Optical mapping of shock-induced arrhythmogenesis in the rabbit heart with healed myocardial infarction: fluorescent imaging with a photodiode array.

Optical mapping of electrical activity in the heart employs digital imaging and voltage-sensitive dyes. These methods have become an increasingly common research tools in basic cardiac electrophysiology. Significant advantages of this approach include simultaneous noncontact recording of entire action potentials free of electrical stimulus-induced artifacts from multiple closely adjacent sites, and adjustable spatial and temporal resolutions. In this way, the activation pattern as well as the repolarization pattern can be monitored by dynamic registration of transmembrane potential changes. As a result, the success of these techniques is most evident in the investigation of the mechanisms of pacing, vulnerability, and defibrillation, in which conventional electrical recordings are hampered by stimulus-induced artifacts. Using optical mapping technology and instrumentation driven by LabVIEW software, we mapped changes in transmembrane voltage during defibrillation shocks and identified the mechanisms of vulnerability and defibrillation in rabbit hearts with healed myocardial infarction (>or=4 wk postinfarction).