Figure 5.

Representative examples of Poincaré plots obtained from the same dog used in the other experiments. Left panels are controls, whereas right panels are under the influence of various drugs. Thirty consecutive LV MAPDs are plotted against the value of the previous beat. Each plot is 200–500 by 200–500 ms. All control plots cluster close to the diagonal line. (a) 8 mg kg⁻¹ moxifloxacin provokes prolongation of the LV MAPD but does not elevate BVR as the dimensions of the plot remain unchanged. (b) 8 mg kg⁻¹ azithromycin has no effect on either LV MAPD or BVR. (c) 25 μg kg⁻¹ dofetilide prolongs LV MAPD as well as increasing BVR as is clearly seen by the increased area of the Poincaré plot. Only dofetilide was associated with proarrhythmia.