Ventricular Ectopic Beats
The most common type of ventricular ectopic beat is premature, causing ventricular contraction before the underlying rhythm would normally depolarise the ventricles. The resultant heartbeat morphology on the ECG often appears wider and taller than that seen with the underlying rhythm.
Ventricular ectopic beats may indicate heart disease, be induced by stimulation (e.g., stress, alcohol, caffeine, medication, cocaine, or amphetamines) or occur naturally. Over half the population have silent, or asymptomatic, ventricular ectopics.
Ventricular ectopics may occur in patterns, such as bigeminy (every other beat), trigeminy (every third beat), or quadrigeminy(every fourth beat). They may also occur in sequences, such as couplets, triplets, salvos (four to seven), or episodes (eight or more).
The ECG trace below shows ventricular bigeminy, in which every other beat is a ventricular ectopic beat. These beats are premature, wider, and larger than the sinus beats.
The next ECG trace shows ventricular trigeminy; the ventricular ectopic beats (three and six) are separated by two sinus beats.
The occurrence of more than one type of ventricular ectopic impulse morphology is evidence of multifocal ventricular ectopics. In this example, the ventricular ectopic beats are both wide and premature, but differ considerably in shape.