | The exercise test was performed immediately after exposure to a single session of either heat therapy or sham, up to  20 min | 
| Peak Diastolic Blood Pressure | Blood pressure was measured in the left arm using a stethoscope and sphygmomanometer prior and during exercise | The exercise test was performed immediately after exposure to a single session of either heat therapy or sham, up to  20 min | 
| Peak Calf Tissue Saturation Index | The tissue saturation index (TSI%) of the most symptomatic leg was assessed with a commercially available NIRS system (Portamon, Artinis Medical Systems, The Netherlands). | The exercise test was performed immediately after exposure to a single session of either heat therapy or sham, up to  20 min | 
| Post-exercise Plasma Endothelin-1 Concentration | Commercially available enzyme-linked immunosorbent assay kits were used to measure the plasma concentrations of ET-1 (DET100, Endothelin-1 Quantikine ELISA Kit, R&D Systems, Minneapolis, MN, United States) | The exercise test was performed immediately after exposure to a single session of either heat therapy or sham, up to  20 min. Ten minutes following completion of the incremental treadmill test, blood samples were obtained for the assessment of serum ET-1 |