Final answer:
In a patient with sinus tachycardia, the wave that might not be visible is the P wave, which represents atrial depolarization, due to the rapid firing of the SA node and increased heart rate.
Step-by-step explanation:
This is because sinus tachycardia is a condition characterized by a fast heart rate, typically above 100 beats per minute, resulting from rapid firing of the sinoatrial (SA) node. During sinus tachycardia, the SA node initiates electrical impulses at a faster rate, which can lead to the atria contracting rapidly.
However, due to the increased heart rate, the P wave, which represents atrial depolarization (contraction), may merge with the T wave or become indistinguishable. In some cases, the P wave may still be visible, but it may be difficult to differentiate it from other waves in the electrocardiogram (ECG) due to the fast heart rate.
In summary, sinus tachycardia can affect the visibility of the P wave, which represents atrial depolarization, due to the rapid firing of the SA node and increased heart rate.