New approaches for high speed, high resolution in vitro cardiac imaging

Cameras used in functional cardial imaging studies are limited to low spatial resolutions in order to reach the frame rates required for mapping fast activation patterns in the intact heart. As a result, single pixels integrate signal from a large tissue volume, which leads to order of maginitude underestimates of action potential upstroke velocities. Temporal pixel multiplexing (TPM) is a new imaging modality that enables high resolution sensors to be used for high speed imaging tasks. A TPM imaging system was used to map voltage transients in a di-4-ANEPPS loaded Langendorff perfused guinea pig heart preparation at kilohertz rates. The TPM system measured action potential upstroke velocities that are far faster than those mapped with conventional sensors; captured values closely match theoretical limits determined from photon scattering simulations of voltage sensitive dye loaded heart preparations. TPM holds promise for overcoming limitations associated with conventional imaging modalities.