By Leila Lopez Marks

Medicine has known for some time that excessive exposure to heat without proper safety measures can cause heat stroke, heat exhaustion and other heat-related ailments.

Now, studies are emerging that show excessive exposure to heat can cause a number of problems for one's heart as well.

An overview of how heat impacts your heart

So how is it that heat causes heart problems? According to Dr. Sadeer Al-Kindi, a cardiologist and researcher at Houston Methodist, heat acts as a stressor to the heart. This causes the heart to pump faster and stronger, which essentially means that at times it works harder than it needs to.

In addition, it changes the viscosity of the blood. Specifically, it makes the blood thinner, meaning it doesn't clot as easily. This may be especially dangerous for people who are already on blood-thinning medication.

"People who have disrupted heart function — for example, people with heart failure and people who've had prior heart attacks, strokes and other cardiovascular issues — are usually more susceptible to the impacts of the change in temperature," says Dr. Al-Kindi.

The question is, does prolonged exposure to heat increase one's chances of developing heart disease?

"We are not 100% sure whether this occurs only in people who have heart disease already or it's a new heart disease that forms," says Dr. Al-Kindi.

Dr. Al-Kindi adds that it's more likely than not that patients who die from heart disease during heat waves already had heart disease. In those cases, the heat makes it worse and causes heart attacks."

Temperature changes, especially quick and drastic ones, can also have an effect on one's body, not just the heart. Examples include hyperthermia (when body temperature gets too high), hypothermia (when body temperature gets too low), coma, organ failure and, in some severe cases, death.

How certain heart medications affect heat tolerance

In addition, certain medications can impact the heart negatively when the body is exposed to heat. There are three main classes of medication that can do this.

• Beta blockers – Most commonly prescribed for blood pressure but also used to help manage heart failure and heart attacks, beta blockers can make people more vulnerable to the heat because they reduce blood flow to the skin and make it harder for the body to cool itself down and regulate temperature.
• Aspirin – A blood thinner, aspirin makes people more sensitive to temperature changes, according to one study.
• Diuretics (water pills) – Typically prescribed to people with kidney problems, congestive heart failure or high blood pressure, diuretics encourage the body to urinate more frequently, which, during hotter weather, can cause electrolyte imbalances and make it harder for the body to regulate its temperature.

"If you live in hot weather, you lose a lot of water through sweat and that may make people more prone to having dehydration because we're prescribing them a water pill at the same time," Dr. Al-Kindi explains.

Heart health, heat & demographics

Older individuals, such as people aged 65 and older, are at higher susceptibility for heat's adverse effects.

"As we age, our homeostatic system, the system that keeps us in check gets weaker, so as you get older you become more vulnerable to the impacts of various environmental exposures," says Dr. Al-Kindi.

Tips to keep your heart healthy during hot weather

Given this new information, what are some mitigation strategies for lessening your chances of potentially developing heart disease or another heart-related illness as a result of excessive heat exposure?

• Try to avoid temperature changes as much as possible. For those of us living in Houston where it is harder to do so, try to stay in air-conditioned places as much as possible. If you work outside for a living, bring cold packs and cold towels to help keep you cool as you work.
• Stay hydrated as much as possible. This is especially important if you are on any of aspirin, beta blockers or diuretics.