How can you differentiate between a PVC and a PAC?

How can you differentiate between a PVC and a PAC?

• A. PVCs lack a preceding P wave while PACs do have a P wave
• B. PVCs have a shorter QRS duration than PACs
• C. PACs appear only in ventricular rhythms
• D. PACs originate from the ventricles while PVCs originate from the atria

Answer: (A)

The differentiation between a PVC (premature ventricular contraction) and a PAC (premature atrial contraction) primarily revolves around the characteristics of their waveforms on the ECG. PVCs arise from the ventricles, whereas PACs originate from the atria. PVCs are typically characterized by a wide and bizarre QRS complex that occurs earlier than expected in the rhythm, and crucially, they do not have a preceding P wave. This absence of a preceding P wave is a key feature because it signifies that the electrical impulse generating the contraction is not initiated from the atria as it would be in a normal sinus rhythm. In contrast, PACs are recognized by the presence of an early beat that does include a distinctly shaped P wave, which reflects the atrial origin of the impulse. When a PAC occurs, it's like a 'premature' heartbeat initiated by an abnormal electrical focus in the atria, before the next normal beat from the sinoatrial node. This fundamental difference in the presence of a P wave is what allows healthcare professionals to accurately identify whether a contraction is a PVC or a PAC during ECG interpretation.

The differentiation between a PVC (premature ventricular contraction) and a PAC (premature atrial contraction) primarily revolves around the characteristics of their waveforms on the ECG. PVCs arise from the ventricles, whereas PACs originate from the atria.

PVCs are typically characterized by a wide and bizarre QRS complex that occurs earlier than expected in the rhythm, and crucially, they do not have a preceding P wave. This absence of a preceding P wave is a key feature because it signifies that the electrical impulse generating the contraction is not initiated from the atria as it would be in a normal sinus rhythm.

In contrast, PACs are recognized by the presence of an early beat that does include a distinctly shaped P wave, which reflects the atrial origin of the impulse. When a PAC occurs, it's like a 'premature' heartbeat initiated by an abnormal electrical focus in the atria, before the next normal beat from the sinoatrial node.

This fundamental difference in the presence of a P wave is what allows healthcare professionals to accurately identify whether a contraction is a PVC or a PAC during ECG interpretation.