2019 Volume 39 Issue 4 Pages 303-314
To evaluate the electrical potential decrease in an in vivo animal myocardial model by oxidation induced by an extracellular photosensitization reaction using talaporfin sodium, the authors studied an in vitro myocardial cell model that has an irrigation system that improves the oxygen supply. To perform this evaluation, the authors compared the in vivo and in vitro models using a new metric to measure the electrophysiological effect on the myocardium/myocardial cells by a photosensitization reaction. The electrical potential in the myocardium on the inside surface of a canine superior vena cava of the in vivo model was measured by a multielectrode ring catheter. In the in vitro model, the spontaneous action potential waveforms were measured using a voltage-sensitive dye. The model used a flowing talaporfin sodium solution—at a rate of approximately three replacements per second—to improve the oxygen supply in the area of the photosensitization reaction. A new metric—the radiant exposure required to decrease the electrophysiological signal to 1/e of its initial value—was used to compare the electrophysiological effects on myocardium/myocardial cells due to the induced oxidation derived from the photosensitization reaction. Based on the agreement between the in vivo and in vitro models regarding the order of magnitude of the defined radiant exposure, the authors believe that the in vitro model with the improved oxygen supply could be useful for investigating in vivo situations with respect to the electrophysiological effects by an extracellular photosensitization reaction on myocardial cells using this new metric.
