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

Figure 2

Effect of regional ischemia on optically recorded action potentials in a representative preparation. CL = 300 ms. (a) OAPD maps in control (left), 6 min after occlusion (middle), and 10 min after occlusion (right). Numbers near isolines show APD in ms. Interval between isochrones is 10 ms. The “x” indicates the occlusion site; the white dotted line indicates the boundary of the ischemic zone. (b) Corresponding activation maps. The numbers near isochrones show the activation time in ms. Interval between isochrones is 2 ms. (c) Normalized optical action potentials at 3 different locations indicated as a, b, c (white circles) in (a). In control (left) the action potentials are practically identical. After 6 minutes the action potentials downstream from the occlusion site start shortening (traces b and c), whereas in nonischemic region (trace a) remains unchanged. After 10 minutes of artery occlusion, the action potentials inside the ischemic region show significant deterioration: their amplitude drops and upstroke duration increases which is indicative of developing conduction blocks.

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