ABSTRACT
Echocardiography represents a gold standard for reliable in vivo cardiac assessment, thanks to its noninvasive nature that overcomes the limits provided by the anatomical location of the heart. An echocardiogram produces a real-time image of the heart, exploiting different acoustic impedances of tissues to high-frequency sound beams: the myocardium appears white because it reflects more ultrasound than blood, which appears black. Electrical activity may be considered the most peculiar characteristic of excitable cells, and several efforts have been made to create sensors capable of following membrane potential changes. The complex spatiotemporal dynamics of excitable cells require high-resolution actuation in combination with optical mapping. A significant implementation in laser scanning microscopy is introduced by nonlinear microscopy. The most used nonlinear microscopy technique in biology is two-photon excitation microscopy. Combining Langendorff’s preparations with fluorescent dyes and two-photon imaging allows for deeper high-resolution imaging in intact hearts.
