Which term refers to premature beats originating in the ventricles?

• A. SpO2
• B. Angina
• C. Premature ventricular contractions
• D. MET

Answer: (C)

Premature beats that originate in the ventricles are called premature ventricular contractions. This happens when an ectopic focus in the ventricles fires a beat before the normal impulse from the atrioventricular node would. On an ECG, that beat looks wide and abnormal in shape because the impulse travels through the ventricular muscle rather than following the usual conduction pathway, and it often occurs earlier than the expected next beat. A brief compensatory pause typically follows.

These contractions can occur in healthy individuals or with various conditions, and they may be harmless or indicate underlying irritability of the ventricular tissue, electrolyte disturbances, or ischemia. In practice, it’s useful to note how often they occur and whether they appear alone or in patterns (such as occurring every other beat or in bursts), and whether they provoke symptoms during activity.

The other terms listed don’t describe a ventricular-origin premature beat: one is a measure of oxygen saturation, another is chest pain from ischemia, and the last is a unit of energy cost for activity. Premature ventricular contractions are the term for premature beats arising from the ventricles.