Effects of hyperkalaemia on sinus nodal function in dogs: sino-ventricular conduction

The effects of hyperkalaemia on electrograms recorded from the sinus node, crista terminalis, Bachmann bundle, right and left atria and His bundle were studied in anaesthetised dogs. Increasing hyperkalaemia up to about 8.5 mol X litre-1 produced: 1) a gradual prolongation of the sino-crista terminalis interval, and 2) a shift in sinus pacemaker location. Hyperkalaemia between 8.5 and 10.0 mmol X litre-1 produced arrest of most of the atria but persistence of electrical activity of the sinus node, crista terminalis, Bachmann bundle, His bundle and ventricles and sustained sino-ventricular conduction. During the course of increasing hyperkalaemia, right atrial electrograms from sites closer to the crista terminalis disappeared later than those from sites more remote from the crista terminalis. Decremental conduction through sites progressively remote from the axis of the crista terminalis (and possibly also other "preferential pathways") seemed to be the basis of hyperkalaemic atrial arrest.