Impact of Extreme Heat on Myocardial Blood Flow and Flow Reserve in Young and Older Adults
试验速览
- 阶段
- 不适用
- 状态
- 进行中（未招募）
- 入组人数
- 24
- 试验地点
- 1
- 主要终点
- Myocardial flow reserve
研究概览
简要总结
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.
研究设计
- 研究类型
- Observational
- 观察模型
- Cohort
- 时间视角
- Prospective
入排标准
- 年龄范围
- 18 Years 至 —（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •Healthy male and female individuals
- •18-35 years or 65+ years of age
- •Free of any underlying moderate to serious medical conditions
排除标准
- •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
研究组 & 干预措施
Young participants
Individuals aged 18-39 years
干预措施: Ambient heat stress (Other)
Older participants
Individuals aged 65 years or older
干预措施: Ambient heat stress (Other)
结局指标
主要结局
Myocardial flow reserve
时间窗: The difference in the change from baseline to a vasodilator stress test and the change from baseline to after 3-hours of heat stress.
Measured via myocardial contrast echocardiography.
Myocardial blood flow
时间窗: The change from baseline to after 3 hours of heat stress.
Measured via myocardial contrast echocardiography.
次要结局
- Core temperature(The change from baseline to after 3 hours of heat stress..)
- Indices of left and right ventricular function(At baseline and after 3 hours of heat stress.)
- Heart rate(At baseline, during exercise- after 20 minutes and 2 hours in the heat, and at rest after 3 hours of heat stress.)
- Blood pressure(At baseline, during exercise- after 20 minutes and 2 hours in the heat, and at rest after 3 hours of heat stress.)
研究者
James MacNamara
Assistant Professor
University of Texas Southwestern Medical Center