Impact of Extreme Heat on Myocardial Blood Flow and Flow Reserve in Young and Older Adults

The University of Texas System (UT)

Status: Enrolling

Conditions: Aging; Heat Stress; Hyperthermia; Heat Strain

Treatments: Other: Ambient heat stress

Study type: Observational

Funder types: Other; NIH

Identifiers

NCT06842784

STU_2019_1759_MCE

1R01AG069005 (U.S. NIH Grant/Contract)

Details and patient eligibility

About

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.

Enrollment: 24 estimated patients

Sex: All

Ages: 18+ years old

Volunteers: Accepts Healthy Volunteers

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.
• 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

Trial design

24 participants in 2 patient groups

Young participants

Description:

Individuals aged 18-39 years

Treatment:

Other: Ambient heat stress

Older participants

Description:

Individuals aged 65 years or older

Treatment:

Other: Ambient heat stress