(Missouri News Service) With summer heat already here, the American Heart Association wants people to remember that extreme temperatures can put extra stress on the heart and increase the risk of death. 

This was the conclusion of an international study of over 32 million cardiovascular deaths over a 40-year-period - published last year in the Heart Association's journal, 'Circulation.' 

Dr. Peter Panagos - professor of emergency medicine and neurology at the Washington University School of Medicine in St. Louis - said the increased risk is most notable for people with cardiovascular disease. 

"And that would be ischemic heart disease," said Panagos, "due to narrowing of the arteries, stroke, heart failure, or arrhythmias or abnormal heart rate."

Panagos said simple steps can help prevent heat-related illness. Avoid being outdoors during the hottest time of day - between noon and 3:00 p.m. 

Wear lightweight, light-colored clothing, a hat and sunglasses. Stay hydrated and apply sunscreen frequently. 

He recommended taking breaks from the sun and cooling down with fluids and water if experiencing light-headedness, cramps or other symptoms of overheating. He added that children and pets should never be left in a car on hot days. 

The human body is well adapted for temperature regulation in hot conditions, Panagos said - but less so in infants, young children and adults over 65. And he noted that some widely used medications can interfere with this regulatory process.  

"Those who are physically ill," said Panagos, "especially individuals with heart disease, high blood pressure, who take certain medications which are very common in our community - such as taking medications for depression, insomnia, or the inability to sleep - or for general conditions of poor circulation."

Panagos explained that heat-related illnesses exist on a spectrum - from sunburn and heat cramps to heat exhaustion and, worst of all, heat stroke. 

"And that's a sudden and progressively increased high body temperature," said Panagos. "Hot red, or dry damp skin, very fast strong pulse, headaches, dizziness, nausea or vomiting. And most importantly, passing out or loss of consciousness."

He cautioned that heat stroke, while rare, is very serious and can be fatal.