IEEM-Heat and Heart Failure

We will test the hypothesis that increasing skin wetness, and thus evaporative cooling, will attenuate the increase in core body temperature and accompanying cardiac stress during heat wave conditions in individuals with congestive heart failure. Secondly, we propose that wearing a water-saturated T-shirt will also be beneficial to attenuate the increase in core body temperature and accompanying cardiac stress during heat wave conditions in individuals with congestive heart failure. To accomplish these objectives, individuals with congestive heart failure and otherwise healthy control individuals will be exposed to the simulated heat wave condition (hot and dry) with the following cooling modalities: A) control trial (no limb immersion or skin wetting), B) skin wetting only trial, and C) water-saturated T-shirt trial in a randomized crossover fashion. Thermoregulatory and cardiovascular responses will be evaluated throughout these simulated heat wave exposures.

Primary outcomes variables will be skin and core temperatures, while secondary variables will include measures of cardiovascular stress, myocardial perfusion, heart rate, and echo-based measures of cardiac function.

Study Overview

• Status: Recruiting
• Conditions: Heart Failure; Hyperthermia
• Intervention / Treatment: Other: Control Trial; Other: Skin-Wetting Trial; Other: Water-saturated T-shirt trial

• Study Type: Interventional
• Enrollment (Estimated): 88
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Craig Crandall, PhD; Phone Number: 214-345-4623; Email: craigcrandall@texashealth.org
• Study Contact Backup: Name: Rachel Cottle, PhD; Phone Number: 214-345-4737; Email: rachelcottle@texashealth.org

Study Locations

• United States
  • Texas
    • Dallas, Texas, United States, 75231
      • Recruiting
      • Institute for Exercise and Environmental Medicine - Texas Health Presbyterian Hospital Dallas
      • Contact: Erin M Harper, B.S.; Phone Number: 214-345-4737; Email: erinharper@texashealth.org
      • Contact: Craig G Crandall, PhD; Phone Number: 214-345-4623; Email: craigcrandall@texashealth.org

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria for healthy control participants:

• Participants must be free of any significant underlying medical problems based upon a detailed medical history and physical exam, and normal resting electrocardiogram. Participants must be 45+ years.

Exclusion Criteria for healthy control participants:

• Known heart disease; other chronic medical conditions requiring regular medical therapy including cancer, diabetes, neurological diseases, and uncontrolled hypertension, lung disease, etc.; as well as serious abnormalities detected on routine screening. Current smokers, as well as individuals who regularly smoked within the past 12 months, will be excluded. Subjects who cannot be age and gender matched to an individual in the heart failure group will be excluded.

Inclusion Criteria for Participants with CHF:

- The participant must have a diagnosis of congestive heart failure (e.g., heart failure with reduced ejection fraction), with the severity categorized as New York Heart Association (NYHA) class II or III. Participants must be 45+ years.

Exclusion Criteria for Participants with CHF:

