1. Group 6

2.  The most common type of arrhythmia (irregular heartbeat)  In AF, atria contract very fast and irregularly.  Atria get pooled by blood.  Blood not being able to go into ventricles completely.  Consequently, atria and ventricles do not work together.  The heart’s electrical signals do not begin in the SA node.  Signals begin in another part of the atria or in pulmonary veins and they don’t travel normally.  The amount of blood pumped by ventricles to the body depends on atrial beats.

3.  Interesting patterns seen in many experiments. Example: Belousov- Zhabotinsky  Usually rotate without changing their shapes  The tip traces out a perfect circle  After getting destabilized, they either drift or meander.

7. Parameters  G Na – Conductance for fast Na + channel  k NaCa – Current for Na + /Ca 2+ exchanger  Na + /Ca 2+ exchanger- An antiport, where three Na + are brought in for one Ca 2+, when the membrane potential is negative and when the cell is depolarized, Na + leaves and Ca 2+ enters.  G Na vs k NaCa

8. Spiral Wave of Day 1 G Na K NaCa Maximal I Na conductance Maximal I NaCa

9. Path of Day 1 G Na Maximal I Na conductance K NaCa Maximal I NaCa

10. Spiral wave Day 2 G Na Maximal I Na conductance K NaCa Maximal I NaCa

11. Path of Day 2 G Na Maximal I Na conductance K NaCa Maximal I NaCa

12. Day 1 VS. Day 2 Wave Comparison

13. Day 1 VS Day 2 Trajectory Comparison

14. Conclusions: Spiral waves are influenced by the concentration of Ions. Different shape of the spirals depending on which concentration is changed first. Low concentration of Sodium Calcium exchanger and high concentration of Sodium produces trajectories that are more chaotic. High Sodium-Calcium concentration and low Sodium concentration produces spiral trajectories that are tight.

15.  Nancy Griffeth  Flavio Fenton  Robert Gilmour  Bard Ermentrout  Aron Wolinetz  Charles Beard  Rachel Spratt  All participants