Characterization of Myocardial Blood Flow During Heat Exposure

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

Official Title
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Characterization of the Increase and Distribution of Myocardial Blood Flow During Heat Exposure

Conditions
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Hot Weather; Adverse Effect, Healthy, Coronary Artery Disease, Aging

Intervention / Treatment
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* Other: Heat exposure


Participation Criteria
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Eligibility Criteria
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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

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Passive heat exposure<br> | Other: Heat exposure<br>* Participants will be exposed to heat exposure via a water-perfused suit to increase internal body temperature by 1.5 degrees Celsius.<br>|

What is the study measuring?
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Primary Outcome Measures

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

Secondary Outcome Measures

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

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Heat, PET imaging, Myocardial blood flow