Heart Beat: Heat and heart failure
Heat and heart failure
Deadly heat waves in the United States and Europe taught us that people with heart failure are especially vulnerable to high temperatures. Although their heart trouble is clearly one reason they have trouble with the heat, blood vessels supplying the skin may contribute to it.
One way we cope with excess heat is by rerouting blood flow. Responding to signals from deep in the brain, blood vessels that supply the internal organs narrow. This limits circulation to the stomach, intestines, liver, and kidneys. At the same time, tiny arteries (arterioles) near the skin relax and open. As extra hot blood flows just below the skin, some of its heat escapes into the air.