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Effects Of Acute Stretch On Cardiac Electrical Properties In Swine, Anuj Agarwal
Effects Of Acute Stretch On Cardiac Electrical Properties In Swine, Anuj Agarwal
Theses and Dissertations--Biomedical Engineering
Stretch is known to result in an electrically less stable ventricular substrate, yet the reported effects of stretch on measured electrophysiological parameters have been inconsistent and even contradictory. The goal of this study was to evaluate the effects of acute mechanical stretch on cardiac electrical features thought to be key in generation of arrhythmia, namely restitution of action potential duration (APD), electrical memory, and onset of alternans.
Microelectrodes were used to record intracellular potentials pre, during, and post-stretch from isolated right ventricular tissues from swine. In separate experiments, the effects of two levels of stretch were quantified. Pacing protocols employing …
Hysteresis In Repolarization Of Cardiac Action Potentials: Effects Of Spatial Heterogeneity And Slow Repolarization Currents, Linyuan Jing
Hysteresis In Repolarization Of Cardiac Action Potentials: Effects Of Spatial Heterogeneity And Slow Repolarization Currents, Linyuan Jing
Theses and Dissertations--Biomedical Engineering
Repolarization alternans, i.e. beat-to-beat variation of repolarization of action potential, is proposed as a predictor of life-threatening arrhythmias. Restitution relates repolarization duration with its previous relaxation time, i.e. diatstolic interval (DI), and is considered a dominant mechanism for alternans. Previously, we observed that different repolarization durations at the same DI during decelerating and accelerating pacing, i.e. restitution displays hysteresis, which is a measure of “cardiac memory”.
Objective of the current study was to investigate in the pig 1) the mechanism for a previously observed hysteresis type phenomenon, where alternans, once started at higher heart rate, persists even when heart rate …