What is the characteristic P wave appearance in sinus tachycardia?

In sinus tachycardia, the characteristic P wave is present and upright. This indicates that the electrical impulses originating from the sinoatrial (SA) node are still following the normal conduction pathway through the heart. The P wave represents atrial depolarization, and in sinus tachycardia, although the heart rate exceeds the normal range (typically over 100 beats per minute), the P waves remain identifiable and continue to reflect the normal sinus rhythm.

The presence and upright orientation of the P waves help in differentiating sinus tachycardia from other forms of tachycardia, such as atrial fibrillation or junctional rhythms, where P waves may be absent or not appear in the expected location. In sinus tachycardia, each P wave is followed by a QRS complex, affirming that the rhythm is indeed originating from the sinus node. This is crucial for clinical assessment and determining the appropriate management strategies.