Cardiovascular Responses to Cold in Hypertension (ColdHTN)
Wintertime is associated with increased morbidity and mortality and a majority is related to cardiovascular causes, such as myocardial infarctions, heart failures, and strokes. It is also known, that both acute and long-term cold exposure increase blood pressure and cardiac workload, and this may contribute to the observed excess morbidity and mortality during the cold season.
Although the effects of cold on blood pressure are known among healthy people, these responses among risk groups, such as hypertensive people, are not established. In addition, changes in cardiac electrical activity or autonomic regulation are largely unknown. The cardiovascular responses in the cold could be different among hypertensive people because of disturbances in the circulatory regulation or function, such as aortic stiffening and increased vasomotor tone of peripheral arteries due to endothelial dysfunction associated with the disease. To assess this, a controlled experiment employing a cold exposure similar to everyday winter circumstances in a subarctic climate was performed.
|Study Design:||Time Perspective: Cross-Sectional|
|Official Title:||Cardiovascular Responses to Cold Exposure in Hypertension|
- Blood pressure response of hypertensive and normotensive subjects to cold exposure [ Time Frame: 2 hours (measured within the controlled experiment) ] [ Designated as safety issue: No ]The study assesses the blood pressure response of hypertensive and normotensive subjects to facial cooling. Blood pressure is measured before (warm, +18°C), during (cold, 15°C) and after (warm, +18°C) the employed cold exposure. The duration of each of these exposures are 30, 15 and 30 min.
- Cardiac autonomic regulation [ Time Frame: 2 hours (measured within each controlled experiment), ECG recorded continuously ] [ Designated as safety issue: No ]ECG is recorded continuously during the controlled experiment (15 min warm 18 C, 15 min cold exposure -15 C and 20 min 18 C) from where cardiac electrical function, as well as autonomic nervous system regulation is assessed.
|Study Start Date:||January 2010|
|Study Completion Date:||November 2011|
|Primary Completion Date:||November 2011 (Final data collection date for primary outcome measure)|
Hypertensive subjects are exposed to brief cold exposure (-15 C for 15 min) mainly subjected to their facial region during which their cardiovascular responses are registered.
Normotensive subjects are exposed to brief cold exposure (-15 C for 15 min) mainly subjected to their facial region during which their cardiovascular responses are registered.
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|University of Oulu|
|Oulu, Finland, FI90014|
|Finnish Institute of Occupational Health|
|Oulu, Finland, FI90220|
|Principal Investigator:||Tiina M Ikäheimo, Ph.D.||University of Oulu|
|Principal Investigator:||Jouni JK Jaakkola, MD, Ph.D.||University of Oulu|