Which of the following is NOT a characteristic of normal sinus rhythm?

Normal sinus rhythm is defined by several key characteristics that ensure the heart functions effectively and at a healthy pace. One of these fundamental attributes is that the heart rate typically ranges from 60 to 100 beats per minute. A heart rate exceeding 100 beats per minute indicates tachycardia, which is outside the bounds of what is considered normal sinus rhythm.

In normal sinus rhythm, the rhythm pattern is regular, meaning there are consistent intervals between beats, which can be easily appreciated on an electrocardiogram (EKG). Additionally, the presence of recognizable waves such as P waves (representing atrial depolarization), QRS complexes (representing ventricular depolarization), and T waves (representing ventricular repolarization) is crucial, as these waves show that the heart is depolarizing and repolarizing correctly.

Moreover, each heartbeat in normal sinus rhythm is initiated by the sinoatrial (SA) node, which is the natural pacemaker of the heart. This ensures that the electrical impulses that regulate heartbeats start from the SA node, maintaining the integrity and administration of heart rhythms.

Therefore, a heart rate exceeding 100 beats per minute does not fit the definition of normal sinus rhythm and is the correct answer in identifying what