Arrhythmias of heart - disturbances of frequency, rhythm and sequence of reductions of departments of heart. Arrhythmias can arise at structural changes in spending system at diseases of heart and (or) under influence of vegetative, endocrine, electrolytic and other metabolic disturbances, at intoxications and some medicinal influences. Quite often even at the expressed structural changes in a myocardium the arrhythmia is caused partly or basically by metabolic disturbances. The factors listed above influence the basic functions (automatism, conduction) all spending system of heart or its departments, cause electric heterogeneity of a myocardium, as leads to an arrhythmia! On occassion arrhythmias are caused by individual congenital anomalies of spending system. The expression of a syndrome of an arrhythmia can mismatch gravity of a basic disease of heart. Arrhythmias are diagnosed mainly on an electrocardiogram.