Sudden cardiac death kills more than 250,000 people each year in the US alone. Physicists have been studying the important role that electricity plays in the heart's health--and how it may be a culprit in disease.
Electrical impulses regularly circulate through cardiac tissue and cause the heart's muscle fibers to contract. In a healthy heart, these electrical impulses travel smoothly and unobstructed, like a water wave that ripples gently in a pond. However, for reasons that have not been perfectly understood, these waves can sometimes develop into troublesome, whirlpool-like spirals of electrical activity that can circulate through the heart.
Investigating these "spiral waves," scientists at McGill University in Montreal studied chick-embryo cardiac cells grown as a sheet of tissue. In the first two days after this arrangement of cells is created, spiral waves often form in the tissue. When the researchers sprinkled the sheet of cardiac tissue with a drug that impairs communication between the cells, they observed that the rotating spiral waves broke up into multiple rotating spirals.
This breakup of spiral waves in the two-dimensional sheet is believed to be similar to the 3D electrical patterns that cause human hearts to undergo ventricular fibrillation, a potentially fatal cardiac rhythm that often occurs when communication between cells is impaired. In a real-world situation, reduced intercellular communication may be caused by a heart attack or by other cardiac diseases, which can produce diseased or damaged heart tissue.
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Contact: Ben Stein
bstein@aip.org
301-209-3091
American Institute of Physics
5-Feb-2002