What is indicated on an EKG if a P wave appears hidden within a QRS complex?

When a P wave is hidden within a QRS complex, it typically indicates that there is a problem with atrioventricular (AV) conduction. Specifically, this phenomenon is commonly seen in a third-degree AV block, also known as complete heart block. In this condition, there is a complete failure of electrical conduction between the atria and ventricles.

In a third-degree AV block, the atria and ventricles are not communicating properly because the impulses from the atria do not reach the ventricles. As a result, while the atria may still be generating electrical signals (P waves), these signals are not being transmitted to the ventricles. If the atrial depolarization (the P wave) happens concurrently with or is buried inside the depolarization of the ventricles (the QRS complex), it can create the appearance that the P wave is hidden within the QRS.

This is critical to recognize because it indicates a serious conduction abnormality that may require intervention, such as the placement of a pacemaker, to restore proper coordination between the heart’s chambers. Other types of AV blocks, like first-degree and second-degree blocks, generally show P waves that are distinct from the QRS complexes, making them easier to differentiate