An observational study in Aging, Heat Stress and Hyperthermia, sponsored by University of Texas Southwestern Medical Center. Active, not recruiting at 1 site in United States. Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-07-30.
Sponsored by University of Texas Southwestern Medical Center · Observational
Extreme heat causes a disproportionate number of hospitalizations and deaths in older adults relative to any other age group. Importantly, many hospitalizations and deaths are primarily due to cardiovascular events such as myocardial infarction. Previous data indicate that older adults have attenuated skin blood flow and sweating responses when exposed to heat, resulting greater increase in core body temperature. Despite these observations, relatively little is known about the risk for myocardial ischemia potentially contributing to the aforementioned higher morbidity and mortality in older adults during heat waves. The broad objective of this work is to determine the impact of ambient heat exposure on myocardial blood flow and flow reserve in young and older adults. Aim 1 will test the hypothesis that older adults exhibit attenuated myocardial flow reserve compared to young adults during heat stress. Aim 2 will determine if the percent of maximal myocardial flow reserve (assess via vasodilator stress) during heat exposure is higher in older adults compared to young adults. The expected outcome from this body of work will improve our understanding of the consequences of aging on cardiovascular responses to ambient heat stress.
111 studies on the registry are indexed under Heat Stress Disorders; 45 are open to participants now.
This study's planned enrollment of 24 is below the median of 55 across 13 observational studies indexed under Heat Stress Disorders.
Browse Heat Stress Disorders studies →University of Texas Southwestern Medical Center is the lead sponsor of 990 studies on the registry; 201 are open to participants now.
Of its 135 completed or terminated interventional studies of FDA-regulated products, 101 (75%) have results posted.
Counted across the registry records on this site, refreshed daily.
The study population will be healthy younger and older individuals identified from the general population.
Exclusion Criteria:
Individuals aged 18-39 years
Other: Ambient heat stress
Individuals aged 65 years or older
Other: Ambient heat stress
3-hour ambient heating in 44°C and 20% relative humidity
Myocardial flow reserve
Measured via myocardial contrast echocardiography.
Time frame: The difference in the change from baseline to a vasodilator stress test and the change from baseline to after 3-hours of heat stress.
Myocardial blood flow
Measured via myocardial contrast echocardiography.
Time frame: The change from baseline to after 3 hours of heat stress.
Core temperature
Measured via ingestible telemetric pill.
Time frame: The change from baseline to after 3 hours of heat stress..
Indices of left and right ventricular function
Measured via echocardiography.
Time frame: At baseline and after 3 hours of heat stress.
Heart rate
Measured via electrocardiogram.
Time frame: At baseline, during exercise- after 20 minutes and 2 hours in the heat, and at rest after 3 hours of heat stress.
Blood pressure
Measured via automated auscultation of the brachial artery.
Time frame: At baseline, during exercise- after 20 minutes and 2 hours in the heat, and at rest after 3 hours of heat stress.
Plan to share: No
No publications or documents are linked to this record.
This study is active, not recruiting, as verified in Aug 2025. You cannot join it, but the record below documents what was studied.
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University of Texas Southwestern Medical Center