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Cold-related cardiovascular disorders
While there is no more doubt that cold weather increases the risk of heart or circulatory diseases, the question remained whether the link is only present in cold climate regions. Not so; ‘cold’ is relative. The mortality rate during Hawaii’s winter increases by 22%, a figure similar to some cold climate regions.
The body reacts to cold by constricting the blood vessels in the periphery of your body. The heart has to work harder to squeeze blood through the narrow vessels. This may be too much for a sick heart. Surveys of blood donors revealed that blood pressure rose significantly after temperature drops. Published figures showed increases of between 12 and 18mmHg. While such an increase is not significant for a healthy person, it is sometimes a deciding factor for a person suffering already from high blood pressure. Medical practitioners should take the seasonal effect into account when treating hypertension.
Lower temperatures also change the composition of the blood. The change is almost immediate and persists for up to two days. The number of particles in the blood, such as platelets, red blood cells, fibrinogen and cholesterol, increases in cold conditions (high platelets level) and make the blood thicker (increased blood viscosity). Some tests showed an increase in viscosity by up to 21%. The risk of blood clots developing increases also and, together with the high viscosity, may lead to blocked blood vessels in the heart, brain or lungs.
People with a history of heart attacks have a higher risk of reacting negatively to the cold than those with no previous heart trouble have, some for 2 to 10 years after an attack. More women than men are burdened with extreme weather sensitivity after a heart attack.
The relationship between weather extremes and mortality rates is well documented.
Extreme heat or cold increases the number of heart attacks dramatically. Just a moderate
drop of 10°C in temperature raises the risk by 13% in the population of middle-
Data collected from patients fitted with heart rhythm regulators (defibrillators)
gave some proof of the relationship between weather extremes and heart diseases.
When scientists compared the result with climatic data obtained form the national
weather service, they found that heart rhythm abnormalities are more frequent on
days with either very high or very low outside air temperatures. Some patients reacted
immediately to temperature changes, others’ reactions were delayed by 2-
