External manipulation of scroll rings

Chaiya Luengviriya and Marcus J. B. Hauser*

Otto-von-Guericke-Universität Magdeburg, Abteilung Biophysik, Institut für Experimentelle Physik, 39016 Magdeburg, Germany

*marcus.hauser@physik.uni-magdeburg.de

Fig. 1. Reorientation of a scroll wave by an external electric current. Top and lateral view projections of a scroll ring whose unit vector S reorients with respect to the vector J of the electric current density (Luengviriya et al., 2008).

Certain cardiac arrhythmias are caused by scroll waves or scroll rings. Their filaments are subject to instabilities, which cause the scroll ring to expand or contract intrinsically depending on the excitability of the medium. In order to better understand how such scroll rings may be manipulated, we have studied experimentally the dynamics of scroll rings in a chemical model system (the Belousov-Zhabotinsky reaction) subjected to a constant external electric current.

The scroll ring reorients with respect to the direction of the applied external electric current. Two stationary orientations were identified and their orientational stability determined. At the stable stationary orientation and in absence of an external current, the scroll rings contract intrinsically and eventually self-annihilate. For low values of the external electric current density, the scroll rings contract, while they expand at higher current densities. Scroll rings of constant radius exist at the bifurcation between contracting and expanding scroll rings, and this bifurcation was mapped experimentally in the 2-dimensional phase space spanned by the initial radius and the current density. Last but not least, the observed current-dependency of the scroll waves was used to manipulate the size and life-time of scroll rings.

Corresponding numerical simulations are in good agreement with the experimental observations. A comparison with predictions form a kinematic description of scroll waves in a gradient field also shows a good agreement with the experimental findings.

References

Luengviriya C., Müller S. C., Hauser, M. J. B.: Reorientation of a scroll wave in an advective field, Phys. Rev. E 77, 015201(R), 2008.

Luengviriya C., Hauser, M. J. B.: Stability of scroll ring orientation in an advective field, Phys. Rev. E 77, 056214, 2008.

Luengviriya C., Braga L. C., Hauser, M. J. B.: External manipulation of scroll rings by electric current, J. Phys. Chem., submitted