Any part of the heart, be it the atrium, the AV node (atrioventricular junction) or an ectopic rhythm point of the ventricle, sends an excitation and then returns to its original location via another conduction pathway in the AV node, causing another depolarization there, thus forming a beat called a repetitive beat. Repetitive beats are different from ordinary folding. The pathway of repetitive beats is open, the number of repetitions is single, the pathway of repetition is unstable, it occurs transiently under certain conditions, and it is often associated with organic heart disease or other causes. In contrast, the pathway of common folding is closed, the number of folds can be multiple or continuous, the folding pathway is stable, can be repeatedly induced, and is not associated with organic heart disease.