What occurs immediately after a sinus arrest?

What occurs immediately after a sinus arrest?

• A. Atrial escape rhythm becomes the dominant pacemaker
• B. Sinus node resumes pacing immediately
• C. Ventricular escape rhythm takes over
• D. Heart goes into complete standstill

Answer: (A)

When a sinus arrest occurs, it signifies a temporary cessation of impulses from the sinus node, which is the heart's primary pacemaker. Following this brief interruption, the heart's rhythm can be restored by an alternative pacemaker. In this instance, an atrial escape rhythm may emerge. This escape rhythm is generated by ectopic pacemaker cells in the atria, which are programmed to kick in when the primary pacemaker fails to produce impulses for a certain period. As a result, this mechanism ensures that the heart maintains some level of electrical activity and prevents a complete standstill or a prolonged cessation of heart function.

While the sinus node may resume its pacing eventually, that resumption does not happen immediately after the arrest, as there is typically a brief period where an escape rhythm takes over. Conversely, both a ventricular escape rhythm and a complete standstill are less desirable outcomes in the case of sinus arrest. A ventricular escape rhythm occurs only if the atrial mechanisms fail, and complete heart standstill signifies complete failure of cardiac pacing, which is not a direct consequence of a sinus arrest. Therefore, the emergence of an atrial escape rhythm demonstrates the heart's backup system working to maintain a rhythm until the primary pacemaker can resume its function.