Effects of Heating on Exercise Pressor Reflex in Peripheral Artery Disease: Exercise Ability
- Conditions
- PAD
- Interventions
- Other: Without HeatingOther: Warm BathOther: Heating SuitOther: Lower limb warm water immersionOther: Neutral BathOther: Gardner walking protocol
- Registration Number
- NCT03900832
- Lead Sponsor
- Milton S. Hershey Medical Center
- Brief Summary
The study objectives of this projects are to examine the hypothesis that the sympathetic and blood pressure responses to exercise will be attenuated during and after heat exposure in patients with peripheral artery disease, via altering the sensitivity of the muscle afferent receptors.
- Detailed Description
Peripheral arterial disease (PAD) affects 8-12 million Americans and its cardinal symptom is leg pain during exercise, termed "intermittent claudication". The diagnosis of PAD involves measuring the ankle-brachial index (ABI, i.e. the systolic pressure in the ankle divided by the systolic pressure in the arm); values below 0.9 are indicative of large vessel obstruction. Intermittent claudication is the most common symptom of this disease and it regularly occurs during exercise/physical activity but is relieved promptly by rest. Previous studies suggest that as the exercise pressor reflex is activated in patients with PAD, BP and heart rate (HR) are exaggerated. The BP rises during walking in the PAD patients were significantly greater than that seen in healthy control subjects. A recent human study from our group further indicates that an early BP response occurred during plantar flexion exercise before claudication was noted by the subjects, which may suggest that the accentuated BP response was due to an augmented muscle mechanoreflex in PAD. Moreover, another recent study from our group also showed that PAD patients have augmented renal vasoconstriction during plantar flexion exercise.
It has been shown that exercise has benefits for patients with PAD. However, exercise becomes limited due to the pain and fatigue associated with the disease. Moreover, the augmented pressor response to exercise in PAD may increase the risk for the end organ damage (e.g. brain and/or heart). Thus, finding alternate/complimentary interventions that modulate the cardiovascular system and autonomic nervous system, and can be tolerated by the patients, would be beneficial.
One possible intervention is heat exposure, since acute bouts of exercise and acute heat exposure have similar acute effects on both the autonomic and cardiovascular systems. For example, both exercise and heat exposure increase body temperature, increase HR, increase cardiac output (CO), increase left ventricular ejection fraction (EF), and enhance myocardial function. In the peripheral circulation, both exercise and heat exposure increase limb blood flow , muscle blood flow, and skin blood flow. Moreover, recent studies suggest that whole body exposure improves the endothelium function in PAD patients (e.g. activates endothelial progenitor cells CD34+).
However, the effect of heat treatment on the ability of walking of PAD patients has not been examined. Moreover, it is unknown if heating can normalize/decrease the accentuated the pressor responses to exercise in PAD patients.
Recruitment & Eligibility
- Status
- RECRUITING
- Sex
- All
- Target Recruitment
- 32
All subjects
- Capable of giving informed consent
- Any race or ethnicity
- Men and women age 21- 85 years (inclusive)
- Fluent in written and spoken English
Patients with peripheral arterial disease (PAD)
- Diagnosed with PAD (i.e., ankle-brachial index below 0.9)
- Fontaine stage II or less - no pain while resting
- Satisfactory history and physical exam
Healthy subjects
- Satisfactory history and physical examination
- Free of acute medical conditions
For patients with PAD and Healthy subjects
- Age < 21 years
- Pregnant or nursing women
- Decisional impairment
- Prisoners
For patients with PAD
- History of CAD with symptoms of unstable angina or myocardial infarction (<6 months)
- History of epilepsy or seizure disorders
For healthy subjects
• Any other chronic diseases (heart, lung, neuromuscular disease or diabetes)
Study & Design
- Study Type
- INTERVENTIONAL
- Study Design
- CROSSOVER
- Arm && Interventions
Group Intervention Description PAD without heating Without Heating Subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol. PAD without heating Gardner walking protocol Subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol. Healthy subjects without heating Without Heating Subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol. Healthy subjects warm bath Warm Bath Subjects will take a warm bath. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol. PAD warm bath Warm Bath Subjects will take a warm bath. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol. PAD warm bath Gardner walking protocol Subjects will take a warm bath. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol. PAD neutral bath Gardner walking protocol Subjects will take a neutral bath. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol. PAD heating suit Heating Suit Whole body heating with the suit will be performed. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol. PAD heating suit Gardner walking protocol Whole body heating with the suit will be performed. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol. PAD lower limb warm water immersion Lower limb warm water immersion Subjects will place their lower legs in warm water. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol. PAD neutral bath Neutral Bath Subjects will take a neutral bath. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol. Healthy subjects warm bath Gardner walking protocol Subjects will take a warm bath. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol. Healthy subjects heat suit Heating Suit Whole body heating with the suit will be performed. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol. Healthy subjects without heating Gardner walking protocol Subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol. Healthy subjects neutral bath Gardner walking protocol Subjects will take a neutral bath. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol. PAD lower limb warm water immersion Gardner walking protocol Subjects will place their lower legs in warm water. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol. Healthy subjects neutral bath Neutral Bath Subjects will take a neutral bath. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol. Healthy subjects lower limb immersion Gardner walking protocol Subjects will place their lower legs in warm water. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol. Healthy subjects heat suit Gardner walking protocol Whole body heating with the suit will be performed. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol. Healthy subjects lower limb immersion Lower limb warm water immersion Subjects will place their lower legs in warm water. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol.
- Primary Outcome Measures
Name Time Method Heart Rate in beats per minute Recorded continuously during the 3-4 hour study visit Electrocardiogram (ECG) patches attached to a Cardiocap will monitor heart rat
Blood pressure in mmHg Recorded continuously during the 3-4 hour study visit Cuffs placed on a finger and arm will monitor blood pressure.
Walking time in minutes Recording walking time to fatigue (up to 22 minutes maximum) during of every 3-4 hour study visit. Walking time on treadmill using Gardner protocol
- Secondary Outcome Measures
Name Time Method Near infrared spectroscopy (NIRS) in arbitrary units Recorded continuously during the 3-4 hour study visit This system is designed specifically for non-invasive measurements of muscle tissue. The system measures the tissue saturation of the investigated muscle, called the 'tissue saturation index' (TSI).
Internal Temperature in degrees C Recorded continuously during the 3-4 hour study visit The internal temperature (Tcore) will be measured from the stomach/intestines via a telemetry pill swallowed by subjects.
Trial Locations
- Locations (1)
Penn State Milton S. Hershey Medical Center
🇺🇸Hershey, Pennsylvania, United States