Cardiovascular Responses to Heat Waves in the Elderly

Active, not recruiting

• Conditions: Hyperthermia; Aging
• Interventions: Other: Simulated heat wave

• Registration Number: NCT04538144
• Lead Sponsor: University of Texas Southwestern Medical Center

Brief Summary

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

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), 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 Timeline

• Study First Submitted: 2020-08-28
• Study First Submitted QC: 2020-09-02
• Study First Posted: 2020-09-03
• Study Start: 2021-01-19
• Status Verified: 2024-01
• Last Update Submitted: 2024-01-29
• Last Update Posted: 2024-01-31
• Primary Completion: 2026-08-31
• Study Completion: 2026-08-31

Recruitment & Eligibility

• Status: ACTIVE_NOT_RECRUITING
• Sex: All
• Target Recruitment: 50

Inclusion Criteria

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

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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

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Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Arm && Interventions

Group	Intervention	Description
Younger participants	Simulated heat wave	Individuals aged 18-39 years
Older participants	Simulated heat wave	Individuals aged 65 years or older

Primary Outcome Measures

Name	Time	Method
Core body temperature	Prior to and throughout each simulated heat wave exposure; an average of 480 minutes.	Core body temperature will be measured from gastrointestinal temperature via an ingestible telemetric pill.
Measures of left ventricular function	Prior to, during, and after each simulated heat wave exposure; approximately 20 min each	Measures of left ventricular function, such as ventricular wall motion and ventricular filling, will be obtained from echocardiography images.

Secondary Outcome Measures

Name	Time	Method
Arterial blood pressure	Prior to and throughout each simulated heat wave exposure; an average of 480 minutes.	Arterial blood pressure will be measured using a standard arm blood pressure cuff
Cardiac output	Prior to, during, and after each simulated heat wave exposure; approximately 20 min each	Cardiac output (how much blood is ejected from the heart) will be measured using echocardiography and nitrous oxide rebreathing approaches.
Heart rate	Prior to and throughout each simulated heat wave exposure; an average of 480 minutes.	Heart rate will be measured from ECG electrodes attached to the participant
Skin temperature	Prior to and throughout each simulated heat wave exposure; an average of 480 minutes.	Skin temperature will be measured from small temperature sensitive electrodes attached to the participant's skin
Cerebral perfusion	Prior to, during, and after each simulated heat wave exposure; approximately 20 min each	Cerebral perfusion will be measured by doppler ultrasound of the internal carotid and vertebral arteries

Trial Locations

Locations (1)

Texas Health Presbyterian Hospital Dallas; 🇺🇸 Dallas, Texas, United States