During a PVC, which wave is typically absent from the EKG?

During a PVC, which wave is typically absent from the EKG?

• A. P wave
• B. T wave
• C. QRS wave
• D. U wave

Answer: (A)

During a premature ventricular contraction (PVC), the P wave is typically absent from the electrocardiogram (EKG). PVCs occur when the ventricles contract prematurely, disrupting the normal rhythm and sequence of heartbeats. In normal conduction, atrial depolarization is represented by the P wave, which precedes the QRS complex that signifies ventricular depolarization. However, in the case of a PVC, the impulse originates from the ventricles rather than the atria, meaning there is no atrial depolarization taking place prior to the ventricular contraction. As a result, the P wave associated with normal atrial activity does not appear on the EKG during the PVC event. The other components, such as the QRS complex, may appear but will generally be wider and abnormal because of the ectopic origin from the ventricles. The T wave, corresponding to ventricular repolarization, is typically seen following the QRS complex even in the presence of a PVC. The U wave is less commonly referenced and is related to post-repolarization phenomena; it generally does not influence the identification of PVCs.

During a premature ventricular contraction (PVC), the P wave is typically absent from the electrocardiogram (EKG). PVCs occur when the ventricles contract prematurely, disrupting the normal rhythm and sequence of heartbeats. In normal conduction, atrial depolarization is represented by the P wave, which precedes the QRS complex that signifies ventricular depolarization. However, in the case of a PVC, the impulse originates from the ventricles rather than the atria, meaning there is no atrial depolarization taking place prior to the ventricular contraction. As a result, the P wave associated with normal atrial activity does not appear on the EKG during the PVC event.

The other components, such as the QRS complex, may appear but will generally be wider and abnormal because of the ectopic origin from the ventricles. The T wave, corresponding to ventricular repolarization, is typically seen following the QRS complex even in the presence of a PVC. The U wave is less commonly referenced and is related to post-repolarization phenomena; it generally does not influence the identification of PVCs.