Actual maps of the spread of activation during the onset of tachycardia induced by a premature stimulus in an isolated rabbit heart atrial preparation.
(A) Map of the basic beat.
(B) Premature beat elicited following a 56 ms delay.
(C) First cycle of the tachycardia (double bars indicate sites of the conduction block).
(D) Refractory period duration as determined for the corresponding sites. (From Allessie, Bonke, and Schopman, 1976.)