Ask Well: Blockages in the Heart and Brain
January 17, 2015 MVP Blog comments
Why do people get blockages in the arteries of the heart and brain, but rarely in other organs?
Actually, blockages in other organs are quite common but may not always cause noticeable symptoms. The ones that occur in the heart and brain are often a matter of life and death, and as a result they come to attention more frequently, said Dr. Curtis M. Rimmerman, a cardiologist at the Cleveland Clinic.
The arteries are essentially a vast highway system, and any part of it is susceptible to a blockage. About eight million Americans, for example, have an often-silent condition known as peripheral artery disease, the narrowing of arteries that supply blood to the arms and the legs.
The disease is caused by the accumulation of plaque, the same process that underlies many heart attacks and strokes. But when a blockage occurs in your leg, your body can sometimes recruit new blood vessels to reroute blood around the obstruction. In the heart and brain, that is usually not the case. A blockage there will often result in tissue loss, Dr. Rimmerman said.
“Since those are vital organs, that’s a big problem,” he added. “Tissue loss in the heart means a heart attack, and in the brain it means a stroke. That is much more critical than, say, a blockage to the liver.”
Atherosclerosis can occur in any artery – but not in the veins. Why?
Dr. Rimmerman said that the arteries are a very high-pressure flow system. This intense pressure disrupts the inner lining of the vessels, creating an environment where things like cholesterol can more easily infiltrate the arteries.
The veins, however, are part of a low-pressure flow system, so they are not as susceptible. But during a bypass operation, doctors can transplant veins from one part of the body to the heart, where they will take on the job of an artery. When that happens, atherosclerosis can occur.
“Those veins over time will develop narrowing similar to the arteries,” Dr. Rimmerman said. “Whereas if those veins were left in place, they basically would never develop a blockage.”