Circadian variation and cardiovascular disease
Article Abstract:
The medical profession and the general public are both aware that heart attacks are more common in the morning than at any other time of day. Many different research studies have examined physiological factor that vary during the normal daily cycle and may contribute to the variations in the risk of heart attack. In the October 3, 1991 issue of The New England Journal of Medicine, researchers have added to this growing body of information by demonstrating that the arteries are more constricted in the morning and therefore provide more resistance to blood flow. These researchers have shown that this constriction seems to by modulated by alpha-adrenergic receptors, specific hormone receptors that operate as a part of the sympathetic nervous system. These findings are important, but much more needs to be learned about the daily changes in heart attack risk. The present study was conducted using healthy volunteers; do the same factors influence the cardiovascular systems of people with high blood pressure? Are the same physiological influences at work in patients with coronary artery disease? Furthermore, while it is plausible that the increase in blood vessel resistance in the morning may affect the risk of heart attack, it is far from certain whether it actually does play a role in the onset of a heart attack. A heart attack results from the interplay of many different factors, and the factors that are most important in accounting for the increased heart attack incidence in the morning remain to be identified. Unfortunately, the results of the present study provide no hints that might be useful in preventing heart attacks. Prevention is critical; the majority of heart attack deaths occur before the patient can be brought to a hospital. About 500,000 deaths each year, a full quarter of all deaths in the United States, are attributed to heart attacks. ("Heart attack" is an imprecise term which includes both myocardial infarction and sudden cardiac death.) Of these deaths, about 300,000 occur before the patient reaches the hospital. Medicine may go a long way simply by encouraging the reduction of risk factors such as smoking and high cholesterol. It may be possible to further reduce the rate of heart attacks by identifying the factors that not only set the stage for the heart attack, but initiate the actual event. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: The New England Journal of Medicine
Subject: Health
ISSN: 0028-4793
Year: 1991
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High-normal blood pressure -- more "high" than "normal"
Article Abstract:
People whose blood pressure is at the high end of the normal range have an increased risk of cardiovascular disease. The high end of the normal range of blood pressure is a systolic, or top number between 130 and 139 and a diastolic, or bottom number between 85 and 89.
Publication Name: The New England Journal of Medicine
Subject: Health
ISSN: 0028-4793
Year: 2001
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