Exposure to snow, cold weather, high winds, or rain may precipitate Angina Pectoris ("Heart Chest pain") and Coronary Occlusion ("Heart Attack") in individuals known to have coronary arterial disease.
As a response to this situation the body loses heat more rapidly, and body temperature drops to a subnormal level risking hypothermia. In these individuals heart failure is the cause of death.
According to a study in the "Chinese Journal of Physiology 1996; 39(2): 111-6", in cold weather the blood has a greater tendency to clot in the circulatory system due to an increase of coagulation factors. This information correlates with the normal physiological response of blood components to cold as follows:
- Red cell count increases
- Platelet count increases
- Blood viscosity increases
- Plasma cholesterol increases
- Fibrinugen ("blood clot factor") increases
(From:
"Weather, Climate and Human Health" Consultant Pharmacist: November 1999)
Of interest is a population study published in England at the J. Epidemial Community Health 1997 Dec, 51(6) 643-8. indicated that from years 1976-92 in individuals over 50 years of age, 20 to 30 days patterns of cold weather below 59° F (15° C) were followed "rapidly by heart attacks".
The American Heart Association recommendation is:
"People who are outdoor in cold weather should avoid sudden exertion, like lifting a heavy snow shovel full of snow. Even walking through heavy, wet snow of snow drifts can strain a person's heart."
References:
- Winter Excercise Mayo Clinic Health Oasis, December 1996.
- Snow Shoveling with Care Mayo Clinic Health Oasis, May 8 2000.
- "Mechanisms of cold intolerance in patients with angina." Journal Am. Coll. Cardiology 1994 Mar 1;23(3):630-6
- "Cardiac demands of heavy snow shoveling." JAMA 1995 Mar 15; 273(11):880-2
- "Excercise-induced angina in the cold." Med Sci Sports Exerc 1985 Oct; 17(5):607-12
