Autonomic Modulation in Patients with Heart Failure Increases Beat-to-Beat Variability of Ventricular Action Potential Duration

Figures

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  Figure 1. (A) Unipolar electrograms recorded from the left ventricular lead demonstrating the good quality of the signals. The moment of local activation (blue star) and of local repolarization (green square) are shown. The lack of any significant distortion of the signal by filtering is shown in the insert. (B) Relationship between the unipolar electrogram and the intracellular ventricular transmembrane potential showing correspondence between activation recovery interval (ARI) and action potential duration (APD). (C) Biventricular pacing device (CRT) programmed to pace from the right ventricular lead (solid line) and record a local electrogram from the left ventricular lead (dashed line).

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  Figure 2. (A) Example of the digitized electrogram trace during a 20 s period of rest. (B) Computed activation recovery interval (ARI) values for the same electrogram trace. (C) Magnitude of the beat-to-beat variation in ARIs during the example 20 s period of rest. APD, action potential duration, STV, short-term variability.

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  Figure 3. (A) Typical blood pressure response during a Valsalva maneuver. (B) Systolic blood pressure trace demonstrating phases of the Valsalva, blood pressure drop between phase I and II, pressure recovery time (PRT), and phase IV systolic overshoot.

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  Figure 4. Pressure recovery time (PRT), phase IV systolic overshoot, and systolic drop from Phase I to II off vs. on bisoprolol (BB). Error bars represent ±1 standard error of the mean.

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  Figure 5. Mean short-term variability (STV) of activation recovery intervals at rest and following Valsalva, off and on bisoprolol. Error bars represent ±1 standard error of the mean.

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  Figure 6. Example of corresponding increases in beat-to-beat variability of ventricular action potential duration and sympathetic nerve activity (SNA) following stimulus onset (start of Valsalva).