Optical mapping studies of murine heart disease models are commonly used to study mechanisms of atrial rhythm disturbances. To study murine atrial models, a high spatial resolution is needed to map electrical activity precisely. Current techniques using dissected tissues are limited because the tissue processing disrupts native electrical pathways and interferes with accurate atrial mapping. In addition, the square sensors commonly used for cardiac optical mapping are not well suited for the shape of bi-atrial preparations. On the other hand, scientific Complementary Metal-Oxide Semiconductor (sCMOS) cameras can produce results with higher spatial resolution of intact bi-atrial preparations, however this results in lower signal-to-noise ratio.
In a recent publication in American Journal of Physiology, G. S. Ramlugun et al. worked to create a novel sCMOS imaging platform for optical mapping of intact rat bi-atrial preparations that could produce higher spatial resolution results, without sacrificing signal-to-noise ratio. The authors prepared their setup using a sCMOS camera and LED excitation with the membrane-voltage dye Di-4-ANEPPS. They imaged intact atria from spontaneously hypertensive rats in a constant flow superfusion chamber at 37°C. Sequential processing steps were implemented, including spatial smoothing, temporal filtering, and ensemble-averaging for stable rhythms.
The results showed that the authors were able to improve signal-to-noise ratio using the sequential processing steps of their protocol. Ultimately, the new protocol offered a robust method for quantifying regional electrical properties in intact rat atria at a higher spatiotemporal resolution than previously reported. This may allow more detailed investigation of mechanisms that give rise to atrial arrhythmias.
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Full citation:
Ramlugun, G. S., Sands, G. B., Zhao, J., LeGrice, I. J., & Smaill, B. H. (2021). A novel system for mapping regional electrical properties and characterizing arrhythmia in isolated intact rat atria. American journal of physiology. Heart and circulatory physiology, 321(2), H412–H421. https://doi.org/10.1152/ajpheart.00185.2021