Coronary heart disease (CHD) currently looms as the greatest health threat to Americans. The rise of coronary heart disease to the top of our medical "to-do list" is relatively recent. In 1900, pneumonia was the leading cause of death in the United States, and the average life expectancy was only 47. During the first half of the 20th century, doctors and scientists focused on treating infectious diseases -- for example, developing new drugs to cure pneumonia and virtually eradicate tuberculosis. These dramatic advances enabled people to live longer -- and inadvertently opened the door to coronary heart disease.
By 1930, average life expectancy in America had risen to about 60, and heart disease had become the number one cause of death. These statistics reflect an important feature of CHD: the incidence of the disease increases strikingly with age. Longer life means more time for arterial plaques to develop and cause problems. The risk of an 85-year-old man having a heart attack is 25 times that of a 45-year-old.
Longer life does not by itself cause CHD, but the combination of longer life and damaging lifestyles increases the risk of developing coronary heart disease. Contemporary lifestyles have created a minefield of risk factors for CHD. Liberated from the grip of infectious diseases, too many of us fill our extra years of life with smoking, eating, and many excuses not to exercise.
THE BATTLE FOR YOUR ARTERIES' HEALTH: THE GENESIS OF CHD
Before we examine the risk factors for coronary heart disease, let's focus on your arteries and the mechanisms by which plaques form. The process begins with damage to the endothelium, a smooth, tile-like layer of specialized cells lining the inner walls of blood vessels through which blood flows on its way to our organs. More than simply a watertight seal to keep the blood inside the artery, the endothelial lining is biologically active, producing chemicals that prevent blood from clotting at its surface. In addition, the endothelium acts as a barrier to prevent toxic substances from entering the blood vessel's wall.
Many of the risk factors for CHD initiate and accelerate disease by damaging the endothelium. Smoking and air pollution increase levels of carbon monoxide and other toxic chemicals in the blood, triggering chemical reactions that assault and damage the endothelium. High blood pressure causes the blood to act like a battering ram, attacking and disrupting the endothelium.
Over the last few years, scientists have recognized that inflammation also damages endothelial cells and contributes to plaque formation. The term inflammation is derived from the Latin meaning "to set on fire." Inflammation is not always bad; it actually represents the body's normal response to injury and infection, and in the appropriate setting it restores health. But when it occurs inside blood vessels, inflammation can initiate plaque formation.
Excerpted from Heart 411: The Only Guide to Heart Health You'll Ever Need (Three Rivers Press)