Each P wave in a normal sinus heart rhythm is associated with:

Each P wave in a normal sinus heart rhythm is associated with:

• A. A single QRS complex
• B. Sinus arrhythmia
• C. Two or more QRS complexes
• D. A premature ventricular contraction

Answer: (A)

In normal sinus rhythm, a P wave marks atrial depolarization and is followed by a single QRS complex for that beat. This 1-to-1 relationship reflects the orderly sequence: the SA node fires, atria depolarize (P wave), impulse travels to the ventricles, and the ventricles depolarize (QRS). Therefore each P wave is associated with one QRS complex. If you ever see more than one QRS after a single P wave, or a QRS without a preceding P wave, that indicates an abnormal rhythm. For example, a premature ventricular contraction typically lacks a preceding P wave and has a wide QRS. Sinus arrhythmia involves variation in interval timing with breathing but still maintains one QRS after each P wave.

In normal sinus rhythm, a P wave marks atrial depolarization and is followed by a single QRS complex for that beat. This 1-to-1 relationship reflects the orderly sequence: the SA node fires, atria depolarize (P wave), impulse travels to the ventricles, and the ventricles depolarize (QRS). Therefore each P wave is associated with one QRS complex. If you ever see more than one QRS after a single P wave, or a QRS without a preceding P wave, that indicates an abnormal rhythm. For example, a premature ventricular contraction typically lacks a preceding P wave and has a wide QRS. Sinus arrhythmia involves variation in interval timing with breathing but still maintains one QRS after each P wave.