Research Article

Evolution of Action Potential Alternans in Rabbit Heart during Acute Regional Ischemia

Figure 7

Abrupt onset of OAPA alternans during ischemia. CL = 200 ms. (a) OAPA alternans maps taken at 1.6 seconds interval. (b) Corresponding OAP upstroke duration alternans maps. Interval between the isolines is 1 ms. (c) Superposition of optical (black trace) and microelectrode recordings taken at 0.5 mm (blue trace) and 3 mm (red trace) under the epicardial surface. The recording site is indicated by the white circle in (a). The insets show the upstrokes of optical and electrical action potentials of the odd and even beats at higher time resolution. (d) The first derivative of the transmembrane potential recordings in (c). Red arrows show alternating fragmentation of the depolarization front and alternans of the maximal depolarization rate from the deeper electrode. Asterisks show stimulus artifacts.
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