In an ECG, what is the significance of P waves preceding every QRS complex?

The presence of P waves preceding every QRS complex is significant as it indicates that there is a normal conduction pathway through the atria. In a healthy heart, the electrical impulse originating in the sinoatrial (SA) node spreads through the atria, resulting in the P wave on the ECG. This leads to atrial contraction followed by the impulse traveling through the atrioventricular (AV) node and into the ventricles, which is represented by the subsequent QRS complex.

When P waves consistently precede QRS complexes, it shows that each QRS complex has been initiated by an atrial impulse, suggesting that the electrical activity is following the normal sequence of conduction without any blockages or interruptions. This is a hallmark of a stable sinus rhythm and indicates effective and coordinated heart function.

In contrast, other options like atrial enlargement or ventricular hypertrophy would have different manifestations on an ECG and would not specifically relate to the consistent presence of P waves in relation to QRS complexes. Left bundle branch block would generally alter the QRS complex morphology and might alter the relationship between the P wave and the QRS complex, leading to different interpretations on the ECG.