Fast optical monitoring of microscopic excitation patterns in cardiac muscle

Müller, Wolfram; Windisch, H.; Tritthart, H. A.

doi:10.1016/s0006-3495(89)82709-2

Cited by 36 publications

(10 citation statements)

References 19 publications

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“…It is still an open question, to which extent inhomogeneities of various size scales can contribute to these polarization induced membrane voltages, which in turn may elicit an action potential, or even stop fibrillation. As was shown in an earlier study by Müller et al [2] small inhomogeneities in guinea pig papillary muscles caused severe distortions in the spread of excitation. In the present paper we used the same type of preparation to study field induced membrane voltages, appearing within the range of 1 mm ( i.e.…”

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confidence: 62%

Structure related membrane polarizations in field stimulated guinea pig papillary muscle

Windisch

Daprà

Köhler

et al.

2001 Conference Proceedings of the 23rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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Abstract-We have performed optical potential mapping with very high temporal and spatial resolution in guinea pig papillary muscles during the application of electrical pulses. We used a surface staining procedure, with the potential sensitive dye di-4-ANEPPS, throughout our experiments which limited the depth of contribution to the optical signal to less than 40 µm [1]. Our results gave clear evidence, that the structural inhomogeneities themselves, in regions within about a space constant (< 1 mm), were able, during the application of an electrical pulse, to cause strong membrane polarizations. These polarizations, occurring far from electrodes, were sufficient to trigger local electrical activities. Our findings strongly support hypotheses, which assume, that the tissue structure -especially in regions far from electrodes or from the surface of the heart -play an important role in the defibrillation process. Keywords -optical potential mapping, field stimulationField induced transmembrane potential changes are the necessary link to the resulting electrical interferences such as e.g. cardiac stimulation or defibrillation work in cardiac tissue. As predicted in several mathematical models, and measured in biological preparations, the tissue structure with its specific shape, dimension and inhomogeneities play a major role in the generation of these pulse induced membrane voltages. It is still an open question, to which extent inhomogeneities of various size scales can contribute to these polarization induced membrane voltages, which in turn may elicit an action potential, or even stop fibrillation. As was shown in an earlier study by Müller et al. [2] small inhomogeneities in guinea pig papillary muscles caused severe distortions in the spread of excitation. In the present paper we used the same type of preparation to study field induced membrane voltages, appearing within the range of 1 mm ( i.e. within about a space constant). II. METHODOLOGYGuinea pig papillary muscles were stained with the voltage sensitive dye di-4-ANEPPS and mounted in a tissue bath. During the whole experiment the preparation was kept under near physiological conditions (Tyrode's solution at 36 o C, Oxygen saturated). A pair of current driven platinum electrodes was used to deliver electrical pulses with the electrical field strength oriented parallel to the main axis of the muscle. During a measurement, the green light of a frequency doubled Neodymium-Yag laser (100 mW, 532 nm) = This investigation was supported by the Austrian Science Fund, Grand No. P 12294-Med was used to excite the fluorescence of the stained specimen, which showed a voltage sensitivity of up to 10 % intensity change per 100 mV membrane potential change. In most cases, a few milliseconds before and after a measurement, the specimen was excited for 2 ms with the violet light of an Argon-Ion laser (457 nm). At this wavelength the voltage sensitivity of the dye is small compared to that of a greenlight excitation [3]. An evaluation of the intensity of the fluorescence ...

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confidence: 62%

Structure related membrane polarizations in field stimulated guinea pig papillary muscle

Windisch

Daprà

Köhler

et al.

2001 Conference Proceedings of the 23rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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“…In our experiments, we have elected to superfuse the preparations with Tyrode solution containing diacetyl monoxime, which is known to totally suppress contractility without altering the electrical activity (19). We also utilized a highly sensitive dye, di-4-ANEPPS (20), which markedly increased the signal-tonoise ratio. Moreover, there has been recent evidence demonstrating good correlation between the signal obtained with a voltage-sensitive dye and that recorded with intracellular electrodes (21).…”

Section: Methodsmentioning

confidence: 99%

Sustained vortex-like waves in normal isolated ventricular muscle.

Davidenko

Kent

Chialvo

et al. 1990

Proc. Natl. Acad. Sci. U.S.A.

