The sticking point
Nick a finger and what happens? Blood oozes out, a clot forms and bleeding soon stops. A clot, or thrombus, can keep you from bleeding to death. But it can also have a dark and dangerous side.
When it plugs an artery, a clot can cause death or disability. Tissues die within minutes without oxygen, so when oxygen-rich arterial blood can’t reach heart muscle, brain tissue or your legs, you’ll have a heart attack, stroke or suffer painful peripheral arterial disease (PAD), which can lead to gangrene and amputation of toes, feet or legs. In fact, cardiovascular disease is the prime cause of death in Canada, responsible for 33 per cent of fatalities in 2002, according to a Statistics Canada report published in 2004.
There are reasons clots develop in our arteries. By dealing with the well-known risk factors we can alter, we can prevent clot formation. We can start by lowering cholesterol or blood pressure levels, exercising, eating a healthy diet, losing weight, controlling diabetes and quitting smoking. (Statistics Canada says 80 per cent of Canadians aged 20 to 59 have at least one of these predictors.)
How do clots forin arteries?
Healthy arteries have smooth, flexible walls but, as early as adolescence, we begin to develop areas of inflammation within them, most often where they branch. Over time, pockets of plaque containing a runny mix of cholesterol and fatty material, cell fragments and calcium form at these sites, just under an artery’s inner lining. While most of us call the process hardening of the arteries, your doctor refers to it as atherosclerosis. It’s a term derived from Greek words: athero meaning gruel and sclerosis denoting hardening. This accumulation of plaque in arteries all through the body is considered a normal part of aging.
Plaque lesions may grow large enough to bulge into the artery and reduce blood flow. If you have angina (chest pain caused by exertion), your heart isn’t getting enough oxygen.
A plaque that bursts presents a more immediate danger of atherothrombosis, where the body tries to plug the rupture with a clot (thrombus). The result may be total blockage of the artery, causing a heart attack, stroke or PAD. A clot could have the same effect if it’s swept off the plaque lesion and lodges further along the bloodstream. These situations are medical emergencies.
All of these events – heart attack, stroke and PAD – are manifestations of the same disease process, so if you have the risk factors, any of these disasters could happen to you.
A sudden blowout
Dr. Alan Bell is a primary care physician in Toronto and a member of committees for the Thrombosis Interest Group of Canada and the REACH Registry, a global health survey of 68,000 patients affected by atherothrombosis. He explains the problem is not plaque that gets bigger and produces more symptoms until the artery is finally blocked. “It’s not a slow, gradual process but a sudden process where plaque, which may be completely symptom-free, suddenly ruptures and causes these events,” he says. “Some plaques are quite fragile and seem to be vulnerable to rupture when they obstruct 40 to 50 per cent of blood flow.”
He says, “If we can reduce the formation of plaques in our arteries, then we will reduce the potential of rupturing those plaques.”
Fighting arterial plaque requires managing lifestyle: a heart-healthy diet with controlled fat intake; weight control; staying active and not smoking. It also means seeing a physician to determine if you have high cholesterol, high blood pressure or diabetes and then aggressively treating the condition. “If we properly approach the management of risk factors,” he says, “we can have a real impact on event rates.”
For those who already have symptomatic plaque, he says, “it is critically important to take drugs that reduce the action of platelets [blood cells active in clotting]. These anti-platelet medications help prevent the complications of plaque rupture and atherothrombosis.
“If we eliminated thrombotic disease, we’d put guys like me out of business, which would be a good thing,” he says wryly.
This special educational feature was produced by the editors of CARP magazine, Bristol-Myers Squibb Canada and sanofi-aventis Canada Inc.