Cardiovascular Responses to Cold Exposure in Hypertension

Introduction.

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 cold season.

Although the effects of cold on blood pressure are established among healthy people, the effects among risk groups, such as hypertensive people, are not known. In addition to blood pressure, information on cardiac electrical activity or autonomic regulation are needed. Cardiovascular responses in the cold could be different among hypertensive people because of disturbances in autonomic nervous system and 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 in a climatic chamber.

Aims of the research.

The objective of the research was to assess how short-term cold exposure affects cardiovascular function of middle-aged untreated hypertensive and normotensive men. The hypotheses of the study were: a) cold exposure induces adverse changes in cardiovascular function, such as higher blood pressure and cardiac workload and b) hypertensive men demonstrate an aggravated response to cold exposure and the recovery of the cardiovascular system to baseline is delayed compared to normotensive subjects.