The relief work of the heart. Rzadkoskurcz is a condition in which the frequency of sinus rhythm is less than 60 the evolution of the heart per minute. It occurs during sleep, in states of increased tension of the nerves wrong. labeled for someone to watch at home or feel a marked change in heart rate under the influence of strong stress stimuli, such as fear, joy, etc. The most accurate and most reliable testing method is to study electrocardiographic arrhythmias, ie, saving cardiac bioelectric activity on the paper, which is drawn up the electrocardiogram using a camera called the electrocardiograph.