Cardiovascular Responses to Heat Waves in the Elderly

October 21, 2025 updated by: Craig Crandall, University of Texas Southwestern Medical Center

Heat Waves in the Elderly: Reducing Thermal and Cardiovascular Consequences

The purpose of this study is to assess the cardiovascular responses of the elderly to heat wave conditions

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Heat waves are lethal and cause a disproportionate number of deaths in the elderly relative to any other age group. It is important to note that such deaths are primarily cardiovascular, not hyperthermia itself, in origin. Nevertheless, we know relatively little about the effects of aging on cardiovascular function during actual heat wave-like conditions. The central hypothesis of this work is that the elderly exhibit greater cardiovascular stress during heat wave conditions. Aim 1 will test the hypothesis that recognized impairments in thermoregulatory capacity in the elderly will culminate in heightened cardiovascular stress during prolonged exposure to heat wave conditions. Comprehensive cardiovascular and thermal responses in the elderly, relative to younger adults, will be evaluated during exposure to two prolonged heat wave conditions: hot and humid (replicating the 1995 Chicago heat wave) and very hot and dry (replicating the 2018 Los Angeles heat wave). The expected outcome from this body of work will re-shape our understanding of the consequences of aging on cardiovascular function during heat waves

Study Type

Interventional

Enrollment (Actual)

59

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Texas
      • Dallas, Texas, United States, 75231
        • Institute for Exercise and Environmental Medicine

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Study Population

The study population will be healthy younger and older individuals identified from the general population.

Description

Inclusion Criteria:

  • Healthy male and female individuals
  • 18-35 years or 65+ years of age
  • Free of any underlying moderate to serious medical conditions

Exclusion Criteria:

  • Known heart disease; other chronic medical conditions requiring regular medical therapy including cancer, diabetes, neurological diseases, uncontrolled hypertension, and uncontrolled hypercholesterolemia.
  • Taking of any medications (such as beta blockers and non-dihydropyridine calcium channel blockers) that have known influences on either cardiac function or sweating responses.
  • Abnormalities detected on routine screening.
  • Individuals who participate in a structured aerobic exercise training program at moderate to high intensities.
  • Current smokers, as well as individuals who regularly smoked within the past 3 years.
  • Body mass index of greater than 30 kg/m^2
  • Pregnant individuals

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Non-Randomized
  • Interventional Model: Crossover Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Other: Younger participants: Hot/Dry then Hot/Humid
Individuals aged 18-39 years who completed the hot/dry trial first and the hot/humid trial second.
Other: Hot and Humid Trial
Individuals will be exposed to a simulated heat wave (hot and humid) condition.
Other: Hot and Dry Trial
Individuals will be exposed to a simulated heat wave (hot and dry) condition.
Other: Older participants: Hot/Dry then Hot/Humid
Individuals aged 65 years or older who completed the hot/dry trial first and the hot/humid trial second.
Other: Hot and Humid Trial
Individuals will be exposed to a simulated heat wave (hot and humid) condition.
Other: Hot and Dry Trial
Individuals will be exposed to a simulated heat wave (hot and dry) condition.
Other: Younger participants: Hot/Humid then Hot/Dry
Individuals aged 18-39 years who completed the hot/humid trial first and the hot/dry trial second.
Other: Hot and Humid Trial
Individuals will be exposed to a simulated heat wave (hot and humid) condition.
Other: Hot and Dry Trial
Individuals will be exposed to a simulated heat wave (hot and dry) condition.
Other: Older participants: Hot/Humid then Hot/Dry
Individuals aged 65 years or older who completed the hot/humid trial first and the hot/dry trial second.
Other: Hot and Humid Trial
Individuals will be exposed to a simulated heat wave (hot and humid) condition.
Other: Hot and Dry Trial
Individuals will be exposed to a simulated heat wave (hot and dry) condition.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Core Body Temperature
Time Frame: Prior to and after the 3-hour simulated heat wave exposure.
Core body temperature will be measured via a telemetric pill or rectal temperature probe.
Prior to and after the 3-hour simulated heat wave exposure.
Change in Peak Mitral Annular Systolic Velocity (S')
Time Frame: Prior to, during, and after each simulated heat wave exposure; approximately 20 min each
Change in peak mitral annular systolic velocity was measured by tissue doppler imaging.
Prior to, during, and after each simulated heat wave exposure; approximately 20 min each

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Ending Skin Temperature
Time Frame: At the end of the 3-hour simulated heat wave exposure.
Skin temperature will be measured from small temperature sensitive electrodes attached to the participant's skin.
At the end of the 3-hour simulated heat wave exposure.
Ending Heart Rate
Time Frame: At the end of the 3-hour simulated heat wave exposure.
Heart rate will be measured via ECG electrodes attached to the participant
At the end of the 3-hour simulated heat wave exposure.
Ending Mean Arterial Pressure
Time Frame: At the end of the 3-hour simulated heat wave exposure.
Arterial blood pressure will be measured using a standard arm blood pressure cuff.
At the end of the 3-hour simulated heat wave exposure.
Change in Cardiac Output
Time Frame: Prior to and after the 3-hour simulated heat wave exposure.
Cardiac output (how much blood is ejected from the heart per minute) was measured using echocardiography.
Prior to and after the 3-hour simulated heat wave exposure.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Texas Southwestern Medical Center

Collaborators

National Institute on Aging (NIA)
American Heart Association

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 19, 2021

Primary Completion (Actual)

February 20, 2023

Study Completion (Actual)

February 20, 2023

Study Registration Dates

First Submitted

August 28, 2020

First Submitted That Met QC Criteria

September 2, 2020

First Posted (Actual)

September 3, 2020

Study Record Updates

Last Update Posted (Estimated)

October 23, 2025

Last Update Submitted That Met QC Criteria

October 21, 2025

Last Verified

October 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • STU_2019_1759
  • 1R01AG069005-01 (U.S. NIH Grant/Contract)

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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