Determinants of Beat-to-Beat Variability of Repolarization Duration in the Canine Ventricular Myocyte: A Computational Analysis
Figure 6
Role of APD and stochastic gating in BVR reverse rate dependence.
A. Magnitude of channel gating stochastics (assessed by Std(Im) for 50 beats) over time for CL of 350–4000 ms using the fully stochastic model under control conditions. B. Rate dependence of total magnitude of Im fluctuations (given by area under Std(Im) curve). C. STV rate dependence in the fully stochastic model during fixed-CL pacing (solid line) or fixed-DI pacing (dash-dotted line), or in the deterministic model during fixed-CL pacing with a CL-independent stochastic term (see Results, section “BVR rate dependence”) added to Im (dashed line). CL-independent stochastic behavior results in a blunted STV rate dependence. D. STV vs. APD relationship at CLs of 500 ms (dark grey symbols), 1000 ms (white symbols), or 2000 ms (light grey symbols). APD was varied through injection of a deterministic stimulus current between −0.1 and 0.1 pA/pF for the duration of the AP.