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Local Heat Stress in Autonomic Failure Patients With Supine Hypertension

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT02417415
Recruitment Status : Suspended (Recruitment is temporarily suspended due to COVID-19 outbreak)
First Posted : April 15, 2015
Last Update Posted : April 10, 2020
Information provided by (Responsible Party):
Italo Biaggioni, Vanderbilt University

Brief Summary:
Patients with autonomic failure are characterized by disabling orthostatic hypotension (low blood pressure on standing), and at least half of them also have high blood pressure while lying down (supine hypertension). Exposure to heat, such as in hot environments, often worsens their orthostatic hypotension. The causes of this are not fully understood. The purpose of this study is to evaluate whether applying local heat over the abdomen of patients with autonomic failure and supine hypertension would decrease their high blood pressure while lying down. This will help us better understand the mechanisms underlying this phenomenon, and may be of use in the treatment of supine hypertension.

Condition or disease Intervention/treatment Phase
Hypertension Pure Autonomic Failure Multiple System Atrophy Autonomic Failure Other: Passive heat stress Other: Control (non-heating) Not Applicable

Detailed Description:

Primary autonomic failure is a neurodegenerative condition characterized by severe impairment of the autonomic nervous system. The clinical hallmark of autonomic failure is disabling orthostatic hypotension, but at least half of patients are also hypertensive while lying down. This supine hypertension can be severe and associated with end-organ damage and worsening of orthostatic hypotension due to increased pressure natriuresis. It also complicates the management of these patients by limiting the use of daytime pressor agents for the treatment of orthostatic hypotension.

It is well known that heat exposure (e.g. hot weather or a hot bath or shower) produces an acute and temporary worsening of orthostatic hypotension in autonomic failure patients. However, the mechanisms underlying this phenomenon are completely unexplored. Factors that may predispose autonomic failure patients to the acute lowering blood pressure effects of heat stress include 1) impaired heat dissipation due to inability to sweat, 2) preserved heat-mediated skin vasodilation, and 3) blunted sympathetic hemodynamic responses to maintain blood pressure. In this study, we test the hypothesis that moderate levels of local (abdominal) passive heat stress will lower blood pressure in autonomic failure patients with supine hypertension.

To test this hypothesis, we propose this pilot study with the following specific aims:

  1. To evaluate the acute blood pressure effects of local passive heat stress in autonomic failure patients with supine hypertension, we will compare changes in BP between controlled local heat stress (~44ºC) using a commercial heating pad that covers the abdomen and part of the torso, and a control (non-heating) study day using the same heating pad but turned off.
  2. To evaluate the mechanisms underlying BP changes during local heat stress, we will compare changes in hemodynamic parameters (cardiac output, stroke volume and peripheral vascular resistance), segmental fluid shifts (measured by segmental bioimpedance), skin blood flow and skin temperature between the heat and non-heating study days.

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Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 21 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Intervention Model Description: randomized, 2-arm crossover study (heat vs. sham)
Masking: None (Open Label)
Primary Purpose: Other
Official Title: Local Heat Stress in Autonomic Failure Patients With Supine Hypertension
Study Start Date : April 2015
Estimated Primary Completion Date : April 2021
Estimated Study Completion Date : September 2021

Arm Intervention/treatment
Experimental: Local Heat Stress
Passive heat-stress using a commercial heating pad applied over the abdomen and part of the torso
Other: Passive heat stress
Passive heat stress will be applied with a commercial heating pad that covers all the abdomen and part of the torso to provide local heating at ~44ºC continuously for 2 hr.
Other Name: Heating pad

Sham Comparator: Control (Non-heating)
Commercial heating pad applied over the abdomen and part of the torso but turned off
Other: Control (non-heating)
Heating pad will be applied over the abdomen and part of the torso but it will be turned off.
Other Name: sham

Primary Outcome Measures :
  1. Systolic blood pressure [ Time Frame: 2 hours of heat stress or when Tcore increases 1ºC ]
    Change from baseline in systolic blood pressure at the maximal Tcore (at 2 hr or Tcore +1ºC)

Secondary Outcome Measures :
  1. Hemodynamic measures [ Time Frame: 1 hour and 2 hours of heat stress or when Tcore increases 1ºC ]
    Changes in cardiac output, stroke volume and systemic vascular resistance

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 80 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Male and female patients, between 18-80 yrs., with primary autonomic failure (Parkinson Disease, Multiple System Atrophy, and Pure Autonomic Failure) and supine hypertension. Supine hypertension will be defined as SBP≥150 mmHg.
  • Patients able and willing to provide informed consent.

Exclusion Criteria:

  • Pregnancy
  • Significant cardiac, renal or hepatic illness, or with contraindications to administration of pressor agents or with other factors, which in the investigator's opinion would prevent the subject from completing the protocol including clinically significant abnormalities in clinical, mental or laboratory testing.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT02417415

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United States, Tennessee
Vanderbilt University
Nashville, Tennessee, United States, 37232
Sponsors and Collaborators
Vanderbilt University
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Principal Investigator: Italo Biaggioni, MD Vanderbilt University
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Responsible Party: Italo Biaggioni, Professor of Medicine, Vanderbilt University Identifier: NCT02417415    
Other Study ID Numbers: 141523
First Posted: April 15, 2015    Key Record Dates
Last Update Posted: April 10, 2020
Last Verified: April 2020
Keywords provided by Italo Biaggioni, Vanderbilt University:
Supine hypertension
Autonomic failure
Heat intolerance
Orthostatic hypotension
Heat stress
Additional relevant MeSH terms:
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Multiple System Atrophy
Shy-Drager Syndrome
Pure Autonomic Failure
Heat Stress Disorders
Vascular Diseases
Cardiovascular Diseases
Pathological Conditions, Anatomical
Primary Dysautonomias
Autonomic Nervous System Diseases
Nervous System Diseases
Basal Ganglia Diseases
Brain Diseases
Central Nervous System Diseases
Movement Disorders
Neurodegenerative Diseases
Wounds and Injuries