Group 6. The most common type of arrhythmia (irregular heartbeat) In AF, atria contract very fast and irregularly. Atria get pooled by blood.

Workshop on Atrial Fibrillation

Group 6

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.

Atrial Fibrillation

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.

Spiral Waves

Inward meandering

Outward meandering

Drifting Spiral Waves

Parameters

GNa – Conductance for fast Na+ channel

kNaCa – Current for Na+/Ca2+ exchanger

Na+/Ca2+ exchanger- An antiport, where three Na+ are brought in for one Ca2+, when the membrane potential is negative and when the

cell is depolarized, Na+ leaves and Ca2+ enters.

GNa vs kNaCa

Spiral Wave of Day 1

GNa

KNaCa

Maxim

al I N

a

con

du

cta

nce

Maximal INaCa

Path of Day 1

GNa

Maxim

al I N

a

con

du

cta

nce

KNaCaMaximal INaCa

Spiral wave Day 2

GNa

Maxim

al I N

a

con

du

cta

nce

KNaCaMaximal INaCa

Path of Day 2

GNa

Maxim

al I N

a

con

du

cta

nce

KNaCaMaximal INaCa

Day 1 VS. Day 2Wave Comparison

Day 1 VS Day 2Trajectory Comparison

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.

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

Acknowledgement