The goal of our study is to overcome these limitations by utilizing optical mapping, the technology, which enables detailed spatiotemporal characterization of action potential alternans and which has been proved particularly to be valuable for the analysis of the alternans’ mechanisms.

Yet, technological capabilities at that time were limited to a small number of electrical recordings, which significantly complicated the experimental investigation of this link. In this context, acute regional ischemia, which is known to cause rapid development of conduction abnormalities and arrhythmias, is a useful model for investigating the link between these abnormalities and alternans at short time scales.Įarly studies have reported different manifestations of electrical alternans during acute regional ischemia and their connection to dangerous arrhythmias.

Multiple clinical studies have demonstrated upsurge in T-wave alternans and repolarization heterogeneity precede spontaneous initiation of ventricular tachyarrhythmias in humans. Recently there has been increased interest towards repolarization alternans as a short-term predictor of cardiac arrhythmias and its utilization for antiarrhythmic therapy. Introductionīeat-to-beat alternation of the action potential at increased heart rates is extensively used as an empirical midterm and long-term ECG-predictor of ventricular arrhythmias and sudden cardiac death. Our findings are consistent with the modeling studies predicting that during acute regional ischemia alternans can be driven by 2 : 1 conduction blocks in the ischemic region. Simultaneous microelectrode recordings from subepicardial and subendocardial layers showed that OAPA alternans coincided with intramural 2 : 1 conduction blocks. During both phases we observed significant beat-to-beat variations of the optical action potential amplitude (OAPA) alternans.

Phase I is followed by gradual decline of alternans (Phase II) in both magnitude and territory. Phase I (3–11 minutes of ischemia) is characterized by rapid increase in the alternans magnitude and expansion of the alternans territory. The alternans pattern significantly changed over time and had a biphasic character reaching maximum at 6–9 min after occlusion. Experiments were carried out in isolated Langendorff-perfused rabbit heart using a combination of optical mapping and microelectrode recordings. This study investigates the development of the spatiotemporal pattern of action potential alternans during acute regional ischemia.

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