141

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Sustained reentrant excitation may be initiated in small (20 X 20 X <0.6 mm) preparations of normal ventricular muscle. A single appropriately timed premature electrical stimulus applied perpendicularly to the wake of a propagating quasiplanar wavefront gives rise to circulation of self-sustaining excitation waves, which pivot at high fequency (5-7 Hz) around a relatively small "phaseless" region. Such a region develops only very low amplitude depolarizations. Once initiated, most episodes of reentrant activity last indefinitely but can be interrupted by the application of an appropriately timed electrical stimulus. The entire course of the electrical activity is visualized with high temporal and spatial resolution, as well as high signal-to-noise ratio, using voltage-sensitive dyes and optical mapping. Two-and three-dimensional graphics of the fluorescence changes recorded by a 10 X 10 photodiode array from a surface of 12 x 12 mm provide sequential images (every msec) of voltage distribution during a reentrant vortex. The results suggest that two-dimensional vortex-like reentry in cardiac muscle is analogous to spiral waves in other biological and chemical excitable media.Many hypotheses have been postulated to explain reentrant excitation in cardiac muscle. Beginning with the classical studies of Mines (1), in which reentry occurs around an anatomical obstacle, through Allessie's leading circle hypothesis (2), to the more recently postulated anisotropic reentry (3), most mechanisms proposed by experimental electrophysiologists are focused on preexisting functional or anatomical inhomogeneities in the myocardium. On the other hand, theoretical studies based on wave propagation in other types of excitable media such as, for example, the BelousovZhabotinsky reaction (4) suggest that these rotating waves, also known as "spiral waves," "reverberators," and "vortices," may occur even in totally homogeneous and continuous media (4-8). As proposed by Winfree (9) and later shown in the whole heart (10), initiation of reentry depends not only on the properties inherent to the myocardium but also on transient local conditions created by the impulse that triggers the reentry. In fact, reentrant excitation may be initiated in the myocardium at a critical point that results from the interaction of a geometrically graded recovery of excitation (i.e., the "tail" of a planar wavefront) with a geometrically graded transverse premature stimulus (10). Our objective was to utilize these concepts to develop an in vitro model of sustained reentry, in which the electrical activity can be closely monitored. Here we demonstrate that self-sustaining vortex-like reentry can be induced in small two-dimensional pieces of cardiac muscle and that the entire course of the excitation-recovery process during the reentrant cycle can be analyzed in detail through the use of optical mapping and voltage-sensitive dyes. METHODSHearts were dissected from anesthetized sheep (sodium pentobarbital, 35 mg/kg, i.v.). Thin slices of left ventricul...

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“…Some micromaps showed striking changes in both, the direction and the magnitude of the conduction velocity within areas of cell sizes. These findings are in accordance with optical measurements of excitation patterns made in our institute [3]. We evaluated the distribution of LATRs (microfluctuations) after changing to low extracellular potassium concentration.…”

Section: Resultssupporting

confidence: 86%

Fast And High-resolution Monitoring Of Extracellular Potentials To Analyze The Excitation Spread In Heart Preparations

Hofer

Schafferhofer²,

Haimberger³

et al.

[1990] Proceedings of the Twelfth Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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The investigation of the influence of microstructures in cardiac conduction disturbances requires a detailed analysis of the propagating process at a microscopic size scale. We present a system for recording extracellular potentials to measure the instant of the local depolarization with very high-resolution ( 3 0~s in time and 15 p m in space ). Micromaps of the extracellular activation indicated discontinuous conduction at a microscopic size scale. Time series of subsequent activation patterns showed an extraordinary small variability of all conduction times (STD < 20ps) under normal conditions. These microfluctuations are influenced by arrhythmogenic factors, antiarrhythmic drugs and uncoupling substances. INTRODUCTIONThe measurement of the excitation spread in cardiac muscle at a microscopic level is becoming of increasing practical importance. Recent experimental and theoretical findings confirm the hypothesis of the discontinuous nature of the propagation in heart tissue corresponding to the complex microstructure [1] [2]. To monitor micropatterns of excitation, measurements of high-resolution in time and space without injury of cells are required. We have developed a recording system to measure extracellular action potentials with the required resolution in time and space. With the described experimental setup sequences of the extracellular action potentials were analyzed and beat-to-beat microfluctuations of conduction velocities were studied.

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Fast optical monitoring of microscopic excitation patterns in cardiac muscle

Cited by 36 publications

References 19 publications

Structure related membrane polarizations in field stimulated guinea pig papillary muscle

Structure related membrane polarizations in field stimulated guinea pig papillary muscle

Sustained vortex-like waves in normal isolated ventricular muscle.

Fast And High-resolution Monitoring Of Extracellular Potentials To Analyze The Excitation Spread In Heart Preparations

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