Characterization of Myocardial Blood Flow During Heat Exposure

Overview

The purpose of this study is to determine the increase in myocardial blood flow during heat exposure and how this response is affected by age and coronary artery disease.

Full Title of Study: “Characterization of the Increase and Distribution of Myocardial Blood Flow During Heat Exposure”

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: N/A
    • Intervention Model: Single Group Assignment
    • Primary Purpose: Basic Science
    • Masking: None (Open Label)
  • Study Primary Completion Date: July 31, 2022

Detailed Description

As a result of climate change, heat waves are more frequent and of longer duration. These heat waves are associated with a higher risk of hospitalization and mortality in vulnerable populations such as people with cardiovascular disease or cardiovascular risk factors. It has been hypothesized that this observation may be explained by the cardiovascular demands imposed by heat exposure.

Heat exposure requires increased cardiac work that may place individuals with cardiovascular disease at risk of ischemic events if the metabolic demand is not compensated by adequate blood supply. However, the extent to which cardiac work increases during heat exposure remains unknown. The aim of this study is to test the hypothesis that heat exposure increases myocardial blood flow and that this increase is affected by age and coronary artery disease.

Interventions

  • Other: Heat exposure
    • Participants will be exposed to heat exposure via a water-perfused suit to increase internal body temperature by 1.5 degrees Celsius.

Arms, Groups and Cohorts

  • Experimental: Passive heat exposure

Clinical Trial Outcome Measures

Primary Measures

  • Global myocardial blood flow
    • Time Frame: Change from baseline to an increase in internal body temperature of 1.5 degrees Celsius, estimated average = 90 minutes
    • Measured by PET imaging with 82rubidium

Secondary Measures

  • Myocardial blood flow distribution
    • Time Frame: Change from baseline to an increase in internal body temperature of 1.5 degrees Celsius, estimated average = 90 minutes
    • Measured by PET imaging with 82rubidium
  • Heart rate
    • Time Frame: Change from baseline to an increase in internal body temperature of 1.5 degrees Celsius, estimated average = 90 minutes
    • Measured by electrocardiogram
  • Systolic and diastolic blood pressure
    • Time Frame: Change from baseline to an increase in internal body temperature of 1.5 degrees Celsius, estimated average = 90 minutes
    • Measured by automated auscultation of the brachial artery
  • Body weight
    • Time Frame: Measured before and after heat exposure, estimated average = 120 minutes
    • Measured with a scale

Participating in This Clinical Trial

Inclusion Criteria for Healthy Participants:

  • Age between 18-40 years or 60-80 years
  • Non-smoker (≥1 year)
  • Non-diabetic
  • Normal kidney function
  • Body Mass Index <30 kg/m2
  • Resting blood pressure <140/<90 mmHg
  • Resting heart rate <100 bpm

Inclusion Criteria for Participants with Coronary Artery Disease:

  • Age between 60-80 years old
  • History of angiographic coronary disease (≥70% arterial diameter narrowing of at least one major epicardial coronary artery) and/or prior coronary revascularization and/or documented prior acute coronary syndrome and/or perfusion defect during stress testing
  • Stable medications (≥4 weeks) prior to enrollment

Exclusion Criteria for Healthy Participants:

  • Diagnosis of heart, vascular, respiratory, neurological or metabolic disease and/or a prescription of medication for the treatment of these diseases
  • Pregnancy or lactation
  • Dyslipidemia not controlled by medication

Exclusion Criteria for Participants with Coronary Artery Disease:

  • Recent hospitalization (<3 months) related to coronary artery disease
  • Unstable angina (<3 months)
  • Recent coronary artery bypass surgery (<3 months)
  • Left branch block
  • Ejection fraction <40% and/or clinical signs of heart failure
  • Severe valvular heart disease
  • Hypertension not controlled by medication
  • Diabetes not controlled by medication and/or serious complications related to diabetes

Gender Eligibility: All

Minimum Age: 18 Years

Maximum Age: 80 Years

Are Healthy Volunteers Accepted: Accepts Healthy Volunteers

Investigator Details

  • Lead Sponsor
    • Montreal Heart Institute
  • Provider of Information About this Clinical Study
    • Principal Investigator: Daniel Gagnon, Principal Investigator – Montreal Heart Institute
  • Overall Official(s)
    • Daniel Gagnon, PhD, Principal Investigator, Montreal Heart Institute
  • Overall Contact(s)
    • Daniel Gagnon, PhD, 514-374-1480, daniel.gagnon.3@umontreal.ca

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