-Patients who do not have confirmed diagnosis of NYHA class II or III heart failure will be excluded from the clinical group. Potential participants with cancer, diabetes, neurological disease, lung disease, and/or uncontrolled hypertension will be excluded. Potential participants with a left bundle branch block on ECG will be excluded. Patients on anticoagulant therapy will also be excluded. Current smokers, as well as individuals who regularly smoked within the past 12 months, will be excluded. Further exclusions will include severe valvular or congenital heart disease, acute myocarditis, NYHA Class IV heart failure, and/or manifest/provocable ischemic heart disease.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Individuals with Congestive Heart Failure (CHF)	Other: Control Trial; All participants will be exposed to a period of hyperthermia (hot and dry). In this condition, participants will not be given an experimental cooling modality.; Other: Skin-Wetting Trial; All participants will be exposed to a period of hyperthermia (hot and dry). In this condition, participants will also be sprayed with water periodically.; Other: Water-saturated T-shirt trial; All participants will be exposed to a period of hyperthermia (hot and dry). In this condition, participants will also wear a T-shirt that has been saturated with water.
Active Comparator: Individuals without Congestive Heart Failure (Control)	Other: Control Trial; All participants will be exposed to a period of hyperthermia (hot and dry). In this condition, participants will not be given an experimental cooling modality.; Other: Skin-Wetting Trial; All participants will be exposed to a period of hyperthermia (hot and dry). In this condition, participants will also be sprayed with water periodically.; Other: Water-saturated T-shirt trial; All participants will be exposed to a period of hyperthermia (hot and dry). In this condition, participants will also wear a T-shirt that has been saturated with water.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Core Body Temperature while wearing a water-saturated T-shirt	Core body temperature will be measured from gastrointestinal temperature via an ingestible telemetric pill or rectal temperature via telemetric pill suppository or rectal thermistor. Core body temperature will be measured at baseline as well as at the end of the hyperthermia simulation. The difference of those temperatures will reflect the change in core body temperature.	Prior to and after each simulated heat wave exposure (approximately 210 minutes.)
Change in Core Body Temperature in Skin-Wetting Trial	Core body temperature will be measured from gastrointestinal temperature via an ingestible telemetric pill or rectal temperature via telemetric pill suppository or rectal thermistor. Core body temperature will be measured at baseline as well as at the end of the hyperthermia simulation. The difference of those temperatures will reflect the change in core body temperature.	Prior to and after each simulated heat wave exposure (approximately 210 minutes.)
Change in Core Body Temperature in Control Trial	Core body temperature will be measured from gastrointestinal temperature via an ingestible telemetric pill or rectal temperature via telemetric pill suppository or rectal thermistor. Core body temperature will be measured at baseline as well as at the end of the hyperthermia simulation. The difference of those temperatures will reflect the change in core body temperature.	Prior to and after each simulated heat wave exposure (approximately 210 minutes.)
Change in Skin Temperature in while wearing a water-saturated T-shirt	Skin temperature will be measured from small temperature sensitive electrodes attached to the participant's skin. Skin temperature will be measured at baseline as well as at the end of the hyperthermia simulation. The difference of those temperatures will reflect the change in skin temperature.	Prior to and after each simulated heat wave exposure (approximately 210 minutes.)
Change in Skin Temperature in Skin-Wetting Trial	Skin temperature will be measured from small temperature sensitive electrodes attached to the participant's skin. Skin temperature will be measured at baseline as well as at the end of the hyperthermia simulation. The difference of those temperatures will reflect the change in skin temperature.	Prior to and after each simulated heat wave exposure (approximately 210 minutes.)
Change in Skin Temperature in Control Trial	Skin temperature will be measured from small temperature sensitive electrodes attached to the participant's skin. Skin temperature will be measured at baseline as well as at the end of the hyperthermia simulation. The difference of those temperatures will reflect the change in skin temperature.	Prior to and after each simulated heat wave exposure (approximately 210 minutes.)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Heart Rate while wearing a water-saturated T-shirt	Heart rate will be measured from ECG electrodes attached to the participant. Heart rate will be measured at baseline as well as at the end of the hyperthermia simulation. The difference of those heart rates will reflect the change in heart rate.	Prior to and after each simulated heat wave exposure (approximately 210 minutes.)
Change in Heart Rate in Skin-Wetting Trial	Heart rate will be measured from ECG electrodes attached to the participant. Heart rate will be measured at baseline as well as at the end of the hyperthermia simulation. The difference of those heart rates will reflect the change in heart rate.	Prior to and after each simulated heat wave exposure (approximately 210minutes.)
Change in Heart Rate in Control Trial	Heart rate will be measured from ECG electrodes attached to the participant. Heart rate will be measured at baseline as well as at the end of the hyperthermia simulation. The difference of those heart rates will reflect the change in heart rate.	Prior to and after each simulated heat wave exposure (approximately 210minutes.)
Rate Pressure Product while wearing a water-saturated T-shirt	Rate Pressure Product is calculated by multiplying Systolic Blood Pressure and Heart Rate.	At the end of each heat wave exposure. Approximately 210minutes after the start of the heat wave simulation.
Rate Pressure Product in Skin-Wetting Trial	Rate Pressure Product is calculated by multiplying Systolic Blood Pressure and Heart Rate.	At the end of each heat wave exposure. Approximately 210minutes after the start of the heat wave simulation.
Rate Pressure Product in Control Trial	Rate Pressure Product is calculated by multiplying Systolic Blood Pressure and Heart Rate.	At the end of each heat wave exposure. Approximately 210minutes after the start of the heat wave simulation.
Change in Cardiac Output while wearing a water-saturated T-shirt	Cardiac output (how much blood is ejected from the heart) will be measured using echocardiography. Cardiac output will be measured at baseline as well as at the end of the hyperthermia simulation. The difference of those heart rates will reflect the change in cardiac output.	Prior to and after each simulated heat wave exposure (approximately 210 minutes.)
Change in Cardiac Output in Skin-Wetting Trial	Cardiac output (how much blood is ejected from the heart) will be measured using echocardiography. Cardiac output will be measured at baseline as well as at the end of the hyperthermia simulation. The difference of those heart rates will reflect the change in cardiac output.	Prior to and after each simulated heat wave exposure (approximately 210 minutes.)
Cardiac Output in Control Trial	Cardiac output (how much blood is ejected from the heart) will be measured using echocardiography. Cardiac output will be measured at baseline as well as at the end of the hyperthermia simulation. The difference of those heart rates will reflect the change in cardiac output.	Prior to and after each simulated heat wave exposure (approximately 210 minutes.)

Collaborators and Investigators

• Sponsor: University of Texas Southwestern Medical Center
• Collaborators: National Institute on Aging (NIA)

Study record dates

Study Major Dates

• Study Start (Actual): October 1, 2025
• Primary Completion (Estimated): July 1, 2030
• Study Completion (Estimated): July 1, 2030

Study Registration Dates

• First Submitted: April 29, 2025
• First Submitted That Met QC Criteria: April 29, 2025
• First Posted (Actual): May 8, 2025

Study Record Updates

• Last Update Posted (Actual): May 26, 2026
• Last Update Submitted That Met QC Criteria: May 21, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: cardiovascular; heat wave; myocardial perfusion; cooling strategies
• Additional Relevant MeSH Terms: Cardiovascular Diseases; Wounds and Injuries; Heart Diseases; Body Temperature Changes; Heat Stress Disorders; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Hyperthermia; Heart Failure
• Other Study ID Numbers: STU20250699; R01AG069005 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No