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Issue Date: January 13, 2002
What You Don't Know About Your Heart
OK, you remember arteries and chambers, but have you heard about keeping your plaque stable and your endothelium clean?
BY FRAPPA STOUT
Everybody knows the heart. It's the body's little powerhouse, a fist-sized organ that pumps 2,000 gallons of blood through the circulatory system each day by expanding and contracting more than 100,000 times. Nestled behind the breastbone, between the lungs, in the middle of the rib cage and above the diaphragm, it's also the body's most protected organ.
But that doesn't mean it's immune to harm.
The heart works in tandem with the blood vessels -- arteries, smaller arterioles and tiny capillaries -- that carry the oxygen- and nutrient-rich blood away from the heart to the body's cells and tissues. Veins bring the "used-up" blood back to the lungs as well as the heart, where it is pumped through the four chambers, reprocessed and sent back into the body for another round.
Sound familiar? We all learned that stuff in eighth-grade science class. But cardiology has made leaps and bounds since those days, and doctors have a greater understanding of the mysterious muscle and its many idiosyncrasies -- especially in the category of "things that can go wrong."
Cardiovascular disease, heart disease and stroke are overwhelmingly the leading cause of death for men over age 30 and women over age 40. As people enter their 50s, heart disease kills far more women than breast cancer does. It has only been in the last century that doctors have understood that the primary cause of heart trouble is atherosclerosis, or clogging of the arteries of the heart. A plaque made up of cholesterol and scar tissue clogs the arterial walls, reducing blood flow to the heart. When the artery becomes completely closed, part of the heart is starved for oxygenated blood and dies. That is a heart attack.
Or so doctors thought. In the past few years, they have discovered they were wrong.
It's not the growth of these plaques that causes heart attacks; in fact, most can be traced to smaller plaques that block less than 50% of the artery, says Richard Stein, a cardiologist and spokesman for the American Heart Association. The real danger comes when the plaque fractures or cracks, causing clotting material to be released and a blood clot to form inside the vessel. The clot can go on to partially block the vessel and create chest pain, or completely block the artery for a real-deal heart attack.
"We've changed the rules of preventive cardiology," Stein says. "And my concept is that if you're going to win, you need to play by the new rules."
So what are the new rules?
For us regular folks, some of the same ones apply: Lowering cholesterol slows plaque buildup. The carbon monoxide in cigarette smoke increases plaque, and nicotine raises blood pressure (which can make plaque more likely to fracture), so quitting is crucial. Regular exercise raises the HDL, or good cholesterol, in your blood, which may inhibit clotting in the arteries. A good cardiovascular workout also increases the low-pressure blood flow through the arteries, which keeps them healthy.
A relatively recent addition to the list of rules is taking aspirin. Because of its anti-inflammatory properties, aspirin may help stabilize plaque. Also, for vessels with existing plaque fractures, aspirin can deactivate the platelets so clots are less likely to form.
For researchers, the focus is no longer on how to shrink the plaques -- a near-impossible feat -- but on defining the plaques that are likely to fracture and finding a way to make them fracture-resistant.
So far, doctors have found the time-bomb plaques to have these characteristics:
An active inflammatory response within the plaque, almost like you'd see around an infection.
More cholesterol in the center of the plaque in its soft form, making it a mushier plaque.
An unhealthy endothelium -- the thin lining of cells inside all blood vessels, which naturally produces a plaque-stabilizing chemical (smoking and other free radicals can harm the endothelium).
"This knowledge has really changed the thinking, optimism and direction of our care to prevent heart disease," Stein says. "We've begun to realize that we can take people with fairly extensive disease, and, if we stabilize their plaques by lowering their cholesterol, improving the health of their endothelium and decreasing their coagulation with aspirin, we can really make a tremendous difference in their heart attack rate and survival.
"We're optimistic now," Stein says, "that many of the patients that come in to see me because of heart disease are going to die with -- but not because of -- their heart disease."
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