Word of Tim Russert's death at 58 shocked many Americans today, and behind the grief came nagging questions about heart attacks, like the one that struck the newsman, and anxiety about how they kill.

Russert's death came in a week when the government reported U.S. life expectancy had risen to 78 years as heart disease and other leading causes of death decline.

About 1.2 million Americans suffer from heart attacks annually, and about 40 percent die from them. Russert sadly fit the profile, in some ways, for those who typically suffer from heart disease — he was overweight and was under heavy stress at times due to his career. He also reportedly suffered from diabetes and people with that disease are at higher risk for heart disease.

The typical heart attack victim is 65, but they can occur at any age in men and women.

Heart disease is the leading cause of death in the United States, and the most common heart disease here is a heart attack, according to the Centers for Disease Control in Atlanta. One American dies every minute from a heart attack.

Heart attacks occur when a clogged artery blocks blood flow to a part of the heart, starving it of oxygen and causing part of the muscle to die and beat irregularly. Arteries don't clog overnight. Rather, plaque accumulates in them over years as a result, in part, of a diet high in cholesterol. High cholesterol foods include all animal products, including meat and dairy.

Part two of the process happens when the plaque in arteries cracks or tears (due to stress), and the body's platelets rally to the location to repair it. That can cause a clot that ironically finishes blocking the artery, causing the heart attack.

Stress is a big part of the heart disease equation, as it causes the heart rate to go up, much higher than most stressed-out people are aware of. One study found that people who experience high amounts of stress at work are more likely to develop Type 2 diabetes. Stress also is related to numerous other diseases, such as psoriasis, eczema and some cancers. It also lowers resistance to viruses.

Spousal discord also raises the risk of heart attacks and makes it harder to recovery from them.

The American Heart Association released new guidelines earlier this year for women on how to avoid heart disease.

Cardiac care has advanced significantly in the past 30 years. While heart attacks still kill, the death rate is much lower today than it once was. In fact, after decades as the leading killer of Americans under age 85, heart disease in 2005 gave way to cancer in the top spot.