Impact of Extreme Heat on Myocardial Blood Flow and Flow Reserve in Young and Older Adults
Trial statusRecruiting
Trial phaseNot listed
Trial typeObservational
Biological sexAll
Age18+
SponsorUniversity of Texas Southwestern Medical Center
About this trial
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.
Eligibility criteria
This trial accepts healthy volunteersQualifiers
Healthy male and female individuals
18-35 years or 65+ years of age
Free of any underlying moderate to serious medical conditions
Disqualifiers
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.
Current smokers, as well as individuals who regularly smoked within the past 3 years.
Trial population
The study population will be healthy younger and older individuals identified from the general population.
Trial design
Design model
Cohort
Time perspective
Prospective
Treatments tested in this trial
Ambient heat stress
Other intervention3-hour ambient heating in 44°C and 20% relative humidity
Treatment groups
24 Participants
are divided into 2 treatment groupsGroup A: Young participants1 intervention
Group B: Older participants1 intervention
Trial outcomes
Primary outcomes
1
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.2
Myocardial blood flow
Measured via myocardial contrast echocardiography.
Time frame
The change from baseline to after 3 hours of heat stress.Secondary outcomes
1
Core temperature
Measured via ingestible telemetric pill.
Time frame
The change from baseline to after 3 hours of heat stress..2
Indices of left and right ventricular function
Measured via echocardiography.
Time frame
At baseline and after 3 hours of heat stress.3
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.4
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.Sponsors and contacts
Click on the lead sponsor to view all of their trials.
University of Texas Southwestern Medical Center
Lead sponsor
National Institute on Aging (NIA)
Collaborator
The American Society of Echocardiography
Collaborator
Source ClinicalTrials.gov