2011 NSF-CMACS Workshop on Atrial Fibrillation

Workshop Dates: January 3, 2011 - January 21, 2011

Workshop Location: Carman Room 118, Lehman College

See also 2010 Workshop on Cellular Signalling Pathways

The Lehman College Workshops on Computational Modeling of Complex Systems are held each January. They are part of an NSF-funded Expedition in Computing, called Computational Modeling of Complex Systems, involving researchers from CMU, NYU, Cornell, University of Pittsburgh, University of Maryland, Stony Brook University, and JPL. The primary goals of the workshop are to motivate students to consider fields in science, especially scientific research, and to train the students to use the methods developed in the program's research activities. The Expedition's research addresses four important societal problems: pancreatic cancer, atrial fibrillation, automotive safety, and aerospace safety.

Students from all CUNY colleges are invited to apply. They are admitted on the basis of grades and recommendations. The workshop staff includes researchers engaged in the ground-breaking research being done on the project. Also, each year, we invite distinguished visitors from various institutions to provide additional insights into the research problems. This year, special visitors included James Glimm from Stony Brook and Robert Gilmour from Cornell.

The theme of the 2011 CMACS Workshop on Atrial Fibrillation was understanding emergent behaviors of cardiac cells in order to improve understanding of both normal and abnormal cardiac rhythms. Better understanding of emergent behaviors in cardiac tissue will support better health care for victims of heart disease, in particular atrial fibrillation, which affects about one in five people who reach the age of 80.

Student Presentations of the data they collected for spiral wave tip trajectories where given on the final day of the workshop. You can see them here

Participants learned important electrophysiological dynamics of cardiac cells that have been discovered experimentally; how these characteristics are modeled; some mathematical techniques for analyzing models, and limitations of the techniques; and how to build and use simulations based on such models to discover and understand emergent properties of cardiac cells. An emergent behavior of particular interest is the development of spiral waves as a precursor to atrial fibrillation.

The approach taken in the workshop was participatory, inquiry-based, and team-oriented, culminating in a project in which participants used simulations to discover and test emergent behaviors in cardiac tissue. The first week of the workshop was based on lecture and guided exercises, the second week developed skill with mathematical and simulation tools, and the final week focused on team-oriented student projects. Participants were provided with scaffolding (based on existing code) for their simulations.

Distinguished visitor Flavio Fenton of Cornell presented the basics of cardiac cell function, as understood from experiment, and discussed how experiments are constructed. He introduced two historically important models, the Hodgkin-Huxley and Fitzhugh-Nagumo models of action potentials in cells. These models describe the behavior of action potentials in individual cells. Action potentials are important to the understanding of both cardiac cells and neurons, because they cause neurons to fire and drive the contractions of cardiac cells. Dr. Fenton also discussed how action potentials propagate in tissue to form waves and how disruptions to propagation can produce spiral waves, which are precursors to atrial fibrillation, as well as introduce mathematical and simulation techniques for studying cardiac behavior.

Participants learned and applied standard mathematical techniques for analyzing models such as Hodgkin-Huxley and Fitzhugh-Nagumo. Since these models and other important models of cardiac cells are based on partial differential equations, techniques for mathematical and numerical analysis of pde’s were discussed along with their limitations.

There are many more models of cardiac behavior, some developed to simplify analysis and others to model specific aspects of behavior in more detail. Participants in this workshop worked with “minimal” three- and four-variable models of cardiac cells developed by Flavio Fenton and Elizabeth Cherry, which were designed to combine accuracy of the model with simulation speed.

This work was supported by the NSF under grant number 0926200.

Nancy Griffeth