Research gets to heart
of arrhythmia causes
Posted May 7, 2009
The rhythm of a human heart, beating along at 70 or so contractions a minute, arises from precisely timed electrical waves. These waves must travel the entire three-dimensional shape of the heart to activate the muscles in a sequence that pumps blood throughout the body.
Unfortunately, human hearts do not always beat just right. In fact, millions of Americans suffer from irregular heartbeats, or recurrent arrhythmias. The most serious arrhythmias can cause sudden cardiac death.
The intricacies of these waves and their link to health problems caught the attention of Jeffrey Fox, a visiting scientist at Cornell University’s Center for Applied Mathematics. As a Cornell graduate student, Fox had worked with physics professor Eberhard Bodenschatz on nonlinear dynamics and pattern formation and with veterinary medicine professor Robert Gilmour, who studies the physiology of cardiac-rhythm disorders. This combination led Fox to research chaotic dynamics in cardiac tissue.
When operating normally, the heart’s sinus node makes a pacemaker electrical signal that generates a smooth, plane wave that travels through the tissue. If that wave hits diseased or dead heart tissue, though, the plane wave can break into spiral waves.
“The rapidly moving spiral waves are like a hurricane in the heart,” Fox says. The spiral waves break into many waves and regions of the heart contract out of sync. “So the heart wiggles instead of pumping.”
Fox and his colleagues are using combinations of mathematical modeling and computer simulations to study the cause of such spiral waves and the resulting cardiac arrhythmias.
Grad students get together
At Cornell, Fox met Colin Hill, who was working on a graduate degree in physics. They started collaborating to model genes. That research led Fox and Hill to the university’s supercomputer, which had 300 processors at the time, making it one of the fastest machines outside the military.
