Figure 4.

Illustrates the nature of F_Cai potentials in the core of the spiral wave reentry. The left panel illustrates selective F_Cai signals during sustained spiral wave reentry. The right panel illustrates the same signals during stimulation at 0.5 Hz. During reentry, there was a 2 mm diameter confluent zone of steady‐state small oscillations (sites 6 and 7). The approach to this zone showed low amplitude signals (site 5). The core of the spiral is made of a small area of tissue, which is depolarized and refractory, thus constituting a functional obstacle. This area is functionally normal during regular stimulation as shown in the right panel