How Does Cold Weather Affect The Heart?

With temperatures quickly dropping, many of you may be feeling the cold, but did you know that cold weather can cause a lot more than just a chattering jaw? Research has found that in winter there are 53% more heart attacks and your chances of having a cardiac arrest increase by 20%. But exactly how does cold weather affect the heart?

How the body reacts to the cold.

1. Preserving body heat.

You may have noticed that when it is cold, your hands and feet are the first to feel the freeze, whilst your torso stays nice and toasty. This is one of your body’s many defence systems to ensure as little heat loss as possible. The body needs to maintain an internal core temperature of 37°C to function effectively. So if your skin’s temperature rises above or drops below 37°C, the hypothalamus (the part of the brain that regulates body temperature) springs into action.

When our body is too hot, blood is directed towards the skin, allowing the excess heat to be transferred out of our system, cooling us down, and when we are in colder conditions, our bodies do the opposite. By constricting the blood vessels near the skin, also known as vasoconstriction, blood is diverted away from the skin to ensure that as little heat as possible escapes. This is why our fingers and toes are usually the first to feel the cold. This defence also reallocates the blood to the torso by pushing the warm blood deeper into the body. Your torso houses all your vital organs, excluding the brain, so it is imperative it stays as warm as possible.

2. An increased need to urinate

Whilst vasoconstriction helps maintain body heat, it increases blood pressure, this is because although the arteries constrict and blood flow to the skin is reduced, the same amount of blood is in the body, just with fewer places to go and more difficult means of travel. As a result, to reduce the blood’s volume and pressure, your kidneys begin to filter out excess fluid in the blood. However, these fluids cannot just simply sit in your body so you will need to urinate more often.

3. Shivering.

When your body’s internal core temperature drops below 35.5°C, it triggers shivering. This coordinated and involuntary response serves as a thermoregulator and consists of your muscles contracting and relaxing, it increases the metabolic rate and burns up to five times the energy of the resting rate, which creates heat.

How does cold weather affect the heart?

While your body does have an incredible natural defence system to shield the heart from the harsh effects of the cold, it is important to understand that this protective mechanism can sometimes inadvertently increase the risk of cardiac events.

1.Increased blood pressure.

Although vasoconstriction is an essential strategy to help maintain body heat and protect the vital organs, it introduces challenges for the heart. As the blood vessels constrict, blood pressure increases. This surge in blood pressure can place an additional burden on the heart, which causes the heart to have to exert additional effort. In individuals with compromised cardiovascular health, such as hypertension or coronary artery disease, the impact can be much greater, with an increased risk of cardiac events such as heart attacks and cardiac arrest.

2.Increased risk of blood clots.

Sudden drops in temperature can induce thermal stress in the body, as it is having to work harder to maintain a constant temperature, which can trigger a thermal reaction. This response can result in your blood thickening and becoming sticky. Whilst this can be harmless, it can potentially result in a heart attack. Normally, your blood’s platelets stick together to form clots and help seal open wounds, however, cold weather can increase the risk for a dangerous blood clot to form. If you have a buildup of plaque or fatty substances in your arteries they could quickly become blocked, leading to a heart attack and potentially cardiac arrest.

How do I protect my heart?

• Keep warm. Wrap up with layers, this will help you maintain your body heat but will help you avoid overheating. Ensure that your home is at least 18°C, to avoid thermal stress to the body.
• Keep your hands, feet and head warm. Wearing gloves, thick socks and a hat will help limit the amount of heat that is able to leave your body.
• Be careful shoveling snow. Research found that heart attacks due to snow shoveling cause around 100 deaths a year, this is due to people overexerting themselves, not realizing how strenuous the task can be.
• Avoid drinking alcohol. Alcohol expands blood vessels in the skin, whilst this makes you feel warmer, it actually draws heat away from your vital organs. So if you are going to be outdoors, avoid drinking alcohol to ensure you stay as warm as possible.

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