Premature beats

Premature beat, abbreviated as premature contraction, refers to cardiac beats caused by premature impulses discharged from ectopic pacemaker sites, and is the most common arrhythmia. It can occur on the basis of sinus or ectopic (such as atrial fibrillation) rhythms. It may be occasional or frequent, and may occur irregularly or regularly after every one or several normal beats, forming bigeminy or coupled premature beats. According to the site of origin, it can be classified into four types: sinus, atrial, atrioventricular junctional, and ventricular. Among these, ventricular premature beats are the most common, followed by atrial, while junctional ones are less common. Sinus premature beats are rare. Premature beats can be seen in normal individuals or in patients with organic heart disease, commonly seen in coronary heart disease, rheumatic heart disease, hypertensive heart disease, cardiomyopathy, etc. Premature beats can also be seen in quinidine, procainamide, digitalis, or antimony poisoning; hypokalemia; and mechanical stimulation of the heart during cardiac surgery or cardiac catheterization.