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Windisch, H; Müller, W; Ahammer, H; Schaffer, P; Dapra, D; Hartbauer, M.
Optical potential mapping helps to reveal discrete-natural-phenomena in cardiac muscle
INT J BIFURCATION CHAOS 1996 6: 1925-1933. Doi: 10.1142/S0218127496001259
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Leading authors Med Uni Graz: Windisch Herbert
Co-authors Med Uni Graz: Ahammer Helmut; Müller Wolfram; Schaffer Peter
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Abstract:: The cardiac muscle is composed of electrically coupled cells which form a complex, three-dimensional structure. Depending on many physiological parameters (e.g. age), the amount of electrical coupling between the cells varies, which leads to nonuniformities in the propagating wavefronts. Optical potential mapping allows one to monitor all kinds of excitation phenomena in Various size scales at many sites simultaneously, implying the whole heart the same as isolated cardiomyocytes. The spatial and temporal resolution requirements depend on the specimen under study and can be increased to about 10 mu m and to excitation delays of some mu s respectively. An optical mapping system with 256 measuring spots, built in our laboratory, allowed us to clearly demonstrate the discrete and discontinuous nature of propagation in rat cardiac tissues. As a unique application, the optical method allows field stimulation studies which mimic defibrillation-like conditions. Recent results obtained in such experiments did not confirm calculations from a one-dimensional strand computer-model of discretely coupled cells, which predicted spatial alternating of membrane potentials within each cell during the imposed stimulus. With a high resolution system built around an inverted microscope, we were able to monitor excitation phenomena in single cells under various experimental conditions, and to show the high amount of electrical coupling within the isolated cardiomyocyte. In more recent studies in other laboratories, using optical potential monitoring, microscopic discontinuities of excitation were assessed in synthetic strands of neonatal rat myocytes with cellular and even subcellular resolution.