Reentrant and focal arrhythmias in low potassium in isolated rabbit atrium
W. J. Lammers, M. A. Allessie and F. I. Bonke Department of Physiology, University of Limburg, Maastricht, The Netherlands. In isolated superfused left atria of the rabbit, tachyarrhythmias became highly inducible with a decrease of the extracellular potassium concentration to 2.0 mM. The nature of...
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Veröffentlicht in: | American journal of physiology. Heart and circulatory physiology 1988-12, Vol.255 (6), p.H1359-H1369 |
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Zusammenfassung: | W. J. Lammers, M. A. Allessie and F. I. Bonke
Department of Physiology, University of Limburg, Maastricht, The Netherlands.
In isolated superfused left atria of the rabbit, tachyarrhythmias became
highly inducible with a decrease of the extracellular potassium
concentration to 2.0 mM. The nature of the arrhythmias was determined with
a high-resolution mapping system. In several cases, abnormal impulse
formation was found, but the majority of arrhythmias (75%) was caused by a
circus movement of the impulse. Furthermore, circus-movement
tachyarrhythmias often degenerated into fibrillatory activity, and
activation maps revealed the presence of multiple wavelets during this
chaotic rhythm. The occurrence of reentrant arrhythmias may be caused
either by an increase in inhomogeneity in conduction or by a shortening of
the wavelength in low potassium. Inhomogeneity in conduction was determined
by calculating the difference in activation times between neighboring
electrodes. In low potassium, premature activation significantly increased
the inhomogeneity index compared with slow rhythm (from 2.2 to 3.9; P less
than 0.001) but was not significantly different from the inhomogeneity
measured at normal potassium concentrations. Low potassium, however, did
shorten significantly the wavelength of the impulse by approximately 40%.
The increased inducibility of reentry in low potassium is therefore caused
by a reduction of the length of the excitation wave and not by an increase
in inhomogeneity in conduction. |
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ISSN: | 0363-6135 0002-9513 1522-1539 |
DOI: | 10.1152/ajpheart.1988.255.6.h1359 |